NOAA Technical Memorandum NMFS-NWFSC-13
Supplemental Information Concerning
a Survey of Alaskan Subsistence Fish,
Marine Mammal, and Invertebrate Samples
Collected 1989-91 for Exposure
to Oil Spilled from the Exxon Valdez
Usha Varanasi, Donald W. Brown, Tom Hom, Douglas G. Burrows, Catherine A. Sloan, L. Jay Field*, John E. Stein, Karen L. Tilbury, Bruce B. McCain, and Sin-Lam Chan
National Marine Fisheries Service
*National Ocean Survey
Office of Resources Conservation and Assessment
Hazardous Materials Response and Assessment Division
7600 Sand Point Way N.E.
Seattle, WA 98115-0070
U.S. DEPARTMENT OF COMMERCE
Ronald H. Brown, Secretary
National Oceanic and Atmospheric Administration
D. James Baker, Administrator
National Marine Fisheries Service
The Northwest Fisheries Science Center of the National Marine Fisheries Service, NOAA, uses the NOAA Technical Memorandum NMFS series to issue informal scientific and technical publications when complete formal review and editorial processing are not appropriate or feasible due to time constraints. Documents published in this series may be referenced in the scientific and technical literature.
The NMFS-NWFSC Technical Memorandum series of the Northwest Fisheries Science Center continues the NMFS-F/NWC series established in 1970 by the Northwest & Alaska Fisheries Science Center, which has since been split into the Northwest Fisheries Science Center and the Alaska Fisheries Science Center. The NMFS-AFSC Technical Memorandum series is now being used by the Alaska Fisheries Science Center.
Reference throughout this document to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA.
Varanasi, U., D.W. Brown, T. Hom, D.G. Burrows, C.A. Sloan, L.J. Field, J.E. Stein, K.L. Tilbury, B.B. McCain, and S-L Chan. 1993. Volume II: Supplemental information concerning a survey of Alaskan subsistence fish, marine mammal, and invertebrate samples collected 1989-91 for exposure to oil spilled from the Exxon Valdez. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-NWFSC-13, 173 p.
National Technical Information Service
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Table of Contents
NOTE: Appendices are in PDF format and requires Adobe Acrobat Reader
Quality Assurance for Analyses for Fluorescent Aromatic Compounds (FACs) (p. 163)
Quality Assurance for Analyses for Aromatic Compounds (p. 163)
QA Tables (p. 167)
The Exxon Valdez ran aground on Bligh Reef, Prince William Sound, Alaska, on March 24, 1989, spilling millions of gallons of Prudhoe Bay crude oil (PBCO). During the weeks following the spill, large amounts of oil flowed towards southwestern Prince William Sound, and as a result, many shorelines were oiled. The spreading of spilled oil raised concerns of native Alaskans that their subsistence seafoods (fish, marine mammals, and invertebrate organisms) were contaminated by the spilled petroleum. At the request of native Alaskans, a study was conducted as a cooperative effort among NOAA, Exxon, and the Alaska Department of Fish and Game to assess the degree of contamination of subsistence organisms by PBCO. In this study, edible flesh of fish, marine mammals, and shellfish from 22 native subsistence food collection areas and from two reference areas (Angoon and Yakutat) were analyzed for aromatic compounds (ACs). Vertebrates can readily biotransform ACs to metabolites that are concentrated in bile for excretion. This process greatly limits the accumulation of ACs in tissues such as edible flesh. Thus, for fish and marine mammals, bile was first analyzed for the presence of fluorescent aromatic compounds (FACs) as an indication of exposure to petroleum.
Based on the concentrations of FACs in bile, it was evident that pink salmon, halibut, and Pacific cod from the Chenega area had been exposed to ACs during 1989, as were pink salmon from Tatitlek, Kodiak, and Old Harbor. The bile method was useful because it quickly identified those fish that were relatively unexposed to ACs and, therefore, of less immediate interest for analysis by the more detailed method for ACs in tissue.
