The 1994

Arctic Ocean Section

The First Major Scientific Crossing

of the Arctic Ocean
1994 Arctic Ocean Section

— Historic Firsts —

• First U.S. and Canadian surface ships to reach the North Pole

• First surface ship crossing of the Arctic Ocean via the North Pole

• First circumnavigation of North America and Greenland by surface ships

• Northernmost rendezvous of three surface ships from the largest Arctic nations—Russia,

the U.S. and Canada—at 89°41′N, 011°24′E on August 23, 1994

— Significant Scientific Findings —

• Uncharted seamount discovered near 85°50′N, 166°00′E

• Atlantic layer of the Arctic Ocean found to be 0.5–1°C warmer than prior to 1993

• Large eddy of cold fresh shelf water found centered at 1000 m on the periphery of the

Makarov Basin

• Sediment observed on the ice from the Chukchi Sea to the North Pole

• Biological productivity estimated to be ten times greater than previous estimates

• Active microbial community found, indicating that bacteria and protists are significant consumers of plant production

• Mesozooplankton biomass found to increase with latitude

• Benthic macrofauna found to be abundant, with populations higher in the Amerasia Basin

than in the Eurasian Basin

• Furthest north polar bear on record captured and tagged (84°15′N)

• Demonstrated the presence of polar bears and ringed seals across the Arctic Basin

• Sources of ice-rafted detritus in seafloor cores traced, suggesting that ocean–ice circulation

in the western Canada Basin was toward Fram Strait during glacial intervals, contrary to the

present Beaufort Gyre

• Cloud optical properties linked to marine biogenic sulfur emissions

• Near-surface fresh water found to be derived from river runoff except in the Nansen Basin

where it comes from melting ice

• Arctic Ocean determined to be a source to the atmosphere and Atlantic Ocean of some

organic contaminants, rather than a sink

• Predominant sources of radionuclide contaminants in the ocean found to be from atmospheric weapons testing and European reprocessing plants
THE 1994 ARCTIC OCEAN SECTION

The First Major Scientific Crossing of the Arctic Ocean

Sponsored by

United States Canada

National Science Foundation Department of Fisheries and Oceans

Office of Naval Research Department of Indian and Northern Affairs

U.S. Geological Survey Department of the Environment

U.S. Coast Guard Canadian Coast Guard

Defense Nuclear Agency

AOS-94 Chief Scientist: Knut Aagaard

U.S. Chief Scientist: Arthur Grantz

Canadian Chief Scientist: Eddy Carmack

Commanding Officer, CCGS Louis S. St-Laurent: Captain Philip O. Grandy

Commanding Officer, USCGC Polar Sea: Captain Lawson W. Brigham

Published by

U.S. Army Cold Regions Research and Engineering Laboratory

72 Lyme Road

Hanover, NH 03755

Special Report 96-23

Edited by Walter Tucker and David Cate

Compiled by Vicki Keating

1996
1994 Arctic Ocean Section Contents

— Contents —

U.S. Preface ................................................................................................................... iv

Canadian Preface ........................................................................................................... v

INTRODUCTION

Introduction .................................................................................................................. 1

Chronology.................................................................................................................... 3

The Ships....................................................................................................................... 8

SCIENCE REPORTS

Introduction .................................................................................................................. 12

Ocean Circulation and Geochemistry

A CTD/Hydrographic Section across the Arctic Ocean .................................................. 17

Total Carbonate and Total Alkalinity: Tracers of Shelf Waters in the

Arctic Ocean ............................................................................................................. 20

Transient Tracers: Chlorofluorocarbons and Carbon Tetrachloride ................................. 23

Distribution of Iron and Aluminum in the Surface Waters of the Arctic Ocean ............. 26

Thorium Isotopes as Tracers of Scavenging and Particle Dynamics in the Arctic Ocean . 29

What Can Be Learned from Barium Distributions in the Arctic Ocean? ........................ 32

Biology and the Carbon Cycle

Cycling of Organic Carbon in the Central Arctic Ocean ................................................ 34

Mesozooplankton Community Structure in the Arctic Ocean in Summer...................... 37

Roles of Heterotrophic Bacteria and Protists in the Arctic Ocean Carbon Cycle............. 40

Contribution of Planktonic and Ice Algae to Dimethylsulfide Production across the Arctic

Ocean in Summer ..................................................................................................... 42

Transfer of Shelf-Derived Carbon to the Interior of the Arctic Ocean ............................ 45

Dimethyl Sulfide in the High Arctic .............................................................................. 47

The Role of Biomass, Bioturbation and Remineralization in Determining the Fate of

Carbon in the Arctic Ocean ....................................................................................... 51

Oxygen Consumption, Denitrification and Carbon Oxidation Rates in Near-Surface

Sediments of the Arctic Ocean................................................................................... 53

Ecology of Marine Mammals

Upper Trophic Level Research: Polar Bears and Ringed Seals ......................................... 55

Contaminants

Artificial Radionuclides in the Arctic Ocean .................................................................. 59

Persistent Organic Contaminants ................................................................................... 62

Air-Water Gas Exchange of Hexachlorocyclohexanes in the Arctic ................................. 64

ii
Volatile Halomethanes ................................................................................................... 67

C2–C6 Hydrocarbons .................................................................................................... 70

Cloud Radiation

Atmospheric Radiation and Climate Program ................................................................ 73

Aerosols ......................................................................................................................... 78

Sea Ice

Sea Ice Characteristics across the Arctic Ocean ............................................................... 81

Measurements of Ice Mechanical Properties ................................................................... 86

Geology and Paleoceanography

Sources of Ice-Rafted Detritus and Iceberg Tracks in the Arctic Ocean ........................... 89

Late Quaternary Paleoceanography of the Canada Basin, central Arctic Ocean .............. 92

Elemental and Isotope Geochemistry of Sediment from the Arctic Ocean ...................... 95

Ship Technology

Real-Time Remote Sensing for Ice Navigation ............................................................... 97

Ship Technology Program .............................................................................................. 100

Hull–Ice Interaction Load Measurements on the CCGS Louis S. St-Laurent .................. 102

COMMUNICATIONS AND DATA MANAGEMENT

Special Communications Solutions ................................................................................ 104

Data Management ......................................................................................................... 106

APPENDICES

AOS-94 Participants ...................................................................................................... 108

Science Stations ............................................................................................................. 114

iii
1994 Arctic Ocean Section

— U.S. Preface —

“Nothing great was ever achieved without enthusiasm.”

—Ralph Waldo Emerson

Enthusiasm, cooperation and the spirit of scientific exploration are terms that aptly apply to

the 1994 U.S.–Canada Arctic Ocean Section. The scientific motivation for the undertaking was

to substantially increase the observational base necessary for better understanding the role of the

Arctic in global change. The expedition’s objective was to make a series of measurements that

would allow the analysis and modeling of the biological, chemical and physical systems related to

the Arctic and their impact on global change, and the controlling processes in these systems.

Cooperation was necessary to bring the scientific, operational and funding mechanisms together. Over five years of planning culminated on the evening of 24 July 1994 when the CCGS

Louis S. St-Laurent and the USCGC Polar Sea steamed northward from Nome, Alaska, when 70

scientists embarked with their scientific equipment on what was planned to be a 60-day expedition.

The expedition could not have happened without enthusiasm. There was scientific enthusiasm

for addressing an important and timely research topic. Also there was enthusiasm within the Coast

Guards of the two nations for undertaking a maritime expedition in the Arctic Ocean that was to

be the first of its type for North America.

Although there were challenges and disappointments along the way, the expedition was highly

successful scientifically. The data analysis, interpretation and publication will continue for several

years, and the work will form the basis for new and ongoing research in the Arctic. The National

Science Foundation is proud to have contributed to the project and it congratulates the men and

women who worked so hard to make it a success.

R.W. Corell

Assistant Director, Geosciences

National Science Foundation

U.S.A.

U.S.Preface

iv
— Canadian Preface —

Unfortunately, in these times of economic restraint, it is not very often that federal managers

get the opportunity to support a highly relevant and focused program that is also stimulating and

exciting. The Arctic Ocean Section provided such an opportunity, and the scientific planners

made sure that the documentation and justification were impeccable. Now that the expedition has

returned and the expectations justified, it is easy to be self-congratulatory. However, without the

considerable groundwork that had been accomplished over a period of several years, nothing would

have happened.

The science plan made sure that maximum use would be made of the platform availability by

considering the broadest possible coverage of issues and disciplines. The legitimacy of the scientific

program was ensured through clear identification of the application of the anticipated results.

Even the logistics and the use of the icebreakers were folded into the science, through programs

dealing with such issues as ice strength, navigation forecasts and hull stresses. Forearmed with

these strong arguments for potential benefits and creative science, the fiscal obstacles proved to

have been surmountable. Despite the considerable difficulties faced, almost all of the anticipated

work was accomplished.

The contents of this report speak, more eloquently than I could possibly hope to describe, on

the success of the mission and the considerable analysis still to be undertaken. It remains for me to

dedicate my thanks to the enormous amount of less exciting, but very necessary planning that laid

the foundation for the funding and approval process.

G.L. Holland

Director General

Oceans Science Directorate

Department of Fisheries and Oceans

Canada

v
1994 Arctic Ocean Section
 — Introduction —

Traditionally both Canada and the United States have relied on aircraft

and drifting ice camps in supporting scientific work in the Arctic Ocean. Early

examples include the so-called Ski Jump project in 1951–1952 and the ice

stations Alpha and Bravo in 1957. These efforts have been particularly successful in advancing process studies, obtaining certain time series measurements and exploring limited areas; they have been less successful in carrying

out synoptic survey work and sophisticated geographically distributed measurements requiring heavy equipment and elaborate laboratory facilities. In

the open ocean the latter are typically done from shipboard, but not until

1987, when the German research icebreaker Polarstern crossed the Nansen

Basin of the Arctic Ocean, did a modern Western research vessel successfully

operate in the Polar Basin.

Russian scientists had also primarily used aircraft and drifting stations, having pioneered these techniques beginning with Papanin’s North Pole I station

in 1937. While the large and powerful Russian polar icebreaker fleet, one of

which first reached the North Pole in 1977, routinely operates within the

Polar Basin, the vessels are generally not used as scientific platforms. Meanwhile, the voyage of the Polarstern in 1987 was followed in 1991 by a remarkable joint Swedish–German undertaking using the icebreakers Oden and Polarstern to cross both the Nansen and Amundsen Basins, reaching the North Pole

and returning to the Atlantic via northeast Greeenland. A U.S. icebreaker, the

Polar Star, started out with the two European vessels but had to turn back near

85°N because of mechanical difficulties.

Inspired by the planned Swedish–German undertaking, but also deeply

concerned that North American scientists would be unable to participate in

ship-supported work in the Arctic Ocean, Ed Carmack and I met with Canadian and U.S. Coast Guard representatives in Ottawa in the fall of 1989 to

inquire about interest in making a scientific crossing of the Arctic Ocean and

about whether the two Coast Guards thought such an undertaking was realistic. The immediate response was positive on both counts, and the initial target

for the crossing was set as the summer of 1993. The next 58 months or so were

filled with a stream of planning activities involving interested scientific parties, the ship operators and funding agencies. Two major changes were made:

• Because of the long planning time required, the expedition was moved

back one year to 1994; and

Introduction
1994 Arctic Ocean Section

• Because the yard schedule for the Polar Sea required her to be in Seattle

on 1 October, the route was altered to return directly to the Pacific from

the North Pole, rather than via the Atlantic, that is, crossing the Canada

Basin twice, but with an expected net saving of time.

Thanks to the efforts of a great many caring people, the myriad pieces in

this planning activity all came together, and late in the evening of the 24th of

July 1994 the Louis S. St-Laurent and the Polar Sea steamed northward from

Nome to start the Canada–U.S. 1994 Arctic Ocean Section.

From the beginning the scientific goal of the undertaking had been to substantially increase the observational base necessary for understanding the role

of the Arctic in global change. The objective was thus to make those measurements that would best promote the analysis and modeling of the biological,

chemical and physical systems related to the Arctic and global change, and the

controlling processes in these systems:

• Ocean properties pertinent to understanding circulation and ice cover;

• Biological parameters essential for defining the Arctic carbon cycle;

• Geological observations necessary for understanding past climates;

• Concentration and distribution of contaminants that impact the food

chain and the environment;

• Physical properties and variability of the ice cover; and

• Atmospheric and upper ocean chemistry and physics relevant to climate.

In the following chapters, we shall see how all this came out.

Knut Aagaard

Chief Scientist, AOS-94

Applied Physics Laboratory

University of Washington

Seattle, Washington, USA

2
— Chronology —

The CCGS Louis S. St-Laurent and the USCGC Polar Sea departed Victoria, British Columbia, together on the evening of the 17th of July 1994. The

majority of the scientific party of 70 persons boarded by helicopter in Nome,

Alaska, on July 24th; several scientists had sailed with the ships from Victoria

to set up equipment and make preliminary measurements. We sailed through

the Bering Strait on July 25th and entered the ice in the northern Chukchi Sea

early in the afternoon of the following day.

During the first few days, the ships worked some distance apart, as the ice

was not severe. However, from the 30th of July onward, ice coverage was typically complete, and the ships moved close together, operating in tandem for

the most efficient icebreaking, taking turns leading. This greatly reduced the

fuel consumption for the trailing icebreaker. The ships icebreaking in tandem

averaged 3–5 knots during the northbound transit. Visibility was generally

poor throughout the time spent in the ice, with fog and overcast the rule. July

31st was the only full clear day. Passive microwave satellite imagery (SSM/I)

received in real time aboard the Polar Sea provided excellent strategic information on ice conditions for planning the northbound route and stations.

Beginning in the central Chukchi Sea, the station line ran northward east

of the Russia–U.S. Convention line, but once past 200 nautical miles from

Wrangell Island, our track turned northwestward across the Chukchi Abyssal

Plain and onto the Arlis Plateau, which we reached on the 3rd of August at

78°N. Heavy multi-year ice limited our eastward penetration down the flank

of the plateau to longitude 174°18′W. We therefore resumed the station line

northward, with the intent of covering the region to the east along 78°N on

the return voyage. Near 80°N we again attempted a section to the northeast,

but difficult ice conditions limited our penetration in that direction to 80°13′N,

172°46′W. We therefore continued working northwestward across the Mendeleyev Ridge and into the Makarov Basin.

On Monday the 8th of August we had an overflight and data transfer by a

Canadian ice reconnaissance flight carrying side-looking radar, which mapped

the ice in a swath 200 km wide and extending 1100 km along our intended

track northward. From this imagery it was clear that difficult ice conditions

lay to the east. Detailed helicopter ice reconnaissance the next few days confirmed this, and on Sunday the 14th, near 85°N, 170°E, we decided to continue onto the Lomonosov Ridge near 150°E before turning east and running

the final northward leg of the outbound voyage along 150–155°W.

Introduction

3
1994 Arctic Ocean Section

On the 15th of August the helicopter-borne CTD party found a new undersea mountain when the wire stopped paying out and they brought up mud

from 850 m where the chart showed 3700 m. Three miles away on either side

they found no bottom at 1450 m.

The next three days brought a northeast gale, snow and poor visibility, and

progress was slow through the heavy ice. On the 19th we reached our station

on the crest of the Lomonosov Ridge at 88°47′N, 143°E, where we planned

to turn eastward. There we found the water at intermediate depth to be about

North Pole

22 Aug ‘94

Keflavik

Halifax

Boston

Panama

Canal

Victoria

Nome

Seattle

Route of the first

surface circumnavigation of North

America and Greenland. The Louis S.

St-Laurent began

and ended its

voyage in Halifax.

The Polar Sea

began and ended

in Seattle.

4
5

Introduction

1°C warmer than we had seen at the base of the ridge, suggesting that the large

gap in the ridge shown in the charts does not exist. We had also observed

sediment-laden ice (“dirty ice”) throughout the long northward track, from

the ice edge in the Chukchi Sea to the North Pole, indicating that sediment

incorporated in the ice on the shallow continental shelves is transported hundreds of kilometers across the Arctic.

Meanwhile, on the 17th we had had ice reconnaissance by a long-range

Canadian aircraft, and on the 19th, while the ships remained on station on

the ridge, we flew a 215-nautical-mile helicopter reconnaissance flight over

the intended track. These showed very heavy ice at the location of our intended

crossing point of the Lomonosov Ridge to the east, so we decided to continue

northward on the section we were on and then return along an alternative

route that would recross the ridge farther south. From there we would attempt

to get onto the eastern flank of the Alpha Ridge to do seismic work and additional piston coring before continuing both these and our many other planned

programs on the long voyage back to Alaska.

However, this was not to be, for shortly after starting northward down the

steep ridge flank, early Sunday morning on the 21st of August, and about 50

nautical miles from the Pole, the Polar Sea lost one of its four blades on the

starboard propeller. Divers also sighted some damage to the blades on the centerline and port shafts. These casualties required that the expedition take the

shortest route out of the ice, which was toward Svalbard. Our intended section northward took us in that direction, and since we had already surveyed

that route by helicopter and knew it to be feasible, we decided to continue on our

course. That same afternoon a U.S. Coast Guard C-130 aircraft from Kodiak

dropped spare parts for our satellite receiver. At 0230 Monday morning, Alaska

standard time, we reached our next science station at 90°N, the first North American surface ships to do so, and the first surface ships ever to do it directly over the

long unexplored route from the Pacific side of the Arctic Ocean. Our station at

the Pole took 28 hours, as we fully deployed every sampling program. Not

only could we compare conditions with those found three years earlier by

Swedish and German investigators, but we could add a great many new measurements (for example, the concentration and distribution of a great variety of

contaminants).

The last few hours before we arrived at the Pole, we had seen a large ship on

the horizon. The ship, which proved to be the Russian nuclear icebreaker Yamal,

had stopped in the ice about 20 nautical miles from the Pole to produce a children’s television program. The Yamal planned to sail south along our intended

track the next day, coincident with the shortest route out of the ice and the one

that we needed to take because of the loss of one of Polar Sea’s propeller blades.

At 0800 on the 23rd we got underway toward Yamal’s position, 20 nautical

miles to the southeast. Before noon an extraordinary rendezvous took place as the

icebreakers of the three largest Arctic nations—Russia, Canada and the United
1994 Arctic Ocean Section

States—commenced a historic polar gathering. More than 550 men, women

and children met near the North Pole on the ice. The Yamal’s officers and crew

hosted a barbecue on the ice, and the three ships were open for tours. This

unprecedented and impromptu rendezvous near the North Pole in many ways

symbolized a new era of international cooperation in the Arctic Ocean.

That evening all three ships sailed southward together toward Svalbard and

made good progress, reaching south of 86°N by Thursday morning the 25th.

At that point the ice conditions had improved, and we parted company with

the Yamal to resume our scientific work, consonant with expeditiously exiting

the Polar Basin. The pattern of southerly progress in somewhat lighter ice

continued, and we occupied several high-quality science stations in the Eurasia Basin. On the 27th we had an airdrop of helicopter parts. The same day we

received word from the U.S. Department of State that we were not permitted

to continue the work southward within 200 nautical miles of Svalbard. We

therefore terminated our in-ice section with a station at 83°51′N, 35°41′E.

On Tuesday the 30th of August we exited the ice northwest of Svalbard, making course for Iceland. On the 31st we stopped the St-Laurent for a contaminant and oceanographic station in the Greenland Sea at 75°N, 6°W. This

proved to provide an excellent end point for the Arctic Ocean Section, since it

showed the prominent role of the Arctic Ocean outflow in changing the convective region of the Greenland Sea in recent years to a warmer and more saline

state.

The Polar Sea disembarked most of its scientific party in Keflavik, Iceland,

on the 3rd of September and then proceeded to Nova Scotia in company with

the St-Laurent, the ships being slowed enroute by a storm with winds exceeding 60 knots. The St-Laurent disembarked its scientific party in Dartmouth

on the 9th of September, bringing to a close a remarkable and productive

The Russian nuclearpowered icebreaker

Yamal, Louis S. StLaurent and Polar

Sea at an unplanned

rendezvous near

the North Pole.

6
Introduction

voyage. We had completed a highly successful scientific voyage literally across

the top of the world, from the Pacific through Bering Strait, across Canada

Basin, to the North Pole and into the Atlantic via Fram Strait.

Knut Aagaard Lawson W. Brigham

Chief Scientist, AOS-94 Captain, U.S. Coast Guard

Commanding Officer, USCGC Polar Sea

Eddy Carmack Philip O. Grandy

Chief Scientist, CCGS Louis Captain, Canadian Coast Guard

S. St-Laurent Commanding Officer, CCGS Louis S.

St-Laurent

7
1994 Arctic Ocean Section

— The Ships —

The Canadian Coast Guard Ship Louis S. St-Laurent, a 120-m icebreaker

of 15,324-ton displacement based in Dartmouth, Nova Scotia, is the largest

icebreaker in Canada. The ship has three fixed-pitch propellers. Five diesel

engines supply three propulsion motors that can deliver a total of 30,000 hp

to the three shafts. The Louis S. St-Laurent used an average of 15,000 hp on

the northbound transit; occasional boosts of power to 25,000 hp were required

in heavier ice conditions. The ship carried two BO 105-BS4 helicopters for ice

reconnaissance and science support. Her total crew for this mission was 61,

including the helicopter pilots and mechanic; the science party was 35.

The CTD/rosette, equipped with 36 ten-liter bottles, was deployed from

the boat deck, starboard side. The rosette lab, a joined 16- × 20-ft container,

was immediately forward of the deployment point, and the CTD lab, an 8- ×

12-ft container, immediately aft. Ice work, including access to the ice, was

from the foredeck, which was serviced by two cranes. Net hauls, pump deployments and box cores were done from the foredeck, starboard side. One winch

serviced the net hauls and pumps, while two winches (working in tandem on

deep casts) serviced the box core. Sample processing on the foredeck was done

in an 8- × 12-ft container. All other laboratories were interior to the ship.

The U.S. Coast Guard Cutter Polar Sea is a 122-m icebreaker of 13,600-

ton displacement based in Seattle, Washington, and is one of two Polar Class

ships, the largest icebreakers in the U.S. The ship has three variable-pitch

propellers. Each shaft can be powered by one or two diesels of 3,000 hp each

(18,000 hp total in full diesel-electric mode) or by a turbine that can supply

20,000 hp in a sustained mode (60,000 hp total in an all-turbine configuration). Only the diesel-electric plant was used during the first portion of the

voyage, but 50 nautical miles from the North Pole the loss of the blade on the

starboard propeller necessitated the use of a gas turbine on the centerline shaft,

boosting her total power to 26,000 hp. The ship carried two HH-65A helicopters for ice reconnaissance and science support. Her total crew for this mission

was 142, including the aviation detachment; the science party numbered 35.

The CTD/rosette, equipped with 24 ten-liter bottles, was deployed from

the main deck, port side, as were the plankton nets. The rosette lab was an

enclosed, fixed, 16- × 14-ft shipboard installation located immediately forward of the deployment area. Ice work, including diving, was done from the

starboard side aft, either using a platform swung from the flight deck by crane

or from the main deck using the gangway. All box and piston coring was done

8
from the fantail, where a coring track and J-frame supported the piston coring

work. Seven containers housed the science activities not accommodated within

internal spaces: two on the maindeck, portside, for seismic work; two on the

maindeck, starboard side, for biology, including radioisotope work; one on

the 02 deck, starboard side, for ice core processing; and two on the 02 deck, port

side, for radiation measurements and air and upper ocean chemistry. The latter

container was adjoined by a liquid-nitrogen generating plant producing 35-

40 L/day in support of a number of science programs. In addition, the port

bridge wing housed a portion of the air sampling equipment. The biological

productivity incubators were sited on the 01 deck, starboard side.

For expedition planning and to enhance navigation through the difficult

ice conditions, an underway “ice center” was established aboard the Louis S.

St-Laurent. Ice information was received from several sources, including realtime satellite imagery, fixed-wing aircraft reconnaissance (synthetic aperture

radar and visual information), helicopter reconnaissance, shipborne radar and

visual surveillance from each icebreaker. Extensive use was made of the real-time

satellite images received and processed aboard the Polar Sea. Special sensor microwave imager (SSM/I from the Defense Meteorological Satellite Program) and

advanced very high resolution radiometer (AVHRR from National Oceanic

and Atmospheric Administration satellites) images were received and processed

using a Terascan system. Sea ice concentration maps derived from the SSM/I

data, which proved invaluable for both strategic and tactical navigation, could

normally be produced and made available for interpretation less than one hour

after a satellite pass. All satellite information could be passed to the ice center

aboard the Louis S. St-Laurent using a VHF-FM ship-to-ship data link.

Effective helicopter ice reconnaissance was crucial to tactical navigation

Introduction

9
1994 Arctic Ocean Section

USCGC CCGS

Polar Sea Louis S. St-Laurent

Year built 1978 1969 (modernized 1988–1993)

Length (m) 122 120

Beam (m) 25.5 24.4

Draft (m) 9.7 9.9

Full-load displacement (tons) 13,600 15,324

Power (hp)

Diesel-electric 18,000 30,000

Turbine 60,000

No. of engines 6 diesel-electric 5 diesel-electric

3 gas turbines

No. of propellers 3 3

Crew 144 59

CCGS Louis S. St-Laurent

USCGC Polar Sea

10
during the expedition. Global positioning system receivers aboard the helicopters provided precise coordinates of large floes, leads and other features that

were plotted aboard both icebreakers. A Canadian Coast Guard helicopter

with an Atmospheric Environment Service ice observer aboard flew daily ice

reconnaissance flights in sectors 20–30 nautical miles ahead along the proposed

expedition track. This information, coupled with radar and visual observations

from both ships, greatly enhanced tactical navigation during the voyage.

Knut Aagaard Lawson W. Brigham

Chief Scientist, AOS-94 Captain, U.S. Coast Guard

Commanding Officer, USCGC Polar Sea

Eddy Carmack Philip O. Grandy

Chief Scientist, CCGS Louis S. Captain, Canadian Coast Guard

St-Laurent Commanding Officer, CCGS Louis S.

St-Laurent

11

Introduction
1994 Arctic Ocean Section

— Science Reports —

Walter Tucker

In 1896 the Norwegian scientist Fridjof Nansen completed his historic

drift across the Arctic Ocean in the ice-strengthened wooden ship Fram. Several years after his epic scientific voyage, reflecting upon the activities and

achievements of Arctic scientists, Nansen predicted that the Arctic Ocean would

become the best known ocean on Earth. Sadly, a century later, it is the most

undersampled and least understood of the world’s oceans. Canadian, U.S. and

Russian scientists have conducted specific investigations from drifting ice camps

and aircraft landings on the ice for many years, but the formidable ice cover of

the Arctic Ocean has prevented traditional comprehensive oceanographic

transects so common in other oceans of the world. Capable icebreaking vessels

equipped for scientific investigations have been available for little more than a

12

The CTD/

rosette being

lowered from

the Polar Sea.

Walter Tucker is from the U.S. Army Cold Regions Research and Engineering Laboratory in Hanover, New

Hampshire, U.S.A.

FPO
decade. Yet the heavy ice conditions of the central Arctic have required that

major expeditions use two ships. The expense of these scientific voyages has

severely limited the number of comprehensive measurements that can be made

to understand natural processes in the Arctic Ocean.

The Arctic Ocean Section was designed to fill in some of the many

knowledge gaps about the Arctic Ocean. While there were several historic

firsts resulting from AOS-94, most were peripheral to the purposes of the

voyage—to increase our understanding of the Arctic Ocean in the context of

global change and to gather baseline data on contaminants in this region.

With global climate change becoming an issue of international concern,

attention has been increasingly focused on the Arctic, where all effects of global

change are predicted to be amplified. It is also clear that the Arctic plays a key

role in the processes that cause climate

change. For instance, the ice cover of the

Arctic Ocean depends on a delicate and

relatively thin mixed layer that effectively

insulates the ice cover from the warmer

water below. Variations in the stratification may alter the heat and moisture

exchanges with the atmosphere, affecting the balance of all Arctic ice masses.

Predicted increases in air temperature will

affect the extent of the ice cover and therfore the amount of the sun’s heat absorbed

Science Reports

13

Erk Reimnitz and

Terry Tucker measuring the albedo of

the ice surface.

U.S. Coast Guard

diver preparing to

collect ice algae

samples.
1994 Arctic Ocean Section

or reflected back to the atmosphere. The fresh water exported from the Arctic

Basin in the form of ice and river runoff into the convective gyres of the Greenland, Iceland and Laborador Seas influences the formation of North Atlantic

deep water and heat transport associated with global thermohaline circulation. The ocean programs on AOS-94 were designed to investigate the ice

cover, water mass structure, origins of the water masses, and ocean circulation

on a major transect of the Arctic Ocean.

Global climate change and the expected increases in atmospheric carbon

dioxide will have a major impact on the carbon cycle of the Arctic Ocean.

