ACCESS NUMBER: 15181 

STUDY TITLE: Trace Metals and Hydrocarbons in Sediments of Elson Lagoon (Barrow, Northwest 

Alaska) as Related to the Prudhoe Bay Industrial Region 

REPORT TITLE: Trace Metals and Hydrocarbons in Sediments of Elson Lagoon (Barrow, Northwest 

Alaska) as Related to the Prudhoe Bay Industrial Region 

CONTRACT NUMBER: 1435-01-98-CA 30909; TASK ORDER (TO): 15181 

SPONSORING OCS REGION: Alaska 

APPLICABLE PLANNING AREA: Beaufort Sea 

FISCAL YEAR OF PROJECT FUNDING: 2001 

COMPLETION DATE OF REPORT: September 2003 

COST: FY 2001: $56,101; CUMULATIVE PROJECT COST: $56,101 

PROJECT MANAGER: A. Sathy Naidu 

AFFILIATION: University of Alaska Fairbanks 

ADDRESS: Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, AK 99775-7220 

PRINCIPAL INVESTIGATORS*: A. Sathy Naidu and John J. Kelley 

KEY WORDS: trace metals, hydrocarbons, contaminants, sediments, Beaufort Sea, Alaskan Arctic 

BACKGROUND:

In recent years, considerable attention has been given to assessing the state of the Arctic environment, 

especially in relation to the presence and biological effects of anthropogenic contaminants. The Arctic 

region, most of which lies far away from major industries, is no longer pristine as attested to by the levels 

of industrial contaminants found in the environment. In order to understand the sources and processes of 

trace metal and hydrocarbon bioaccumulation in the Alaskan Arctic seas, it is pertinent to first document 

the regional concentrations and historical changes in trace metals and hydrocarbons in the sediments. 

Such information will be critical for any effort relating to ecological risk assessment of marine areas with 

the potential for high input of anthropogenic inorganic and organic contaminants. Marine sediments, 

which serve as an initial sink for particle-reactive trace metals and hydrocarbons, could be a major source 

of contaminants for benthic animals and other organisms having a close link with sediments and which 

can serve as pathways for the contaminants to higher trophic levels. Stratigraphic changes in the 

concentrations of trace metals in dated sediment cores provide an insight into the temporal changes of 

metal contamination. For the Alaskan Arctic seas, however, little information is available on 

bioaccumulation of contaminants and the pathways involving sediments therein. 

The possible anthropogenic sources of contaminants in the Beaufort Sea could be industrial activities 

such as those relating to petroleum exploration and development, offshore dredging for gravel, and/or 

discharge of municipal sewage, litter by local residents and military activities. It is possible that sediments 

located along the north Arctic coast contain such high levels of contaminants that they could result in 

deleterious effects on the region’s biota. Understanding the composition of contaminants and relating 

them to their possible sources is important for environment management. As part of a long term program 

on contaminant monitoring a one-year study (2001–2002) was conducted to determine the current 

concentrations and historical changes in selected trace metals and hydrocarbons in sediments of Elson 

Lagoon, northwest Alaskan Beaufort Sea. Elson Lagoon is a nearshore region which is impacted by 

urban-related activities, involving residents from the community of Barrow. One of the objectives of this 
ACCESS NUMBER: 15181 

study was to compare the trace metal and hydrocarbon data in sediments from Elson Lagoon with those 

collected by us in an earlier study from the Colville Delta–Prudhoe Bay region, to help set a geochemical 

basis for differentiating sources of contaminants derived from urban-impacted and petroleum-related 

activities in the North Slope nearshore region. This report addresses the results of that study. 

