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

The highest concentrations of mixtures of potentially toxic chemicals primarily occurred in
samples from Elliott Bay and Sinclair Inlet, the two most highly urbanized and industrialized
bays within the 1998 study area. Similarly, the sediments analyzed during the 1997 survey of
northern Puget Sound indicated that chemical concentrations were highest in Everett Harbor,
which was one of the most urbanized bays in that survey.
ToxicityIChemistry Relationships
It was not possible to identify and confirm which chemicals caused toxic responses in the urchin
fertilization, MicrotoxTM, and RGS tests in the samples from either central or northern Puget
Sound. Determinations of causality would require extensive toxicity identification evaluations
and spiked sediment bioassays. However, the chemical data were analyzed to determine which
chemicals may have contributed to toxicity.
Typically in surveys of sediment quality nationwide, NOAA has determined that complex
mixtures of trace metals, organic compounds, and occasionally ammonia showed strong
statistical associations with one or more measures of toxicity (Long et al., 1996). Frequently, as
a result of the toxicity/chemistry correlation analyses, some number of chemicals will show the
strongest associations leading to the conclusion that these chemicals may have caused or
contributed to the toxicity that was observed. However, the strength of these correlations can
vary considerably among study areas and among the toxicity tests performed.
In both central and northern Puget Sound, the data were similar to those collected in several other
regions (e.g., the western Florida Panhandle, Boston Harbor, and South CarolinaIGeorgia
estuaries). Severe toxicity in the amphipod tests was either not observed in any samples or was
very rare, and, therefore, correlations with toxicity were not significant or were weak. However,
correlations with chemical concentrations were more readily apparent in the results of the
sublethal tests, notably tests of urchin fertilization and microbial bioluminescence, as conducted
in Puget Sound.
The sea urchin tests performed on pore waters extracted from the sediments and the MicrotoxTM
and RGS tests performed on solvent extracts showed overlapping, but different, spatial patterns
in toxicity in central Puget Sound. Because of the nature of these tests, it is reasonable to assume
that they responded to different substances in the sediments. The strong statistical associations
between the results of the sea urchin and RGS tests and the mean ERA4 quotients for 25
substances provides evidence that mixtures of contaminants co-varying in concentrations could
have contributed to these measures of toxicity. Percent sea urchin fertilization was statistically
correlated with the guideline-normalized concentrations of all chemical classes of contaminants.
Furthermore, the highly significant correlations between enzyme induction in the RGS assays and
the concentrations of PAHs normalized to effects-based guidelines or criteria suggest that these
substances occurred at sufficiently high concentrations to contribute to the responses.
The data showed that urchin fertilization was statistically associated with several trace metals
(notably arsenic, lead, mercury, tin and zinc) some of which occurred at concentrations above
their respective ERL and SQS levels. The data from the northern Puget Sound study indicated
very similar results, i.e., urchin fertilization was highly correlated with the concentrations of
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