Evaluating the internal cycling of carbon plus the fluxes from rivers and adjacent seas is important in understanding what the effect will be on biogeochemical cycling and the ability of the Arctic Ocean to sequester carbon dioxide.

The Arctic Ocean and its marginal seas have only recently been recognized as

areas of high biological productivity during the favorable solar radiation seasons. Primary productivity converts atmospheric carbon dioxide to organic

carbon in the ocean, where it may then be recycled by organisms back to the

atmosphere, remain dissolved in the ocean or be deposited on the sea floor as

particulates. The Arctic Ocean is believed to play an important role in the

global carbon cycle, but too little work has been done to quantify that role. A

major goal of AOS-94 entailed examination of primary productivity levels

and the organic and inorganic carbon pools of the central Arctic.

There is also major international concern that the Arctic has been polluted

by a variety of contaminants, including heavy metals, organochlorines and

radionuclides. Contaminants have been dumped directly into the Arctic Ocean.

14

Dave Paton and

Ikaksak Amagoalik

collecting snow

samples for contaminant studies.
More important, however, is the ocean’s role as a receptor for contaminants

carried northward by major geochemical transport mechanisms involving the

atmosphere, rivers, sediment, sea ice and currents. Little is known about sources,

background levels, transport pathways and residence times of the various contaminants. Obtaining information on the levels of a variety of contaminants

in the atmosphere, ice, ocean and sediments was the focus of the AOS-94

contaminants program.

AOS-94 was truly multidisciplinary. Fifty individual research programs were

pursued, and the expedition indeed sampled across the entire Arctic Ocean.

The word “section” implies measurements of the seafloor, ocean, ice and atmosphere—a slice from the top of the atmosphere to the bottom of the ocean.

The major disciplinary efforts and their major objectives were:

Ocean Circulation and Geochemistry

Hydrographic surveys and geochemical sampling to improve our understanding of Arctic Ocean circulation and water mass structure.

Biology and the Carbon Cycle

Measurement of standing stocks and production rates of the dominant

organisms and their relation to the distribution of particulate and dissolved carbon and nitrogen.

Ecology of Marine Mammals

Studies of the distribution, migration, population dynamics, genetic history and food chains of polar bears and other marine mammals.

Contaminants

Trans-Arctic sampling of atmosphere, snow, ice, water column and sea

15

Sediment trap

being lowered into

the water to collect

samples for contaminant chemistry

studies.

Science Reports
1994 Arctic Ocean Section

Jim Rich in the

biology van on the

Polar Sea.

16

floor to detect the presence of radioactive wastes and organochlorines.

Cloud Radiation

Characterization of the aerosol and optical properties of clouds, and determination of the greenhouse effect of the Arctic Ocean by quantification

of the major greenhouse gases, UV radiation and photosynthetically active

radiation.

Sea Ice

Determination of ice mechanical, physical and chemical properties, sediment transport by ice, ice biota, contaminants, and albedo of the mottled summer ice surface.

Geology and Paleoceanography

Geoscience sampling to allow an interpretation of tectonic history, past

climates and paleoceanography, and active transport processes in the Arctic Ocean.

Ship Technology

Determination of the utility of real-time remote sensing data for enhancement of navigation through ice and measurement of hull loads

and structural response of the hull to ice loads.

Planned seismic surveys were not accomplished, so the tectonic evolution

program was not successful. All other programs, however, were successful in

spite of the loss of the Polar Sea’s propellor blade, which shortened the voyage.

The following brief reports present details and preliminary results of many of

the research projects.
— Ocean Circulation and Geochemistry —

A CTD/Hydrographic Section across the Arctic Ocean

James Swift

The objectives of our water column work were:

• To study the origin and circulation of the waters of the

Arctic Ocean and nearby seas;

• To determine the surface-to-bottom distributions and

sources of the physical and chemical characteristics;

• To study the location, origin and structure of subsurface

boundary currents; and

• To contribute to studies of the response of the regimes to

environmental forcing.

The water column program provided the trans-Arctic section a

complete program of CTD (conductivity, temperature and

depth) and “small-volume” hydrographic measurements meeting World Ocean Circulation Experiment parameter and quality

recommendations.

The Louis S. St-Laurent is well equipped for high-latitude

CTD/rosette work. On the starboard side of the vessel there is a

small CTD/computer van and a large double-van rosette room.

The rosette was launched through a large A-frame. The Louis S. St-Laurent is also

outfitted with a full suite of laboratories for the analytical equipment.

We collected water column measurements at 35 hydrographic stations along

the AOS-94 route: beginning on the Chukchi shelf, then across the Chukchi

Abyssal Plain and Makarov Basin, then down the Eurasian side of the Lomonosov

Ridge to the North Pole. Water column work was cut short at that point

because the Polar Sea developed mechanical problems. Both ships exited the Arctic together through Fram Strait, occupying an additional four stations en route.

The U.S./Canadian water column measurement team on the Louis S.

St-Laurent carried out full-depth CTD profiling and 36-level rosette sampling. Water samples were collected for chlorofluorocarbons (CFCs), helium,

oxygen, CO2 system components, AMS 14C, tritium, 18O, nutrients, salinity,

trace metals, radionuclides and organic contaminants. CTD and water sampling was carried out at 39 stations and was remarkably trouble free.

We examined sections of potential temperature, salinity and density anomalies referred to 0 and 2000 db from the CTD data for our section from the

James Swift is from the Scripps Institution of Oceanography in La Jolla, California, U.S.A.

17

Ocean Circulation and Geochemistry

The CTD/rosette

being lowered from

the Louis S.

St-Laurent.
1994 Arctic Ocean Section

Chukchi shelf to the North Pole. We observed multiple warm cores in the

Atlantic layer (depths of about 200–400 m) near 1.0°C along the Chukchi

boundary and warmer than 1.5°C on the Eurasian side of the Lomonosov Ridge.

Earlier data from the Makarov Basin showed no water in this layer warmer

than 0.5°C. In 1993 the Institute of Oceanographic Sciences (Patricia Bay)

group found water warmer than 1°C on the Makarov slope just north of the

Chukchi Sea. The AOS-94 data extend this finding, showing the Atlantic

layer near both the Chukchi and Lomonosov ridge boundary areas to be 0.5°C

warmer than measured before 1993. In some places the insulating fresh, cold

upper layer was somewhat eroded, though far from completely. One of the

important issues facing us now is to place this warming in context. Such subdecadal variability is important to climate models.

We found the central Canadian sector of the Arctic Ocean to be an oceanographically active environment, not a “dead end” isolated from any active

role in the global circulation by the shallow sill through the Bering Strait, the

Lomonosov and other ridges, and its sheer distance from the North Atlantic

Ocean. Instead, the Canadian sector is importing water, modifying it and

exporting it in ways that have important effects and consequences.

For example, biological activity on the Chukchi shelf is so high in summer that

phytoplankton photosynthesis can supersaturate oxygen in the surface waters there

by almost 50% in places, yet the debris left behind by those organisms and their

predators sinks and decays, regenerating nutrients and using up oxygen on the

bottom of the shelf. These shelf-bottom waters can get rather dense, due partly to

brines released from ice formation above, and then flow off the shelf, carrying

regenerated nutrients and, potentially, contaminants into the central basin.

18

Potential temperature section from the

Chukchi shelf (left)

to the Eurasian

flank of the Lomonosov Ridge (right).

The warm cores

appear at approximately 200–400 db

above each primary

bathymetric feature.

The station numbers

are across the top

of the figure.
Winter shelf waters have been

thought to reach rather high densities. Although there are observations

of this, establishing a direct connection to the deep waters, which seems

essential to models of deep water formation in the Arctic, has been elusive. We found during AOS-94 what

is perhaps an important new piece to

this puzzle: At station 22, on the periphery of the Makarov Basin, we saw

a bolus of water dense enough to be

centered at 1000 m, with unique

characteristics indicating that it could

have come only from the shelf. Relatively high CFC concentrations confirmed

its recent origin. This bolus has entered the Makarov Basin and now slowly

freshens the deep water. This may be the first direct observation of “new”

high-density shelf water actually in the deep basins.

There is a weak, deep horizontal salinity gradient across the Chukchi–

Makarov sector, with higher deep salinities near the pole on the Canadian side

of the Lomonosov Ridge. At station 22 in the southeastern Makarov Basin we

saw deflections in the salinity isopleths due to the bolus of relatively fresh,

cold, young deep water.

Isopycnals generally slope slightly down from pole to shelf across the domain

covered by this section, with more significant deflections associated with each

principal bathymetric feature, and circulation associated with the bolus of

young deep water found at station 22. Sharp isopycnal slopes over the Lomonosov Ridge (stations 30–34) showed geostrophic adjustment to relatively strong

upper-layer flow along the ridge crest. The most intense deep deflections in

sigma-2 were found on the Eurasian flank of the Lomonosov Ridge and, to a

lesser extent, on the southeast flank of the Makarov Basin.

On their own the AOS-94 CTD/hydrographic/tracer/contaminant data are

a unique, well-placed and important data set, providing the first referencequality section across the Chukchi Abyssal Plain and Makarov Basin and a

careful, synoptic section of closely spaced stations across the Eurasian flank of

the Lomonosov Ridge near the North Pole. The AOS-94 section also joins to

the Oden 1991 section in the Makarov Basin near the Lomonosov Ridge, and

these in turn can be joined to the Polarstern 1987 Nansen Basin section to

form a nearly complete, shelf-to-shelf trans-Arctic section of high-quality surface-to-bottom multi-tracer stations.

Ocean Circulation and Geochemistry

0 40 80 120 160

200

160

120

80

40

Oxygen Saturation (%)

Pressure (db)

Saturation of oxygen vs. pressure for

the AOS-94 stations

over the Chukchi

shelf (Stations 1–6).

19
1994 Arctic Ocean Section

Total Carbonate and Total Alkalinity:

Tracers of Shelf Waters in the Arctic Ocean

E. Peter Jones

Modern oceanographic measurements include a suite of many tracers, each

of which often has a significance in determining the origin of a particular

water mass and tracing its circulation. In the Arctic Ocean, total carbonate and

total alkalinity have been shown to be effective tracers of waters that have

flowed into central regions from the continental shelves. In addition, these

measurements are an integral part of an assessment of carbon fluxes into and

within the Arctic Ocean.

Total alkalinity and total carbonate in seawater are closely related to salinity, with small deviations from a linear relationship resulting primarily from

the dissolution or precipitation of calcium carbonate. In near-surface water,

carbon from biological decay can also be a significant contributor to changes

in total carbonate. Biological productivity can be assessed with the aid of total

alkalinity and nutrient measurements, and the total carbonate and total alkalinity data will contribute to an assessment of the carbon budget of the Arctic

Ocean.

Total alkalinity and total carbonate analyses are best carried out on “fresh”

samples: the analyses were done onboard ship within about 20 hours after

they were collected, using standard techniques (potentiometric titration and

coulometry). Samples were collected at almost all oceanographic stations at

almost all sampling depths, typically 36 from the surface to the bottom, using

the rosette sampler. The time between stations did not allow water from every

sampling depth to be analyzed, though more than 90% of them were. The

quality of the data is high, reflected in replicate analyses with an average difference of just over 1 part per thousand for total alkalinity and 0.9 parts per

thousand for total carbonate.

Higher total alkalinity values observed in the near-surface water at many

stations during AOS-94 are attributed to dissolved calcium carbonate brought

into the Arctic Ocean by runoff. This signal helps to determine the sources of

fresh water by separating river runoff from sea ice meltwater, and it helps in

tracing the circulation pattern of river runoff. Near-surface “excess” alkalinity,

indicating the presence of river runoff, was found at all stations in the Canada

20

E. Peter Jones is from the Bedford Institute of Oceanography in Dartmouth, Nova Scotia, Canada.
21

Ocean Circulation and Geochemistry

Upper profiles of total carbonate at Stations 10 and 35 (the North Pole). The maximum values in total carbonate at

Station 10 correspond to maximum values in the nutrient profile and minimum values in the oxygen profile.

2300 2400 2500 2600

Normalized Total Alkalinity (μM/L)

Pressure (dbar)

0

50

100

150

200

250

300

2300 2400 2500 2600

Normalized Total Alkalinity (μM/L)

0

50

100

150

200

250

300

2100 2200 2300 2400

Normalized Total Carbonate (μM/L)

Pressure (dbar)

0

50

100

150

200

250

300

2100 2200 2300 2400

Normalized Total Carbonate (μM/L)

0

50

100

150

200

250

300

Upper profiles of total alkalinity at Stations 10 and 35 (the North Pole).

Station 10

Station 10

Station 35

Station 35
1994 Arctic Ocean Section

22

Basin and in the Amundsen Basin. In the Nansen Basin the “excess” total alkalinity was much reduced or not present, indicating that most of the nearsurface fresh water in these regions of the AOS-94 path comes from melting

sea ice.

High values of total carbonate were also observed near the surface. These

correspond to the total alkalinity maximum and are consistent with dissolved

calcium carbonate being brought into the Arctic Ocean by river runoff. There

are also high total carbonate values in the halocline (depth about 100 m) of

the Canada Basin that correspond closely with the nutrient maximum, consistent with the “excess” total carbonate being regenerated along with nutrients

during the decay of biogenic matter. These high values were not present after

Station 14, where the nutrient maximum also disappeared. The total carbonate in the near-surface water and in the halocline can be used to assess the

amounts of carbon entering the Arctic Ocean from the Siberian tundra (river

runoff) and the amount entering as a result of carbon fixation on the continental shelves.

Profiles of both total alkalinity and total carbonate show small variations in

deeper water that are greater than the precision of these measurements. These

structures may be interpretable in terms of the water masses present and

processes such as the sequestering of anthropogenic carbon dioxide, but any

definitive interpretation will have to await more detailed data analysis, not to

mention inspired thought.
Transient Tracers: Chlorofluorocarbons and Carbon Tetrachloride

E. Peter Jones and Fiona A. McLaughlin

The cloud of international concern over the growing anthropogenic releases of

refrigerants, aerosols and solvents and their impact on climate and the ozone

layer, ironically, has had a silver lining for oceanographers. The measurement

of chlorofluorocarbons (CFCs) and carbon tetrachloride (CCl4) in seawater,

from the surface to the bottom, provides a tool for tracing water masses since

they were last at the sea surface with a time clock that spans most of this

century. Such data give important information about the various layers within

the ocean, for example: Are they rapidly flushed or isolated? Are the waters

transported from other oceans or nearby shelves? These are important questions in Arctic Ocean research, as they relate directly to the transport of contaminants—such as organochlorines and radionuclides—to the Arctic food chain.

Measuring CCl4 may also contribute to understanding the ocean’s ability

to absorb carbon dioxide, a critical question for those attempting to predict

global warming. CCl4 can be used as a surrogate for estimating levels of atmospheric carbon dioxide, as both compounds have been increasing in the atmosphere in a similar fashion since the turn of the century. The depth at which

CCl4 is found in the ocean thus signals the depth at which anthropogenic

carbon dioxide, produced in the twentieth century, is found.

AOS-94 provided an opportunity to measure a suite of CFCs (CFC-12,

CFC-11 and CFC-113) and CCl4 on a transect crossing the Arctic Ocean.

Samples were collected at almost all oceanographic stations at almost all sampling depths, typically 36 from the surface to the bottom, using the rosette

sampler. The samples were analyzed using a standard purge-and-trap gas chromatograph.

Previous cruises sampled different regions in different years: the Nansen

Basin in 1987, the Nansen and Amundsen Basins and the North Pole in 1991,

and the southwestern Canada Basin in 1993. The latter cruise yielded information suggesting that the structure and circulation of water masses in the

Arctic Ocean may be undergoing a major change. AOS-94 CFC data will

allow us to determine the rate, magnitude and extent of these changes.

Although results are preliminary, certain key features are evident. CFC and

Ocean Circulation and Geochemistry

23

E. Peter Jones is from the Bedford Institute of Oceanography in Dartmouth, Nova Scotia, Canada. Fiona McLaughlin is from the Institute of Ocean Sciences in Sidney, British Columbia, Canada.
1994 Arctic Ocean Section

0

0

1000

2000

3000

4000

Pressure (dbar)

Concentration (pM/L)

5 10 15

CFC-113


CFC-11


CCl4

0

0

1000

2000

3000

4000

Concentration (pM/L)

5 10 15

CFC-113


CFC-11


CCl4

24

0

1000

0

2000

3000

4000

Pressure (dbar)

Concentration (pM/L)

5 10 15

CFC-113


CFC-11


CCl4

Profiles of CFC-11, CFC-113 and CCl4 at Station 19 above the Mendeleyev Ridge and Station 29 in the central

Makarov Basin.

Profiles of CFC-11, CFC-113 and CCl4 at Station 35 in

the Amundsen Basin.

Station 19 Station 29

Frank Zemlyak and Fiona McLaughlin examining strip chart data in the chemistry lab on the

Louis S. St-Laurent.
CCl4 profiles obtained at Station 19 above the Mendeleyev Ridge, where boundary currents are believed strong, and at Station 29 in the central Makarov

Basin, where flows are believed to be weak, show important differences in

both the concentrations and the penetration depths of all the compounds.

This suggests that transport mechanisms are stronger around the basin’s exterior than at its interior and that bathymetry plays a major role in the circulation of the Arctic Ocean.

Furthermore, Station 35, east of the Lomonosov Ridge in the central

Amundsen Basin, shows higher values of CFCs and CCl4 in intermediate water layers compared to the central Makarov Basin. This suggests a closer connection with laterally transported incoming source waters. In the deep waters

of the Makarov Basin, greater than 2000 m, concentrations of CFCs and CCl4

are below detection limits, indicating that these waters have a residence time

longer than a century. In the Amundsen Basin the penetration is deeper, with

CCl4 values above the detection limit to beyond 3000 m, signaling that these

waters are less isolated than those in the Makarov Basin. A mesoscale feature is

apparent from temperature and salinity measurements and is confirmed by

CFC concentrations at Station 22 between 900 and 1400 m, about 20% higher

than nearby stations. This eddy-like structure is evidence of a mechanism

whereby waters from the Siberian Shelf are transported into the interior of the

Makarov Basin.

Ocean Circulation and Geochemistry

25
1994 Arctic Ocean Section

Distribution of Iron and Aluminum

in the Surface Waters of the Arctic Ocean

Chris Measures

Extremely low concentrations of dissolved iron in the surface waters of

parts of the remote ocean such as the sub-Arctic Pacific are believed to play a

crucial role in limiting the biological productivity of these regions, despite an

abundance of the major nutrients in the surface waters. Phytoplankton require

iron for various biochemical processes, including the conversion of sunlight

energy and the reduction of the nutrient nitrate.

The levels at which iron becomes limiting to phytoplankton growth, and

the effects of its sporadic introduction into surface waters on growth rate, species dominance and carbon export, are the subject of intense study in various

oceanic regimes.

While iron is delivered to the edges of the ocean in copious quantities

through fluvial run-off, little of this material escapes the intense scavenging

removal of these high-productivity regions to reach the surface waters of the

gyres. In the temperate and tropical oceans, iron is delivered to the surface

ocean by the dissolution of eolian-transported continental dust; the regions in

which iron is found to be limiting are those that receive only low inputs of this

eolian material.

Mineral dust inputs to the Arctic are low, and with its annual cycle of variable ice cover, the supply of iron by this route to the surface waters is likely to

be low and highly sporadic in both time and space. Little or nothing is known

of the distribution of iron in the surface waters of the Arctic Ocean, because it

is difficult to collect uncontaminated samples for an element that is ubiquitous in manufactured materials and because of analytical difficulties associated

with determining iron at extremely low concentrations.

Recent advances have resulted in the development of analytical methodology that can be operated onboard ship and is capable of determining iron at

ambient surface water concentrations. AOS-94 provided an opportunity to

deploy this system to investigate the input of the eolian-transported trace metals

iron and aluminum across the surface waters of the basin. Since sampling

close to the ship raises questions of contamination from the ship’s iron hull,

26

Chris Measures is from the Department of Oceanography at the University of Hawaii in Honolulu, Hawaii,

U.S.A.
surface samples were obtained at stations by hand-dipping bottles from the

edge of ice floes located upwind of the ship.

The results indicate that concentrations of iron in the surface waters across

the basin are relatively high and quite variable, with generally higher values

(3.2 nM) in the western Arctic dropping to relatively low values (0.75 nM) in

the Nansen Basin. Within this general trend, though, are localized regions of

extremely high iron concentrations (>8 nM), particularly in the vicinity of the

Mendeleyev Ridge. These highest values occur in regions where the ice floes

were observed to contain significant quantities of sediment on their surface,

known as “dirty ice.” The suggestion that ice-rafted sediment is the source of

these high iron values in the surface water is further supported by the enrichment of aluminum in the same regions.

The entrainment of sediments into ice floes during freezing at the edge of

the basin and the subsequent advection and partial melting of the ice in the

center of the basin represents a unique pathway for delivering reactive trace

metals such as iron to the center of a basin. The partial melting of ice floes

during the summer apparently is capable of delivering high levels of iron to

the surface stratified waters. This delivery mechanism results in relatively high

concentrations of iron, which may favor the development of the ice algae

community that grows on the underside of the ice floes and is thought to

make a major contribution to the primary productivity of the Arctic Ocean.

Large organisms such as ice algae require higher ambient iron concentrations

27

Ocean Circulation and Geochemistry

Concentrations of iron and aluminum in the surface waters vs. Louis S. St-Laurent

station numbers.

8

6

4

2

0 10 20 30 40

Station Number 

Fe

(nM)

25

20

15

10

5

0

Al

(nM)

Chukchi

Sea

Mendeleyev

Ridge

Makarov

Basin

Amundsen

Basin

Nansen

Basin

Al

Fe

Dirty Ice
1994 Arctic Ocean Section

than smaller organisms to meet their iron needs since their requirement scales

with volume but their ability to transport scales with their surface area.

The ice rafting of sedimentary material from the edges to the center of the

basin and its effect on primary production represent a unique biogeochemical

pathway connecting physical, chemical and biological processes. The susceptibility of this transport route to future perturbations of Arctic climatology is

unknown. However, it seems that any change that resulted in the dimunition

of ice-edge freezing in winter might lead to significant changes in the nature

and magnitude of primary productivity of the central Arctic.

28

Chris Measures

in the laboratory

on the Louis S.

St-Laurent
Thorium Isotopes as Tracers of Scavenging and

Particle Dynamics in the Arctic Ocean

S. Bradley Moran, Katherine M. Ellis,

Richard W. Nelson and John N. Smith

The role of the Arctic Ocean in the global carbon cycle remains a key question in studies of global climate change. The Arctic Ocean and its adjacent

seas are characterized by spatial and temporal extremes in the rate of biological

sequestration of atmospheric CO2, ranging from oligotrophic conditions in

the central Arctic to production rates in the Bering and Chukchi Seas that are

among the highest reported for any ocean. An important objective of Arctic

research is to quantify the fraction of total primary production exported from

Arctic surface waters to the ocean bottom in the form of sinking particulate

organic carbon and associated biogenic debris. In addition, the Arctic has the

largest ratio of shelf to deep waters of any oceanic region, making it a particularly good place to study the importance of shelf–basin interactions on particle dynamics and chemical transport.

As part of AOS-94, field sampling was conducted with the primary goals

of:

• Using 234Th as a tracer to quantify scavenging and the export flux of

organic carbon by particle sinking from the upper waters and the coupling of chemical transport between the shelves and the interior Arctic

Ocean; and

• Using 230Th and 232Th to quantify rates of particle cycling in the intermediate and deep Arctic waters.

Collection of these data within the framework of other AOS-94 field programs will contribute to the international effort to better understand the role

of the Arctic Ocean in the global carbon cycle and climate change. Summarized here are preliminary 234Th results of this research. Samples were also

collected for determination of full-depth vertical profiles of long-lived 230Th

(half-life = 7.5 × 104 years) and 232Th (half-life = 1.4 × 1010 years) at several

locations along the cruise track. These samples are being analyzed using highly

sensitive thermal ionization mass spectrometry.

29

Ocean Circulation and Geochemistry

S. Bradley Moran is from the Graduate School of Oceanography at the University of Rhode Island in Narragansett, Rhode Island, U.S.A. Katherine Ellis, Richard Nelson and John Smith are from the Bedford Institute of

Oceanography in Dartmouth, Nova Scotia, Canada.
1994 Arctic Ocean Section

During AOS-94 the naturally occurring, short-lived 234Th isotope (half-life

= 24.1 days) was used as a tracer to quantify scavenging and the export of sinking biogenic particulate matter and associated elements. In the surface ocean

the disequilibrium between 234Th and its soluble parent 238U varies in response

to short-term changes in particle export on a time scale of approximately 1–

100 days. Because of its short half-life, it was essential to measure 234Th at sea

using a low-energy pure germanium detector.

The 234Th/238U activity ratios in the surface mixed layer (0–30 m) indicates the amount of particle scavenging along the cruise track. The low

234Th/238U activity ratio of 0.22 at Station 1 is consistent with removal of

234Th from the water column by particle scavenging within the particle-rich

Chukchi Sea. In contrast, surface waters in the interior Arctic generally show

no significant 234Th/238U disequilibrium and hence very low rates of particle

scavenging. An exception is the relatively low 234Th/238U activity ratio of

0.68 at Station 23, which may be due to enhanced biological productivity and

associated biogenic particle scavenging of 234Th at this location.

Vertical profiles of 234Th, 238U and silicate are another way of viewing

particle scavenging. A striking observation is the subsurface deficit in total

234Th evident in the Makarov Basin (Station 26). The low 234Th activities

may result from scavenging removal of 234Th due to enhanced local biological

Cruise track of the

CCGS Louis S.

St-Laurent and stations occupied for

vertical sampling of

234Th. Shown in

parentheses are

234Th/238U activity

ratios in the surface

mixed layer (0–30 m).

Activity ratios less

than one indicate

preferential removal

of 234Th by particle

scavenging, whereas

ratios equal to one

indicate 234Th/238U

equilibrium and very

low rates of particle

scavenging.

30
Ocean Circulation and Geochemistry

Depth profiles of 234Th (dpm: disintegrations per minute) and

dissolved silicate in the Makarov Basin and at the North Pole.

238U activities were calculated from salinity (238U = 0.069 ×

salinity).

productivity. On the other hand, the 234Th deficit may also reflect a scavenging “history” due to 234Th removal within the particle-rich shelf waters and

advection into the Arctic interior. In contrast, results from the North Pole

(Station 35) indicate no significant 234Th/238U disequilibrium and hence no

appreciable scavenging of 234Th.

These 234Th profiles show for the first time a marked spatial variability in

particle scavenging in the upper Arctic Ocean. Ongoing studies aim to determine the relative importance of 234Th scavenging due to in-situ biological

productivity and advective transport of shelf water containing low 234Th into

the central Arctic.

Finally, the 234Th results are being used to quantify the sinking flux of

biologically produced particulate organic carbon ( POC) from the surface mixed

layer (0–30 m). Preliminary estimates indicate that the export flux of POC

ranges from approximately 400 mg C/m2-day in the Chukchi Sea to 1–10 mg

C/m2-day in the Arctic interior. These particulate carbon fluxes are comparable to the limited number of carbon flux measurements obtained using sediment traps in the Arctic Ocean.

31







100



200

300

400

Depth (m)

Si (μM)

0 20 40 60

0 0 20 40 60 20 40 60

0 20 40 60

234Th (dpm/L)

Diss. 234Th


Part. 234Th


Total 234Th


Diss. 238Th


Si (μM)

Makarov


Basin

North


Pole

Diss. 234Th


Part. 234Th


Total 234Th


Diss. 238Th


Si (μM)
1994 Arctic Ocean Section

What Can Be Learned from Barium Distributions

in the Arctic Ocean?

Kelly Kenison Falkner

Barium is one of several naturally occurring inorganic elements that are

being studied as part of a larger project to track river- and shelf-modified

water inputs to the central Arctic. In the open oceans, dissolved barium displays

nutrient-type behavior, being depleted from surface waters in conjunction

with biological processes and enriched at depth by regeneration. River waters

tend to be enriched in dissolved barium with respect to surface seawaters, and

riverine signals are further augmented in estuaries where barium adsorbed on

riverine clays is desorbed as the clays encounter the more abundant cations of

seawater.

AOS-94 samples have been analyzed for dissolved barium content by isotope

dilution-inductively coupled plasma quadrupole mass spectrometry. Several

interesting observations can be made when these results are taken in the context of previously reported barium data for the Arctic (Falkner et al. 1994) and

recent results from 1993–1995 field efforts, including extensive sampling along

the Russian and Siberian estuarine and shelf regions, in the Mackenzie Delta

as well as the 1993 USS Pargo and 1995 Cavalla nuclear submarine missions

(Falkner and Guay, unpublished data). All of these data sets have been calibrated to a common barium standard and have a precision of 3% or better.