As expected, most fish muscle samples were not contaminated with ACs (< 10 ng/g). In fact, the highest concentration of ACs found in muscle samples of fish caught during this study was 100 ng/g in a pink salmon caught near Kodiak (city) in 1989. In contrast, two samples of smoked salmon obtained from Tatitlek and Old Harbor contained 23,000 and 8,100 ng/g ACs, respectively.
Bile and tissue samples were collected from 33 harbor seals and 10 sea lions in 1989 and 1990. As with fish, the concentrations of FACs in bile of harbor seals varied considerable. Nine of the 12 bile samples with the highest concentrations of FACs were from animals collected in 1989 that were visibly oiled. With two minor exceptions, samples of muscle, liver, and kidney from harbor seals and sea lions, as well as blubber from 12 of the harbor seals were minimally contaminated (10 to 99 ng/g), and samples of blubber from 4 harbor seals were moderately contaminated with ACs (100 to 1,000 ng/g).
Invertebrates from most of the sampling areas were not contaminated or were minimally contaminated by ACs (<100 ng/g). Therefore, results are presented for only those few stations where higher concentrations of ACs were found. Molluscs from some stations at the Chenega, Windy Bay, Kodiak, and Old Harbor sampling areas were moderately or highly contaminated (>100 ng/g) with ACs. For example, some of the mollusc samples from 4 of the 12 stations in the Chenega area (CHE1, CHE7, CHE10, CHE24) were moderately or highly contaminated with ACs. Mollusc samples from Windy Bay stations WNB1 and WNB3 contained concentrations of ACs as high as 18,000 ng/g; 34 of 106 invertebrate samples contained concentrations of ACs greater than 100 ng/g. The only two stations on Kodiak Island where mollusc samples had mean concentrations of ACs (by year for individual species) greater than 100 ng/g (moderately or highly contaminated) wer KOD3 and OHA4. Most of the mollusc samples (26 of 30) from station KOD3 (located on Near Island about ¼ mile from Kodiak's boat harbor) were moderately or heavily contaminated with ACs (>100 ng/g). Station OHA4 was adjacent to the village of Old Harbor near the boat harbor, and the concentrations of ACs in molluscs collected at this site in 1989 and 1990 were just within the moderately contaminated category or lower.
Aromatic compounds were present in molluscs at concentrations high enough to evaluate in terms of temporal trends only at some stations. For example, the concentrations of ACs declined significantly with time in mussels at: 1) Chenega stations CHE9 and CHE10 (1990 to 1991), and 2) at the combined Windy Bay stations WNB1/WNB3 (1989 to 1991). The degree of contamination of invertebrates from WNB1 and WNB3 stations varied with sampling year and by species. Specifically, some of the mussel samples from Windy Bay station WNB1 (1989) and from WNB3 (1990) were highly contaminated (>1,000 ng/g), whereas the concentrations of ACs in mussels from these stations in 1991 were minimally to moderately contaminated (10 ng/g to 1,000 ng/g). The decline in concentrations of ACs in these molluscs probably related to decreased exposure which resulted from weathering of the spilled oil at the particular stations. The concentrations of ACs in molluscs at some other stations did not decline significantly with time. For example, the concentrations of ACs in butter clams from Kodiak station KOD3 did not consistently decline over four sampling periods during 1990.
