ACCESS NUMBER: M13AC00002

STUDY TITLE: Distribution and behavior of select trace metals in Beaufort Sea ice

REPORT TITLE: Distribution and behavior of select trace metals in Beaufort Sea ice

CONTRACT NUMBER(S): M13AC00002

SPONSORING OCS REGION: Alaska

APPLICABLE PLANNING AREA(S): Chukchi and Beaufort Sea

FISCAL YEAR(S) OF PROJECT FUNDING: 2013

COMPLETION DATE OF REPORT: December 2016

COST(S): (by fiscal year): FY 2013: $262,073 

CUMULATIVE PROJECT COST: $262,073

PROJECT MANAGER(S): Robert D. Rember

AFFILIATION (of project manager): University of Alaska, Fairbanks

ADDRESS: International Arctic Research Center, UAF, Fairbanks, AK, 99775

PRINCIPAL INVESTIGATOR(S)*: Robert D Rember, Ana M. Aguilar-Islas

KEY WORDS: Trace metals, sea ice, seawater, Chukchi Sea, Beaufort Sea, land-fast 

ice

BACKGROUND: 

Full suites of chemical parameters have been measured in and around offshore oil 

exploration and production facilities on the inner shelf in the Beaufort Sea for several 

decades. A key theme amongst these earlier studies was to provide a better 

understanding of the background chemical environment of this region, so that a 

reference concentration was available in case monitoring was required due to a future 

spill or other event in the near shore. This project was undertaken to provide for the first 

time dissolved and particulate trace metal data in sea ice near the North Slope oil and 

gas operations. To do so, it was required to first design, build, and test a trace-metal 

clean ice corer. Results from this study provide data of background levels of trace metals 

in sea ice that will be useful in the event a spill were to impact the sea ice cover in the

Beaufort Sea shelf. The data could be of further use if incorporated into models. 

OBJECTIVES:

Our objectives were to: 1) collect seawater samples in the Chukchi Sea to better 

understand the trace metal distribution in shelf regions affected by sea ice, 2) build and 

test a trace metal clean sea ice corer using tank experiments, 3) collect snow, sea ice 

and seawater samples in the Colville River Delta after a full winter of sea ice growth, 4) 

analyze the samples to provide a basic understanding of how trace metals partition 

among seawater, snow and sea ice, and how their dissolved and particulate distribution 

varies within these reservoirs. Our goal was to gain understanding of the cycling of trace 

metals in Arctic environments impacted by sea ice. In particular, we wanted to know 

whether dissolved trace metals are impacted by sediment inclusions, excluded during 

sea ice formation, concentrated in the ice, or remain in approximate constant proportions 

with other salts as sea ice forms.

DESCRIPTION:

Seawater samples were collected during the Chukchi Sea expedition in late summer 

2013 using a 12-bottle trace metal clean rosette. The study area in the Chukchi Sea 

covered from the Bering Strait through the broad shelf and into the Canada Basin. A 

total of 20 trace metal casts were taken during the cruise and are accompanied by 

conductivity, temperature, dissolved oxygen, transmissometer, fluorometer and 

photosynthetic active radiation (PAR) data. Suspended particulate samples from the 
cruise were analyzed for aluminum (Al), iron (Fe), manganese (Mn), copper (Cu), zinc 

(Zn), nickel (Ni), cobalt (Co) lead (Pb) and titanium (Ti), and seawater was analyzed for 

dissolved Fe, Mn, Cu, Zn, Ni, and Pb. A total of 50 sea ice cores, 5 snow samples and 9 

seawater samples were collected in the nearshore Beaufort Sea (Oliktok Point) during 

the Spring of 2015. Seawater samples were collected through a hole in the ice using a 

Teflon pump and Teflon-lined tubing, snow samples were collected using clean scoops 

to fill bottles, and ice cores were collected using our newly designed trace-metal-clean 1-

m ice corer. These samples were analyzed for a similar suite of metals as the Chukchi 

Sea samples. Overall the data quality appears to be excellent. 

SIGNIFICANT CONCLUSIONS:

Results from the Chukchi Sea show trace metal values that are oceanographically 

consistent with water masses originating from the Pacific Ocean through Bering Strait. 

Variability in metal concentrations from south to north reflect different currents, surface 

and subsurface water masses, and interactions with resuspended sediment. Trace metal 

micronutrients such as Fe and Zn show decreases in surface waters in the northern 

Chukchi shelf when compared to the Bering Strait, suggesting that biological productivity 

likely plays an important role in regulating select surface trace metal concentrations in 

the region. The variability in dissolved and particulate metal concentrations was 

monitored at a time-series station. During the 2 weeks the station was occupied, a front 

moved through the site. The front caused a number of notable changes including 1) 

increased the density of the surface waters, 2) mixed the water column including the 

bottom boundary layer and oxygenated the bottom waters, 3) considerably increased the 

concentrations of Ni and labile Mn in surface waters, and 4) decreased light transmission 

throughout the water column, indicating an enhanced suspended particle load. 