Consistent with its higher suspended sediment loads, the Mackenzie River

appears markedly enriched in barium compared to the rivers of the eastern

Arctic sector. Sub-ice surface (< 25 m) barium concentrations in the central

Arctic range from 35 to 70 nM and show a spatial distribution reflecting both

the varying riverine inputs and the integrated surface ice motion. The highest

values are concentrated in the Beaufort Gyre region, which is influenced by

Mackenzie inputs. Intermediate values influenced by the Siberian rivers track

the transpolar drift and are bordered toward the Fram Strait and Barents Shelf

by low values characteristic of North Atlantic surface waters.

As previously observed, halocline waters that display elevated silicon contents and are believed to originate from the Bering–Chukchi regions also show

pronounced barium maxima (up to 140 nM). At stations where halocline

32

Kelly Kenison Falkner is from the College of Oceanic and Atmospheric Sciences of Oregon State

University, Corvallis, Oregon, U.S.A.
Ocean Circulation and Geochemistry

waters do not show a nutrient maximum, barium displays a halocline minimum at levels that correspond to those observed for the eastern Arctic shelf

regions (30–35 nM). Underlying waters of Atlantic origin contain distinctly

higher barium contents of 45–50 nM. These data demonstrate that barium

has considerable promise for complementing other tracers of surface currents

and halocline water formation. Full interpretation of these and other features

in the barium data await complete analyses of the 1995 samples.

REFERENCE

Falkner, K.K., R.W. MacDonald, E.C. Carmack and T. Weingartner (1994)

The potential of barium as a tracer of Arctic water masses. In The Polar Oceans

and Their Role in Shaping the Global Environment: The Nansen Centennial

Volume, American Geophysical Union, Geophysical Monograph 85, p. 63–

76 (O.M. Johannessen, R.D. Muench and J.E. Overland, Ed.), Washington,

D.C.

33

Frank Zemlyak in the

Louis S. St-Laurent

chemistry lab.
1994 Arctic Ocean Section

— Biology and the Carbon Cycle —

Cycling of Organic Carbon in the Central Arctic Ocean

Patricia A. Wheeler

The central Arctic Ocean has been characterized as a region of very low

biological production due to the year-round presence of ice and a short photosynthetic season. Past studies have postulated that the high concentrations of

dissolved organic carbon in surface waters result from the slow growth and

metabolism of bacteria at low temperatures. To determine if biological processes play a significant role in the Arctic carbon cycle, the investigators of the

biology program measured nutrients, particulate and dissolved organic carbon,

standing stocks of algae, micro- and mesozooplankton, and rates of primary production and bacterial production. Standing stocks and production rates are

described in reports by Gosselin et al., Sherr et al., and Thibault. In this summary, I describe major patterns in the distribution of nutrients and organic

carbon along the transect. Then, using biomass and rate measurements made

by other investigators, I estimate the turnover time for the pool of dissolved

organic carbon. The results clearly indicate that significant in-situ production

and utilization of organic carbon takes place in the central Arctic Ocean and

that biological processes play an important role in the Arctic carbon cycle.

Samples were collected at 16 major stations across the Arctic, starting in

the Chukchi Sea, proceeding to the North Pole and exiting on the Atlantic

side. Water samples were collected with a CTD/rosette, after moving ice away

from the ship when necessary. Water samples from 12–24 depths in the upper

300 m were analyzed for nutrient concentrations, particulate carbon and nitrogen, and dissolved organic carbon and nitrogen. Nutrients were analyzed

onboard, while the other samples were stored for later analysis in our shorebased laboratory.

In general, the major nutrients (nitrate, phosphate and silicate) were present

in sufficient concentrations in surface water (0–25 m) to support the primary

production of phytoplankton and ice algae. The one exception was low nitrate

concentrations at stations between 76 and 80°N, 173 and 178°W. In this

region, ice algae in particular may have been nitrogen-limited. Phosphate concentrations decreased from 1.0 to 0.6 μM along the transect, while silicate

34

Patricia Wheeler is from the College of Oceanic and Atmospheric Sciences at Oregon State University in Corvallis, Oregon, U.S.A.
concentrations decreased from 10 to

5.0 μM. These decreases may reflect

the relative strength of influence of

Pacific and Atlantic water masses, or

they may reflect biological utilization

of nutrients in water moving in the

Transpolar Drift. Nitrate, however,

showed the opposite pattern. Nitrate

concentrations increased from 1.0 to

4.0 μM along the transect. Nitrate

concentrations varied more with

depth from 0 to 300 m than did

phosphate and silicate concentrations. The wider range in concentrations combined with differences in

diffusion and other mixing processes may account for the differences in patterns of changes in nutrients along the transect.

Particulate organic carbon (POC) ranged from 3.5 to 8.0 g/m2 and generally decreased along the transect. Particulate organic nitrogen (PON) ranged

from 0.4 to 1.3 g/m2 and also generally decreased along the transect. The C/N

ratio of particulate organic material ranged from 8 to 14 and nearly doubled

along the transect. These levels of POC and PON are relatively high; this

material is composed of approximately 40% living material—10% phytoplankton and 30% heterotrophs (bacteria and protists). Zooplankton standing stocks

ranged from 0.2 to 2 gC/m2, making a significant additional contribution to

the total organic carbon and accounting for about 40% of the total particulate

organic carbon in the central Arctic.

The largest pool of organic carbon was dissolved organic carbon (DOC),

which ranged from 60 to 120 μM. DOC and zooplankton standing stocks

both increased in the poleward direction, reaching maximum values around

85 to 87°N. Earlier investigators attributed the high DOC concentrations to

the refractory nature of DOC from riverine inputs and presumably low rates

of bacterial metabolism due to low temperatures in the central Arctic. Gosselin et al. measured significant rates of DOC excretion by phytoplankton and

ice algae; these results, along with the similar spatial patterns of the distribution for zooplankton and DOC, strongly suggest the importance of biological

production of DOC.

Bacterial production ranged from 17 to 53 mg C/m2-day, comparable to

rates measured in Antarctic waters. Since bacteria are the main consumers of

dissolved organic carbon, bacterial production can be used to estimate the

mean turnover time of DOC. Bacterial carbon utilization divided by concentrations of DOC indicated that the average turnover time for the total DOC

pool is less than one year in the central Arctic. Since the mean residence time

35

Biology and the Carbon Cycle

Pat Wheeler in the

wet lab aboard the

Polar Sea.
1994 Arctic Ocean Section

of surface water in the central Arctic is about 10 years, some portion of the

DOC is being recycled many times.

Previous studies of the Arctic Ocean carbon cycle assumed that, since production appeared to be low in the central basins, most organic carbon was either

derived from river inputs or imported from the extensive shelf regions. Our

new measurements of primary production, bacterial production and zooplankton standing stocks suggest a more dynamic carbon cycle in the surface waters

of the central Arctic. Higher estimates of primary production result from the

activity of ice algae, which were not sampled in previous studies. Direct measurements of DOC excretion by both ice algae and phytoplankton indicate that

at least a portion of the high DOC found in the central Arctic is produced in

situ. Measurements of rates of bacterial production indicate a significant turnover of DOC in the central Arctic. High standing stocks of mesozooplankton

are further evidence for significant cycling of organic carbon in the upper 100

m of the central Arctic. Primary production by the ice algae and the production of DOC in the central Arctic both appear to be key processes in the Arctic

carbon cycle. Our results indicate that the central Arctic is not a biological

desert but rather supports an active biological community that contributes to

the cycling of organic carbon through dissolved and particulate pools.

70 80 90 80

Latitude (°N)

80

60

40

20

0

2.0

1.6

1.2

0.8

0.4

0

140

120

100

80

60

DOC Excretion (%) Mesozooplankton C (gC/m2) DOC (μM)

a

b

c

36

DOC and standing stocks vs. latitude.

a. Percentage of the phytoplankton production released as extracellular carbon, measured by Michel Gosselin.

b. Zooplankton standing stocks for 0–100

m. Zooplankton were collected in vertical

net tows (200 mm mesh, 0.75 m opening),

dried onboard ship, weighed and then analyzed for carbon with a CHN analyzer. The

curve is a second-order regression with r 2 =

0.834.

c. Dissolved organic carbon in the surface

water. Samples were collected in duplicate

and stored frozen with no preservative. The

curve is a second-order regression with r 2 =

0.634.
Mesozooplankton Community Structure

in the Arctic Ocean in Summer

Delphine Thibault

Ocean organisms range in size from tiny bacteria (0.1–1 μm) to whales

(over 30 m). Mesozooplankton (200–2000 μm) represent a link between

smaller organisms (<200 μm), such as phytoplankton and microzooplankton (on which they graze) and larger grazers (>200 μm), such as macrozooplankton and fish (which feed on them). By knowing their biomass,

composition and metabolism, we can estimate the role of mesozooplankton in the pelagic food web and the carbon cycle.

During AOS-94, as part of the biological study, the biomass, the specific

composition and the chemical composition of mesozooplankton were estimated in the upper 500 m of the Arctic Basin. Where possible, three layers

were sampled at each station (0–100, 100–200 and 200–500 m). Also, the

content of the gut pigments, as an

indicator of grazing, was directly

measured on the main species and

stages in the upper layer.

The mesozooplankton biomass

in the first 100 m increased quadratically with latitude (r2 = 0.82),

showing a maximum around 87°N.

A high mesozooplankton biomass

(19–42 mg dry weight/m3) was observed in the upper two layers (0–

200 m), while in the deepest layer

(200–500 m) the biomass was much

lower, ranging from 4 to 16 mg DW/m3. The integrated mesozooplankton

standing stock varied between 0.4 and 10 g DW/m2 and appear to be significantly higher than previously reported for the Arctic Ocean (Conover and

Huntley 1991).

The mesozooplankton carbon content was nearly constant over the

whole study area (around 40% of the dry weight), although it appears to

be lower at the ice edge stations. Those variations might be related to modifications in the zooplanktonic population. The C/N (g/g) ratio for the

37

Biology and the Carbon Cycle

Delphine Thibault is from the Départment d’océanographie of the Universite du Québec à Rimouski, Quebec,

Canada.

The plankton net

being lowered for

sampling on the

Polar Sea.
1994 Arctic Ocean Section

mesozooplankton population was high (6.5–8.5) compared to lower latitudes (4.5), but it stayed in the range typical at high latitudes (6.3–12.5)

(Bamstedt 1986). The high lipid content (used as reserve) observed in the

zooplankton may explain these high values.

The Arctic mesozooplankton taxonomic composition did not change

along the transect and within the three depths. This population was mainly

represented by copepods (70–90% of the total number) and specifically by

three large species (Calanus hyperboreus, C. glacialis and Metridia longa) and

three small genera (Oithona, Oncea and Paracalanus). However, the first group

of species accounts for more than 80% of the total biomass and includes

mainly late stages (C4, C5 and adult). The two species of Calanus are typical Arctic species. A third species of Calanus is present but less abundant

(C. finmarchicus, Atlantic species). The highest concentration of this species

was found at the last stations in the Nansen Basin, closest to the inflow of

Atlantic water. In total, 21 species of copepod were identified. This low

number is consistent with the diminution in the number of zooplankton

species with latitude (there are approximately 100 species in the Mediterranean Sea). The other taxa were mainly amphipods, ostracods, pteropods,

isopods, chaetognaths, siphonophores, appendicularia, medusa and

euphausiacea.

The ingestion of phytoplankton by the main species of copepod was

estimated by analyzing the gut pigment content. The values are expressed

38

70 80 90 80

Pacific Atlantic Latitude (°N)

60

50

40

30

20

10

0

Gut Pigment Contents (ng Chl a eq/ind)

70 80 90 80

Pacific Atlantic Latitude (°N)

60

50

40

30

20

10

0

Biomass (mg/m3)

Gut pigment contents of Calanus hyperboreus female in

the upper 100 m along the transect. The solid line is a

second-order regression, and the dashed lines show the

99% confidence interval, r 2 = 0.86.

Mesozooplankton biomass in the upper 100 m along the

transect. The solid line is a second-order regression, and

the dashed lines show the 99% confidence interval, r 2 =

0.8158.
39

Biology and the Carbon Cycle

in term of chlorophyll a equivalent (Chl a + pheopigments). The gut pigment content ranged from 1 to 60 ng Chl a eq/individual, with maximum

values (> 10 ng Chl a eq/individual) in the Chukchi Sea and the Nansen

Basin. As with the biomass, those values are well described by a secondorder regression. A good relationship appears between the gut pigment

content and the primary production (for Calanus hyperboreus female, r2 =

0.69). But the high zooplankton biomass in the first 100 m cannot be supported by the chlorophyll a concentration (r2 = –0.7552). On the other hand

this uncoupling, confirmed by the low gut pigment content, might be

explained by the omnivorous character of the main copepods; they can

feed on either phytoplankton or microzooplankton.

All these data give us new information on the role of mesozooplankton

in the Arctic food web. In the Arctic Ocean the zooplankton biomass in late

summer was similar to values reported for other oceans (Reid 1962, Be et

al. 1971). Copepods represent 80% of the whole mesozooplanktonic population of the Arctic Ocean. The contribution of the mesozooplankton in the

carbon cycle is important, accounting for approximately 40% of the total

particulate organic carbon in the upper 100 m of the water column. The

mesozooplankton also feed on phytoplankton but probably more on microzooplankton.

REFERENCES

Bamstedt, U. (1986) Chemical composition and energy content. In The Biological Chemistry of Marine Copepods (E.D.S. Corner and S.C.M. O’Hara, Ed.),

Oxford: Clarendon Press, p. 1–58.

Be, A.W.H., M. Forns and O.A. Roels (1971) Plankton abundance in the

North Atlantic ocean. In Fertility of the Sea, p. 17–50.

Conover, R.J. and M. Huntley (1991) Copepods in ice-covered seas—Distribution, adaptations to seasonally limited food, metabolism, growth patterns

and life cycle strategies in polar seas. J. Mar. Syst., 2: 1–41.

Reid, J.L., Jr. (1962) On circulation, phosphate–phosphorus content, and

zooplankton volumes in the upper part of the Pacific ocean. Limnology and

Oceanography, 7: 287–306.
1994 Arctic Ocean Section

Roles of Heterotrophic Bacteria and Protists

in the Arctic Ocean Carbon Cycle

Barry F. Sherr, Evelyn B. Sherr and David Kirchman

Our role in the AOS-94 expedition was to determine the distribution and

activity of heterotrophic microbes (bacteria and phagotrophic protists) in the

context of the overall food web of the upper column. Prevailing theory suggests that bacteria and heterotrophic protists have a minor role in the food

webs of polar ecosystems compared to those of temperate and tropical oceanic

regions, because low water temperatures inhibit microbial growth. According

to this concept, the lack of heterotrophic microbial activity results in a greater

fraction of plant production being available for larger consumers in polar food

webs.

We determined:

• Biomass per unit volume and per square meter for bacteria and for three

size classes of protists;

• Bacterial production and growth rate; and

• Rates of bacterivory.

We also investigated the hypothesis that marine bacterioplankton are metabolically suppressed by extremely low water temperature, by investigating standing stocks and turnover of labile sugars and amino acids and the response of

bacterioplankton to the addition of substrates and to temperature.

The preliminary results indicate an active microbial community. Bacterial

abundances were high (0.5–1.5 × 106 cells/mL) in the upper 50 m of the water

column, declining to < 0.2 × 106 cells/mL below 100 m. Both bacterial and

heterotrophic protist biomass was in the range of 0.4–1.0 g C/m3; the total

biomass of heterotrophic microbes often exceeded the phytoplankton biomass.

Measured phytoplankton production was insufficient to support the rates of

bacterial production; extracellular polysaccharides produced by bottom-ice diatoms are a probable additional source of organic substrate for pelagic bacteria.

Bacterial activity had Q10 values of 2–3 over a temperature range of –1°C

to +15°C. The maximum growth rate was observed at a temperature of about

15°C.

40

Barry Sherr and Evelyn Sherr are with the College of Oceanic and Atmospheric Sciences at Oregon State University in Corvallis, Oregon, U.S.A. David Kirchman is with the Graduate College of Marine Studies, University of

Delaware, Lewes, Delaware, U.S.A.
The assemblage of heterotrophic protists was dominated by phagotrophic dinoflagellates from 6 to >50 μm

in size. Ciliates were also common in most samples. There

were few choanoflagellates in

the water column under the

ice pack, although choanoflagellates were abundant in

ice-free waters of the Chukchi

and Greenland Seas, as others

have previously found. The

smallest protists observed were 1–2 μm heterokont flagellates, which appeared to

be feeding both on bacteria and on 1-μm eukaryotic phytoplankton, tentatively

identified as Micromonas pusilla, which were present in abundances of 103–104

cells/mL in the upper 50 m. The protist biomass ranged from 0.006 to 0.1 g

C/m3 and often exceeded estimates of phytoplankton biomass determined

from chlorophyll a concentrations. All size classes and taxonomic groups of

heterotrophic protists appeared to be consuming phytoplankton cells.

Based on the data on standing stock abundance and activity of heterotrophic

microbes in the central Arctic Ocean, and on biomass and production of phytoplankton and ice algae, we developed a preliminary budget of carbon fluxes

through the pelagic microbial food web of the central Arctic Ocean. Integrated

over the upper 50 m, stocks of bacterioplankton ranged from 0.27 to 0.70 g

C/m2, and of heterotrophic protists from 0.37 to 0.79 g C/m2. Estimates of

productivity of autotrophs and heterotrophs in the upper 50 m were comparable: 0.02–0.14 g C/m2-day for bacteria, 0.03–0.25 g C/m2-day for phytoplankton plus ice algae, and 0.05–0.15 g C/m2-day for phagotrophic protists.

Assuming a gross growth efficiency of 40%, heterotrophic microbes could

consume on the order of 0.2–0.7 g C/m2-day. As primary production occurring at the time of the cruise could not provide this daily amount of organic

carbon, we infer that the heterotrophic community was also supported by the

organic carbon present in the water as particulate material (3 g C/m2) and as

dissolved organic compounds (60 g C/m2). This detrital organic matter may

have been produced earlier in the growing season by blooms of ice algae in the

central Arctic.

Our results suggest that, contrary to the initial concept of a minor role of

heteorotrophic microbes in polar ecosystems, heterotrophic bacteria and phagotrophic protists are significant consumers of plant production in the food webs

of the central Arctic Ocean.

41

Biology and the Carbon Cycle

Deck incubator for

productivity measurements on the

Polar Sea.
1994 Arctic Ocean Section

Contribution of Planktonic and Ice Algae to Dimethylsulfide

Production across the Arctic Ocean in Summer

Michel Gosselin, Maurice Levasseur, Nathalie Simard, Sonia Michaud,

Sangeeta Sharma, Peter Brickell and Timothy Bates

Algae produce a sulfur compound that seems not only to be a key link in

the global sulfur cycles but that also influences the formation of clouds and

therefore the Earth’s temperature. Understanding how these algae affect cloud

formation in the remote oceans could be crucial to predicting how the Earth

will respond to global warming. The link between marine microscopic algae

and climate involves dimethylsulfide, or DMS, the gas that gives air its bracing smell. It forms from the enzymatic breakdown of a salt, dimethylsulfoniopropionate (DMSP). Marine algae produce DMSP to keep their osmotic balance

with seawater, without which water would leave the cells of the algae, killing

them. DMSP may also play a role as a cryoprotectant for microalgae living in

very-low-temperature marine environments, such as polar waters and ice. The

processes by which DMSP is released into the sea are not well understood, but

most researchers think it occurs when algae die or are grazed by zooplankton.

In the sea DMSP breaks down to form DMS. A fraction of this DMS, perhaps

42

Michel Gosselin is with the Département d’océanographie of the Universite du Québec à Rimouski, Rimouski,

Quebec, Canada. Maurice Levasseur, Nathalie Simard and Sonia Michaud are with the Institut Maurice-Lamontagne, Ministére des Péches et des Océans, Mont-Joli, Quebec, Canada. Sangeeta Sharma and Peter Brickell are

with Atmospheric Environment Service, Downsview, Ontario, Canada. Timothy Bates is with the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory, Seattle, Washington, U.S.A.

Marine biogeochemical cycle of

DMS: production,

transformation and

utilization pathways

that may ultimately

influence the quantity of DMS lost to

the atmosphere.
a tenth, then enters the atmosphere. The rest is either consumed by bacteria or

broken down by sunlight to form dimethylsulfoxide (DMSO).

Algae exploit several habitats in the polar environment. In ice-free polar

seas, microscopic algae are found mainly in the upper part of the water column. They are called the planktonic algae, or phytoplankton. In ice-covered

seas, algae are found mainly:

• At the surface of the ice in melt pools formed by thawing surface ice,

flooding or a combination of flooding and thawing;

• In the bottom 2–5 cm of the ice, where they form a brownish layer; and

• In the seawater immediately under the ice, where they form huge mats

and strands up to 3 m long.

These unicellular algae that grow in and on the ice are called the sea ice algae.

In the Arctic, phytoplankton and ice algae both contribute to DMS production.

The goal of our study was to determine the contribution of planktonic and

sea ice microalgae to the production of DMSP and DMS in the western and

central Arctic Ocean during summer. Sampling was conducted on the

multi-year ice of the Arctic Ocean from 26 July to 26 August 1994, onboard

the USCGCPolar Sea. The transect began in the continental shelf of the Chukchi Sea on the western side of the Arctic and terminated in the deep Nansen

Basin on eastern side of the Arctic. Along the transect the ice thickness varied

from 1 to 5 m, and ice coverage varied from 50 to 100%. Bottles specifically

designed for oceanographic research were used to collect surface water samples, while melt pools were sampled by means of a bucket. An ice corer was

used for collecting the bottom-ice samples. Finally, the sub-ice samples were

collected by U.S. Coast Guard scuba divers, using a 2-L syringe sampler called

a “slurp gun.” In the laboratory, various measurements were performed on the

melted ice and water samples. Chlorophyll a concentrations, an index of algal

biomass, were determined using the fluorometric method. Particulate DMSP,

dissolved DMSP and free DMS were determined by gas chromatography.

Significant DMS concentrations were measured in all the habitats studied.

In surface water, DMS concentrations were highest on the continental shelf of

the Chukchi Sea and rapidly decreased toward the Pole. Surface DMS concen43

Biology and the Carbon Cycle

Biological communities found in sea ice

and in the upper

part of the water

column in a North–

South section of the

Arctic Ocean during

summer. Bottom ice community Sub-ice community Melt pools community Planktonic community
1994 Arctic Ocean Section

trations were also relatively high in

cracks (openings in the multi-year

ice). These cracks, called leads, tend

to be narrow (tens to hundreds of

meters in width) but may extend for

many kilometers. In some situations

leads may reach several kilometers in

width and are termed polynyas. Of

the ice habitats, the highest algal biomass and DMS concentrations were

found in the bottom of the ice on the

eastern side of the transect. On a volume basis, the maximum DMS concentrations were three times higher

in the bottom of the ice than in surface water. Significant DMS concentrations were also measured in the algal mats loosely attached to the bottom surface of the ice. These mats,

composed of the centric diatom

Melosira sp., were found mostly in the

Canada Basin (from 75° to 80°N and

from 86° to 88°N) and in the Makarov Basin (from 89° to 90°N). We

also measured detectable levels of

DMS in melt pools, which covered

up to 20% of the surface of the ice.

These results indicate that physical

and biological processes occurring at

the marginal ice zone of the Chukchi Sea favor DMS production. In the

ice-covered central Arctic, although

local sources of DMS exist, DMS

sea-to-air fluxes are probably limited by the gas-tight ice cover. At these high

latitudes, DMS produced by ice algae and phytoplankton may only reach the

atmosphere through leads and other openings in the ice cover.

Latitudinal changes of the DMS concentration in surface water, in the bottom of the ice,

at the water–ice interface and in melt pools

in the Arctic Ocean in the summer of 1994. DMS Concentration (nM)

10

8

6

4

2

0

a. Surface Water

30

20

10

0

b. Bottom Ice

5

4

3

2

1

0

c. Sub-ice

2.5

2.0

1.5

1.0

0.5

0

70° 80° 90° 80°

North Latitude

d. Melt Pools

44
Transfer of Shelf-Derived Carbon to the

Interior of the Arctic Ocean

Raymond Sambrotto

The upper water column fluxes of carbon in the Arctic Ocean have been

characterized as dominated by the lateral movement of total dissolved inorganic

carbon (ΣCO2) regenerated from productive shelves to deep water regions. At

least some of this movement is associated with the production and sinking of

brine during sea ice formation on the shelves. This suggests a simple carbon

system in which the abundant organic matter produced on the Arctic shelves

provides the source for the elevated ΣCO2 found in the upper halocline of

most of the stations thus far examined. At the same time, however, the dominance of such a horizontal flux of carbon would make the Arctic dramatically

different from the carbon systems in lower-latitude basins, which are thought

to be dominated by the vertical flux of organic matter.

Determining the amount of carbon that enters the Arctic is important to

efforts to understand the role of the ocean as a whole as a sink for atmospheric

carbon dioxide and other greenhouse gases that have increased in recent years

due to human activities. The major goal of my research during AOS-94, therefore, was to evaluate the carbon flux in the interior of the Arctic Ocean quantitatively, particularly in the Canada Basin, which has been sparsely sampled.

A total of 164 bottle samples were collected from the surface 400 m of 15

stations along the AOS-94 cruise track of the Polar Sea and were analyzed for

ΣCO2 using a coulometric technique. Most samples were analyzed onboard,

except samples from the last few stations, which were analyzed upon return to

the laboratory.

The ΣCO2 values measured during the Polar Sea cruise were positively

correlated with salinity, and the maximum values were associated with salinities characteristic of the upper halocline (approximately 33.1 psu). Also, ΣCO2

concentrations were correlated with those of silicate, which suggests that both

signals share a common source on the surrounding shelves, which are sites of

prodigious diatom production during the summer months. The organic material

that is the source of the remineralized ΣCO2, therefore, may be in large part

attributable to diatoms, whose frustules provide much of the silicate as they

dissolve.

45

Biology and the Carbon Cycle

Raymond Sambrotto is with the Lamont–Doherty Earth Observatory in Palisades, New York, U.S.A.
1994 Arctic Ocean Section

The ΣCO2 maximum associated with the upper halocline is most obvious

at stations near the shelf break of the Canada Basin. However, by the northern

end of the Canada Basin, in the vicinity of the former T3 ice station, only

silicate retains a clear maximum in the halocline and ΣCO2 exhibits only a

slight increase between 100 and 150 m. Finally, by the Nansen Basin, little

evidence of any subsurface maximum in nutrient concentrations of any kind

remains.

Perhaps the most significant results of my sampling thus far have been in

characterizing the continuity in ΣCO2 between the shelf and interior regions

of the Canada Basin. With the effect of salinity removed, the large gradient

between the shelf and oceanic regions is clear. The section reflects the continuity between shelf and slope as high-ΣCO2 water (greater than 2200 μM/kg)

detaches from the shelf edge and enters the upper halocline at approximately

100 m. This continuity presumably follows an isopycnal surface between the

two regions.

Additional ΣCO2 data are available for the Canada Basin from a U.S. Navy

submarine cruise in 1993. These data suggest that a significant amount of

inorganic carbon has accumulated under the ice in the central Canada Basin,

where the ΣCO2 content of the upper 300 m is at least 30 moles greater than

the surrounding regions. Thus, the Canada Basin may be an important reservoir for oceanic carbon. Analysis is now focused on isolating the rate at which

shelf carbon is supplied to central regions and the ultimate role of the Arctic in

the global carbon budget.

46

Profiles of ΣCO2 (mM/kg) from both the AOS-94

cruise and the 1993 U.S. Navy submarine cruise.

The solid lines represent the average profiles for

the stations in the vicinity of the Lomonosov Ridge,

Chukchi borderlands or central Canada Basin (right

to left, respectively).

0

100

200

300

2100 2200 2300 2400 2500

ΣCO2 (μM/kg)

Depth (m)

Section of ΣCO2 (mM/kg) from the Chukchi shelf on the left to

the interior of the Canada Basin on the right. The data have

been normalized to a salinity of 35 psu.
Dimethyl Sulfide in the High Arctic

Sangeeta Sharma, Fred Hopper, Peter C. Brickell, Michel Gosselin,

Maurice Levasseur, Natalie Simard and Timothy S. Bates

Natural and anthropogenic emissions contribute approximately equally to

the total global sulfur budget. It is estimated that up to 30–50% of these

natural sulfur emissions are released from the oceans. This can be the largest

source of atmospheric sulfur in ocean regions far from anthropogenic sources

of sulfur.

