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

Summary
The majority of compounds for which chemical analyses were conducted on the 100 sediment
samples from central Puget Sound were measured at levels below state criteria and national
guidelines (i.e., ERM, SQS, and CSL values). Eleven stations, located in Port Townsend,
Possession Sound, the central basin, the Bainbridge basin, and East Passage, all exceeded
Washington State SQS and CSL levels for the compound 4-methylphenol. Three stations, one
west of Bainbridge Island and two in Dyes Inlet, exceeded state criteria for benzyl alcohol. One
of these, in Dyes Inlet, also exceeded state criteria for mercury. The six stations in Sinclair Inlet
also exceeded SQS and CSL levels for mercury, while five of the six also exceeded the ERM
level for mercury. Sediment samples collected at stations located in Elliott Bay and the
Duwamish River clearly showed an increase in the number of compounds exceeding state criteria
and national guidelines from outer to inner Elliott Bay, and into the Duwamish River. The suites
of compounds exceeding criteria differed between the shorelinelmid-Elliott Bay samples and
those collected around Harbor Island and further up the Duwamish River, reflecting differing
sources of contamination. In general, spatial patterns of chemical contamination indicated that
the highest chemical concentrations invariably occurred in samples collected in
urbanlindustrialized embayments, including Elliott Bay, Sinclair Inlet, Dyes Inlet, and Port
Townsend. Often, these samples contained chemicals at concentrations previously observed to
be associated with acute toxicity and other biological effects. Concentrations generally decreased
steadily away from these embayments and were lowest in Admiralty Inlet, Possession Sound,
Rich Passage, Bainbridge Basin, and most of the central basin.
Spatial Extent of Chemical Contamination
Table 14 summarizes the numbers of samples in which ERM, SQS, and CSL concentrations were
exceeded and an estimate of the spatial extent of chemical contamination (expressed as the
percentage of the total survey area these samples represent) for all compounds with chemical
guidelines. For some compounds, the data were qualified as "undetected" at method quantitation
limits that exceeded the chemical guideline values. hi these cases, the spatial extent of chemical
contamination was recalculated after omitting the data that were so qualified (shown as ">QL
only" on Table 14).
Among the trace metals, the concentration of arsenic exceeded ERM, SQS, and CSL values at
station 197, West Harbor Island (0.04% of the study area). The level of zinc also exceeded the
ERM value at this station. Mercury exceeded all three sets of criteria in sediment collected from
9 to 14 stations in Sinclair and Dyes Inlets, and in Elliott Bay, representing 1.1 (ERM), 2.0
(SQS), and 1.9% (CSL) of the study area. The ERM value for nickel was exceeded in four
samples. As stated earlier, however, Long et al. (1995) suggested that there was a limited degree
of reliability in this value. For all trace metals (excluding nickel), there are a total of 10 (ERM),
15 (SQS), and 13 (CSL) samples exceeding guidelines or criteria levels, encompassing a total of
2.5,2.0, and 1.9%, respectively, of the total study area.
Many of the low and high molecular weight polynuclear aromatic hydrocarbons (LPAH and
HPAH) were found at concentrations that exceeded the guidelines in samples from Elliott Bay,
West Harbor Island, and the Duwamish River. As noted earlier, different suites of PAHs
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