Publication Summary

For this 2007 study, contaminants were measured in surface sediments and tissues of English sole from greater Elliott Bay.

Median levels of dioxins/furans in sediments of 2 depths were 7.7 and 5.9 ng/kg Toxic Equivalents (TEQ). English sole whole-body tissue and skinless fillet samples had 0.99-1.71 and 0.26-0.57 ng/kg (wet weight) TEQ dioxins/furans, respectively. Tissue preparation influenced levels more than where fish were collected.

Levels of most organic contaminants in 0-2 and 0-10 cm sediment samples did not differ, but most trace metals and PCBs were significantly lower in 0-2 cm samples. Sediment contaminant levels at 5 of 30 stations may represent area background conditions.

During 2007, the Washington State Department of Ecology (Ecology) collected surface sediment and fish tissue samples from greater Elliott Bay (Seattle) to fulfill needs of various regulatory and monitoring programs.

Sediment chemistry results were intended to: 1. Help define contaminant levels representing an area background. 2. Characterize current levels of chlorinated dioxins/furans throughout the area. 3. Determine if levels of contaminants differ between 0-2 and 0-10 cm samples.

In addition, English sole (Parophrys vetulus) tissue samples, both whole body and skinless fillets, were tested for levels of dioxins/furans. This was done to augment the scant data available on these contaminants in Puget Sound bottom fish.

Surface sediments from 0-2 and 0-10 cm depth intervals were collected from 30 locations. Sampling locations were chosen using a stratified, random design. Ecology measured selected conventional sediment parameters, trace metals, and organic contaminants (PAHs, PCBs, and chlorinated dioxins/furans) in the 0-2 cm samples. The same parameters were measured in a random subset of 18 matching 0-10 cm samples. A total of 15 fish tissue samples were tested for dioxins/furans only. All laboratory results were usable.

Contaminant levels found in 5 of the 0-10 cm sediment samples may represent area background levels. These results are summarized in the report.

Median values for dioxins/furans for the 0-2 and 0-10 cm samples were 7.7 and 5.9 ng/kg Toxic Equivalents (TEQ), respectively. Levels of most organic contaminants measured in the 0-2 and 0-10 cm samples did not differ. Most trace metals and PCBs, however, were significantly lower in the 0-2 cm sediment samples.

Dioxins/furans in skinless English sole fillets contained 0.26-0.57 ng/kg (wet weight) TEQ. Whole body tissue samples were found to contain 0.99-1.71 ng/kg (wet weight) TEQ. The type of tissue samples tested -- skinless fillets vs. whole body -- had more influence on results than where fish were collected. Mean levels of 2,3,7,8-tetrachlorodibenzodioxin (TCDD) did not appear to exceed the National Toxics Rule threshold.

Link to EIM data for User Study ID UWI_EB07