47

Sangeeta Sharma, Fred Hopper and Peter Brickell are with Atmospheric Environment Service, Downsview,

Ontario, Canada. Michel Gosselin is with the Département d’océanographie of the Universite du Québec à

Rimouski, Rimouski, Quebec, Canada. Maurice Levasseur and Nathalie Simard are with the Institut MauriceLamontagne, Ministére des Péches et des Océans, Mont-Joli, Quebec, Canada. Timothy Bates is with the National

Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory, Seattle, Washington, U.S.A.

Sun

Clouds

Ventilation AIR

OCEAN

Non-sea-salt Sulphate

(particulate)

Cloud Condensation

Nuclei

Change in

Cloud Reflectivity

Dry or Wet

Acid Deposition

Dissolved DMS

(gas)

MSA

(particulate)

DMS

(gas)

Algae

Climate 

Effects

Atmospheric fate of DMS, its climate effects and biogeochemical sulfur

cycling in the marine environment.

Biology and the Carbon Cycle
1994 Arctic Ocean Section

 Dimethyl sulfide (DMS) is the dominant

biogenic sulfur species produced in the

oceans. It is produced by phytoplankton and

is released into the atmosphere at a rate that

depends on variables such as the concentration of DMS dissolved in the water phase,

the wind speed and the temperature. Even

small fluxes of gases from ocean waters can

be globally significant when multiplied by

the area covered by the oceans.

 DMS is of particular interest because

of its possible role in climate change. Photochemical oxidation of DMS in the

atmosphere produces fine particles known as cloud condensation nuclei (CCN)

upon which water vapor can condense and form cloud droplets. Changes in the

regional abundance or characteristics of CCN can alter the distribution or properties of clouds, altering the radiative balance through a change in cloud albedo. It

has been hypothesized that DMS is a major link in ocean–atmosphere coupling and may provide a feedback mechanism through which changes in the

global climate are amplified.

48

Equipment used on

the Polar Sea to

analyze DMS samples. The system

consists of a gas

chromatograph with

a sulfur chemiluminescence detector.

Distribution of aqueous dimethyl sulfide

concentrations during the AOS-94

expedition.
49

Biology and the Carbon Cycle

Numerous model studies have suggested that polar regions are very susceptible to changes in climate. The in-situ measurements of DMS in air and

water made from the USCGC Polar Sea during the transect of the Arctic Ocean

basin have significantly increased the data available on DMS source strengths

and distribution in this sensitive region. Together with the concurrent measurements of CCN and other aerosol and chemical properties of the Arctic

atmosphere, they provide a unique opportunity to investigate the possible

link between DMS, CCN and clouds.

We collected water samples for DMS analysis at the science stations either

with Niskin bottles at various depths or from the ship’s uncontaminated seawater pumping system. DMS dissolved in water was separated by purging,

preconcentrating on adsorbent cartridges and then thermally desorbing into a

gas chromatograph with a sulfur chemiluminescence detector. DMS concentrations in surface seawater samples collected between 24 July and 3 September

ranged from less than 0.1 to 9.1 nM/L. The concentration range was similar

to that observed during the 1991 Oden expedition. Maximum concentrations

were observed along the ice edge and minimum concentrations (below the

detection limit of 0.1 nM/L) at the North Pole.

We collected atmospheric DMS samples using a portable sampler, always

Distribution of atmospheric dimethyl sulfide concentrations

during the AOS-94

expedition.
1994 Arctic Ocean Section

on the upwind side of the ship, away

from ship stack emissions and other

sources of contamination. The samples,

collected on cartridges, were kept frozen until analysis (usually within 48

hours of collection). DMS was thermally desorbed from the sample cartridges

by placing the cartridges in the injector

of a gas chromatograph. The DMS was

then transferred to the analytical column

for separation and determined quantitatively by a flameless sulfur chemiluminescence detector. Samples collected

from 18 July to 8 September showed

atmospheric concentrations from less

than 0.25 nM/m3 (the detection limit) to 50.7 nM/m3, with a median value

of 1.95 nM/m3.

The highest DMS concentrations were found near the ice edge at 67–70°N,

in the Bering Strait and Chukchi Sea regions, and the levels decreased as a

function of ice cover as the ship moved into higher latitudes. This pattern

reversed as the ship exited the ice pack into the Greenland Sea, consistent with

results from the Oden expedition. A diurnal variation was observed in open

water areas, with samples collected at night having values up to four times

higher than in the samples collected during the day in the lower latitudes.

There was not much variation in the ambient concentration once the ship

moved well into the ice pack, but most of these samples were below or just

above the detection limit of the analytical system.

To identify source areas of chemical constituents in the air, we calculated

Langrangian back-trajectories and applied them to the data to determine the

path of air parcels reaching the sampling stations. The most frequent source

area was the northwest Pacific Ocean via the Bering Strait and Chukchi Sea.

Many back-trajectories showed that the air was representative of the high Arctic and had been within this region for several days. A third group of trajectories

showed air originating near Greenland and Iceland.

These results are in agreement with earlier findings on the distribution of

dissolved and atmospheric DMS in the eastern Arctic. Not only was the aqueousphase DMS low in the ice-covered central Arctic Ocean, but ocean–atmosphere

exchange is inhibited by the presence of the ice pack. However, the data available from this complete transect of the Arctic Ocean basin clearly demonstrate that the distribution of DMS along the ice margin and in nearby open

ocean areas is asymmetric. In particular, atmospheric DMS concentrations

were up to ten times higher in the Bering Strait and Chukchi Seas than in the

eastern Arctic.

50

60

40

20

0

20 40 60 80 100

Ice Cover (%)

DMS (nM/m ) 3 Variation of atmospheric dimethyl

sulfide as a function

of ice cover.
51

The Role of Biomass, Bioturbation and Remineralization

in Determining the Fate of Carbon in the Arctic Ocean

Lisa M. Clough, William G. Ambrose, Jr., and J. Kirk Cochran

The goal of biological studies during AOS-94 was to understand the role

of the Arctic in the global carbon cycle. In support of this goal, our research

examined the fate of organic matter reaching the seafloor. Little work had

been done on benthic (seafloor) carbon in the Amerasia Basin prior to this

cruise, but based on work from the Eurasia Basin we surmised that a greater

portion of carbon fixed by pelagic (water column) phytoplankton would reach

the bottom in the entire Arctic Ocean than in other oceans. Possible explanations

for a greater pelagic/benthic coupling included low zooplankton abundance and

feeding rates and a temperature-supressed microbial loop. One of the major

strengths of this cruise was that other researchers were addressing pelagic phytoplankton, zooplankton and microbial processes simultaneously throughout the

cruise.

Our main hypothesis was that the relatively abundant and active benthic

community found in the Arctic is the major factor controlling (both directly

and indirectly) the fate of sedimentary carbon in polar regions. We focused on

some of the possible fates of carbon reaching the benthos by examining patterns

of benthic biomass (how many animals there were), particle bioturbation (how

deep the animals were mixing particles in the sediment) and a variety of estimates of benthic food availabilty (how much total carbon, organic carbon,

chlorophyll, phaeopigments and biologically available protein). In addition

we determined a suite of rate measurements, including remineralization (how

much oxygen is being used by the animals) and bioirrigation rates (how quickly

the animals mix water from above the sediment into the sediment). We collected boxcores from 19 stations along the transect from the coastal waters of

Alaska to the deep basins of the Barents Abyssal Plain. Because of pressure

effects, remineralization experiments were only performed on cores collected

from less than 2000 m deep.

Macrofaunal biomass was ten times higher than has been previously reported

for the Arctic Ocean, supporting the observations made by other members of the

biology group. Mixing rates of both particles and water were directly correLisa Clough is with the Department of Biology at East Carolina University in Greenville, North Carolina,

U.S.A. William Ambrose is with the Department of Biology at Bates College in Lewiston, Maine, U.S.A. J. Kirk

Cochran is with the State University of New York at Stony Brook, New York, U.S.A.
1994 Arctic Ocean Section

lated with macrofaunal abundance, as were sediment

remineralization rates. Given that the surface waters

appeared to be capable of consuming all food being

produced during the cruise, this result is surprising.

It argues that the food supporting the benthos must

be reaching the bottom during the early part of the

summer. We will only be able to test this hypothesis

by being in the Arctic during the early summer.

 As a subset of our major question we hypothesized that benthic biomass and processes would

decline from a maximum in the Chukchi Sea to a

minimum under the permanent ice pack and then

begin to increase again towards the more productive

marginal ice zone north of Fram Strait. Instead, we

found that macrofaunal biomass and mixing processes were typically higher in the Amerasia Basin

than in the Eurasia Basin. We are developing a relationship between benthic micro- and macrofaunal

biomass and the flux of particles to the bottom of

the ocean for other regions of the Arctic (in collaboration with Jody Deming of the University of Washington). We hope to be able to use our AOS-94 benthic data to calculate

particulate flux along the AOS-94 transect (a measurement that was not possible during the cruise).

Our analyses of sediment characteristics support the patterns discussed

above. As expected, the depth of the water column above the bottom also

appeared to have an effect on the simple Amerasia versus Eurasia pattern described above. Samples collected from both the Mendeleyev and Lomonosov

Ridges contain more chlorophyll, phaeopigments (breakdown products of chlorophyll) and total carbon than samples collected from deeper depths, even if

the deeper stations were collected nearer to the Alaskan Shelf.

When we combine and compare the estimates of water column productivity, particle flux, gradient-driven sedimentary oxygen flux and sedimentary

carbon burial, we will be able to determine both the degree of pelagic/benthic

coupling in the Arctic Ocean and the role that the benthic animals play in

carbon cycling in the present-day Arctic. Interpreting biological modification

of stratigraphic and pore-water profiles will be critical in determining the present

state of carbon preservation, as well as in understanding the history of the

Arctic Ocean (in conjunction with the researchers studying the geology of the

Arctic Ocean Basin).

Lisa Clough preparing a mud sample

on the Polar Sea.

52
Oxygen Consumption, Denitrification and Carbon Oxidation Rates

in Near-Surface Sediments of the Arctic Ocean

John P. Christensen

As part of the multidisciplinary AOS-94 expedition, boxcores and piston

cores were collected at a variety of sites across the Arctic Basin. From these

cores, several pore-water solutes, including oxygen, nutrients, alkalinity, pH,

soluble iron and manganese, and sulfate, were measured. Sites ranged from

the continental slope off the Chukchi Sea to the abyssal plains and midbasin

ridges. Ten short cores were used for oxygen profiles, and seven longer cores

were used for the other dissolved solutes over the entire depth of the boxcore.

Profiles of pore-water-dissolved solutes help describe the biogeochemical

sequence of reactions occurring within the sediments. A slight lowering of the

oxygen concentrations was found within the upper few centimeters of pore

waters in all cores. In sites on the continental slope off the Chukchi Sea, porewater nitrate profiles show lowered nitrate concentrations at depth in the sediments. This reduction in nitrate concentrations is attributable to anaerobic

denitrification in the deeper strata of these sediments. These sediments also

received considerable inputs of biogenic material, as indicated by the elevated

levels of dissolved silicate in the pore waters. In contrast, most of the sediments throughout the central basins of the Arctic Ocean are oxygenated over

53

John Christensen is with the Bigelow Laboratory for Ocean Science in West Boothbay Harbor, Maine, U.S.A.

Biology and the Carbon Cycle

Kevin O’Toole, John

Christensen, and

Walt Olson standing

by for a box core on

the Polar Sea.
1994 Arctic Ocean Section

at least the upper 30–40 cm. No evidence is present for lowered redox conditions, which would support dramatic solubilization of iron or manganese.

Silicate concentrations were elevated over bottom water contents by only 20–

30 μM/L. Measurements of titration alkalinity show concentrations within

the sediments to be higher than those in the bottom waters.

The oxygen gradients will be used to calculate the oxygen fluxes into the

sediments. As this flux is driven by the oxidation of organic matter, rates of

carbon oxidation will be calculated. The alkalinity of the pore waters was increased over bottom water concentrations due to either organic matter oxidation or dissolution of solid-phase carbonate. Fluxes of titration alkalinity out

of the sediments can be compared with fluxes of oxygen to evaluate the relative

importance of these two reactions. Thus, the pore-water profiles will allow us

to estimate the rates of carbon oxidation and carbonate dissolution within

these sediments. In conjunction with estimates of burial and productivity, the

results regarding the rates of organic matter oxidation and carbonate dissolution will be useful in constructing a present-day carbon budget for the central

Arctic Basin.

54
— Ecology of Marine Mammals —

Upper Trophic Level Research: Polar Bears and Ringed Seals

Malcolm Ramsay and Sean Farley

Nearshore Arctic waters are home to more than a dozen species of mammals

from three orders (Cetacea, Carnivora and Pinnipedia). Prior to the AOS-94

transect, our knowledge of these mammals found in Arctic waters off the continental shelf consisted primarily of anecdotal accounts from explorers’ journals and ships’ logs. Logistical constraints have limited opportunities for biologists to work in the offshore pack ice, so there were few hard data, even on

simple presence or absence, for species outside of a narrow band (about 200

km) from shore accessible by shore-based aircraft. The AOS-94 transect offered

the first dedicated opportunity to monitor polar bears and observe other marine mammals in the permanent pack ice environment of the Arctic Ocean.

Although closely related to the terrestrial brown and black bears of North

America and Asia, polar bears have adopted a marine-associated life style and

are intimately associated with the sea ice of the Arctic Basin. Their southern

range approximates, to a very high degree, the maximum extent of that ice in

winter. They roam over the sea ice in search of their prey, primarily ringed

seals, but bearded and ribbon seals as well. As carnivores, polar bears are at the

top of the relatively long Arctic marine food chain and, accordingly, are nowhere abundant. Furthermore, individual bears move over very large areas

each year in search of their prey.

All polar bears studied to date have been found to be members of relatively

discrete, coastal subpopulations. The northern boundaries for those subpopulations on the periphery of the Arctic Ocean are poorly known. Prior to AOS94, marine mammal researchers assumed that the central Arctic Basin was a

biological desert that could not support a significant biomass of upper trophic

level vertebrates. We viewed participation in the AOS-94 as a pilot project to

determine whether it is feasible for vertebrate ecologists to work productively

in heavy pack ice and whether polar bears and other marine mammals could

be located there.

If bears were found, we wanted to determine what their affinities were with

known coastal-associated populations and how the movement patterns of in55

Ecology of Marine Mammals

Malcolm Ramsay is from the Department of Biology at the University of Saskatchewan in Saskatoon, Saskatchewan,

Canada. Sean Farley is from the Department of Zoology at Washington State University in Pullman, Washington, U.S.A.
1994 Arctic Ocean Section

dividual bears compare with those of bears found nearer to the continental

shelves. To meet our goals we planned to capture as many polar bears as possible and to determine, using genetic and morphological methods, their degree

of affinity with animals from known populations.

The increased use this century of environmentally persistent chlorinated

hydrocarbon (CHC) compounds in industrial and agricultural practices has

led to global contamination of the world’s ecosystems. Although human population densities and industrial activity are low in Arctic regions, CHCs

released in more southerly latitudes are advected north through a variety of

physical processes and eventually reach the Arctic Ocean and its fauna. These

compounds are lipid soluble and tend to become sequestered in the energy

storage tissues of exposed organisms. At each successive stage in a food web,

CHCs become more concentrated in the tissues of the animals, a process called

bioaccumulation. Polar bears are at the top of the relatively long Arctic marine

food web, so their contaminant loads are relatively high and reflect an integration of the entire marine environment. Polar bears can be considered an “early

warning” species reflecting global changes in the Arctic. Consequently a second

goal on the voyage was to collect tissue samples from live-caught polar bears

for monitoring the extent of organochlorine contamination in the remotest

parts of the Arctic marine environment.

A watch for marine mammals was conducted from the bridges of both vessels.

The sea ice was scanned in a narrow band no more than a few kilometers wide

along the track of the ships’ path. When helicopters forayed out from the

56

Mother and cub

prior to capture.
ships, the crews watched for signs of marine mammals. During at least 25% of

the observation time, fog and other atmospheric conditions limited visibility

to a few hundred meters from the ships and precluded helicopter flights.

When animals were seen, their species, number and behavior were recorded.

Polar bears were captured using helicopters and standard immobilization techniques. For each animal, sex was determined, uniquely numbered ear tags

attached, and matching tattoos applied to the left and right upper lip for subsequent identification of recaptured individuals. Age was derived by counting

annuli in the cementum of an extracted vestigial premolar tooth.

Animals were weighed using an electronic scale suspended from an aluminum tripod. Blood samples, adipose tissue biopsies from superficial depots,

and milk samples were collected for subsequent contaminant assay and DNA

sampling. Satellite-communicating radio collars were fitted to adult female

bears to allow us to track them after capture.

We saw 12 polar bears and 15 additional sets of tracks on the expedition. Of

the bears sighted, seven were captured. The remaining five were unavailable

for capture because climatic conditions or extensive open water at the time

made capture unsafe for both the bears and us. Those not captured included

three solitary bears and a female with a yearling cub. We captured and sampled two families, one juvenile male and one juvenile female. None of the

bears handled had previously been marked in any of the ongoing national

polar bear studies along the periphery of the Arctic Ocean.

Both adult females were fitted with a radio transmitter that communicated

with the Service Argos satellites. These radios allowed us to obtain informa57

Ecology of Marine Mammals

Captured bear

being prepared

for weighing.
1994 Arctic Ocean Section

tion on location and activity patterns. Unfortunately both satellite radio transmitters failed within four months of attachment, possibly due to battery failure. Prior to the loss of radio contact, both bears moved off in a northeasterly

direction, staying in regions of 90% ice cover or greater.

Tissue samples from the bears handled were assayed for organochlorines.

The contaminant loads in the adipose tissue samples from the captured bears

have been determined by R.J. Norstrom (Environment Canada, Ottawa). The

sum of all polychlorinated biphenyls (PCBs) in the bears ranged from 1.7 to

6.6 μg/g lipid, that of the pesticide chlordane from 0.8 to 2.7 μg/g lipid, and

that of the pesticide DDT from 0.1 to 0.4 μg/g lipid. These CHC contaminant loads were in the lower range of values determined for polar bears from

most of the circumpolar, near-land populations. For all three measured contaminants, mean contaminant values in the adipose tissue fell within the lower

50% of mean values for the circumpolar populations of polar bears that have

been sampled previously.

As with bears, more ringed seals were seen than we expected—more than

150, usually singly or in groups of fewer than three. The sighting frequency of

seals remained relatively constant once we were past the continental shelf.

Seals were observed on all except eight days of the transect. On five of those

days, heavy fog limited visibility.

Our sampling protocol was not intended to estimate the population size for

polar bears or ringed seals. We found far more bears (12), tracks of bears (15)

and ringed seals (>150) along our line of transect than anticipated. Clearly

there is a food resource (seals) available to polar bears in the Arctic Basin, and

therefore there may be a resident population of bears. The failure of the satellite tracking program did not allow us to monitor the movements of the two

adult females. The results of the DNA assays and stable-isotopic signatures

from the bears are not yet completed. It is hoped they will support or belie the

hypothesis that polar bears inhabiting the Arctic Ocean basin are indigenous.

Estimating the size of any population of marine mammals in the deep Arctic

Basin is a more difficult problem and will require a concerted effort by researchers from many countries.

Michel Gosselin and other biological oceanographers collected data during

AOS-94 suggesting that a significant, if not major, portion of the food web

exploited by polar bears is associated with the epontic algae, gammarid amphipods and Arctic cod of the multi-year ice floes and not with the pelagic

food column. If corroborated, these findings will give considerable insight

into the ecology of marine mammals. The relative importance of ice algae and

amphipods compared with phytoplankton and copepods may influence the

bioaccumulation of CHCs in the higher trophic levels. Certainly the feeding

ecology of seals and polar bears in any region of the Arctic is poorly understood. As vertebrate ecologists, we eagerly anticipate another opportunity to

study the marine mammals in such a remote and fascinating environment.

58
— Contaminants —

Artificial Radionuclides in the Arctic Ocean

Katherine Ellis, Richard Nelson, John N. Smith,

Linas Kilius and Brad Moran

Recent reports of the dumping of radioactive wastes by the former Soviet

Union in the Barents and Kara Seas have caused concerns regarding levels of

radioactive contaminants in the Arctic areas of North America and their impact

on the environment and human health. These concerns have led to the current

investigation of radionuclide levels and transport pathways in the Arctic Ocean

and the ultimate fate of artificial radionuclides such as 137Cs, 90Sr and 239,240Pu

in the Arctic ecosystem. In addition, these isotopes can provide useful information on transit times for water movement in the Arctic Ocean by relating

isotope concentrations and ratios to their source functions.

Sources of artificial radioactivity of the Arctic Ocean include:

• Fallout from atmospheric nuclear weapons tests carried out mainly in the

1950s and 1960s;

• Effluent from European reprocessing plants (including Sellafield in the

U.K. and Cap le Hague in France);

• Releases during the Chernobyl accident in 1986;

• Solid and liquid radioactive waste, including spent reactor cores from

nuclear submarines and ships, dumped in the Barents and Kara Seas by

the former Soviet Union;

• Nuclear wastes transported down Russian rivers; and

• Nuclear wastes discharged into coastal waters associated with the present

Russian nuclear fleet.

Artificial radioactivity is transported into the Arctic Ocean via several pathways. Atlantic water, carrying atmospheric fallout and effluent from Sellafield

and Chernobyl, is transported into the Arctic Ocean via Fram Strait or the

Barents Sea, where it may incorporate releases from Russian radioactive waste.

Pacific water flowing in through Bering Strait carries atmospheric fallout from

the Pacific Ocean. Surface water on the Russian continental shelves, containing Atlantic and Pacific water and river runoff, is mixed and advected into the

Arctic Ocean surface layer. Dense saline plumes, produced during ice freezing

59

Katherine Ellis, Richard Nelson and John Smith are with the Bedford Institute of Oceanography in Dartmouth,

Nova Scotia, Canada. Linas Kilius is with IsoTrace Laboratory at the University of Toronto in Toronto, Ontario,

Canada. Brad Moran is with the University of Rhode Island in Narragansett, Rhode Island, U.S.A.

Contaminants
1994 Arctic Ocean Section

in shelf regions, are transported down

into the halocline, intermediate and

deep water layers of the Arctic Ocean.

Particle reactive isotopes can also be

transported into the interior of the

Arctic Ocean through incorporation

into ice and subsequent release of the

ice-rafted radioactive contaminants

into the water column and sediments

by melting or breakup of the ice.

 Until recently, studies of the transport of artificial radioactivity into the

Arctic Ocean had been limited to

measurements conducted from a few

ice stations, such as LOREX (1979),

FRAM3 (1981), CESAR (1983), AIWEX (1985) and the Canadian Ice

Island (1985–1989). The use of icebreakers during AOS-94 has vastly increased the number of sampling locations in the western Arctic Ocean. Water samples were collected from many of

the major areas of the Arctic Ocean, including the Chukchi Sea and the Canada, Makarov, Amundsen and Nansen Basins. Sediment cores were collected

in areas of sediment accumulation along the cruise track.

The levels of artificial radionuclides in Arctic Ocean water are low and

require concentration from large volumes of water in order to measure the

levels by conventional counting techniques. Samples were collected either by

combining several Niskin bottle samples from the rosette sampler or by using

pumps to pass water through resins and absorbers that remove and concentrate specific isotopes. Cesium isotopes (137Cs and 134Cs) were counted on

KCFC (potassium cobalt ferrocyanide) resin. Strontium, plutonium and americium isotopes (90Sr, 239,240Pu, 238Pu and 241Am) were concentrated from 60

to 100 L by precipitation, and the concentrates were returned to the laboratory for further purification and counting. Sediment cores were subsampled

and analyzed at 1-cm intervals. Sediment analyses are being used to calculate

sediment inventories of artificial radionuclides and to identify areas of net

accumulation.

Preliminary measurements for 137Cs and 129I clearly show the presence of

Sellafield and Chernobyl contaminants in surface and Atlantic-layer water

throughout the Arctic Ocean. The main exception was surface water in the

Chukchi Sea, where Pacific-origin water, containing only atmospheric fallout,

flows in through the Bering Strait. The highest activities (12–15 Bq/m3 for

137Cs and 80–100 × 107 atoms/L for 129I) were found over the Lomonosov

Ridge near the North Pole, consistent with the surface circulation pattern of

Sources of artificial

radionuclides in the

Arctic Ocean.

60

Atlantic Water Flow

Effluent From Russian

Processing Plants

Russian Nuclear

Test Sites

Russian Radioactive

Dumpsite

Effluent From the 

Sellafield 

Processing Plant

Effluent from Russian

Processing Plants

Russian Nuclear

Test Sites

Russian Radioactive

Dumpsite

Effluent from the

Sellafield

Processing Plant

Atlantic Water Flow
the Trans Polar Drift, which carries surface

water from Siberia across to Greenland. The

high activities and ratios of isotopes 129I/

137Cs and 134Cs/137Cs identify the source

as European reprocessing plants and Chernobyl fallout and indicate that the late-1970s

peak of Sellafield-labeled water has now

passed over the central Arctic Ocean, approximately 15 years later. A comparison of the

137Cs profile measured at the North Pole to

profiles measured in 1979 and 1991 illustrates the history of the transport. In 1979

the water column contained 137Cs mainly

derived from atmospheric fallout, before the

Chernobyl accident and before effluent from

European reprocessing plants had reached the Atlantic layer of the central

Arctic Ocean. A large increase in the 137Cs inventory in surface waters by

1991 and 1994 was caused by the arrival of Sellafield and Chernobyl 137Cs.

The 137Cs levels below 1000 m are not significantly different from those measured in 1979, indicating the continued maintenance of a pronounced Sellafield signal at this depth since 1979. The results from the sediment analysis

indicate that the shelf slope sediments of the Chukchi Sea contain the highest

inventory of artificial radionuclides, while the central Arctic areas have the

lowest inventories.

Preliminary results provide little evidence of radioactive contamination of

the Arctic Ocean from Russian sources. However, the transport pathways of

potential contaminants can be delineated through studies of tracers from European reprocessing plants. Although the magnitude of the artificial radionuclide

signal measured in the Arctic Ocean may be a factor of ten greater than levels

due to atmospheric nuclear tests, these levels are significantly lower than levels

that would constitute a radiological threat to organisms or humans along the

North American coast.

137Cs profiles measured at the North

Pole in 1979, in

1991 and during

AOS-94.

5000

0 8 12 16 20 4

4000

3000

2000

1000

0

137Cs (Bq/m3)

Water Depth (m)

LOREX (1979)


Oden (Sta. 173, 1991)


AOS (Sta. 35, 1994)

61

Contaminants
1994 Arctic Ocean Section

Persistent Organic Contaminants

Robie Macdonald and Fiona McLaughlin

AOS-94 provided a unique opportunity to collect contaminant samples

across a large, unsampled portion of the Arctic Ocean. One strength of this

contaminant study is that the transect crossed all major atmospheric and ice

transport routes, water bodies and three of the four main basins within the

Arctic Ocean. A second strength is that samples were collected in conjunction

with physical and biological data. In contrast, because of limited accessibility,

previous investigations have produced a patchwork of data, collected by different groups using a variety of methods over time, generally focusing on smaller,

specific regions.

 Our strategy for sample collection was to examine each of the major environmental compartments; ice, water, particles, plankton, fish and sediments.

Beginning with the water column, we adopted several strategies. Vertical profile

samples were collected for the most water-soluble organochlorine contaminant, hexachlorocyclohexane

(HCH; one form, alpha, is the pesticide Lindane), at

selected stations from the Chukchi to the Greenland

Seas. These samples will provide the basis for producing an HCH budget for the Arctic Ocean and

may allow us to separate the contributions by source

or pathway (southeast Asia versus northern Europe).

Other less-soluble organochlorine contaminants, such

as PCBs, require collection of larger quantities of water

in order to make reliable measurements. To collect

samples for these analyses, we moored submersible

pumps equipped with columns and filters to obtain

the 400 L or more of water required to exceed detection limits. Vertical profile samples for these less-soluble contaminants were collected at two stations; these

data will augment the limited profile data collected

at the Hobson’s Choice Ice Island in 1986 and in

the Beaufort Sea in 1992.

62

Robie Macdonald and Fiona McLaughlin are with the Institute of Ocean Sciences in Sidney, British Columbia,

Canada.

Rob MacDonald

collecting Arctic

cod for contaminant studies.
Samples of suspended particulate material

were collected in the top 30 m of the water column at many stations using a system capable of

pumping and filtering large volumes of water

quickly. These samples will help us to determine

the fractionation of contaminants between dissolved and particulate phases, an important aspect

of the process of scavenging and removal of contaminants from the euphotic zone.

Samples of zooplankton were collected using

vertical net hauls in the top 100 m of the water

column. These will be analyzed for organochlorine contaminants, which will determine the level

of biomagnification in the lower part of the food

chain. Cod, a species higher in the food chain,

were collected opportunistically across the transect. By combining the zooplankton and cod data,

we have a unique view of both bioaccumulation

and biomagnification of organochlorines in the

food chain across this section.

