ACCESS NUMBER: 85294-74464 

STUDY TITLE: Trace Metals and Hydrocarbons in Sediments of the Beaufort Lagoon, 

Northeast Arctic Alaska, Exposed to Long-term Natural Oil Seepage, Recent 

Anthropogenic Activities and Pristine Conditions

REPORT TITLE: Trace Metals and Hydrocarbons in Sediments of the Beaufort 

Lagoon, Northeast Arctic Alaska, Exposed to Long-term Natural Oil Seepage, Recent 

Anthropogenic Activities and Pristine Conditions

CONTRACT NUMBER: 1435-01-02-CA-85294; TO: 74464 

SPONSORING OCS REGION: Alaska 

APPLICABLE PLANNING AREA: Beaufort Lagoon, Northeast Arctic Alaska 

FISCAL YEARS OF PROJECT FUNDING: 2003–2005 

COMPLETION DATE OF REPORT: January 10, 2006 

COSTS: 2003: 94,189 

 2004: 72,449 

PROJECT MANAGER: A. Sathy Naidu 

AFFILIATION: School of Fisheries and Ocean Sciences, University of Alaska Fairbanks 

ADDRESS: P.O. Box 757220, Fairbanks, Alaska 99775 

PRINCIPAL INVESTIGATOR: A. Sathy Naidu 

This project addressed the concern that concentrations of trace metals and 

hydrocarbons in the sediments of the Alaskan Arctic can occur as a result of petroleum 

exploration and production activities. Lagoon sediments of the North Slope, if they were 

to be the ultimate sink for both organic and inorganic anthropogenic chemicals, could be 

a major source of contaminants for benthic animals as well as organisms which have a 

close link with sediments and which serve as transfer pathways of contaminants to 

higher trophic levels. Recognizing the pending lease sales scheduled by MMS in 2003–

2007 we have extended our investigations to establish baselines on trace metals and 

hydrocarbons in the sediments of the Beaufort Lagoon located at the remote eastern 

margin of the north Alaskan Arctic coast and far from intense industrial activities. 

This report presents the highlights of a two-year study (2003–2005) which had as its 

major objective the measurement of the concentrations of a suite of 12 trace metals 

(copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), vanadium (V), lead (Pb), tin 

(Sn), zinc (Zn), arsenis (As), barium (Ba), iron (Fe) and manganese (Mn) in the mud 

fraction (<63 um size), and total mercury (THg), sediment grain size, organic carbon 

(OC) and hydrocarbons (normal and isoprenoid alkanes, triterpenoids and steranes and 
ACCESS NUMBER: 85294-74464 

polycyclic aromatic hydrocarbons) in the gross sediments of the Beaufort Lagoon. The 

choice of the above metals and hydrocarbons was based on the fact that these 

chemicals are often present in drilling effluents, crude, and petroleum development and 

production activities. The purpose of this study was to close a gap in the baselines for 

sediment metals and hydrocarbons for a remote region of the North Slope Coast. 

Sediment samples (Van Veen grab) from the Beaufort Lagoon were collected at 22 

selected stations spread over three sectors. Six of the samples were in close proximity 

to natural oil seeps, another six samples from an area that was impacted by military 

activities connected with a DEW line station (now defunct), and a third suite of 10 

samples from east lagoon which is presumed pristine. The methods for the analyses of 

the trace metals and hydrocarbons on the sediments was essentially the same as those 

adopted in previously supported CMI/MMS studies elsewhere along the North Slope 

nearshore region. The QA/QC (quality assurance/quality control) protocol prescribed by 

the U.S. Environmental Protection Agency (EPA) for metal analysis was followed. 

QA/QC for the organic analyses included successful participation in the (NOAA/National 

Status and Trends Program). 

Statistical analysis consisted of the determination of the correlation coefficients between 

trace metals, OC, N, and the silt and clay percents in the mud fraction to deduce the 

geochemical partitioning of the metals in the mud analyzed. Cluster analysis was 

conducted to determine if there were groupingsof samples based on trace metal 

concentrations. In addition, principal component analysis was conducted to deduce the 

cause of the regional variations in metal concentrations. 

Interpretations of the trace metal and hydrocarbon data provide the following 

conclusions. There are no significant disparities in the metal concentrations between the 

regions exposed to long-term natural oil seep, past anthropogenic activities related to 

the DEW line military station and the pristine environment of the lagoon. Any of the 

trace metals investigated in this study that might have originated from oil seeps or 

human activity are widely dispersed and diluted. The effect of any point sources on the 

metal content in the sediment is not discernable. 

Two time interval comparisons of the mean concentrations of metals in muddy 

sediments taken at 26-year intervals (1977–2003) show a significant decrease in V, an 

increase in Mn and Cu, and similar values in Cr, Ni and Zn. These differences likely 

reflect the differences in granulometry and organic carbon contents between the 1977 

and 2003 samples. 

The mean concentration of all trace metals in the mud of Beaufort Lagoon are generally 

at the same level as those reported by us from the Colville delta, Prudhoe Bay-Canning 

delta region. 

The significantly higher Hg values in Beaufort Lagoon gross sediments (mean: 57ng/g) 

than in the Colville Delta-Prudhoe Bay-Canning Delta region (mean: 19 ng/g) is 
ACCESS NUMBER: 85294-74464 

probably due to differences in the natural input of the metal from the hinterland, a 

proposition that remains to be further investigated. 

Correlation coefficient analysis between metals, OC, and granulometry, suggests that 

clays and Fe oxy-hydroxide presumably play an important role in metal scavenging and 

their deposition in the Beaufort Lagoon. This conclusion is consistent with our results on 

metal partitioning in the adjacent nearshore regions of Beaufort Sea. 

Based on principal component analysis, it is evident that a southeast-northwest high to 

low gradient is present in the study area in the concentrations of the trace metals. This 

trend may be attributed to net regional variations in granulometry, organic carbon 

contents and/or possible changes in the natural input of metals contents along the 

above gradients, rather than a reflection of a gradient resulting from decreasing inputs 

from potential point sources of contaminants, such as from natural oil seeps and/or from 

past activities of the Distant Early Warning (DEW) line station located south of 

Nuvagapak Point. 

The hydrocarbon components in gross sediments from the Beaufort Lagoon are 

biogenic and terrestrial. Their general composition is very similar to those found in the 

sediments from Elson Lagoon, Colville Delta, Prudhoe Bay, Canning Delta and adjacent 

Canadian deltaic and inner shelf region and the inner shelf of the Beaufort Sea. The 

data provide no evidence to document the contribution of petroleum hydrocarbons to 

the Beaufort Lagoon sediments analyzed from the oil seeps located in the vicinity and 

anthropogenic activities. The trace metal and hydrocarbon levels are either similar to or 

below those reported for unpolluted near-shore regions of the world. The Beaufort 

Lagoon sediments have remained uncontaminated as far as the analyzed trace metals 

and hydrocarbons are concerned. 

The mean concentrations of As, Cu and Ni in the mud of the Beaufort Lagoon are above 

the threshold level of the Effects Range-low (ERL), as stated in Long et al., (1995, 

1998), that can cause adverse effects on benthic and demersal organisms. However, 

the mean concentrations of all the selected 14 hydrocarbons in the gross sediments of 

Beaufort Lagoon are below the ERL, which implies that no adverse effects can be 

expected from current levels of hydrocarbons on the above organisms.