Water profiles collected for trace metals along the Chukchi continental margin show 

that there were enhanced concentrations of most metals in the upper 300 m of the water 

column resulting from the transport of Pacific Summer and Winter Waters (Chukchi Shelf 

water) into the deeper basins. Concentrations below those depths tended to be more 

consistent, particularly in the layer dominated by Atlantic Water, which entered the basin 

from either Fram Strait or the Barents Sea.

The sea ice data collected during this study is the first to be reported for trace metals 

in the near shore Beaufort Sea. As a whole, dissolved trace metal concentrations in the 

sea ice were substantially lower compared to those in seawater collected from below the 

ice. Interestingly, these spring 2015 sea ice metal concentrations were also lower than 

those observed in snow and river water collected during previous studies in this region, 

and also lower than surface seawater metal concentrations observed during fall 2013 

over the Chukchi shelf. These results are incongruous with sea ice studies in Antarctica 

where sea ice trace metal concentrations tend to be higher when compared to water 

column concentrations. We were also surprised to have obtained much lower 

concentrations of dissolved trace metals in our sea ice samples than what typically has

been observed in Antarctic sea ice. We had expected that due to the higher particulate 

loads in Arctic ice as compared to Antarctic sea ice, dissolved trace metal 

concentrations would be enhanced from particles leaching metals into sea ice brine

pockets over time. Because we sampled at a time when ice had begun to melt, it is likely 

that the bulk of the dissolved trace metals had been released prior to our sampling. Our 

spring 2015 sampling took place at the end of the season, when the warming of sea ice 

by enhanced solar radiation results in the connection of brine pockets into brine 

channels which allow for the early release of dissolved constituents. Decoupling 

between the earlier release of dissolved and the later release of particulate trace metals 

from sea ice has been documented in Antarctic sea ice. These results lead us to 
conclude that to better understand the cycling of trace metals in Arctic sea ice, a 

temporal study of sea ice during freezing, growing and melting stages is needed.

Sampling in late winter/early spring would provide information on the role of particle 

loads within the sea ice on the concentration of dissolved trace metals prior to brine loss.

STUDY RESULTS:

This work represents the first trace metal measurements for dissolved and particulate 

trace elements in sea ice from the near shore Beaufort Sea. In addition, we also 

obtained some of the first trace metals measurements for seawater in the Chukchi Sea 

and Canada Basin. Although the process of building an ice corer from the design phase, 

through prototyping, to arrive at a functional piece of equipment in this time frame was 

challenging, we feel our efforts were rewarded. We are happy to report that values

obtained for these easy-to-contaminate metals were in the low concentration range 

expected for marine samples, and that variability in particle load within the ice, did not 

result in sample cross contamination. In addition, much of the data collected during this 

study can be combined with other studies conducted by BOEM during the same time 

periods for the Chukchi and Beaufort Seas. Finally, we plan to assemble a more 

complete picture of select trace metals in the near shore Beaufort Sea that can now 

include sea ice along with riverine, seawater, snow and sediment data collected over the 

past several decades.

STUDY PRODUCT(S):

Rember, R.D., Aguilar-Islas, A.M., Distribution and behavior of select trace metals in 

Beaufort Sea ice. In University of Alaska Coastal Marine Institute Annual Report 

20, Calendar Year 2013. Fairbanks, Alaska. OCS Study BOEM 2014-0052 

Aguilar-Islas, A., Rember R.D., Distribution and behavior of select trace metals in

Beaufort Sea ice: preliminary findings. CMI Annual Review oral presentation,

January 15, 2014

Rember, R.D., Aguilar-Islas, A.M., Distribution and behavior of select trace metals in

Beaufort Sea ice. In University of Alaska Coastal Marine Institute Annual Report

21, Calendar Year 2014. Fairbanks, Alaska. OCS Study BOEM 2015-015

Aguilar-Islas, A, Seguret, M., Rember, R., Nishino, S., Sedimentary input of trace metals

from the Chukchi Shelf, 2014 Fall Meeting AGU, San Francisco Calif. 15-19 Dec.

Aguilar-Islas, A., Rember R.D., Distribution and behavior of select trace metals in

Beaufort Sea ice: preliminary findings. CMI Annual Review oral presentation,

January 23, 2015

Domena, V., Aguilar-Islas, A., Rember, R.D., Dissolved and Particulate Trace Metal

Concentrations in Sea Ice at Oliktok Point, Alaska, Alaska Marine Science

Symposium, January 26, 2016

Aguilar-Islas, A., Rember R.D., Distribution and behavior of select trace metals in

Beaufort Sea ice: preliminary findings. CMI Annual Review oral presentation,

January 29, 2016

Rember, R.D., Aguilar-Islas, A.M., Distribution and behavior of select trace metals in

Beaufort Sea ice. In University of Alaska Coastal Marine Institute Annual Report

22, Calendar Year 2015. Fairbanks, Alaska. OCS Study BOEM 2016-013
Focus area for samples collected during the R/V Mirai Cruise in 2013. Red dots show 

trace metal stations, the blue dot shows the time series station

Focus area for sea ice samples collected during the cANIMIDA III Spring Sampling effort 

in May 2015. Black dots show sea ice trace metal stations.

Oliktok Point