Sediment cores were collected at eight stations

spanning the cruise track. Samples from these

cores will be analyzed to provide information on particle-active contaminants,

for example, lead, highly chlorinated organochlorines and PAH (polynuclear

aromatic hydrocarbon). The levels of these contaminants will be examined to

determine both the spatial trends across the transect and the importance of

sediments as sinks for contaminants within the Arctic Ocean.

Although many samples are already under analysis, we do not yet have any

contaminant data for AOS-94. The process of analysis is complex and lengthy,

involving several analytical tools, for example, high-resolution mass spectrometry

and electron-capture gas chromatography. Information from the Larsen-93 cruise,

which collected samples from a region that overlaps the early portion of the AOS94 transect, suggests that we will find regional differences in contaminants

produced both by delivery mechanism (transport within water masses) and by

removal mechanism (biological productivity and the supply of particles). Understanding the relative importance of these mechanisms is crucial to our ability to predict the effects these compounds are likely to have on the Arctic

community and the time required for a response to any environmental change,

including a removal of the source.

63

Contaminants

Fiona McLaughlin

drawing water samples from the Niskin

bottles for chemistry

analysis on the

Louis S. St-Laurent
1994 Arctic Ocean Section

Air-Water Gas Exchange of Hexachlorocyclohexanes in the Arctic

Liisa Jantunen and Terry Bidleman

Our objectives for the AOS-94 cruise were to measure the transfer of chlorine-containing pesticides between the atmosphere and the Arctic Ocean. The

focus was on pesticides that have largely been banned in Canada and the United

States but are still used in other countries. These chemicals are emitted into

the atmosphere through current usage and volatilization of old residues from

soils. Air currents carry them to remote areas worldwide, including the Arctic.

One pesticide of special interest was hexachlorocyclohexane (HCH).

HCH is applied as a technical mixture that contains several isomers, largely

α-HCH (60–70%), β-HCH (5–12%) and γ-HCH (10–15%) (Iwata et al.

1993). The active ingredient, γ-HCH, is also produced in pure form and sold

as the pesticide Lindane. Both insecticides were produced during World War

II and are still in large-scale use today. Canada banned technical HCH in

1971, followed by the United States in 1978. Lindane is still registered for restricted applications in these countries and is the main HCH product used in Europe

(Barrie et al. 1993, Hinckley et al. 1991). Technical HCH was heavily used in

Asian countries throughout the 1980s. Reports from India range from 20,000 to

47,000 tons/year (Iwata et al. 1993, Hinckley et al. 1991). It is estimated that the

cumulative worldwide use since the introduction of HCH products is over 500,000

tons (Voldner and Li 1995). Because of their widespread usage and ease of transport, HCHs are the most abundant pesticides in the Arctic air and surface

waters.

Air was sampled by drawing approximately 700 m3 per day through a filter

followed by a polyurethane foam cartridge. HCHs were extracted from water

by passing 4–20 L through a filter followed by a C8-bonded silica cartridge.

Analysis was done in the home laboratory, using capillary gas chromatography

with electron capture detection and negative ion mass spectrometry.

The accompanying figures show the results of air and water sampling for

α-HCH; they also contain data collected in the Bering and Chukchi Seas in 1993

aboard the Russian R/V Okeah to complete the overall picture. The figures show

the spatial distribution of α-HCH, from the Bering Sea to the Greenland Sea over

the North Pole. Concentrations of α-HCH in water of the Bering and Chukchi

Seas averaged 2.00 ± 0.48 ng/L (Jantunen and Bidleman 1995), increased in

64

Liisa Jantunen and Terry Bidleman are with the Atmospheric Environment Service, Downsview, Ontario,

Canada.
65

Contaminants

6

5

4

3

2

1

0

140

120

100

80

60

40

20

0

Latitude (°N)

(ng/L) (pg/m3)

HCH E ti i R ti

a. Water

b. Air

50 - 5455 - 5960 - 64

 65 - 69

70 - 7475 - 7980 - 8485 - 8989 - 8584 - 8077 - 6767 - 6155 - 45

α-HCH Concentration

Bering Sea Greenland Sea

Surface water and air concentrations of α-HCH measured on BERPAC93 and AOS-94, averaged within

bands of 5° latitude.

the Arctic Ocean to 4.61 ±0.45 ng/L and decreased

in the Greenland Sea to 1.52 ±0.33 ng/L. The

trend of α-HCH in air was opposite to that found

in the water. The concentrations were highest over

the Bering and Chukchi Seas (123 ±16 pg/m3)

and the Greenland Sea (119 ±16 pg/m3) but decreased dramatically over the Arctic Ocean (57 ±20

pg/m3). The dip over the polar ice cap may be due

to rain scavenging by fog and drizzle and inhibited

revolatilization from surface water by the ice cap.

The water/air fugacity ratio can be calculated

from the α-HCH concentrations in air and water

and the temperature-dependent Henry’s Law constant. The fugacity ratio expresses the saturation

state of surface water relative to the partial pressure

of the α-HCH in air. In the 1980s fugacity ratios

of α-HCH were less than 1.0 in Arctic and subArctic waters, indicating that the surface water was

undersaturated and the net flux was air to sea. Our

measurements in the Bering and Chukchi Seas

(Jantunen and Bidleman 1995) and on the AOS94 cruise show that concentrations of α-HCH in

the air have decreased by three-fold since 1990.

Reducing the partial pressure of α-HCH in air has

raised fugacity ratios to above 1.0. Thus the surface

waters are now oversaturated and volatilizing αHCH.

Release of α-HCH from the ocean can be sensed

by following the proportion of its two enantiomers

in water and air. Enantiomers are mirror-image

molecules that have the same physicochemical

properties but that often differ in their biochemical characteristics. Right- and left-handed amino

acids are familiar examples, and α-HCH is similar. The enantiomeric ratio (ER) of α-HCH is defined as (+)α-HCH /(–)α-HCH. The ER in the

manufactured pesticide is 1.00 (racemic) and is

not changed by abiotic reactions such as hydrolysis and photolysis. However, enzymes can and frequently do react selectively with one enantiomer,

leading to ERs that differ from 1.00 (Buser and

Muller 1995). We have found selective depletion

of either (+) or (–) α-HCH in surface water, pre1.2

1.1

1.0

0.9

0.8

0.7

1.2

1.1

1.0

0.9

0.8

0.7

Latitude (°N)

α-HCH Enantiomeric Ratio

c. Water

d. Air

50 - 5455 - 5960 - 64

 65 - 69

70 - 7475 - 7980 - 8485 - 8989 - 8584 - 8077 - 6767 - 6155 - 45

Bering Sea Greenland Sea

Enantiomeric ratios of α-HCH in surface water and

air in the same bands of 5° latitude.
1994 Arctic Ocean Section

sumably the result of microbial degradation. These enantiomeric “signatures”

of α-HCH are reflected in the overlying air, providing a direct indication of

sea-to-air transfer.

The accompanying figures show the ERs of α-HCH in water and air with

latitude. In the Bering and Chukchi Seas the ERs are greater than 1.00, indicating a degradation of (–)α-HCH relative to (+)α-HCH. Selective breakdown

of (+)α-HCH in the Arctic Ocean and the Greenland Sea reverses the ERs to

less than 1.00. These enantiomeric profiles are also found in air samples collected over open-water regions, indicating volatilization of α-HCH from surface

water. The α-HCH in air over the ice cap was near racemic. Fugacity ratios at

higher latitudes also show the potential for α-HCH to volatilize (this work and

Falconer et al. 1995), but fluxes are probably inhibited by the ice cover.

 Using the ER of α-HCH provides a way of distinguishing α-HCH that has

been microbially processed and recycled to the atmosphere by the oceans from

“fresh” α-HCH that has undergone aerial transport from source regions.

Enantiomers of chiral pesticides, such as α-HCH, chlordanes and heptachlor,

may also prove useful for tracing water masses with different ER signatures

when employed with traditional tracers such as salinity, temperature, nutrients and dissolved oxygen.

REFERENCES

Barrie, L.A., D. Gregor, B. Hargrave, R. Lake, D. Muir, R. Shearer, B. Tracey

and T. Bidleman (1992) Arctic contaminants—Sources, occurrence and pathways. Science of the Total Environment, 122: 1–74.

Buser, H., and M. Muller (1995) Isomer and enantioselective degradation of

hexachlorocyclohexane isomers in sewage sludge under anaerobic conditions.

Environmental Science and Technology, 29: 664–672.

Falconer, R., T. Bidleman and D. Gregor (1995) Air–water gas exchange and

evidence for metabolism of hexachlorocylohexanes in Resolute Bay, NWT.

Science of the Total Environment, 160/161: 65–74.

Hinckley, D., T. Bidleman and C. Rice (1991) Atmospheric organochlorine

pollutants and air–sea exchange of hexachlorocylohexane in the Bering and

Chukchi Seas. Journal of Geophysical Research, 96: 1702–1713.

Iwata, H., S. Tanabe, N. Sakai and R. Tatsukawa (1993) Distribution of persistent organochlorines in the oceanic air and surface seawater and the role of

oceans on their global transport and fate. Environmental Science and Technology, 27: 1080–1098.

Jantunen, L., and T. Bidleman (1995) Reversal of the air–water–gas exchange

direction of hexachlorocyclohexanes in the Bering and Chukchi Seas. Environmental Science and Technology, 29 (4): 1081–1089.

Voldner, E., and Y. Li (1995) Global usage of selected persistent organochlorines. Science of the Total Environment, 160–161, 201–206.

66
Volatile Halomethanes

Robert M. Moore and Charles Geen

Volatile organohalogens have an important influence on atmospheric chemistry. In particular, halogenated methanes provide a source of atmospheric

chlorine and bromine radicals, which can affect ozone concentrations. There

has been shown to be a strong correlation between elevated atmospheric concentrations of brominated substances and sudden tropospheric ozone depletion

events, especially during the Arctic spring. There are also indications that brominated compounds play a significant role in stratospheric ozone destruction.

It is important to distinguish between natural and anthropogenic inputs of

these compounds. In attempting to understand the ozone depletion events in

the Arctic boundary layer, there has been considerable interest in examining

the natural Arctic marine origins of volatile bromine compounds (bromoform

in particular) as potentially significant sources of gaseous halogens to the atmosphere. Our research group has previously found evidence of an ice-algal source

of bromoform and dibromomethane in the Arctic. Evidence also exists in northern waters for a phytoplankton source of volatile iodine compounds, which

can play a role in the biogeochemical cycling of iodine and in atmospheric

chemistry.

Our objective in participating in the AOS-94 cruise was to extend the database of measurements of distributions and concentrations of brominated, chlorinated and iodinated methanes in the Arctic Ocean. This would contribute to

the goal of determining the natural origins of these compounds; in fact, this

expedition was the culmination of a five-year, Arctic-wide study of the sources

of such substances. Measurements were also made of the trace gas concentrations

in seawater that had been allowed to equilibrate with the atmosphere; these

are needed for calculating fluxes of the gases between the ocean and the atmosphere.

Almost 500 seawater samples were analyzed by gas chromatography during the cruise. Vertical profiles from many stations provided further general

oceanographic knowledge of water column distributions of the halomethanes

and generally showed the concentrations of the halocarbon gases of interest to

be higher in the surface waters and to decrease with depth. However, since our

67

Contaminants

Robert Moore is with the Department of Oceanography at Dalhousie University at Halifax, Nova Scotia,

Canada. Charles Geen is with Bovar-Concord Environmental in Toronto, Ontario, Canada.
1994 Arctic Ocean Section

interests were principally the origins and behavior of naturally produced volatile halocarbons in the upper ocean, the work focused on surface-water

distributions and the results from the equilibration experiments. Initial data

analysis centered on the primary compounds of interest—bromoform (CHBr3),

dibromomethane (CH2Br2) and chloroiodomethane (CH2ClI)—but data are

being processed for other compounds in our suite of analytes, including bromodichloromethane (CHBrCl2), chlorodibromomethane (CHBr2Cl), methyl

iodide (CH3I) and diiodomethane (CH2I2).

The results of the equilibration experiments indicate that the direction of

flux will be from the ocean to the atmosphere, since the water is supersaturated

with respect to the air. The water column is stably stratified, so there is little

downward mixing. Other dissipation processes, such as hydrolysis and substitution reactions, are relatively slow, so ventilation to the atmosphere is likely to

be the main short-term removal mechanism for any of these dissolved gases in

the seawater.

The results of our seawater measurements during AOS-94 indicate that

some of the halomethane concentrations in the upper water column at these

high latitudes beneath the polar ice pack are relatively high, even during late

summer and early fall. For example, bromoform concentrations at most stations

are equal to or greater than any others that we have previously measured from

spring to autumn in the open ocean waters or beneath the ice of several Arctic

regions, including Baffin Bay, Alert, Resolute Bay, the Beaufort Sea, the Bering

Sea and the Chukchi Sea. It would appear that while temporal variations may

be relatively large in open ocean areas and in regions where the ice cover melts for

part of the year, they may not be as great in permanently ice-covered regions.

The unexpected picture emerging from the AOS-94 expedition—that halomethane concentrations remain high beneath the polar ice cap throughout

68

Laboratory on the

Polar Sea equipped

for analysis of atmosphere and ocean

contaminants.

[Photo by Peter

Brickell.]
the summer and into the fall—means it is likely that even in winter, when

such substances may not be produced, large amounts would still be present in

surface waters. If in fact there is a fairly constant source of halomethanes beneath the ice pack, any lead, crack, polynya or open water could provide a flux

of these gases to the atmosphere at any time. In this case the question of the

possible origins of the Arctic springtime atmospheric pulse of bromine then

becomes one of physics and ice dynamics. That is, how often, and for how

long, are open-water areas present in the Arctic during the dark winter and

early spring?

Finally, in pursuing our questions of possible biological sources of these

gases, it will be of interest for us to examine our halocarbon data at particular

stations in collaboration with information provided by other AOS-94 colleagues. While halomethane concentrations may not be directly correlated

with bulk phytoplankton biomass, they might demonstrate some correlation

with the presence or species abundance of particular ice algae or phytoplankton identified by other researchers during the expedition.

69

Contaminants
1994 Arctic Ocean Section

C2–C6 Hydrocarbons

Peter C. Brickell and Jan W. Bottenheim

In recent years there has been growing concern about human impact on the high Arctic regions. Light hydrocarbons

(C2–C6) in the environment include species that are primarily anthropogenic (for example, acetylene) and those that are

primarily biogenic in origin (for example, isoprene). These

species are of concern in the troposphere because they play a

major role in ground-level ozone formation in urban and urbanimpacted regions. The study of the light hydrocarbon composition of the high Arctic troposphere can provide one more

indication of human impact on the region. In addition, the

study of light hydrocarbons in background environments can

lead to a better understanding of photochemical reaction pathways occurring in these and other more polluted locations.

The high Arctic environment is generally free of the myriad

of local and regional anthropogenic hydrocarbon sources that

complicate the study of hydrocarbon photochemistry in southern continental

regions.

The goals of the light hydrocarbon measurement program during AOS-94

were to:

• Develop a reference light hydrocarbon database for the very high latitudes

in summer;

• Compare these data with those previously taken from land-based sites in

the high Arctic (for example, Barrow, Alaska; Alert, N.W.T., Canada; and

the Norwegian Arctic);

• Look for evidence of unusual patterns of chemical processes in the Arctic

troposphere; and

• Investigate the levels and patterns of anthropogenic light hydrocarbons at

very high latitudes and compare these with the levels of other anthropogenic tracers measured during AOS-94.

Air for light hydrocarbon analysis was sampled in two ways. We collected

air in electropolished stainless steel canisters using a battery-powered pump,

70

Peter Brickell and Jan Bottenheim are with the Atmospheric Environment Service in Downsview, Ontario,

Canada.

The aft port bridge

of the Polar Sea,

showing the tripleheaded air sampling

manifold leading

into a rear window

of the bridge superstructure.
and samples were stored for later analysis. Air was also drawn through a stainless steel sampling line mounted 22 m above the water line above the port

flying bridge. The line was routed to the laboratory, where samples were preconcentrated and then immediately analyzed by in-situ gas chromatography. Canisters could also be analyzed by this system for intercomparison measurements

with our laboratory in Toronto.

Because the location of the sampling line was fixed, this second method of

sampling could only be used when a substantial breeze (more than 3 m/s) was

blowing off the port side of the ship. This was necessary to avoid sampling

emissions from the vessel itself, and it essentially limited sampling to times

when the ship was stopped for science stations and when other sources of

contamination (such as helicopters) were absent. Suitable conditions for sampling were determined by monitoring the real-time output of carbon monoxide and condensation nuclei counter instruments. Sampling with the portable canister system was more flexible and allowed air to be

collected from any upwind location on the ship

or even on the ice if conditions warranted it. In

total 113 canister samples and 53 direct samples were collected; 40 of the canister samples

were analyzed with the on-board gas chromatography system.

Canister data are available for the lowmolecular-weight alkanes and acetylene. During AOS-94 the mean ethane concentration

from 73to 80°N was 836 ± 68 pptv on the Pacific side of the Arctic Ocean. This agrees well

with the concentrations observed during the

1988 ABLE 3A aircraft study based at Barrow,

Alaska. Farther north, from 81to 87°N, ethane

concentrations dropped to 726 ±36 pptv. From

87°N through the Pole and down to 80°N on

the Atlantic side of the Arctic Ocean, ethane

concentrations rose slightly to 765 ±51 pptv.

Propane concentrations followed a similar pattern for the three areas. Acetylene concentrations were initially 56 ±6 pptv and rose slightly

to 64–65 pptv in the high-latitude and Atlanticside areas. The Pacific-side data agree well with

those from the 1988 ABLE 3A for Alaska, and

the high-latitude and Atlantic-side concentrations compare very favorably with those for the

Norwegian Arctic.

71

Contaminants

70 80 90 80

Pacific Atlantic Latitude (°N)

100

90

80

70

60

50

40

Acetylene Concentration [ppt(v)]

70 80 90 80

Pacific Atlantic Latitude (°N)

1000

900

800

700

600

Ethane Concentration [ppt(v)]

Acetylene concentration vs. latitude during AOS-94.

Ethane concentration vs. latitude during AOS-94.
1994 Arctic Ocean Section

Ratios of acetylene and propane to ethane concentrations were also calculated for this data set. The acetylene-to-ethane ratio for the Pacific side data is

consistent with the one for Alaska, but the Atlantic-side ratio is higher than

for the Norwegian Arctic. This difference is due to the lower AOS-94 ethane

results for the Atlantic side. Propane-to-ethane ratios are slightly higher than

those reported by other researchers for both the Pacific side and Atlantic side.

The difference on the Pacific side is attributable to the somewhat higher propane concentrations, and on the Atlantic side the difference is again due to

lower ethane concentrations.

The preliminary data from the light hydrocarbon canister sampling program agree well with work that has been done previously in the Alaskan and

Norwegian Arctic. The lower ethane concentrations on the Atlantic side of

the Arctic Ocean are probably attributable to increased distance from terrestrial sources. The ethane concentrations observed in the high-latitude portion

of the transect may be useful for determining the degree of aging of the air

mass encountered in this area. These light hydrocarbon concentrations will

provide additional data for estimating the background tropospheric volatile

organic compound levels used to input advective inflows for continental atmospheric modeling. In addition, although only data from the high Arctic regions

have been presented here, we collected hydrocarbon and some additional atmospheric data throughout the entire circumnavigation of the North American

continent during AOS-94. This has yielded a unique data set for assessing the

nature of continental and oceanic air masses, as well as providing an extended

latitudinal profile from 7 to 90°N for these atmospheric species. Finally, once

the Arctic data are available from all the compounds analyzed with the in-situ

gas chromatograph, it is expected that an improved understanding of background atmospheric chemical processes will have been derived from the sampling carried out on this unique expedition.

AOS-94 light hydrocarbon concentrations and ratios compared with

those from other researchers for Alaska and the Norwegian Arctic.

Ethane Acetylene Propane Acetylene/ Propane/

(pptv) (pptv) (pptv) Ethane Ethane

Pacific (73–80°N) 836 ± 68 56 ± 6 69 ± 12 0.061 0.084

High Latitude (80–87°N) 726 ± 36 64 ± 7 64 ± 8 0.088 0.089

Atlantic (87–90–80°N) 765 ± 51 65 ± 8 87 ± 59 0.085 0.113

Alaska* 865 ± 59 57 ± 17 53 ± 15 0.066 0.061

Norwegian Arctic† 1195 ± 27 67 ± 18 87 ± 30 0.056 0.073

* From Blake, D.R., D.F. Hurst, T.W. Smith, W.J. Whipple, T. Chen, N.J. Blake and F.S.

Rowland (1992) Summertime measurements of selected nonmethane hydrocarbons in

the Arctic and Subarctic during the 1988 Arctic Boundary Layer Expedition (ABLE 3A).

Journal of Geophysical Research, 97: 16,559–16,588.

† From Hov, O., S.A. Penkett, I.S.A. Isaksen and A. Semb (1984) Organic gases in the

Norwegian Arctic. Geophysical Research Letters, 11: 425–428.

72
— Cloud Radiation —

Atmospheric Radiation and Climate Program

Dan Lubin and Robert H. Whritner

One of the major physical components of climate change is the way in

which solar energy is redistributed in the Earth–atmosphere system. This subject also includes the simultaneous emission of thermal (infrared) energy from

the Earth’s surface and its partial entrapment by the atmosphere (the “greenhouse” effect). Globally well-mixed increases in carbon dioxide abundance are

believed by many to be enhancing the greenhouse effect and increasing the

global surface temperature field. This could have serious repercussions for Arctic

Ocean climate, as the Arctic Ocean surface exists for much of the year at

temperatures just below the freezing point of water. A small increase in surface

temperature could potentially have a large impact on the geographic extent of

Arctic sea ice, with resulting changes to the energy balance between the atmosphere and ocean.

Most of the scientific community’s insight into potential “global warming”

scenarios comes from large computer simulations called general circulation

models (GCMs). The GCMs are quite sophisticated but often suffer from a

lack of experimental input data and input physics from many remote regions

throughout the world, particularly the Arctic. AOS-94 offered a unique opportunity to deploy state-of-the-art atmospheric radiation budget measurement apparatus in the high Arctic and to allow them to gather data continuously for several weeks. This was the first high-Arctic expedition to deploy

these advanced optical instruments, and the large resulting data set should

enable better representation of the Arctic atmosphere in the GCMs.

The California Space Institute project consisted of three major components, all deployed aboard the Polar Sea. The first was a battery of broad-band

solar and infrared flux radiometers mounted above the pilothouse. Three Eppley Laboratory radiometers measured downwelling short-wave (0.28–2.8 μm),

near-infrared (0.78–2.8 μm) and middle-infrared (4–50 μm) radiation reaching the Arctic Ocean surface. A Biospherical Instruments radiometer measured

downwelling solar ultraviolet and visible radiation at 0.308, 0.320 and 0.380 μm,

as well as radiation in the intervals 0.580–0.680 μm (to match a satellite radiomCloud Radiation

73

Dan Lubin is with the California Space Institute at the Scripps Institution of Oceanography in La Jolla, California, U.S.A. Robert Whritner is with the Arctic and Antarctic Research Center at the Scripps Institution of

Oceanography in La Jolla, California, U.S.A.
1994 Arctic Ocean Section

eter) and 0.400–0.700 μm (total photosynthetically active radiation). These

radiometers operated automatically and recorded data in one-minute averages

continuously throughout the cruise.

The second component consisted of the shipboard satellite tracking facility, the TeraScan system manufactured by the SeaSpace Corporation. In addition to providing weather and ice navigation for the expedition, the satellite

tracking enabled this project to measure energy reflected and emitted to space

at the same time that the shipboard instruments were measuring solar and

terrestrial radiation impinging on the Arctic Ocean surface. The TeraScan system was used to track NOAA polar-orbiting satellites, obtaining 1.1-km spatial

resolution images from the advanced very high resolution radiometers

74

The California

Space Institute

experiment design

during AOS-94.
(AVHRR), which measure radiation at five visible and infrared wavelengths. The

Defense Meteorological Satellite Program (DMSP) satellites were also tracked,

giving this project access to the special sensor microwave imager (SSM/I), which

was used to map sea ice along the expedition’s track. Throughout the cruise,

the Polar Sea TeraScan facility tracked between five and ten satellite overpasses

per day.

The third component consisted of a Fourier transform infrared (FTIR)

spectroradiometer operating in the middle infrared (5–20 μm) with a spectral

resolution of 1 cm–1 (Lubin 1994). FTIR data collection was coordinated

with the NOAA satellite overpasses, and a total of 178 sky scenes were studied

with the FTIR instruments. This instrument made detailed measurements of

radiation trapped by the atmosphere in the middle-infrared window (8–13

μm). Under clear skies the atmosphere is relatively transparent in this wavelength range, and a large portion of the heat given off by the ocean surface

escapes to space. Under cloudy skies, this window is mostly closed, meaning

that far less radiation escapes to space and the greenhouse effect is enhanced.

These greenhouse enhancements due to clouds are more than an order of

magnitude larger than what is expected from a doubling of carbon dioxide in

the atmosphere, so understanding the role of clouds in the atmospheric energy balance is critical before we can make meaningful “global warming” predictions with GCMs.

During the summer of 1994, the atmosphere over the Arctic Ocean exhibited a great deal of complexity, much more than is now represented in the

GCMs. A common occurrence was multiple-layered cloud systems. The accompanying figure is an image of terrestrial infrared radiation (10.5–11.5 μm)

emitted by the Arctic

ocean–atmosphere

system to space, expressed in units of

equivalent brightness

temperature. At the

time of this satellite

overpass (4 August)

the Polar Sea was at

78°N, roughly in the

center of the image,

where there were three

distinct temperature

ranges in the cloud

fields corresponding

to three distinct ranges in cloud top height.

When the atmosphere

Cloud Radiation

75

AVHRR image

obtained from the

shipboard TeraScan

system on 4 August

1994 during AOS94. Brighter shading

refers to lower cloud

top temperatures.

NOAA-12 AVHRR

Channel 4 (Deep infrared)

04 August 1994 0057Z

 0

–4

–8

–12

–16

Deg C
1994 Arctic Ocean Section

contains a large amount of liquid or ice

water, as is the case with these multiplelayered cloud systems, a large portion of

the sun’s energy is reflected back to space

or absorbed by the atmosphere before

reaching the surface.

 Two examples of atmospheric emission spectra from the CalSpace FTIR instrument are shown in the figure to the

left, under low atmospheric opacity.

Here the instrument is measuring terrestrial energy trapped by the atmosphere

and emitted straight back down toward

the ship. The middle infrared window exists between 800 and 1300 cm–1 on

this plot. The dotted curve, obtained under clear skies, shows that there is

very little energy being trapped and re-emitted by the atmosphere in the window, meaning that most is escaping to space. For wave numbers shorter than

800 and longer than 1300 cm–1, the atmosphere is largely opaque, and most

of the energy emitted by the Earth’s

surface at these wave numbers is always

trapped by carbon dioxide and water

vapor. The upper (solid) curve was obtained under a high ice cloud, and we

can see that in the window this cloud

results in nearly an order of magnitude

more energy at the ocean surface.

 The figure to the left shows two

FTIR emission spectra obtained under

overcast skies (the most frequent sky

condition during AOS-94). The upper

(dotted) curve was obtained on 4 August, the same day as the AVHRR and

solar radiometer data discussed above. At the time of this measurement there

was so much liquid water in the atmosphere that the atmosphere radiated

energy to the surface almost like a perfect blackbody, as signified by the smoothness of this curve. In this situation, when we have a combination of high

cloud layers appearing very cold in the satellite data (that is, they are radiating

relatively little energy to space) and low cloud layers radiating nearly as much

energy as possible to the surface, at nearly the surface temperature, the greenhouse effect of the atmosphere is nearly at a maximum. The lower (solid) curve

was obtained under a single-layer stratus cloud. The middle infrared window is

almost but not quite closed. This is because the cloud base is several degrees

colder than the surface and because the cloud emissivity is less than one, mean76

Atmospheric

emission spectra

measured by the CalSpace FTIR under

conditions of low

atmospheric opacity.

Atmospheric emission

spectra measured

by the CalSpace FTIR

under conditions

of high atmospheric

opacity.
77

ing that the cloud does not contain enough liquid water to emit radiation like

a perfect blackbody. A doubling of carbon dioxide in the Earth’s atmosphere is

expected to increase the flux of infrared radiation at the surface by 3–4 W/m2.

The enhancements in surface infrared radiation related to changing cloud liquid water content and emissivity are on the order of tens of watts per square

meter.

The FTIR cloud emission spectra can be used to estimate the effective radius

of the cloud droplet size distribution (Lubin 1994), which in turn can indicate

whether or not continental air masses are influencing cloud microphysics.