OBJECTIVES:

The specific objectives of the study were 1) to determine concentrations of arsenic (As), barium (Ba), 

cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), Manganese (Mn), nickel (Ni), tin (Sn), vanadium 

(V) and zinc (Zn) in the sediment mud fraction (<62 μm size), and concentrations of total and methyl 

mercury (THg and MeHg), saturated hydrocarbons (normal and isoprenoid alkanes, triterpenoids and 

steranes) and polycyclic aromatic hydrocarbons (PAHs) in gross sediments of the nearshore Alaskan 

Beaufort Sea; 2) to assess from sediment stratigraphy the temporal changes in the trace metals 

concentrations during the past 70–80 years; and 3) to compare the trace metal and hydrocarbon 

concentrations of Elson Lagoon with those collected earlier from the Colville Delta–Prudhoe Bay region, 

to set a basis for distinguishing differences in contaminant chemistries resulting from urban and 

petroleum-related activities. 

DESCRIPTION:

In August 1999, van Veen grab sediment samples were collected at five stations from Elson Lagoon, the 

study area. Sediment core samples were also collected at three locations. Acid solutions of the mud 

fractions (<63 μm size fraction) were analyzed for all of the trace elements (except As and Hg) either by 

AAS/graphite furnace or ICP/MS. The As analysis was by PSA Excaliber automated hydride generation 

AFS. The analysis of THg in gross sediment was by CV-AAS, and that of MeHg was by CVAF detector 

following cryogenic GC separation.The sediment geochronology on one core sample was by the 210Pband 137Cs-based methods. After solvent extraction and GC separation the saturated fraction of 

hydrocarbons was analyzed for alkanes by a Varian 3400 GC equipped with an SPI injector. Normal and 

isoprenoid alkanes were quantified by GC/FID by the internal standard method using dodecylbenzene. 

PAHs were quantified by GC/MS in the selective ion monitoring mode using deuterated internal standard 

mixtures. 

The concentration levels of all the trace metals in the lagoon are generally below or similar to those in 

shales and unpolluted nearshore marine sediments. Encompassing the past ~70 years, stratigraphic 

samples show a net significant increase (p < 0.05) up the core in Ba, Cr and Mn accompanied by a 

significant (p < 0.05) down core increase in THg, and no significant change in the other metals. The up 

core increase in the three metals may be explained in terms of three possibilities: 1) the lagoon is getting 

contaminated with the metals, 2) a reflection of up core stratigraphic changes in lithology (granulometry, 

mineralogy) and/or organic matter, or 3) diagenetic upward mobilization of Mn and Cr in solution from 

subsurface anoxic sediments and subsequent oxidative coprecipitation of the two metals at the surface. 

The down core increase in THg may be due to increased concentration of Hg by methylation in 

progressively anoxic sediment layers. 

Long et al. [1995] defined the guideline values effects range–low (ERL) and effects range–median (ERM), 

representing possible-effects ranges, pertaining to concentrations of trace metals and organics in 

sediments, for the occurrence of adverse effects on biota at varying frequencies. ERL and ERM were 

determined for nine trace metals and several categories of organic compounds. The concentrations of 

eight metals in Elson Lagoon sediments were compared with corresponding metals in Long et al.’s study 

(their ninth metal, silver, was not included in this study). The comparison indicates that the concentrations 

of As, Cr, Cu and Ni in Elson Lagoon sediments are at levels such that adverse effects on biota would 

occasionally occur, whereas the concentrations of Cd, Pb, Zn and THg are below such levels. However, 

we suggest that the conclusions, based on the extrapolation of Long et al.’s guidelines to Elson Lagoon, 

must be verified by detailed site-specific investigations, including assessment of the proportion of a total 

metal in sediment that may be available for bioaccumulation and studies involving cause & effects relating 

to individual metals on resident organisms of the lagoon. 
ACCESS NUMBER: 15181 

Trace metal data in mud from the urban-impacted Elson Lagoon were compared with those from the oilrelated industrialized region of Colville Delta–Prudhoe Bay. By comparison, the Elson Lagoon muds have 

significantly higher concentrations (p < 0.05) of Cr, Ni, V and THg, with no significant regional difference 

