SCREENING 2010 – 2011 SEDIMENT PAH CONCENTRATIONS FOR POTENITAL BENTHIC ORGANISM TOXICITY WITHIN THE NORTHEASTERN CHUKCHI CORRIDOR

Douglas H. Dasher1*, Stephen C. Jewett1, Terri Lomax2, and Ian Hartwell3 1University of Alaska Fairbanks Institute of Marine Science & School of Fisheries and Ocean Sciences

2Alaska Department of Environmental Conservation 3NOAA National Status and Trends Program

*Primary contact : E-mail: dhdasher@alaska.edu Phone 907-474-6840

Methods

The Alaska Department of Environmental Conservation (ADEC) with its University of Alaska partner established an Alaska Monitoring and Assessment Program (AKMAP) focused on conducting aquatic resource surveys of Alaska’s waters. In 2010 – 2012, AKMAP, with the participation of NOAA, sampled 74 Chukchi Sea stations from Pt. Hope to Barrow, Alaska. The surveyed region lies within a 25- to 50-mile exclusion corridor between the ~10-50 m depth and the BOEM Oil and Gas Lease Sale #193 area. There have only been limited studies of sediment contaminants, such as polycyclic aromatic hydrocarbons in the corridor region.

Introduction

Grab sediment sampling was accomplished using a stainless steel double Van Veen following EPA Quality Assurance Protocols (EPA, 2001). The surficial sediment layer (top 2-3 cm) was sampled with a clean high-grade stainless steel scoop and composited for chemical contaminant analyses (hydrocarbons, pesticides, PCBs, trace metals), total organic carbon (TOC), carbon/nitrogen isotopes, and grain size analyses. Analyses for contaminants and TOC was accomplished at the University of Texas GERG laboratory. Forty-six PAH (parent and alkylated groups) were measured. Total PAH, as discussed here consist of the 13 PAHs used to develop the ERL and ERM (Long et al., 1996). The ESBTU values consists of 34 PAHs and sediment TOC values (EPA, 2003).

In regards to the sediment Total PAH (13 PAHs) sampled within the exclusion corridor : • TPAH concentrations were lower than the ERL

concentration by an order of magnitude or greater. • Lower Ledyard Bay stratum had the highest values.

• Further investigation will assess individual PAH profiles, sediment grain size and TOC.

• Ratios of phenanthrene-to-anthracene were >10 for 69% of the stations suggesting principal PAH sources are petrogenic (Pait et al., 2012).

Objectives

Screen sediments for Total Polycyclic Aromatic Hydrocarbons (TPAH ) toxicity to benthic organisms using NOAA SQUIRT Table Effects Range Low (ERL) and Effects Range Median and EPA Equilibrium Partitioning Sediment Benchmark Toxicity Units (ESBTU) (Buchman, 2008; EPA, 2003).

Preliminary Assessment Results & Discussion

The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Government. Mention of trade names, commercial projects or other partners does not constitute their endorsement by the U.S. Government nor Alaska Department of Environmental Conservation or University of Alaska.

This project is funded with qualified outer continental shelf oil and gas revenues by the Coastal Impact Assistance Program, U.S. Fish and Wildlife Service, U.S. Department of Interior. Funding was also provided by Shell Exploration and Production Company to support the sea bird and marine Mammal observers.

This study is part of a larger effort conducted by the Alaska Department of Environmental Conservation, the 2010-2012 northeastern Chukchi Sea Condition Assessment.

Equilibrium Partitioning Sediment Benchmarks Toxicity Units (ESBTU)

ESBTU are another method of assessing PAH mixture toxicity to benthic organisms (EPA, 2003). • ESBTU consists of 34 individual PAHs. • ESBTU values ≤1 are considered acceptable for the

protection of benthic organisms while values >1 may unacceptably affect sensitive benthic organisms.

• Ratio of ESBTU13 (13 PAHs containing no alkylated PAHs) to the total ESBTU34 (34 PAHs) suggests possible PAH sources, such as pyrogenic (combustion of organic matter) and petrogenic (geological timeframe formed fossil fuels)

• ESBTU13/ESBTU34 of ~0.1 suggest petrogenic source. • ESBTU13/ESBTU34 with a ~ 0.5 suggests pyrogenic

source. The following observations apply: • Overall TPAH concentration are considered acceptable for

protection of benthic organisms. • Only one station in the Ledyard Bay stratum

exceeded 1, with a ESBTU of 1.06. • The ESBTU13/ESBTU34 mean ratio for the region is

0.18±0.06 suggesting the PAH source is principally petrogenic.

Sediments examined in the corridor did not exhibit TPAH concentrations considered harmful to benthic organisms. The preliminary analysis suggest the primary source for PAH in the corridor is petrogenic. Further environmental forensics will be carried out to more definitively assess the PAH sources.

References Buchman, M. F., 2008. NOAA Screening Quick Reference Tables, NOAA OR&R Report 08-1, Seattle WA, Office of Response and Restoration Division, National Oceanic and

Atmospheric Administration, 34 pages. EPA. 2001. Environmental Monitoring and Assessment Program (EMAP): National Coastal Assessment Quality Assurance Project Plan 2001-2004. U.S. Environmental

Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, Gulf Breeze, FL. EPA/620/R-01/002. EPA. 2003. Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: PAH Mixtures. EPA-600-R-02-

013. Office of Research and Development, Washington DC. Long, E. R., A. Robertson, et al. (1996). "Estimates of the Spatial Extent of Sediment Toxicity in Major U.S. Estuaries." Environmental Science & Technology 30(12): 3585-

3592. Pait, A.S., Whitall, D.R., Dieppa, A., Newton, S.E., Brune, L., Caldow, C., Mason, A.L., Apeti, D.A., Christensen, J.D. 2012. Characterization of organic chemical contaminants

in sediments from Jobos Bay, Puerto Rico. Environmental Monitoring and Assessment, 184: 5065 – 5075.