Radiative transfer analysis of the AOS-94 cloudy sky emission spectra suggest

that 30% of the stratiform clouds sampled have effective droplet radii of 7 μm

or smaller, in which case they are probably influenced by continental air masses

and aerosol concentrations. By showing this type of microphysical phenomenon, along with the large variability in cloud optical depth that can occur (0–

50), this program has illustrated that the summer atmosphere in the high

Arctic is as dynamically and radiatively complex as that over any other continent or ocean.

REFERENCE

Lubin, D. (1994) Infrared radiative properties of the maritime Antarctic

atmosphere. Journal of Climate, 7: 121–140.

Cloud Radiation
1994 Arctic Ocean Section

Aerosols

John D. Grovenstein, Richard Leaitch and Fred Hopper

Aerosols, especially those that influence cloud microphysics (droplet size

spectra), are important in atmospheric research because they influence climate

directly by backscattering and absorption of incoming solar radiation and indirectly by affecting cloud albedo. Wigley (1989) suggested that the latter

effect could be the reason that the planet has not exhibited heating as predicted by global climate models of the

“greenhouse effect.” Generally

climate models are poorly parameterized for aerosol and cloud microphysics, especially in the remote

Arctic. Therefore, it is necessary to

measure these parameters to provide data sets for modelers and to

diagnose future environmental

change.

 The figure at the left is a time

series of aerosol concentration

from AOS-94. The uppermost

dotted line is the condensation

nuclei (CN) concentration measured by TSI models 3025 and

3022 condensation nuclei counters. This number represents the concentration of the finest nuclei (nucleation mode) with a radius of 0.003 μm to the

larger aerosols up to a radius of 3 μm. The uppermost solid line is the cloud

condensation nuclei (CCN) concentration active at 1% supersaturation. These

measurements were taken with an instantaneous CCN spectrometer introduced by Fukuta and Saxena (1979). For this study the spectrometer was operated at a range of 0.2–1.3% supersaturation. The spectrometer makes one

spectral sweep every 15 s. The middle dotted line is the CCN concentration

active at 0.33% supersaturation measured by the DH Associates cloud con78

John Grovenstein is with the Department of Marine, Earth and Atmospheric Sciences at North Carolina State

University in Raleigh, North Carolina, U.S.A. Richard Leaitch and Fred Hopper are with the Atmospheric

Environment Service, Downsview, Ontario, Canada.

Time series of

aerosol concentration for the AOS-94

expedition.

208 212 216 220 224 228 232 236 240

Day (1994)

10000

1000

100

10

1

Concentration (cm–3)

CN


CCN (1% S)


CCN (0.33% S)


PCASP
79

densation nuclei counter. This instrument records the number of CCN active

at a single supersaturation (set at 0.33% for this study). The lowermost dotted

line is the large aerosol concentration (0.3–1.0 μm) measured with a Particle

Measuring Systems passive cavity aerosol spectrometer probe (PCASP-100X).

The instrument provides a histogram of aerosol concentration in 15 size ranges. The concentration from each size range is totaled to provide the concentration reported in the figure.

Sampling began on day 208 with instruments running on a continuous

basis. The concentration of aerosols measured by all instruments decreased

sharply upon entering the ice. The concentration of CN, CCN (active at 1%

supersaturation) and CCN (active at 0.33% supersaturation) “track” each other

through the time series, with the PCASP-100X showing this trend but not as

dramatically as the other measurements. Generally CCN concentrations in

maritime air masses rarely exceed 100 cm–3; however, concentrations above

100 cm–3 were measured over a time of days in the remote Arctic Ocean (days

218–224 and days 228–232). These large CCN concentrations also accompanied large CN concentrations, which in one instance (day 224) exceeded 7000 cm–3.

The concentrations of the larger aerosols,

measured by the PCASP-100X and the CCN

active at 0.33% supersaturation, never exceeded 100 cm–3 while we were sampling in the

ice. The observations of the largest CN and

CCN (active at 1% supersaturation) concentrations correspond to the lowest observed concentrations of the large aerosol with the

PCASP-100X. This suggests that the elevated

CN concentrations may be due to a local production mechanism. The reduction of the largest aerosol removes a significant surface area

for the condensation of precursor gases. The

concentration of these gases increases until, by

the process of gas-to-particle conversion, they

are converted into fine aerosol particles. Between days 218 and 224 the concentration of the finest aerosols are out of phase with the concentrations of the

largest aerosols; the peaks in concentration of one corresponds to the minimums of the other. Although this scenario may not be the cause of the observed concentrations, the high concentrations of the precursor gases necessary have been recorded in the Arctic. The figure above shows the relationship

between ice coverage and CCN concentration, illustrating the possible production of CCN from precursor gases. When the gas supply is limited by ice

cover, CCN concentration decreases. Regardless of the source, the particles are

present and are modifying the climate of the remote Arctic.

CCN concentration

at two supersaturations plotted against

ice coverage.

Cloud Radiation

500

400

300

200

100

0 2 4 6 8 10

Ice Coverage (tenths)

Concentration (cm–3)

CCN (1.0% S)


CCN (0.33% S)

1994 Arctic Ocean Section

REFERENCES

Fukuta, N., and V.K. Saxena (1979) A horizontal thermal gradient cloud

condensation nuclei spectrometer. Journal of Applied Meteorology, 18, 1352–

1362.

Saxena, V.K., and J.D. Grovenstein (1994) The role of clouds in the enhancement of cloud condensation nuclei concentrations. Atmospheric Research, 31,

71–89.

Twomey, S. (1977) The influence of pollution on the shortwave albedo of

clouds. Journal of Atmospheric Science, 34, 1149–1152.

Wigley, T.L.M. (1989) Possible climate change due to SO2 derived cloud

condensation nuclei. Nature, 339, 365-376.

80
— Sea Ice —

Sea Ice Characteristics across the Arctic Ocean

Walter Tucker, Anthony Gow, Hazen Bosworth,

Erk Reimnitz and Debra Meese

The Arctic ice cover separates the ocean from the atmosphere, so it is a key

component in the exchange of heat, mass and momentum between the two.

The properties of the ice cover in summer are especially important, as this is

the period of maximum solar radiation. During summer the ice properties

become extremely variable, having changed from a highly compact, reflective

snow-covered surface during winter and spring to a mottled surface consisting

of melt ponds, bare ice and deteriorating snow with many open leads. Major

changes occur in the overall surface albedo, the ice cover warms accompanied

by draining brine and melting ice, and incorporated sediment and contaminants can be released. The amount of light penetrating into the ocean stimulates biological activity, because a major part of the Arctic Ocean food chain is

within a few meters of the ice.

The ice characterization component of AOS-94 consisted of surface albedo

measurements, melt pond characterization, snow depth surveys, aerial photography surveys, ice-borne sediment sampling and ice coring. Ice cores were

used for thickness, salinity, temperature, chemistry and structural analyses,

and samples were provided to associates for stable isotope measurements.

Visual observations and satellite imagery obtained on the section indicated

that the concentration of ice increased rapidly from 50–70% south of 72°N

to 90–100% for the remainder of the section until the marginal ice zone in

the Eurasian Arctic was reached. Ice thickness also increased with northward

progress from about 1 m in the first-year ice of the southern Chukchi Sea to

about 2.7 m at the North Pole, as verified from visual observations and ice

core measurements. With the exception of three ice cores obtained in the

Chukchi Sea, all cores on the section were collected from second-year or multiyear ice. The cores revealed thermally degraded ice near the surface above the

water level and extremely well drained ice below. Temperatures of the ice were

consistently near zero at the surface, increasing linearly to about –1.5°C at the

ice–water interface. Salinities were also consistent with previous measurements

of summer sea ice (Tucker et al. 1987, Eicken et al. 1995), being zero at the

81

Sea Ice

Walter Tucker, Anthony Gow, Hazen Bosworth and Debra Meese are with the U.S. Army Cold Regions Research

and Engineering Laboratory in Hanover, New Hampshire, U.S.A. Erk Reimnitz is with the U.S. Geological

Survey in Menlo Park, California, U.S.A.
1994 Arctic Ocean Section

surface and increasing to 3–4‰ at depth. In general,

the thicker ice had greater salinities near the bottom.

 Examination of the crystalline structure revealed

that 89% of the total ice sampled consisted of columnar ice. Of the remainder, 9% consisted of granular

or frazil ice, and 2% contained platey ice, large platelettype ice that may have been associated with freezing

of under-ice melt ponds as suggested by Jeffries et al.

(1995). Much of the granular ice was associated with

previously deformed ice, identified by inclined columnar crystals in adjacent sections typical of tilted blocks.

 Surveys of snow depth were obtained at all ice sampling stations. South of 80° in the western Arctic, the ice appeared to be snow

covered, with very few bare ice spots visible. Close inspection of the snow

cover characteristics revealed very large grains, close to 1 cm in diameter. We

believe this indicates thermally deteriorated ice, rather than snow. Survey measurements showed mean depths of 6–13 cm of the deteriorated ice. Between

80° and 82°N metamorphosed corn snow was evident. In this region, mean

depths ranged from 10 to 15 cm. From 83° to 86°N depths of the old corn

snow decreased to 6–8 cm. North of 86° and into the eastern Arctic, new snow

was present, generally covering the old coarse snow, and the combined depths

were 6–15 cm. At all sites north of 80°, snow depths were variable, usually 0–

5 cm on flat thin ice and up to 46 cm on the flanks of pressure ridges. North

of 85° it appeared that the melt season was complete, and the depth of the

aged snow may represent the minimum for the 1994 ablation season.

 Melt ponds in the Chukchi and southern Beaufort Seas were numerous, but farther north the ponds

began to freeze and eventually became snow covered.

Image analysis of aerial photographs obtained from

helicopter surveys allowed quantitative estimates of

the melt pond fraction. On 31 July at 76°N the total

pond fraction was 12% and the lead fraction was

6%. On 13 August at 86°N the open pond fraction

was 3%, yet 10% consisted of identifiable frozen

ponds with a 2- to 5-cm ice cover. The lead fraction

had increased to 11%. At 88°N on 18 August no

open ponds were identified in the photographs, but

an areal fraction of 3% frozen ponds was evident.

The open water fraction remained at 11%. Measured

melt pond depths ranged from 20 to 60 cm. Six of

the 19 ponds sampled were saline and highly stratified, with near zero salinity at the surface to 30‰ at

the bottom of the ponds. Saline ponds, though ap82

0

100

200

300

400

Ice CoreThickness (cm)

5

10

15

20

Mean Snow Depth (cm)

Latitude (°N)

70 75 80 85 85 90

Pacific Atlantic

Ice core thickness

and mean snow

depth versus latitude during AOS-94.

The straight line is

the best-fit linear

regression.

0

50

100

150

200

250

300

–2 –1 0

Depth (cm)

Temperature (°C)

2 4

Salinity (‰)

0

Temperature and

salinity profiles for

the same core from

the North Pole.
83

Sea Ice

Ice crystal structure

of multi-year ice

sampled at the

North Pole.

pearing to have solid bottoms, obviously had an established hydraulic link

with the ocean below. Cores through

the bottom ice verified this, showing

rotten ice with interconnecting channels. Colors of the ponds varied from

very light blue to deep dark green. The

color depended on the pond depth, the

condition of the bottom ice and biological activity. Chlorophyll a concentrations were found to be substantially

larger in green freshwater ponds than

in the light-blue ponds. The albedos

of the ponds also depended on depth

and color. Deep ponds with rotten bottom ice had albedos of 0.09; albedos were

as high as 0.3 for shallow light-blue ponds. Frozen snowcovered ponds farther north exhibited albedos of 0.8.

A two-stream radiative transfer model (Perovich 1990)

has been used to estimate the partitioning of incident solar

radiation into that reflected back to the atmosphere, that

absorbed by the ice, and that penetrating the ice to the

ocean or directly into leads. The results show a dramatic

decrease in the solar radiation absorbed into the ice after

18 August, when fresh, light snow covered the ice. The

model points out that most of the radiation absorbed by

the ocean comes from the absorption by leads, rather than

through the ice.

Relative areas of

ice and partitioning

of incident solar radiation for 31 July,

13 August and 18

August 1994. The

contribution from

different surface

conditions to the

disposition of the

solar radiation is

also show

100

80

60

40

20

0

(%)

7/31 8/13 8/18 7/31 8/13 8/18 7/31 8/13 8/18 7/31 8/13 8/18

Area Covered Solar Radiation

Reflected

Solar Radiation

Absorbed in Ice

Solar Radiation

Transmitted to Ocean

Leads

Melt Ponds

Frozen Ponds

Ice
1994 Arctic Ocean Section

Sediment was observed in and on the ice from the ice edge in the Chukchi

Sea to the North Pole. Near the ice edge, sediment covered an estimated 10–15%

of the surface of the ice. Farther north it covered less than 1% of the surface and

was extremely “patchy” in occurrence. Sediment was notably absent in the Eurasian Arctic, where it has been frequently observed on other expeditions.

Bulk samples of sediment were collected for analysis, and in many locations

ice cores were obtained through the dirty ice. Sediment entrained within the

ice was invariably associated with granular (frazil) ice formation. Frazil ice is

normally associated with turbulent growth conditions. Analyses of the particle sizes found primarily silt- and clay-sized particles; only 5.3% of the total

sediment collected was sand, while the proportions of silt and clay were 32.7%

and 62.0%, respectively. The few pelecipodes, ostracodes and foraminifera

found in the sediment indicate the shallow circum-Arctic shelves as the source

of the entrained sediment. The combined evidence indicates that sediment is

likely entrained into the ice by ice crystals scavenging suspended sediment

during stormy conditions on the continental shelves. Diffraction analysis of

the clay fine portion showed it to be composed of primarily illite and chlorite,

with smaller amounts of kaolinite and smectite. The smectite proportion increased

from near zero in the south to 10–15% in the more northerly samples.

Reverse trajectories calculated for the ice parcels from velocity fields produced by the International Arctic Buoy Program indicate that the shelf source

areas from the southernmost samples were the Canadian and Alaskan shelves,

while the East Siberian Sea appears to be the source of the more northerly

samples. Comparisons of organic carbon between the ice-borne sediment and

benthic sediments showed that three times more organic carbon (2.6%) was

present in the ice sediments than in the benthos (0.8%). It is likely that the

larger amounts in ice are due to biological activity. Conversely the benthic

sediments had ten times more carbonate than the ice sediments (10.3 vs. 0.9%,

84

Tony Gow, Erk

Reimnitz, Bill

Bosworth and Terry

Tucker taking cores

of dirty ice.
respectively), probably due to higher concentrations of foraminifera on the

sea floor. The visual estimates of sediment on the ice surface would indicate

that the amount of sediment being transported by the ice is small, yet because

it was observed across most of the Arctic Ocean, it is capable of transporting

and redistributing shelf sediments across the entire Arctic Basin.

A primary objective of the detailed ice-sediment study was to determine if

radiocesium was present within the ice-entrained sediment. In the ice-borne

sediments, 137Cs activities ranged from 4.9 to 73 Bq/kg (dry weight). Many

of the samples had 137Cs activities exceeding those found in benthic sediments in the deep basins or the shelves of the Beaufort, Chukchi or Bering

Seas, though the levels are far too low to be of concern to health. The highest

value (73 Bq/kg), found north of the Chukchi Sea, is comparable to levels

present in the sediments of the Yenesey and Ob River estuaries and the Kara

Sea. However, the three-year reverse trajectory indicated that the source area

for this parcel of ice was the offshore Banks Island region. Since there is no

known source in the Banks Island area, either the ice parcel was far older than

three years and had been incorporated elsewhere in the Beaufort Gyre or the

trajectory calculation neglected the possibility of easterly transport along the

Siberian shelf. Another remote possibility may be that radiocesium levels are

enhanced during the process of sediment entrainment into ice.

REFERENCES

Eicken, H., M. Lensu, M. Lepparanta, W.B. Tucker III, A.J. Gow and O.

Salmela (1995) Thickness, structure, and properties of level summer multiyear ice in the Eurasian sector of the Arctic Ocean. Journal of Geophysical

Research, 100: 22,697–22,710.

Jeffries, M.O., K. Schwartz, K. Morris, A.D. Veazey, H.R. Krouse and S.

Cushing (1995) Evidence for platelet ice accretion in Arctic sea ice development. Journal of Geophysical Research, 100: 10,905–10,914.

Perovich, D.K. (1990) Theoretical estimates of light reflection and transmission by spatially complex and temporally varying sea ice covers. Journal of

Geophysical Research, 95: 9,557–9,567.

Tucker, W.B. III, A.J. Gow and W.F. Weeks (1987) Physical properties of

summer sea ice in the Fram Strait. Journal of Geophysical Research, 92: 6,787–

6,803.

85

Sea Ice
1994 Arctic Ocean Section

Measurements of Ice Mechanical Properties

F. Mary Williams

During AOS-94, ice mechanical properties were measured by the Institute

for Marine Dynamics. Williams (1994) gives details on the methods and results. The program was supported by Ship Safety, Canadian Coast Guard, as

part of a broad ship technology program.

Under the ship technology program, ice loads at three locations on the hull

of the Louis S. St-Laurent were monitored throughout the voyage, and significant events were recorded. Ship performance was documented by continuous

recording of propulsion system parameters, as well as ship speed and position.

The ice properties that influence hull loads and ship performance are the thickness, strength and density of the ice and the quality of the snow cover.

Ice temperature and salinity were measured at 10-cm intervals, and ice

density was measured at selected depths in vertical ice cores. Two cores were

taken at every science station in the ice using the Rapid-Core, a crane-deployed

coring device operated from the deck of the ship. Additional cores at sites

distant from the ship were taken using a hand corer. Often, average ice temperatures were –2°C, and average salinities were around 2‰. The ice contained

large brine channels, and brine in the upper layers had drained out.

Measurements of ice density from core samples are difficult at these temperatures. The result depends strongly on the amount of brine trapped in the

sample, which in turn depends on both the structure of the ice in the core and

sample handling. Most of the local density values were between 0.82 and 0.92

Mg/m3.

The inertial and buoyant forces of ice on the ship depend on the global, insitu ice density. This quantity, determined from freeboard measurements and

adjusted for the snow burden, was consistently between 0.92 and 0.93

Mg/m3.

A beam test is a direct measure of the flexural strength of the ice. When

logistics permitted, beam tests, in a standard size and configuration (Williams

and Parsons 1994), were carried out on the ice immediately after cutting the

samples. A typical result is a series of eight beams of columnar-grained ice at

–1.8°C, with an average flexural strength of 499 kPa. Some beam samples

were cold soaked and tested in the coldroom onboard the ship.

86

F. Mary Williams is with the Institute for Marine Dynamics in St. John’s, Newfoundland, Canada.
87

When ice fails against the ship hull, the relationship between the average

ice pressure and the loaded area depends, in part, on the maximum pressure

sustained over actual contact areas, or hot spots. In materials that deform

plastically, this pressure, called the hardness, may be considered a material

property. Hardness was measured using a 136° pyramid Vickers Indenter.

Hardness decreased as contact area increased, from maxima near 60 MPa over

10–5 m2 to values near 15 MPa over 10–4 m2. The effects of temperature and

of work done on the ice are being investigated.

Since ice thickness varies with date and location, a ship-based measurement is not representative of the entire Arctic. However, such a measurement

is appropriate in an analysis of ship performance and hull loads. A video camera aimed at the ice surface near the starboard shoulder of the ship ran continuously throughout the trip. A computer-generated scale, calibrated at the ice

surface, overlaid the image on the video record and measured the thickness

and length of ice pieces turned up by the ship. Statistical results will not be

available until these data have been carefully analyzed.

To determine the ice crystal structure, rough thin sections of ice from some

of the cores and all of the beams were prepared in the coldroom and photographed through crossed polaroid filters. Most of the photos show highly

metamorphosed, unoriented, largely granular ice in a range of grain sizes. One

surprise was an ice sample with zero salinity and very large grains (>8 cm in

diameter) inadvertently taken from a concealed, refrozen melt pond.

Snow reduces ship performance through the inertial, buoyant and friction

forces it exerts on a moving ship. The water content and grain size of snow

affect imagery collected by satellite-borne microwave sensors by changing the

apparent brightness temperature of the ice surface. Thus, snow density and

type are key links between remotely sensed ice imagery and actual ship performance. Global snow density was measured in small full-thickness samples,

Mary Williams

measuring the flexural strength of ice

beams.

Sea Ice
1994 Arctic Ocean Section

and the type was recorded qualitatively. Typical global

snow densities were 0.42 Mg/m3 for large-grained, wet

snow and 0.25 Mg/m3 for fine, new snow.

 For evaluating the ship’s performance, and also for

interpreting the ice forces on the hull of the ship, the

ice and snow mechanical properties data were separated

into four navigation zones. Up to latitude 80°N, there

was considerable surface melt and brine drainage. The

ice was porous and contained many flaws, allowing

relatively easy ship passage. However, mean ice temperatures indicate that layers of intact, relatively cold

ice were present in some floes, with a risk of significant hull loads.

North of 80°, where air temperatures were lower, mean ice temperatures

were slightly higher than in the first zone. This apparent paradox is due to

melt surfaces advancing more rapidly than conduction isotherms and is recognized in icebergs (Diemand 1984). The ice was close to its melting point and

presented low strengths throughout the thickness.

The heavy ice at the highest latitudes, 88°N and beyond, was composed of

extensively damaged, worked and reconsolidated ice features. For this fairly

homogeneous ice, a higher ice strength applies to both ship performance and

load risk.

The transit was rapid and the sampling sparse from 90°N south to 85°N.

Hence, it is not certain where to place the boundary between zone 3 and zone

4. However, south of 85°N the ice was clearly thinner, less complex and of

lower concentration. The drained, low-salinity ice had begun to refreeze. The

completely frozen freshwater melt pond at Station 37 was an illustration.

Because of extensive flaws due to melting, the mean ice strength was low, but

the presence of solid, low-salinity ice pushed up load risk levels.

REFERENCES

Diemand, D. (1984) Iceberg temperatures in the North Atlantic—Theoretical and measured. Cold Regions Science and Technology, 9(2): 171–178.

Williams, F.M. (1994) The Canada/U.S. 1994 Arctic Ocean Section—Ice mechanical properties measurements. Institute for Marine Dynamics: TR-1994-29.

Williams, F.M., and B.L. Parsons (1994) Size effect in the flexural strength of

ice. 13th International Conference on Offshore Mechanics and Arctic Engineering, Houston, Vol. IV, p. 15–22.

88

Ice properties in four navigation zones

during AOS-94. The maximum ice

strength is an index of maximum hull

loads, and the mean ice strength is an

index of ship performance.

Ice Floe Max Mean

Latitude cover size strength strength

(°N) (10ths) (km) (kPa) (kPa)

70–80 8 to 9+ 0.5 470 250

80–88 9+ to 10 3.0 250 250

88–90 10 1.0 500 500

85–81 8 to 9+ 0.5 600 300
89

Geology and Paleoceanography

— Geology and Paleoceanography —

Sources of Ice-Rafted Detritus and Iceberg Tracks in the Arctic Ocean

Dennis A. Darby and Jens F. Bischof

The sources of ice-rafted detritus (dropstones) were determined by matching the elemental composition of iron oxide grains and percentages of grain

types in Arctic Ocean deep-sea sediment cores to potential sources around the

Arctic Ocean. This “fingerprinting” technique required prior characterization

of source areas in the Arctic providing debris that could be rafted into the

central Arctic Ocean by icebergs or sea ice. Eleven statistically unique source

areas were defined by grain type percentages and microprobe chemical analyses of thousands of individual iron oxide grains (Darby and Bischof 1996).

For the first time the sources of ice-rafted grains in the Arctic Ocean were

traced with a high level of statistical probability. This allowed us to reconstruct the ice drift tracks and the ocean surface currents in the past and to get

a better understanding of the nature and history of Arctic glaciations. Finally

the potential of pollutants being spread throughout the Arctic Ocean from

point sources on the Russian shelves can be assessed.

The major sources of detritus in 17 of the deep-sea cores thus far analyzed

(4 of 18 cores from the AOS-94 cruise and 13 from previous expeditions) are

the Banks and Victoria Island area and the Sverdrup Basin area around Ellef

Ringnes Island and northern Melville Island. The Mackenzie River basin conDennis Darby and Jens Bischof are with the Department of Geological Sciences at Old Dominion University in

Norfolk, Virginia, U.S.A.

Erk Reimnitz collecting sediment

from the ice.
1994 Arctic Ocean Section

tributes on average less than 10% to the ice-rafted detritus in the cores analyzed. Areas of existing ice caps such as Ellesmere Island, Axel Heiberg Island

and Greenland contribute even less to the western Arctic Ocean. About 25%

of the iron oxide grains in the studied Arctic Ocean core samples were from

unknown source areas. All glacial sources except those of the Barents Shelf and

adjacent land masses were sampled to varying degrees of thoroughness. We

suspect that many of the iron oxide grains from presently unknown sources

(the average from 17 cores is 26%) may have been rafted by sea ice from the

Russian shelves. This has serious implications because of the modern pollution

from radioactive dumps and other pollutants attached to sediment in parts of this

shelf area.

Down-core changes in source area contributions show that cyclic surging of

ice sheets and ice caps has occurred at least throughout the last 780,000 years

in the Arctic. The cyclicity is less than about 30,000 years and probably less than

10,000 years during glacial intervals, but because of the lack of a more detailed

chronostratigraphy in the Arctic cores, the frequency cannot be resolved further.

Pulses of ice rafting from different sources in 14C-dated Holocene sediments

(<10,000 years old) of the central Arctic Ocean lasted less than 2,000 years.

The Laurentide ice sheet that calved into the Arctic Ocean from Melville or

Banks Island to the Mackenzie Delta area coexisted with several small ice caps or

possibly a larger ice sheet over the Queen Elizabeth Islands. This is based on the

discovery of detritus from both ice masses in the same 0.5- to 1-cm-thick core

samples.

The last glaciation in the Queen Elizabeth Islands transported little ma90

ALASKA

GREENLAND

10

9

8

4

3

2

1

6

7 5

Mackenzie Delta

and Tributaries

North

Slope Melville and

Bathurst Is.

Axel HeibergEllef Ringnes Is.

Northern

Axel Heiberg Is.

Ellesmere Is.

Devon Is.

Banks and

Victoria Is.

Grinnell Peninsula

Lancaster Sound 70° N

70° W

65° N

CANADA

Source areas for

Arctic ice-rafted

debris based on

statistically unique

grain-type content

and chemistry of

iron oxide grains.

Not shown is

another area in the

Kara Sea and the

102 till and glaciomarine sediment

sample locations

used to define

these areas.
terial from the interior areas, inland from the Arctic

Ocean, such as the Precambrian Shield. Grain-type

percentages in glacial deposits on and around these

islands closely match rock types of local formations.

Heavy mineral and iron oxide grains show less-clear

affinities to local rock types but generally corroborate the local nature of tills and glaciomarine sediments in the Queen Elizabeth Islands.

Today’s Beaufort Gyre circulation in the western

Arctic Ocean, a clockwise ice drift, cannot explain

the observed compositional differences between widely spaced core locations. The data obtained thus far

suggest that the surface circulation in the western

Arctic was toward Fram Strait, even along the Canadian Arctic coast during glacial intervals. This means

that surface currents were opposite or perpendicular

to the southwestward currents today within a couple

of hundred kilometers of the Canadian Arctic coast. Thus large numbers of

icebergs moved northeastward near the coast and into the North Atlantic during glacial maxima, while a thick floating ice cap blocked or greatly inhibited

icebergs from reaching the central and western parts of the Arctic Ocean. This

is further supported by the slower sedimentation rates in these central areas.

Unusual magnetite spherules (40–60 μm) with about 6–18% zinc oxide

and 18% nickel oxide were found at over 30 sites in the Queen Elizabeth

Islands and in several Arctic Ocean cores in sediment as old as 780,000 years.

Iron meteorites lack zinc because of its volatility at temperatures of atmospheric entry, so an impact event in zinc-bearing limestones such as the Haughton Astrobleme (~22 million years ago) is still considered to be a likely explanation for such spherules. However, a detailed search for these spherules in

ejecta from the Haughton Astrobleme on Devon Island was negative. Thus, if

these spherules were formed by such an event, it is yet to be discovered in the

Queen Elizabeth Islands.

REFERENCE

Darby, D.A. and J.F. Bischof (1996) A statistical approach to source determination of lithic and Fe oxide grains: An example from the Alpha Ridge, Arctic

Ocean. Journal of Sedimentary Research, 66: 599–607.

91

Geology and Paleoceanography

Iceberg drift tracks

and surface currents

for earlier glacial

maxima in the western Arctic Ocean

based on dropstones and iron

oxide grains. The

zone of thick ice

inhibits iceberg drift

and causes low

sedimentation rates.