in other metals. A possibility for the higher concentrations of the four metals in Elson Lagoon is a greater 

input of natural or anthropogenic metals from local sources. Alternate possibilities are a relatively lower 

rate of sedimentation in Elson Lagoon resulting in lower dilution of metals in sediments, or local focusing 

in Elson Lagoon of anthropogenic metal contaminants derived from Eurasia via long-distance 

atmospheric transport and subsequent deposition in precipitating snow and rain. The latter explanation is 

consistent with the report of Snyder-Conn et al. [1997] and Garbarino et al. [2002] of relatively higher 

concentrations of several metals in Elson Lagoon snow samples than samples from the Colville Delta–

Prudhoe Bay region, under similar snow and rain accumulation rates in both regions. A lack of significant 

(p < 0.05) correlation between all of the trace metals and clay percent in mud either suggests that the 

sediment granulometry is not an important factor partitioning the metals, or it is an artifact of the limited 

samples analyzed. 

The overall molecular compositions of alkanes and polycyclic aromatic hydrocarbons, which are very 

similar to those reported in our previous study for sediments of the Colville Delta–Prudhoe Bay region, are 

characteristic of biogenic origin and very little petroleum input is reflected in their composition. Preliminary 

qualitative analyses indicate the presence of small amounts of coprostanol, a sewage sterol, and 

coprostanone, but no linear alkylbenzenes, a sewage tracer from household laundry. This suggests that 

sewage input in the sediments, if at all present, may not be important. Among a selected group of the 

PAHs examined, in context of Long et al.’s guidelines, the concentration of 2-methylnaphthalene in only 

one of the three samples (EL-3) of Elson Lagoon sediments is between ERL and ERM threshold levels 

wherein adverse effects on biota would occasionally occur. As suggested for the trace metals, these 

conclusions must be clarified by site-specific studies on resident organisms. 

SIGNIFICANT CONCLUSIONS:

In summary, our study indicates that Elson Lagoon (as well as the Colville Delta–Prudhoe Bay nearshore 

of the North Slope of Alaska) has remained generally a relatively clean environment as far as sediment 

trace metals and hydrocarbons are concerned, despite the minor increase in some metals subsequent to 

accelerated urban-related anthropogenic activities in the lagoon during the past 70 years. The database 

on Elson Lagoon should be considered a baseline for monitoring inorganic and organic chemical 

contaminants in the lagoon region, an urban-impacted section of the North Slope of Alaska. These data 

will be useful for efforts relating to ecological risk assessment of the study area in the context of 

contaminant inputs. 

STUDY RESULTS:

The highlights of our investigation are as follows: 1) The study area has remained a relatively clean 

environment as far as the trace metal and hydrocarbon concentrations are concerned, despite the minor 

increased levels of Ba, Cr and Mn identified during the past ~70 years. The concentrations of the trace 

metals in contemporary sediments are still below or at levels reported for the world’s unpolluted marine 

argillaceous sediments. 2) The relatively higher concentrations of Cr, Ni, V and THg in the Elson Lagoon 

muds compared to those in the Colville Delta–Prudhoe Bay region, may be due to relatively higher input 

in Elson Lagoon of metals derived from natural and/or anthropogenic local sources (unknown as yet), 

lower sediment accumulation rates, or higher local focused accumulation of metals derived from long 

distance transport and codeposition in snow. 3) Based on the criteria developed by Long et al., the 

concentrations of As, Cr, Cu and Ni in Elson Lagoon sediments are at levels that would occasionally 

result in adverse affects on biota, whereas the concentrations of Cd, Pb, Zn and THg are below such 

levels. 4) The overall composition of the hydrocarbons, which are similar to those in the Colville Delta–

Prudhoe Bay area, are characteristic of biogenic origin and very little petroleum input is indicated. 

