Contaminant problems in industrialized embayments of Puget Sound are 
diverse both in terms of concentration and chemical composition. This 
diversity can be revealed in the visual appearance of sediments. For 
example, sediment cores collected in many urban embayments of Puget Sound 
are anoxic, greenish black muds with a thin layer of brown oxidized 
sediment at the surface. In contrast, sediment collected near a major 
outfall of a now-closed copper smelter on the Ruston-Pt. Defiance Shore¬ 
line of Tacoma consists of bands of richly colored sediment that derive 
from high concentrations (>10,000 ppm) of several metals. A completely 
different sediment can be collected in Eagle Harbor (Figure 4), where an 
accidental spill or intentional dumping of creosote has created 
pitch-black sediments that ooze brown oil. These latter sediments caused 
100 percent mortality in a range of laboratory bioassays (Tetra Tech 1986c 
and references therein) and required dilution to 0.6 percent of the 
original material in clean sediment before insignificant toxicity was 
observed (Swartz et al. in preparation). PAH concentrations in subsurface 
sediment from this area exceeded 2,000 ppm (Tetra Tech 1986c). 
In addition to diversity in chemical composition, highly contaminated 
sediments in Puget Sound industrialized embayments often occur in patches 
near point sources. For example, contaminated problem areas in 
Commencement Bay that exhibited biological effects are shown in Figure 7. 
High concentrations of PAH (>20 ppm) were found close to the head of 
Hylebos Waterway in Tacoma’s Commencement Bay (Figure 7) near a ditch that 
discharges waste from an aluminum plant. At the mouth of the same 
waterway near a chemical manufacturing plant, several chlorinated 
compounds including chlorinated butadienes (industrial by-products) were 
found at well over 1,000 times reference conditions. Other chemicals 
measured at over 1,000 times reference conditions were alkylated phenols 
in sediments adjacent to the main outfall of a major pulp and paper mill 
in St. Paul Waterway, and four metals (antimony, arsenic, copper, and 
mercury) in sediments adjacent to the main outfalls of the copper smelter 
described earlier on the Ruston-Pt. Defiance Shoreline. The most extreme 
biological effects were found at these same sites in St. Paul Waterway and 
on the Ruston-Pt. Defiance Shoreline. 
A patchy distribution of contamination is characteristic of all of 
the industrialized embayments, including Elliott Bay off Seattle 
(Figure 8). In Elliott Bay, patches of high contamination along the 
Duwamish Waterway contrast with large areas of lower contamination in the 
outer bay. An area of intermediate contamination is found in the outer 
bay around the Four-Mile Rock dredged material disposal site (Figure 8). 
Historical Trends 
By using chemical dating methods and measuring the contaminant 
concentrations in different sediment layers, the history of contamination 
can be evaluated. Detailed historical sediment data exist for only some 
contaminants in Puget Sound, including PAH, PCBs, and most metals. 
Concentrations of nearly all contaminants measured in this fashion are low 
in sediments that were deposited in Puget Sound before about 1880. The 
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