Arrows depict iceberg drift from the

Laurentide Ice Sheet

(open arrows) and

glaciers from the

Queen Elizabeth

Islands (solid

arrows). Core locations used for this

reconstruction are

shown as black dots.

Thick

Ice
1994 Arctic Ocean Section

Late Quaternary Paleoceanography of the Canada Basin,

Central Arctic Ocean

William M. Briggs and Thomas M. Cronin

This project is based on quantitative analysis of the ostracodes present in

seafloor boxcores and piston cores collected during AOS-94. Ostracodes are

small, bivalved crustaceans whose shells, or valves, are made up of calcium

carbonate in the form of the mineral calcite, which also contains trace amounts

of magnesium.

Seafloor sediments of the central Arctic Ocean (CAO) contain two types of

deep-sea ostracodes: cladocopids and podocopids. Cladocopid ostracodes are

extremely abundant in the CAO, where they are represented by about 13 species

of the genus Polycope. Cladocopids are part of the epifaunal bottom community, and they can swim for short distances just a few centimeters above the sea

bottom. The podocopid ostracodes of Arctic Ocean sediments, with one exception, are bottom-dwelling species, some living at the sediment–seawater interface

(epifaunal) and others living in the substrate just below the interface (infaunal).

The exception is the genus Acetabulastoma, which has a lifestyle of commensalism on at least two species of gammarid amphipods that are part of the

under-ice community in Arctic marine environments. Whether due to the

death of the host amphipod species or the release of ostracode shells from the

host species by accidental detachment, death or molting, the shells of Acetabulastoma eventually sink through the water column and come to rest on the seafloor, where they become part of the ostracode bottom fauna. Their shells are

therefore not indicative of the ostracode assemblages used to characterize certain water masses. The presence or absence of Acetabulastoma in downcore

ostracode assemblages can be used as a proxy indicator of the magnitude and

extent of ice cover in the CAO. This has important implications for CAO icecover history and its linkages to paleoceanography, paleoclimatology and global change.

Many ostracodes in the marine realm live within narrowly defined environmental tolerance limits, and their distribution on the seafloor is governed

by variables such as the temperature, salinity, oxygen concentration and nutrients in the overlying water column and the type of sediments on the seafloor.

92

William Briggs is with the Institute of Arctic and Alpine Research at the University of Colorado at Boulder,

Colorado, U.S.A. Thomas Cronin is with the U.S. Geological Survey at Reston, Virginia, U.S.A.
Studies of ostracodes in surface sediments

from piston core and boxcore tops, collected mainly from the Eurasia Basin of

the Arctic Ocean and analyzed using

multivariate quantitative and clustering

techniques, have shown that many ostracode species that form assemblages in the

Arctic Ocean have distinct bathymetric

ranges that are related to the depthstratified water masses of the present-day

water column. Thus, we are able to recognize assemblages of ostracodes that are diagnostic of:

• Polar surface water (0–100 m), below which lies a 100-m-thick halocline layer;

• Arctic intermediate water (Atlantic water) (200–800 m); and

• Arctic Ocean deep water (to 4000 m or more).

These water masses are in themselves easily differentiated from one another

because each has a characteristic temperature–salinity signature, which is related

to water density, which in turn, determines their position in the stratified water

column. We, therefore, are able to recognize and “calibrate” these modern analog

ostracode assemblages with what is known of the physicochemical properties of

each water mass or subdivisions of the water mass into upper and lower parts.

Thus, “depth-related” ostracode assemblages in modern-day Arctic seafloor sediments are proxy indicators of water mass type. Moreover, downcore changes in

ostracode assemblages, when compared to the modern analog coretop assemblages by a quantitative method called the modern analog technique (MAT),

will result in a proxy record of the water-mass history over a basin, abyssal

plain, ridge, rise or plateau in the deeper (≥4 km) to shallower (~1 km) parts of

the Arctic Ocean during late Quaternary time.

We have found:

• Well-preserved ostracodes and good biostratigraphies downcore in boxcores from the Mendeleyev and Lomonosov Ridges and slopes;

• Ostracodes in 18 boxcore tops; and

• Well-preserved adult specimens of the deep-sea ostracode genus Krithe to

be used in shell-chemistry studies.

The longest of the 18 boxcores is 46 cm long. On average, sedimentation rates

are on the order of 1–2 cm per 1000 radiocarbon years (1 kyr) in the CAO for

the Holocene (the last 10,000 kyr). Sedimentation rates during the last glaciation have been variously estimated at 0.1–0.2 cm/kyr up to 0.5 cm/kyr, based

on accelerator mass spectrometry (AMS) 14C dating. Thus, the ages of the preHolocene sections of the boxcores in all likelihood span all of the last glaciation, which dates from approximately 70–10 kyr ago, and may be older. All of

the boxcores, then, must record the time of the last glacial maximum (approximately 18 kyr ago) through to the present.

93

Geology and Paleoceanography

Liz Osborne processing seafloor

cores in the Polar

Sea core laboratory.
1994 Arctic Ocean Section

Our objective is to study the ostracodes in boxcore sections from the last

glacial maximum through Termination 1a and 1b to the present. Termination

1a marks the beginning of the last deglaciation, dated at 15.7 kyr ago (16,650

calendar years B.C.), and Termination 1b marks the end of the last glacial–

deglacial transition, dated at 7.2 kyr ago (6,000 calendar years B.C.). Modern

surface and deep-sea circulation patterns and seasonal ice-free conditions are

believed to have been established in the northern North Atlantic and Arctic

Oceans following Termination 1b. These changes are in direct response to the

drawdown and final collapse of the great Northern Hemisphere ice sheets (the

Laurentide and the Fennoscandian). Quantitative analysis of the downcore

ostracode assemblages by the MAT will record upslope and downslope

migrations of ostracode assemblages in response to changing oceanographic

conditions due to changes in circulation following the decay and collapse of

these ice sheets.

To date, we have sampled five of the eighteen boxcores from sites on the

Mendeleyev Ridge and slope, the Lomonosov Ridge and slope, and the Pole

Abyssal Plain. All of these cores have well-preserved ostracodes, except for the

one from the Pole Abyssal Plain, which has poorly preserved ostracodes in the

top few centimeters downcore and no calcareous faunas of any type farther

downcore. The well-preserved downcore ostracodes will greatly aid in the paleoceanographic history of the Mendeleyev and Lomonosov Ridges and other

ridge areas of the Arctic Ocean. High-resolution downcore AMS 14C and oxygen isotope records, which will be made available by Glenn Jones and William

Curry of the Woods Hole Oceanographic Institution, will be indispensable to

the project. These records, when augmented by the ostracode biostratigraphy,

will allow us to pinpoint the timing of paleoceanographic events in the Arctic

Ocean over the last few centuries and millennia, and these data will help predict future change. We are separating out adult specimens of two species of

the deep-sea ostracode genus Krithe for use in downcore single-valve geochemical analyses by Paul Baker and Gary Dwyer of Duke University, who, in collaboration with Thomas M. Cronin, are developing geochemical proxy tools to

determine paleotemperatures and other physicochemical variables in the deep

ocean based on the shell chemistry of Krithe. New distribution records of the

ostracodes in coretop samples will allow us to fine tune the Arctic Ocean

Database, and these data will greatly enhance the resolution of the MAT. We

will also examine selected piston cores for much older paleoceanographic and

paleoclimatic records when samples from these cores become available.

94
Elemental and Isotope Geochemistry of

Sediment from the Arctic Ocean

Bryce L. Winter, David L. Clark and Clark M. Johnson

Elemental and radiogenic isotope studies of marine silicate sediment have

greatly increased our understanding of the lower-latitude and southern oceans.

However, no comprehensive study had been conducted in the Arctic Ocean.

Elemental and radiogenic isotope compositions of marine silicate sediment

are powerful tools for understanding the sediment source region, including its

location, general lithologic composition, age and crustal depth of exposure.

Upon identifying the source location and using sediment compositional variations to establish distribution patterns, it may be possible to reconstruct sediment transport pathways and infer transport mechanisms. This may provide

independent information concerning paleoceanographic or paleoatmospheric

circulation patterns and contribute to better paleoclimate reconstructions.

Surface sediments collected along the AOS-94 track (Mendeleyev Ridge,

Makarov Basin, Lomonosov Ridge, Amundsen Basin and Nansen Basin) have

been analyzed for major and trace elements via instrumental neutron activation

and x-ray fluorescence. We are completing Rb–Sr, Nd and Pb isotope analyses

via thermal ionization mass spectrometry. We have analyzed the major and

trace element compositions for 20 other deep-ocean sediments (Canada Basin,

Northwind Ridge and Alpha Ridge), 3 sea ice samples and 19 samples of

sediment from rivers and shelf areas that are potential source regions (Queen

Elizabeth Islands, northern Canada, Kara Sea, Ob River, Yenisey River and

Pechora Sea).

Initial examination of the elemental data shows that all deep ocean sediment, except that from the Canada Basin, has much higher concentrations of

transition elements, such as Co and Ni, than does sea ice sediment and the

sediment samples from potential source regions. Transition elements are concentrated in hydrogenous oxide coatings, which accumulate on sediment particles at the sediment–water interface in marine settings. Sediment from the

Canada Basin is deposited by turbidity currents at much higher sedimentation

rates than other areas of the central Arctic Ocean; hence, there is less accumulation of hydrogenous oxide coatings on sediment from the Canada Basin.

Sediment from the Ob and Yenisey Rivers and the Kara Sea have much

higher concentrations of compatible elements (such as Cr and Sc) than all the

95

Bryce Winter, David Clark and Clark Johnson are with the Department of Geology and Geophysics at the

University of Wisconsin-Madison in Madison, Wisconsin, U.S.A.

Geology and Paleoceanography
1994 Arctic Ocean Section

other sediments that have been analyzed.

This is consistent with the high concentrations of smectite in this region and indicates that the extensive Mesozoic basalt

complexes of the adjacent continental land

mass are important sources of sediment to

this shelf region. However, these rivers and

the Kara Sea shelf in general cannot be important sources of sediment for the central

Arctic Ocean.

 Late Cenozoic sediments on the Alpha

Ridge in the central Arctic Ocean (~5 m

thick) were deposited at very low sedimentation rates (~1 mm/ky) and can be separated

into two distinct sedimentary packages based

on lithology. The lower package (~5–2.4 Ma) is composed of silty lutites that

are interpreted to have been deposited by sea ice. The upper sedimentary package (~2.4–0 Ma) is composed of alternating sandy and silty lutites and has

glacial dropstones occurring throughout the sequence. The younger cyclic sequence is interpreted to have been deposited by glacial ice; the coarse layers

were deposited during glacial maxima and deglaciation, whereas the fine intervals were deposited during interglacial periods. We have analyzed detrital

silicate material, planktonic foraminifera and the diagenetic (oxide) fraction of

ferromanganese micronodule (50–300 μm) separates throughout a composite Late

Cenozoic sedimentary sequence for variations in Nd, Sr and Pb isotopes and rare

earth elements. The oxide fractions of Fe–Mn micronodule separates were isolated using a chemical reductant. The foraminifera and the diagenetic fractions record the isotope variations of Arctic seawater.

The Sr, Nd and Pb isotope compositions of the siliciclastic fraction are

homogeneous during the time of sea ice sedimentation (~5–2.4 Ma), whereas

87Sr/86Sr and 206Pb/204Pb ratios progressively increase and 143Nd/l44Nd ratios

decrease during the time of glacial sedimentation. We interpret these isotope

variations to indicate a progressive change in the source of sediments to the

central Arctic Ocean beginning at the time of initiation of continental glaciation (~2.4 Ma). All the isotope systems are remarkably consistent and indicate

that the sediment source region during glacial sedimentation (~2.4–0 Ma)

had a greater supracrustal component and/or an older average age relative to

the source that supplied sediment during the time of sea ice sedimentation

(~5–2.4 Ma). The isotope data are consistent with derivation of the older

(~5–2.4 Ma) sediment entirely from the Siberian shelf, whereas the Canadian

Island region became a progressively more important source of sediment since

~2.4 Ma. The general increase in the amount of coarse sediment since ~2.4

Ma is consistent with this hypothesis. We intend to further refine and substantiate sediment source regions by analyzing circum-Arctic river and shelf

sediments for isotope variations.

96

Sr isotope variations of components

of Late Cenozoic

sediment from the

Alpha Ridge, central

Arctic Ocean. The

components that

were analyzed include the oxide fraction of ferromanganese micronodules

(solid circles), the

silicate fraction of

ferromanganese micronodules (open

circles) and bulk silicate sediment

(open triangles).

0

1

2

3

4

5

0.705 0.710 0.715 0.720 0.725

500x

Analytical Precision

Age (Ma)

Sea Ice Sediment Glacial Sediment

Brunhes Matuyama Gauss Gilbert

Seawater

Oxide

Fraction

Silicate

Fraction

Sr/ Sr 87 86
97

— Ship Technology —

Real-Time Remote Sensing for Ice Navigation

Caren Garrity, Dan Lubin and Réné O. Ramseier

AOS-94 explored areas never before studied by surface ships. An investigation of historical ice conditions indicated that we could expect an average of

83 ±11% ice concentration along the planned route to the North Pole. A

major advantage of this expedition was the installation onboard the Polar Sea

of a TeraScan receiver and processing system developed by SeaSpace Corporation. The system was capable of real-time reception and processing of imagery

from the advanced very high resolution radiometer (AVHRR) on NOAA satellites as well as the special sensor microwave imager (SSM/I) data from the

Defense Meteorological Satellite Program (DMSP) satellites.

The AVHRR imagery is in the visible and infrared wavelengths, and these

sensors are useful for real-time weather information. Their usefulness for monitoring ice motion on this voyage was extremely limited due to the nearly constant cloud cover and considerable fog. During AOS-94, 5.3% of the transit days

to the North Pole were nearly cloud free, and 17 days were free from fog. To be

useful for ice navigation, a satellite sensor needs to “see” through clouds and fog.

Sensors using the microwave frequency range such as the SSM/I have this capability.

Three SSM/I algorithms were used to map sea ice during AOS-94: NASA

Team (NASA, U.S.), AES (Canadian Atmospheric Environment Service) and

85 GHz (Scripps, U.S.). The former two algorithms provide coarser-resolution

ice maps by combining the lower-frequency channels of the satellite sensor (19

and 37 GHz). Previous comparisons of these are summarized, including an

error analysis, in Steffen et al. (1992). The 85-GHz ice concentration maps

have twice the resolution (12.5 km), and the new 85-GHz algorithm is summarized in Lomax et al. (1995). The reported error for derived total ice concentrations during the winter is approximately 9% for the NASA Team and AES

algorithms. This error is due to signature uncertainty and the uncertainty in

atmospheric parameters, including instrument noise effects. As a result of this

experiment the 85-GHz algorithm has been evaluated (Lubin et al. 1996)

While AOS-94 was useful for comparing the ice concentrations derived

from the three algorithms, it is difficult to “validate” the sea ice algorithms,

since observing ice from the bridge of a ship is somewhat qualitative and the

visibility is limited to a small area. The visibility was estimated to be from 0.05 to

Caren Garrity and Réné Ramseier are with the Microwave Group–Ottawa River, Inc., in Dunrobin, Ontario,

Canada. Dan Lubin is with the California Space Institute at the University of California–San Diego in La Jolla,

California, U.S.A.

Ship Technology
1994 Arctic Ocean Section

10 nautical miles during the

transect. Often the ice concentrations were overestimated, since the farther one

looks towards the horizon,

the less open water can be

seen. When the ship is progressing slowly through a

vast old ice floe, for example,

from the ship the ice concentration could appear to

be 100%.

The total ice concentration along the ship’s track was derived from each of

the algorithms and estimated from visual ice observations. The average visually

estimated ice concentration was 93% along the total ship’s track (A.R. Engineering, and Science and Technology Corporation 1994). The AES and 85-GHz algorithms show an average of 88% and 84%, respectively; the NASA team algorithm, which appears to underestimate the ice concentration, averaged 78%.

The microwave sensors are influenced by cloud liquid water content and

snow wetness, which cause an increase in the brightness temperature detected

by the sensors. The NASA Team and AES algorithms, using the lower frequencies, are less sensitive to atmospheric moisture than the 85-GHz algorithm.

The derived ice concentrations are significantly affected by the snow wetness,

however (Garrity 1991, 1992). For example, the 85-GHz derived ice concentrations can be as large as 110%. When using the 85-GHz algorithm over regions

of lower ice concentration, the reference polarizations in a given image must

be chosen with care because there the polarization-based algorithm is more

sensitive to cloud opacity and can easily and substantially underestimate the

ice concentration (Lubin et al. 1996). However, near the ice edge, the 85-

GHz derived ice concentrations were closer to visual observations than the

conventional algorithms were, most likely due to better resolution. Comparison of 85-GHz brightness temperatures measured from space with both the

lower-frequency measurements and with the shipboard observations shows

that much of the information about surface properties, including snow wetness and volume scattering in multiyear ice, is contained in the 85-GHz signal, despite the higher atmospheric opacity.

Using the 85-GHz algorithm, ice concentrations greater than 100% are reduced to 100% and a colored ice map is produced for operational use. The influences of the atmosphere and snow wetness on derived ice concentrations are

less than 10% for the high ice concentrations encountered during AOS-94, so

this is not a critical problem. For determining total ice concentration during summer in the high Arctic, the new 85-GHz algorithm is as good as the conventional

lower-frequency algorithms, if not better because of the doubled resolution.

98

Julian Day

Total Ice (%)

40

60

80

100

120

NASA 

AES 85 GHz 

Visual

210 215 220 225 230

Ice concentration

along the Polar

Sea’s track to the

North Pole.
The 85-GHz SSM/I ice product

aided navigation and planning of

scientific station stops on a daily

basis. For example, the ship was rerouted to the west of 180° because

of the 100% total ice concentration

to the east. The 100% ice concentration areas were consistent during

the experiment, and the consistency

was confirmed using the three algorithms and helicopter surveys. The

SSM/I ice maps provided an overview, which aided the process of deciding how to proceed from the North Pole. The SSM/I and AVHRR data

provided ice and weather information during AOS-94 and met the criteria for

being operational, that is, timeliness, coverage and interpretation. It was clearly demonstrated that the ships could easily reach their goal by having a miniice center in the high Arctic, where communication is difficult and expensive.

REFERENCES

A.R. Engineering, and Science and Technology Corporation (1994) Hull/

ice interaction loads measurements on-board the Louis S. St-Laurent during

the 1994 trans-Arctic voyage: Trip report and data summary. Submitted to

Fleet Systems, Canadian Coast Guard, by A.R. Engineering, Calgary, Alberta,

Canada, and Science and Technology Corporation, Columbia, MD, U.S.A.

Garrity, C. (1991) Passive microwave remote sensing of snow covered floating

ice during spring conditions in the Arctic and Antarctic. Doctor of Philosophy, Graduate Programme in Earth and Space Science, York University, North

York, Ontario, Canada.

Garrity, C. (1992) Characterization of snow on floating ice and case studies of

brightness temperature changes during the onset of melt. In Microwave Remote

Sensing of Sea Ice. Geophysical Monograph 68, p. 313–326.

Lomax, A.S., D. Lubin and R.H. Whritner (1995) The potential for interpreting total and multiyear ice concentrations in SSM/I 85.5 GHz imagery.

Remote Sensing of Environment, 54: 13–26.

Lubin, D., C. Garrity, R.O. Ramseier and R.H. Whritner (1996) Evaluation

of the special sensor microwave imager 85.5 GHz channels for total sea ice

concentration retrieval during the 1994 Arctic Ocean Section. Submitted to

Remote Sensing of the Environment.

Steffen et al. (1992) The estimation of geophysical parameters using passive

microwave algorithms. In Microwave Remote Sensing of Sea Ice. Geophysical

Monograph 68, p. 201–231.

99

Ship Technology

Caren Garrity

measuring snow

wetness.
1994 Arctic Ocean Section

Ship Technology Program

Larry Schultz and Rubin Sheinberg

The AOS-94 ship technology program consisted of two parts. One part

was concerned with measuring the icebreaking capability of the two icebreakers,

the USCGC Polar Sea and the CCGS Louis S. St-Laurent, while transiting

high-Arctic ice conditions. The other part involved measuring the loads imposed

on the hull of the Louis S. St-Laurent due to impact with the ice.

Icebreaking performance data typically define the power required for an

icebreaker to break a given thickness of uniform ice at a given speed. Plans were

made to perform dedicated performance tests in a range of uniform conditions if

such were encountered. No uniform ice conditions suitable for performance testing were encountered, however, in the entire expedition.

 In contrast, trafficability data provide information on the ability of an

icebreaker to transit from

point to point in a given

geographic area in a realworld mix of ice conditions. Ice trafficability

data were recorded hourly during the entire time

the ships operated in ice,

resulting in about 500

hours of data on ship propulsion, environmental conditions and ice conditions. The data on ice conditions included the classification of the ice as first

year, second year or multiyear; the lead width; the average and maximum floe

size; the concentration of the ice cover broken down in increments of thickness; the average and maximum thickness; the pressure ridge encounter rate;

and the average and maximum sail height of the pressure ridges. The environmental data included the snow depth and type, a characterization of the ice

pressure, and the diameter and concentration of melt ponds. Data on openwater performance and seakeeping were collected during the open-water transit legs of the expedition.

100

Larry Schultz is with Advanced Marine Enterprises, Inc., in Arlington, Virginia, U.S.A. (He was formerly with

Science and Technology Corporation in Columbia, Maryland.) Rubin Sheinberg is with the U.S. Coast Guard in

Baltimore, Maryland, U.S.A.

Polar Sea

breaking ice.
Finally, the performance study also included an analysis of the shipboard

science spaces and equipment onboard both ships, based on observations and

interviews with the scientists. The trafficability and performance data will

contribute to the knowledge base available for the design of future icebreakers

in terms of ship resistance and powering and in terms of a realistic mix of ice

conditions and operating modes for high-Arctic transit. Since the expedition

completed a full transect of the Arctic Ocean from the Pacific to the Atlantic

via the North Pole, the data recorded on ice conditions and environmental

conditions will be extremely valuable in planning future high-Arctic icebreaker

expeditions.

The ice impact loads portion of the program is part of an ongoing joint

effort between the Canadian and U.S. Coast Guards to improve ice load impact

criteria for ice-going ships. Collaborative work between the two governments

to measure the pressure distribution on the hull of an icebreaker during ice

impact incidents started in 1982 with a bow measurement panel on the Polar

Sea. Since then data have been collected and analyzed from five deployments

of the Polar Sea in both the Arctic and the Antarctic, one extended deployment of the Swedish icebreaker Oden to the Arctic Ocean, and one deployment of the Nathaniel B. Palmer to the Weddell Sea in Antarctica in winter.

The measurements have provided the first insight into the magnitudes of local

ice impact pressures and how they vary with time, contact areas and ice conditions. The data collected on the Louis S. St-Laurent during AOS-94 focused

on the relative magnitude of forces and pressures on three areas of the hull

structure: the bow, the shoulders and the bottom. Additionally, vessel maneuvering and powering data were collected for characterizing the vessel operations during the recorded hull–ice impact events. Data were also gathered on

the environmental and ice conditions during the events.

Data for 3217 impact events were recorded on the data acquisition system.

The system was configured such that an impact on any single measurement

area could trigger an event. In some cases, simultaneous impacts were recorded

on two or all three of the measurement areas. The greatest number of impacts

were recorded at the bow, as would be expected. Side impacts were the next

most frequent, followed by bottom impacts. If the multiple-impact cases are

taken into account, the total number of recorded impacts is 4037. Preliminary analysis has shown that the magnitude of the forces and pressures is consistent with previous measurements in multiyear ice. Ongoing data analysis will

determine data trends and correlate impacts with ship operating and ice conditions. Extreme load profiles will then be developed and relationships established for the frequency, magnitude and pattern of the loads on the three

instrumented hull areas. The relationships will then be compared with those

specified in the Revised Canadian Hull Construction standards, and recommendations will be made as appropriate.

101

Ship Technology
1994 Arctic Ocean Section

Hull–Ice Interaction Load Measurements

on the CCGS Louis S. St-Laurent

David Stocks

A strategic objective of the Canadian Coast Guard Northern Operations

Programme is to support the scientific community in their requirements for

platforms to conduct investigations in the Canadian Arctic. A further departmental objective, with respect to ensuring safety and environmental protection

in the Canadian Arctic, requires that regulations be developed for ships operating in these regions.

The U.S. and Canadian Coast Guards have, over the last decade, cooperatively executed an extensive program of ice–ship hull interaction investigations on ice-strengthened ships. This initiative was stimulated by the joint

need to develop structural standards for the design of ice-strengthened ships

and has, for the most part, focused on the most highly loaded area of the ships’

hull, the bow. Several ships have been instrumented for dedicated ice trials of

their bow areas, including the CCGS Louis S. St-Laurent and the USCGC

Polar Star. More recently the USCG and CCG combined their resources to

conduct experiments on the Swedish icebreaker Oden during its 1991 North

Pole voyage and the American icebreaker the Nathaniel B. Palmer during its

1992 voyage to the Antarctic.

The objective of this component of AOS-94 was to enhance the body of

knowledge with respect to the structural response of ice-strengthened ships,

specifically in areas of the ship’s hull never before examined, such as the ship’s

side aft of the bow and bottom forward, and in areas of Arctic ice never before

encountered by Western vessels. The benefits of this work are two-fold; first,

to aid in the development and verification of the Arctic Shipping Pollution

Prevention Regulations (structural standards), and second, to demonstrate and

prove the capability of the platform to support the scientific missions.

The project was jointly sponsored by the CCG and USCG, and contracts

were let to A.R. Engineering Ltd., Calgary, Alberta, Canada, and Science and

Technology Corporation, Columbia, Maryland, U.S.A. Three phases were contracted:

• The installation of instrumentation onboard the ship;

• The acquisition of data during the voyage; and

• The synthesis and analysis of data after the voyage.

102

David Stocks is with the Canadian Coast Guard in Ottawa, Ontario, Canada.
The Canadian contractor was primarily responsible for the first phase, the

second phase was a joint responsibility, and the third phase is being completed,

primarily by the U.S. contractor.

A hull loads data acquisition system was installed on the CCGS Louis S.

St-Laurent to acquire strain gauge data from three locations on the hull: the

bow (24 strain gauges), the shoulder (28 strain gauges) and the bottom (11

strain gauges). To support the load measurements a ship navigation data acquisition and video monitoring system was also installed.

The data acquisition system

was designed to trigger the data

recorder to record significant

impact events when a predetermined load was exceeded. It simultaneously recorded the

speed, power and direction of

the ship, as well as ice thickness

and strength, for later correlation

to ice condition and vessel operations.

The data acquisition system was operational from when the ship entered

the ice on 26 July (70.08°N, 168.38°W) until it exited on 31 August. A total

of 4037 separate events were recorded during that period. Ice observations

were made continuously from the bridge of the Polar Sea. The forward-looking video system recorded the encountered ice, and the after-looking video

system recorded the interaction of broken ice at the location of the strain

gauges. Physical ice data were collected on an opportunity basis by ice science

partners from the Institute of Marine Dynamics, St. John’s, Newfoundland,

to establish the thickness and strength of the encountered ice. The average ice

thickness varied from 1.0 m (3.2 ft) on entry to 2.0 m (6.7 ft) at the Pole. The

maximum ice thickness (excluding ridges) was 3.54 m (11 ft).

The data set derived from this voyage is the largest ever collected on a

single deployment and doubles the quantity of information collected on previous collaborative USCG–CCG projects. The ongoing analysis will reduce

the strain data to pressure loads and assess the trends in data versus ice and

ship operating conditions, compute extreme value statistics and compare results between other areas of this ship and other ship experiments.

103

Ship Technology

Louis S. St-Laurent

breaking ice.
1994 Arctic Ocean Section

— Communications and Data Management —

Special Communications Solutions

Michael Powers

The unique environment of the deep Arctic requires special communications solutions, especially with an expedition of the complexity of AOS-94.

Two of the special communications systems developed for and used on AOS94 were the Internet e-mail system and the inter-ship communications system.

Providing Internet e-mail service on polar expeditions poses special problems

as the ship proceeds north of the range of standard geosynchronous communications satellites. Members of the Polar Sea’s communications team explored

a number of options in preparation for the expedition. The solution chosen

was to use the Lincoln Experimental Satellites (LES) to link with the University of Miami ATS Satellite Control Facility at Malabar, Florida.

The two Lincoln Experimental Satellites, LES-8 and LES-9, were developed by MIT’s Lincoln Labs for the Air Force and operate on the military

UHF band (225–400 MHz). Both LESs follow inclined geosynchronous orbits, moving 17.8° north and south of the equator each 24 hours. The Polar

Sea used LES-9 while it was north of the equator, which provided at least four

hours of access each day.

