Sediment Quality in Puget Sound Year 2 - Center for Coastal ...

Conclusions
The conclusions drawn from the analysis of 100 sediment samples collected from central Puget
Sound during June 1998 for toxicity, chemical concentrations, and benthic infaunal composition
study, included the following:
A battery of laboratory toxicity tests, used to provide a comprehensive assessment of the
toxicological condition of the sediments, indicated overlapping, but different, patterns in
toxicity. Several spatial patterns identified with results of all the tests were apparent in this
survey. First, highly toxic responses in the sea urchin, MicrotoxTM, and cytochrome P450
HRGS tests were observed in the inner strata of Elliott Bay and the lower Duwamish River.
Toxicity in these tests decreased considerably westward into the outer and deeper regions of
the bay. Second, many of the samples from the Liberty Bay and Bainbridge basin area were
toxic in the MicrotoxTM and cytochrome P450 HRGS assays. The degree of toxicity
decreased steadily southward down the Bainbridge basin to Rich Passage, where the
sediments were among the least toxic. Third, samples from two stations (167 and 168)
located in a small inlet off Port Washington Narrows were among the most toxic in two or
more tests. Fourth, several samples from stations scattered within Sinclair Inlet indicated
moderately toxic conditions; toxicity diminished steadily eastward into Rich Passage. Finally,
samples from Port Townsend, southern Admiralty Inlet, and much of the central main basin
were among the least toxic.
The spatial extent of toxicity was estimated by weighting the results of each test to the sizes
of the sampling strata. The total study area was estimated to represent about 732 kilometer!
The area in which highly significant toxicity occurred totaled approximately 0.1 % of the total
area in the amphipod survival tests; 0.7%, 0.2%, and 0.6% of the area in urchin fertilization
tests of 10096, 50%, and 25% pore waters, respectively; 0% of the area in microbial
bioluminescence tests; and 3% of the area in the cytochrome P450 HRGS assays. The
estimates of the spatial extent of toxicity measured in three of the four tests in central Puget
Sound were considerably lower than the "national average" estimates compiled from many
other surveys previously conducted by NOAA. Generally, they were comparable to the
estimates for northern Puget Sound. However, in the cytochrome P450 HRGS assays, a
relatively high proportion of samples caused moderate responses. Overall, the data from
these four tests suggest that central Puget Sound sediments were not as toxic relative to
sediments from many other areas nationwide. The large majority of the area surveyed was
classified as non-toxic in these tests. However, the data from the RGS assays indicated a
slight to moderate response among many samples.
Chemical analyses, performed for a wide variety of trace metals, aromotic hydrocarbons,
chlorinated organic hydrocarbons, and other ancillary measures, indicated that the surficial
area in which chemical concentrations exceeded effects-based sediment guidelines was
highly dependent upon the set of critical values that was used. There were 2 1 samples in
which one or more ERM values were exceeded. They represented an area of about 2 1 km2,
or about 3% of the total survey area. In contrast, there were 94 samples in which at least one
SQS or CSL value was exceeded, representing about 99% of the survey area. Without the
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