Sewage input in the sediments, if any, is unimportant. In context of Long et al.’s criteria, the 

concentrations of 2-methylnaphthalene in only one of the three sediment samples analyzed is between 

ERL and ERM threshold levels wherein adverse effects on biota would occasionally occur. 
ACCESS NUMBER: 15181 

STUDY PRODUCTS: 

The concentrations and depositional fluxes of the trace metals and hydrocarbons are available in readily 

accessible electronic format through the Minerals Management Service. Please refer to the tables 

attached showing results of the statistical analysis, station-wise specific sediment trace metal and 

hydrocarbon data, which are also available in computer-aided graphic or tabulated form. 

Naidu, A.S., and J.J. Kelley. 2002. Trace metals and hydrocarbons in sediments in Elson Lagoon 

(Barrow, northwest Arctic Alaska) as related to the Prudhoe Bay industrial region, p. 102. In University 

of Alaska Coastal Marine Institute Annual Report No. 8. OCS Study MMS 2002-001, University of Alaska 

Fairbanks and USDOI, MMS, Alaska OCS Region. 

Naidu, A.S., and J.J. Kelley. 2002. Trace metals and hydrocarbons in sediments in Elson Lagoon 

(Barrow, northwest Arctic Alaska) as related to the Prudhoe Bay industrial region. University of Alaska 

Coastal Marine Institute Annual Research Review, February 2002, Fairbanks, Alaska. 

Naidu, S., and J. Kelley. 2002. Monitoring contaminants in Elson Lagoon, Northwest Arctic Alaska: 

Progress of investigations on heavy metals and hydrocarbon concentrations in sediments, p. 11. In Proc. 

1st Workshop on Collaborative Marine Physical and Biogeochemical Research in Barrow. Fairbanks, 18 

October 2002. Frontier Research System for Global Change/International Arctic Research Center, Univ. 

Alaska Fairbanks. 

Naidu, A.S., J.J. Kelley and J.J. Goering. 2003. Trace metals and hydrocarbons in sediments in Elson 

Lagoon (Barrow, northwest Arctic Alaska) as related to the Prudhoe Bay industrial region, p. 49–56. In

University of Alaska Coastal Marine Institute Annual Report No. 9. OCS Study MMS 2003-003, University 

of Alaska Fairbanks and USDOI, MMS, Alaska OCS Region. 

Naidu, A.S., J.J. Kelley and J.J. Goering. 2003. Three decades of investigations on heavy metals in 

coastal sediments, North Arctic Alaska: A synthesis. Paper orally presented by A.S. Naidu at the XII 

International Conference on “Heavy Metals on the Environment”, 26–30 May 2003, Grenoble, France. 

The full paper is published in Journal de Physique IV, Vol. II, 107:913–916. 

Naidu, A.S. and M.I. Venkateson. 2003. Highlights of the trace metal study and hydrocarbon 

investigations on Elson Lagoon sediments. MMS Information Transfer Meeting on Elson Lagoon, 

Anchorage and Barrow, March 2003. 

Naidu, A.S., J.J. Kelley, J.J. Goering and M.I. Venkateson. 2003. Trace metals and hydrocarbons in 

sediments in Elson Lagoon (Barrow, northwest Arctic Alaska) as related to the Prudhoe Bay industrial 

region. Final Report. OCS Study MMS 2003-057, University of Alaska Coastal Marine Institute, University 

of Alaska Fairbanks and USDOI, MMS, Alaska OCS Region, 33 p. 

*P.I.’s affiliation may be different than that listed for Project Manager(s). 
ACCESS NUMBER: TO-15181

Applicable planning area: Beaufort Sea area of the Arctic Subregion 

Pt. Barrow

Barrow

Elson Lagoon

Chukchi Sea

Research Beaufort Sea Site

71 15′

71 20′

156 50′ 156 40′ 156 30′ 156 20′

4

5

1

2

3

Sampling sites in Elson Lagoon