Using the installed Navy Satellite Communications System equipment,

the Polar Sea used data packet technology to send and receive information

with a minicomputer at University of Miami’s site in Malabar, Florida. The

minicomputer provided Internet access for e-mail and file transfer, using the

standard Internet file transfer protocol (ftp).

Aboard the Polar Sea, scientists and crew members prepared outgoing

e-mail as text files on floppy diskettes. E-mail from scientists on the Louis S.

St-Laurent was initially delivered on floppies by helicopter and later by the

inter-ship communications system described below. Incoming e-mail was

printed and delivered to the recipients.

The Internet e-mail connection allowed scientists to communicate with

colleagues ashore throughout the expedition. In one case the ability to communicate by e-mail allowed the scientists and technicians aboard the Polar Sea

to successfully troubleshoot a problem with their equipment. This meant that

they were able to conduct their tests without interruption.

The connection was also used to download ice imagery from the National

104

Cdr. Michael Powers was Executive Officer of the USCGC Polar Sea.
105

Ice Center. While the Polar Sea’s installed TeraScan system provided real-time

ice imagery, the capability of accessing National Ice Center information provided an option had there been a problem with TeraScan.

For inter-ship communications a VHF-FM line-of-sight link between the

Polar Sea and the Louis S. St-Laurent was installed by Coast Guard technicians

while the expedition was transiting from Victoria, British Columbia, to Nome,

Alaska. This link was tied into each ship’s telephone system, allowing one to pick

up the phone on the Polar Sea and call someone on the Louis S. St-Laurent. This

communications link proved invaluable in allowing the senior leaders of the

expedition on both ships to consult and plan for each day’s operation.

In addition, the link allowed scientists on the Louis S. St-Laurent to send

and receive their e-mail electronically, which was much more reliable than

waiting for the next helicopter flight between the two ships.

Communications and Data Management
1994 Arctic Ocean Section

Data Management

Claire S. Hanson and David L. McGinnis

Data from AOS-94 are valuable national and international scientific resources and must be preserved for analysis by both current and future generations of scientists. To ensure preservation, data management coordination for

AOS-94 will be provided by the National Snow and Ice Data Center (NSIDC),

University of Colorado at Boulder. NSIDC is funded by the National Science

Foundation’s Office of Polar Programs as the Data Coordination Center for

the Arctic System Science (ARCSS) Program; the AOS-94 data will be integrated into the ARCSS data management project.

A data archiving plan is being developed in collaboration with the AOS-94

project leaders to ensure that AOS-94 data sets and data products, along with

complete documentation, will be archived at NSIDC and accessible through

discipline-appropriate data centers. Examples of these centers with which

NSIDC has close working relationships include the NOAA National Geophysical Data Center’s Marine Geology and Geophysics Division and its Paleoclimate Group, the NOAA National Oceanographic Data Center, the NOAA

National Climatic Data Center, and the Department of Energy’s Carbon Dioxide Information and Analysis Center. Copies of the marine core data, bathymetric data, physical oceanography and primary productivity data, and atmospheric chemistry and related data from AOS-94 will be sent to these centers

for incorporation into their databases. In cases such as biology and contaminants where there is currently no national center having responsibility for a

particular discipline, NSIDC will maintain that AOS-94 data and provide access services until a discipline center is developed or designated.

NSIDC’s ARCSS Data Coordination Center emphasizes ease of access, comprehensive documentation, and a researcher-centered philosophy. Our goal is

to make the migration of valuable data as easy as possible. For adding data to

the archive we develop a plan with each investigator. When an investigator

and the NSIDC ARCSS staff agree that the data are ready, data sets are transferred to NSIDC and made available via electronic means such as anonymous

ftp and/or the World Wide Web. When logical groupings of data are identified, and the volume is sufficient to warrant it, a CD-ROM is considered as an

Claire Hanson and David McGinnis are with the National Snow and Ice Data Center at the

Cooperative Institute for Research in Environmental Sciences at the University of Colorado in Boulder, Colorado, U.S.A.

106
Communications and Data Management

additional data delivery medium. The ARCSS data management effort is a

two-way street; we work with investigators to archive their data while making

these same data readily available for other investigators.

Data sets and products from AOS-94 will be listed in the on-line and hardcopy versions of the ARCSS Data Catalog, as well as in the Global Change

Master Directory, the Arctic Environmental Data Directory and the International Arctic Environmental Data Directory. These on-line information services provide a means of notifying the international science community of

these data sets, with up-to-date contact information to order the data. In addition, NSIDC maintains an ARCSS Web site (http://arcss.colorado.edu) that

will explicitly list AOS-94 data with ordering information and/or links to download the data from within a Web browser. News of ARCSS data issues and

activities is available in the quarterly newsletter NSIDC Notes, obtainable by

free subscription and on the NSIDC Web site.

The AOS-94 data archiving plan will stipulate a period of exclusive use by

the investigators, perhaps two years from the end of the cruise, after which the

data should be moved into the archive and released for general distribution.

The time period of exclusive use has not yet been negotiated with the project

leaders or the individual investigators.

107
1994 Arctic Ocean Section

Kent Berger-North, Biology

Axys

Sidney, British Columbia

Hazen W. Bosworth, Sea ice

U.S. Army Cold Regions Research and

Engineering Laboratory

Hanover, New Hampshire

Peter C. Brickell, Atmospheric and upper ocean

chemistry

Air Quality Measurements and Analysis

Research Division

Atmospheric Environment Service

Downsview, Ontario

John P. Christensen, Seafloor geochemistry

Bigelow Laboratory for Ocean Sciences

West Boothbay Harbor, Maine

Lisa Clough, Biology

Department of Biology

East Carolina University

Greenville, North Carolina

Charles Geen, Atmospheric and upper ocean

chemistry

Bovar-Concord Environmental

Toronto, Ontario

Michel Gosselin, Biology

Department of Oceanography

University of Quebec at Rimouski

Rimouski, Quebec

Anthony J. Gow, Sea ice

U.S. Army Cold Regions Research and

Engineering Laboratory

Hanover, New Hampshire

Arthur Grantz, Marine geology

U.S. Geological Survey

Menlo Park, California

John D. Grovenstein, Atmospheric and upper

ocean chemistry

Department of Marine, Earth and Atmospheric

Sciences

North Carolina State University

Raleigh, North Carolina

Patrick Hart, Marine geology

U.S. Geological Survey

Menlo Park, California

Daniel Lubin, Atmospheric radiation and

climate

California Space Institute

University of California, San Diego

La Jolla, California

Bonnie J. Mace, Biology

Lamont-Doherty Earth Observatory

Palisades, New York

Steven May, Marine geology

U.S. Geological Survey

Prescott, Washington

Sandy Moore, Biology

College of Oceanic and Atmospheric Sciences

Oregon State University

Corvallis, Oregon

Michael Mullen, Marine geology

U.S. Geological Survey

Menlo Park, California

Mary O’Brien, Biology

Institute of Ocean Sciences

Sidney, British Columbia

Walter Olson, Marine geology

U.S. Geological Survey

Menlo Park, Californi

Elizabeth Osborne, Marine geology

McLean Laboratory

Woods Hole Oceanographic Institution

Woods Hole, Massachusetts

— Appendices —

— AOS-94 Participants —

108

USCGC Polar Sea
Kevin O’Toole, Marine geology

U.S. Geological Survey

Menlo Park, California

Fred Payne, Marine geology

U.S. Geological Survey

Menlo Park, California

Larry Phillips, Marine geology

U.S. Geological Survey

Menlo Park, California

Erk Reimnitz, Sea ice

U.S. Geological Survey

Menlo Park, California

James Rich, Biology

Graduate College of Marine Studies

University of Delaware

Lewes, Delaware

William Robinson, Marine geology

U.S. Geological Survey

Menlo Park, California

Larry Schultz, Ship technology

Advanced Marine Enterprises

Arlington, Virginia

Rubin Sheinberg, Ship technology

Naval Engineering Division

U.S. Coast Guard

Baltimore, Maryland

Evelyn Sherr, Biology

College of Oceanic and Atmospheric Sciences

Oregon State University

Corvallis, Oregon

Nathalie Simard, Biology

Department of Oceanography

University of Quebec at Rimouski

Rimouski, Quebec

Delphine Thibault, Biology

Department of Oceanography

University of Quebec at Rimouski

Rimouski, Quebec

Walter Tucker, Sea ice

U.S. Army Cold Regions Research and

Engineering Laboratory

Hanover, New Hampshire

Patricia Wheeler, Biology

College of Oceanic and Atmospheric

Sciences

Oregon State University

Corvallis, Oregon

Robert A. Whritner, Atmospheric radiation and

climate

Arctic and Antarctic Research Center

Scripps Institution of Oceanography

University of California, San Diego

La Jolla, California

109

AOS-94 Participants

Knut Aagaard, Oceanography

Applied Physics Laboratory

University of Washington

Seattle, Washington

Louise Adamson, Contaminants

Institute of Ocean Sciences

Sidney, British Columbia

Ikaksak Amagoalik, Oceanography

Institute of Ocean Sciences

Sidney, British Columbia

Ken Asmus, Sea ice and remote sensing

Ice Services Branch

Atmospheric Environment Service

Ottawa, Ontario

Janet E. Barwell-Clarke, Oceanography

Institute of Ocean Sciences

Sidney, British Columbia

Louis S. St-Laurent

Eddy Carmack, Oceanography

Institute of Ocean Sciences

Sidney, British Columbia

Sylvester Drabitt, Documentation

Institute of Ocean Sciences

Sidney, British Columbia

Brenda Ekwurzel, Oceanography

Lamont-Dougherty Earth Observatory

Palisades, New York

James A. Elliott, Oceanography

Bedford Institute of Oceanography

Dartmouth, Nova Scotia

Katherine Ellis, Contaminants

Bedford Institute of Oceanography

Dartmouth, Nova Scotia
1994 Arctic Ocean Section

Sean Farley, Marine mammals

Department of Zoology

Washington State University

Pullman, Washington

Caren Garrity, Sea ice and remote sensing

Microwave Group-Ottawa River

Dunrobin, Ontario

Wayne Grady, Documentation

Macfarlane, Walter and Ross

Toronto, Ontario

Michael Hingston, Oceanography

BDR Research Ltd

Bedford Institute of Oceanography

Dartmouth, Nova Scotia

Oolateetah Iqaluk, Oceanography

Institute of Ocean Sciences

Sidney, British Columbia

Liisa M. Jantunen, Contaminants

Atmospheric Environment Service

Downsview, Ontario

E. Peter Jones, Oceanography

Bedford Institute of Oceanography

Dartmouth, Nova Scotia

Robie Macdonald, Contaminants

Institute of Ocean Sciences

Sidney, British Columbia

Fiona McLaughlin, Oceanography/contaminants

Institute of Ocean Sciences

Sidney, British Columbia

Christopher Measures, Oceanography

Department of Oceanography

University of Hawaii

Honolulu, Hawaii

David A. Muus, Oceanography

Scripps Institution of Oceanography

University of California, San Diego

La Jolla, California

Richard Nelson, Contaminants

Bedford Institute of Oceanography

Dartmouth, Nova Scotia

Stefan Nitoslawski, Documentation

Galafilm, Inc.

Montreal, Quebec

David Paton, Contaminants

Institute of Ocean Sciences

Sidney, British Columbia

Rick Pearson, Oceanography

Institute of Ocean Sciences

Sidney, British Columbia

Ron Perkin, Oceanography

Institute of Ocean Sciences

Sidney, British Columbia

Malcolm Ramsay, Marine mammals

Department of Biology

University of Saskatchewan

Saskatoon, Saskatchewan

Ron Ritch, Ship technology

A.R. Engineering

Calgary, Alberta

James A. Schmitt, Oceanography

Scripps Institution of Oceanography

University of California, San Diego

La Jolla, California

Douglas Sieberg, Oceanography

Institute of Ocean Sciences

Sidney, British Columbia

James St. John, Ship technology

Science and Technology Engineering Corporation

Columbia, Maryland

James H. Swift, Oceanography

Scripps Institution of Oceanography

University of California, San Diego

La Jolla, California

Darren Tuele, Contaminants

Institute of Ocean Sciences

Sidney, British Columbia

Christopher Walker, Documentation

Institute of Ocean Sciences

Sidney, British Columbia

Robert T. Williams, Oceanography

Scripps Institution of Oceanography

University of California, San Diego

La Jolla, California

F. Mary Williams, Sea ice

NRC Institute for Marine Dynamics

St. John’s, Newfoundland

Frank Zemlyak, Oceanography

Bedford Institute of Oceanography

Dartmouth, Nova Scotia

110
AOS-94 Participants

111

USCGC Polar Sea Crew

Officers

CAPT Lawson W. Brigham Commanding Officer

CDR Michael N. Powers Executive Officer

LCDR Daniel K. Oliver Engineering Officer

LCDR Robert L. Kaylor Senior Aviation Officer

LCDR Stephen M. Wheeler Deck Watch Officer/Ice Pilot

LCDR Steven G. Sawhill Operations Officer

LT Edward J. Hansen Aviation Engineering Officer

LT Kevin M. Balderson Aviation Operations Officer

LT Theodore R. Salmon Aviation Administration Officer

LT April A. Brown Deck Watch Officer/Marine Science Officer

LTJG Karen Arnold Deck Watch Officer/Exchange Officer

LTJG Lawrence C. Goerss Damage Control Assistant/Morale Officer

LTJG Edward J. Lane III Deck Watch Officer/Communications Officer

LTJG John D. Reeves Assistant Engineering Officer

ENS Vincent J. Skwarek Student Engineer

CCGS Louis S. St-Laurent Crew

Commanding Officer Philip Grandy Chief Engineer Mark Cusack

Chief Officer Michael Hemeon Sr Electrical Officer Phillip Seaboyer

First Officer William Turner Jr Electrical Officer William Falconer

Second Officer Stephen Baxter Senior Engineer Nigel Hawksworth

Third Officer Thomas Lafford First Engineer Mark Frogley

Bosun Abraham Welcher Second Engineer Matthew Turner

Carpenter Phillip Walker Third Engineer David Baker

Leading Seaman Dale Hiltz Supernumery Engineer Darrin Arkerman

Leading Seaman Leslie Drake Electrician Chris Wood

Leading Seaman Kenneth Baker Electrician Edward Ginter

Seaman Rico Amamio Engineroom Supervisor David Baur

Seaman Alfred Jarvis Engineroom Technician Wayne Ryan

Seaman Albert Sears Engineroom Technician Kenneth Pettipas

Seaman Karl Gouthro Engineroom Technician Stephen Baxter

Seaman William Wallace Engineroom Technician William Fagan

Seaman Arthur Larkin Oiler Phil Macpherson

Oiler Robert Boucher

Logistics Officer James Purdy Oiler Greg Engler

Logistics Officer Elizabeth Campbell Oiler Thomas Hann

Chief Cook Randy Turner Oiler Stephen Gagnon

Senior Storekeeper David Wallingham Oiler Winston Langille

Storekeeper Rick Strickland Oiler Alexander Myers

Clerk Angela Macdonald

Cook Stephen Oliver Radio Operator Gordon Stoodley

Cook Daneil Jones Electronics Technician Robert Brown

Steward Graham Weldon Ice Observer Alfred Kooz

Steward Graham Ritchie Helicopter Pilot Yvan Giroux

Steward Graeme Garrett Helicopter Pilot Ralph Hemphill

Steward Jacqueline Bourdon Helicopter Engineer Percy Gammon

Steward Leo Higgins Nurse Cylethia Lee

Steward Ralph Bowley

Steward Mark Lewis

Steward Robert Schoots

Steward Thomas Beaver
1994 Arctic Ocean Section

112

ENS Sean M. Carroll Deck Watch Officer/Administrative Officer

CW04 Charles R. Steele, Jr. Supply Officer

CW04 James J. Levesque Engineering Watch/Electronics Officer

CW03 Donald A. Knesebeck Deck Watch Officer/First Lieutenant

CW02 Harry J. Poland Medical Officer

CW02 James E. Carlin Engineering Watch/Main Propulsion Asst.

Enlisted Personnel

EMCM Warren E. Booth DCC Michael W. Andreucci

EMC Jann H. Millard DC2 Michael J. McAndrews

EMC Carl D. Pieplow DC2 Ronald C. Plowman

EM2 Robert T. Nietering DC3 David C. Garner

EM2 Gerard A. Hebert Jr.

EM2 Charles G. McPhee

EM3 Terry L. Maurer Jr. MKCM Jeffery J. Andrie

EM3 Oscar O. Beck MKC Glenn J. West

EM3 Clinton S. Thurlow MKC Troy T. Luna

MK1 Daniel L. Lenz

ETCS Peter W. Churchill MK1 Garry D. Bennett

ETC Robert J. Reiter MK1 Donald S. Nothem

ET1 Johnny N. Allen MK1 Marvin L. Heeter Jr.

ET3 Randall C. Kibler MK2 Thomas L. Dammann

ET3 Cary D. Biss MK2 James E. Hale II

ET3 Todd A. Grant MK3 Eric C. Alfred

ET3 Stuart D. Robertson II MK3 Juan C. Juarez

MK3 Raymond A. Morris III

TT2 James E. Riley MK3 Jeffrey R. Siron

MK3 Jason T. Watkins

FN Barbara C. Bennett FN Richard E. Russell

FN Larry W. Bishop FN Patrick J. Vincler

FN Eric F. Cheigh FA Louis E. Frattarelli Jr.

FN Patrick J. Corso FA Sean P. McSweeney

FN Daniel R. Ferguson FA Jeffrey P. Pierce

FN John R. Hays FA Maurice Ponce

FN Stephen L. McVay FA Thomas J. Scheidemantel

QMCM Gary A. Thurston YNC Terrence J. Brennan

QM2 Gil A. Contreras YN1 Langston D. Brooks

QM3 Jennifer M. Hogge YN2 Brian P. McClure

QM3 Peter J. Kanavas

QM3 Laura L. Knehr SKC Dana V. Hanberg

SK2 Robert T. King

BMCS Charles D. Buckley SK1 Bryan D. Petersen

BM1 Christopher R. Buell SK3 Michael B. Sanicharra

BM2 Anthony D. Whiting SN Joseph A. Bergman

BM3 Hans Esteves

HSC Mark L. Stocks

GM1 Vincent L. Demeyer HS2 Jeffrey W. Ongemach

SN Mitchel H. Barker SN Robert J. Odaniel

SN Jason M. Crandall SN Andy R. Stafford

SN Derrick L. Cross SN Jason A. Stouffer

SN Adam P. High SN Bradley R. Tull

SN Loren D. Huggins SA Jakobb N. Baldwin

SN Peter M. Jagel SA Lura D. Etchison
AOS-94 Participants

113

SN Sean M. Johannsen SA David B. Gore

SN Justin R. Jolley SA Matthew E. Kor

SN Matthew M. Kenny SA Jason T. Lopez

SN Cobran D. Lappin SA Collin A. Maas

SN Wesley McMillan III SA Aaron S. Schmude

SN James A. McMurphy SA Jeffrey E. Williams

MST1 Corey A. Bennett RM1 Steven M. Schofield

MST2 John T. Pierce RM2 Matthew J. Dini

MST3 Noell A. Bolleurs RM2 Paul J. Gladding

MST3 Elisa M. Fusco RM2 Jeffrey D. Spears

RM3 Scott D. Haywood

SSCS Alan R. Walsh RM3 Rod E. Koepp

SS1 Michael T. Lapolla

SS1 Michael R. Sieg ADC Robert C. Fawcett

SS1 Joseph Grant AD1 William D. Anderson

SS2 Nathaniel Hightower AE1 Mark R. Mobley

SS3 Douglas A. Van Kampen AT1 Scott W. Thiel

SS3 Jonathan R. Carton AD2 Michael B. Kellams

SS3 Jimmie L. Patterson AT2 Henry C. Parker

SS3 Ruston C. Johnson AE2 William J. Shaw

SNSS Kenneth J. Bennett AM3 J. Guillermo Verde
1994 Arctic Ocean Section

— Science Stations —

Polar Sea

No. Date N Lat. Long. Depth (m) Sampling program*

1 25 Jul 67°59′ 168°50′W 49 Bc

2 26 Jul 70°00′ 168°45′W 40 P, B, Bc (5), I

3 27 Jul 72°00′ 168°51′W 55 P, B, I

4 28 Jul 74°01′ 168°50′W 120 P, B, I

5 30 Jul 75°25′ 170°44′W 900 P, B, I

6 30 Jul 75°21′ 170°30′W 525 B, Bc (2)

7 1 Aug 76°39′ 173°20′W 2250 P, B, Bc (2), I

7b 2 Aug 77°49′ 176°21′W I

8 3 Aug 78°08′ 176°48′W 1047 P, B, Bc (2), Pc, I

8a 3 Aug 78°09′ 176°02′W 1426 Pc

9 4 Aug 78°08′ 176°41′W 1035 Pc

10 4 Aug 78°09′ 174°38′W 1673 Pc

11 4 Aug 78°58′ 175°48′W 1050 B

12 5 Aug 79°59′ 174°17′W 1638 B, Bc, Pc (2), I

13 6 Aug 80°09′ 173°17′W 2654 P, B, Pc

13a 6 Aug 80°09′ 173°22′W 2556 Bc, I

14 7 Aug 80°13′ 172°46′W 3098 Pc

15 7 Aug 80°12′ 173°19′W 2726 Pc

16 8 Aug 80°20′ 178°43′W 1568 B, Bc (3), Pc, I

17 9 Aug 81°15′ 179°00′E 2255 P, B, Bc (2), I

18 10 Aug 81°34′ 176°58′E I

19 11 Aug 82°26′ 175°50′E 2414 P, B, Bc (2), I

20 12 Aug 83°10′ 174°06′E 3145 Bc, Pc, I

21 13 Aug 84°06′ 174°59′E 3205 P, B, Bc, Pc, I

22 14 Aug 84°50′ 170°42′E I

23 15 Aug 85°54′ 166°50′E 3535 P, B, Bc (2), I

24 16 Aug 87°09′ 160°32′E 4020 P, B, Bc, Pc

25 18 Aug 88°04′ 147°47′E 2191 P, B, Bc (2), I

26 19 Aug 88°48′ 143°29′E 1034 B, Bc (2)

27 19 Aug 88°52′ 141°55′E 1634 Pc

28 19 Aug 88°52′ 140°31′E 2015 Bc, Pc, I

29 20 Aug 88°56′ 138°55′E 3047 Bc, Pc

30 20 Aug 89°01′ 137°41′E 4064 Bc, I

31 22 Aug 89°59′ 031°45′E 4290 P (2), B (2), Bc, Pc, I

32 25 Aug 85°43′ 037°50′E 3585 P, B, Bc (2), I

33 26 Aug 84°16′ 034°37′E 4052 P, B, Bc, I

*P-production, B-biomass, Bc-box core, Pc-piston core, I-ice.

114
115

Science Stations

Combined P and B stations include CTD, nutrients, pCO2, halocarbons,

organics, DMSP, DOC, DON, POC, PON, zooplankton, chlorophyll, phytoplankton, heterotrophic protists, bacteria, primary production, nutrient uptake, bacterial production, protistan herbivory, bactivory, zooplankton excretion, and zooplankton herbivory.

B stations include CTD, nutrients, halocarbons, and chlorophyll.

Box cores (Bc) were variously sampled depending on whether they served

the geological or biological programs.

I stations include ice cores, albedo, sediments, and ice contaminants.

Depths are uncorrected.

In addition, over 1300 nautical miles of video and still photography ice

morphology survey lines were flown to measure floe and melt pond size distributions.

Atmospheric chemistry and physics measurements were made throughout

the voyage, either continuously or through flask sampling or intermittent

pumping. These observations include volatile organics, dimethyl sulfide, ozone,

carbon monoxide and dioxide, organohalides, sulfur dioxide and acid gases,

major ions and stable isotopes, aerosols and condensation nuclei. Measurements of halomethanes in water, snow and ice were made while on station.

Radiation measurements were also made throughout the voyage. These

were done with a Fourier transform IR spectroradiometer (mid-IR), an experimental near-IR detector, a total IR pyrgeometer, a solar pyranometer, a nearIR pyranometer and a UV radiometer.
1994 Arctic Ocean Section

Louis S. St-Laurent

No. Date N Lat. Long. Depth (m) Sampling program *

1 25 Jul 67°47′ 168°47′W 50 O, C

2 27 Jul 72°08′ 168°50′W 53 O, C, I

3 28 Jul 73°00′ 168°49′W 66 O, C, I

4 28 Jul 73°30′ 168°51′W 116 O, C, I

5 28 Jul 73°59′ 168°44′W 184 O, C, I

6 29 Jul 74°30′ 168°50′W 195 O, C, I

7 29 Jul 75°00′ 169°59′W 261 O, C, I

8 29 Jul 75°27′ 170°35′W 887 O, C, I

9 30 Jul 75°45′ 171°14′W 1679 O, C, I

10 30 Jul 75°57′ 171°40′W 1886 O, I

11 1 Aug 76°38′ 173°19′W 2227 O, C, I

12 2 Aug 77°20′ 175°02′W 1852 O, I

13 2 Aug 77°48′ 176°18′W 1217 O, C, I

14 3 Aug 78°09′ 176°54′W 956 O, C, I

15 4 Aug 78°08′ 174°18′W 1853 O, I

16 4 Aug 78°59′ 175°49′W 1062 O, C, I

17 5 Aug 79°59′ 174°19′W 1670 O, C, I

18 6 Aug 80°09′ 173°15′W 2655 O, C, I

19 7 Aug 80°09′ 176°46′W 2115 O, C, I

20 8 Aug 80°20′ 178°38′W 1436 O, C, I

21 8 Aug 80°43′ 179°59′W 1640 O, C, I

22 9 Aug 81°15′ 179°01′E 2208 O, C, I

23 9 Aug 81°35′ 176°52′E 2524 O, C, I

24 10 Aug 82°28′ 175°40′E 2430 O, C, I

25 11 Aug 83°10′ 173°56′E 3088 O, C, I

26 12 Aug 84°04′ 175°04′E 3135 O, C, I

27 13 Aug 84°51′ 170°42′E 3323 O, C, I

28 15 Aug 85°54′ 166°42′E 3456 O, C, I

29 16 Aug 87°09′ 160°42′E 3939 O, C, I

30 18 Aug 88°04′ 147°50′E 2130 O, C, I

31 19 Aug 88°47′ 142°44′E 1029 O, C, I

32 19 Aug 88°52′ 140°00′E 1983 O, C, I

33 20 Aug 88°57′ 139°12′E 2938 O, C, I

34 20 Aug 89°01′ 137°09′E 4080 O, C, I

35 22 Aug 90°00′ 4215 O, C, I

36 25 Aug 85°44′ 37°45′E 3471 O, C, I

37 26 Aug 84°15′ 35°05′E 3979 O, C, I

38 27 Aug 83°51′ 35°41′E 3954 O

39 31 Aug 75°00′ 6°03′W 3448 O, C

*O-oceanography, C-contaminants, I-ice.

116
117

O stations include CTD, oxygen, nutrients, carbonate and alkalinity, CFCs

(including CC14, helium-tritium, 18O, 14C and trace metals.

C stations include hydrocarbons, HCHs, other organics (e.g., toxophenes),

radionuclides and trace metals, using both large-volume bottle sampling and

submerged and surface pumps. Contaminant samples were also collected from

snow samples, net hauls and box cores.

I stations variously include vertical temperature and salinity profiles in the

ice, beam tests, crystallography, and electrical and physical properties of the

snow cover. There were also continuous ship-based radiation measurements at

37 GHz, vertically polarized.

Depths are uncorrected.

In addition, 72 CTD stations to 1500 m were occupied using a portable

system carried by helicopter and deployed from the ice. Two 48-hr contaminant moorings were also deployed and recovered by helicopter. Finally, the marine

mammals program made detailed studies of seven polar bears, again working

from helicopters.

Science Stations
1994 Arctic Ocean Section
1994 ARCTIC OCEAN SECTION

0 200 1000 2000 3000 4000 5000

DEPTH (meters)

Cruise track of the Louis S. St-Laurent and the Polar Sea between July 24 and September 3, 1994.

The dots represent the science stations. (Map created by Christopher Guay.)

Ship and helicopter photos on previous page by Peter Brickell.
1994 Arctic Ocean Section

DMSP SSMI 85GHZ

15 Aug 94 2325Z

Total Ice Cont.

90–100%

70–80%

45–55%

20–30%

0–3%

Total ice concentration for August 15, 1994. The track of the Polar Sea is shown in white. This

Defense Meteorological Satellite Program (DMSP) image was derived using the 85-GHz passive

microwave channel of the Special Sensor Microwave Imager (SSM/I). The images were received

and processed in near real time by the TeraScan system aboard the Polar Sea. For more information

about how images such as this were created and used during AOS-94, see p. 97.

Photo on back cover by Charles Geen