The relative concentrations of the hundreds of different ACs in various petroleums and petroleum products can vary considerably. The patterns of these concentrations can be useful for purposes of comparison. The patterns of these concentrations can be useful for purposes of comparison. The patterns of some ACs (phenanthrenes and dibenzothiophenes) in selected mollusc samples from Chenega area stations CHE1 and CHE10 and Windy Bay stations WNB1 and WNB3 were similar to that of weathered PBCO. Because the overall patterns of ACs in molluscs did not exactly match that of PBCO, other observations were also important in considering sources. For example, following the spill, oil was observed in the area of station CHE1 and at CHE10, a tar mat about 1 mi wide extended the length of the beach at the high tide line. Also, stations WNB1 and WNB3 were observed to be moderately to heavily oiled. Thus, based on the patterns of ACs in molluscs and the known proximity of the spilled oil to these areas, oil from the Exxon Valdez may have been the source of ACs in mollusc samples from CHE1, and most likely was the source of ACs in mollusc samples from CHE10, WNB1, and WNB3. The patterns of ACs in selected samples from Kodiak Island stations KOD3 and OHA4 were also similar to those for mollusc samples from CHE1, CHE10, WNB1, and WNB3. However, the presence of naphthalenes in the patterns was more prominent in the samples from KOD3 and OHA4 than in the Chenega and Windy Bay samples. This finding implies exposure of the KOD3 and OHA4 molluscs to a less weathered source of ACs. Therefore, the ACs in molluscs from KOD3 and OHA4 are suspected to be from a local continuing source of petroleum. Additional support for this conclusion includes: 1) KOD3 and OHA4 were near active boat harbors which could be a source of ACs, 2) the spilled oil was not observed to impact these areas, and 3) the concentrations in molluscs at KOD3 did not continually decline over four samplings during 1990. Based on patterns, PBCO was probably a minor source of the ACs in mollusc samples from station CHE7. The pattern of ACs implied that the source of these compounds in selected molluscs from CHE7 was due to exposure to creosote (perhaps from the creosoted pilings located near the sampling station) and/or products of combustion. Based on the patterns of ACs in selected samples, PBCO was probably not a source, or only a minor source of the ACs in molluscs from Tatitlek station T1. More likely, the source of the ACs in mollusc samples from T1 was products of combustion processes.
Interestingly, of the ACs found in fish muscle, unsubstituted ACs predominated, which was probably due to the more rapid metabolism of alkylated ACs than of unsubstituted ACs by fish liver. Conversely, molluscs, which have little ability to metabolize ACs, had both alkylated and unsubstituted ACs, and the patterns of ACs in molluscs more closely resembled that for petroleum components. Furthermore, in the blubber samples from harbor seals with elevated concentrations of ACs, the concentrations of alkyl-substituted ACs were similar to or greater than the concentrations of the corresponding nonsubstituted ACs. This pattern is similar to what was found in PBCO and molluscs, and generally the opposite of what was observed in fish.
In conclusion, the finding of elevated concentrations of FACs in some bile samples from fish and marine mammals was clear evidence of their exposure to petroleum. Generally, ACs were not found in muscle tissue of fish, harbor seals, and sea lions. Some harbor seal blubber samples did contain ACs; however, the concentration of ACs in most blubber samples was less than 100 ng/g. Smoked salmon contained higher concentrations of ACs (8,000 to 20,000 ng/g) than any of the untreated subsistence samples. The concentrations of ACs were elevated in some mollusc samples (as high as 18,000 ng/g), and the concentrations of ACs exceeded 1,000 ng/g in 24 samples.
The results to date provide important information on level of contamination of subsistence fish, shellfish, and marine mammals from fishing areas of native Alaskan villages in and near Prince William Sound. In an advisory opinion, the Food and Drug Administration has indicated that little risk is involved in the consumption of the nonsmoked subsistence foods studied. Subsistence food gatherers were advised not to collect or consume food if oil was observed to be present. The results also show that in future oil spills, shellfish tissues should be given the highest priority for analysis, whereas rapid screening of bile from fish and marine mammals should be sufficient to provide information on level of exposure.
The material contained in this volume supplements NOAA Technical Memorandum NMFS-NWFSC-12, Volume I: Survey of Alaskan Subsistence Fish, Marine Mammal, and Invertebrate Samples Collected 1989-91 for Exposure to Oil Spilled from the Exxon Valdez. We have repeated the Executive Summary from Volume I in the preliminary pages for an overview of the study covered.
Six sections cover the following subjects:
Table of Contents