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

assays, enzyme induction was very highly correlated with trace metals, chlorinated organics,
PAH concentrations, and mean ERM quotients for all 25 substances.
Among all the possible toxicity/cl~emistry correlations, the strongest statistical association was
between the cytochrome P450 HRGS responses and the concentrations of 13 PAHs normalized
to their respective ERM values (Rho = 0.928, pg.0001) as shown in Table 15. These data are
shown in a scatterplot (Figure 24) to illustrate the relationship. In general, cytochrome P450
HRGS responses increased as PAH concentrations increased. Induction was greatest in the
sample from station 184 which also had the highest concentrations of PAHs; thereby,
contributing to the highly significant statistical correlation.
Toxicity vs. Individual Chemicals
Correlations between measures of toxicity and concentrations of individual trace metals
determined with partial digestions are summarized in Table 16. Most metal concentrations were
highly significantly correlated (pg.0001) with cytochrome P450 HRGS induction, while a few
were correlated to a lesser extent with percent urchin fertilization and microbial
bioluminescence. None were correlated with amphipod survival. Urchin fertilization was most
significantly correlated with lead, suggesting that fertilization success diminished as the lead
concentration increased. However, the scatter plot of this data (Figures 25), indicated that there
was not a clear pattern of decreasing percent fertilization corresponding with increasing lead
concentrations. Furthermore, none of the samples had lead concentrations above the state
standards. Better correspondence was seen in the scatter plot of microbial bioluminescence
EC50s and cadmium concentration, with EC50 values decreased to their lowest level at cadmium
concentrations greater than 0.5ppm (Figure 26).
Because the microbial bioluminescence and cytochrome P450 HRGS tests are performed with
organic solvent extracts, trace metals are not expected to contribute significantly to the biological
responses in these tests. The correlations between results of these two tests and concentrations of
trace metals (Table 16) that appeared to be highly significant may reflect the co-variance in
concentrations of metals and the organic toxicants that were eluted with the solvents.
Correlations between measures of toxicity and concentrations of individual trace metals
determined with total digestions are summarized in Table 17. Again, no significant correlations
are seen with Amphipod survival. Similar to the results observed for the partial digestions,
percent fertilization and microbial bioluminescence were correlated with the concentrations of
just a few metals determined with total digestions, while cytochrome P450 HRGS induction was
highly correlated with most of the metals. The urchin tests were performed with pore waters,
instead of organic solvent extracts. Also, these animals are known to be sensitive to trace metals.
Therefore, if the presence of trace metals in the samples contributed to toxicity observed in these
tests, the correlation coefficients between urchin fertilization and metals concentrations might be
expected to increase with the data for total digestions relative to those for partial digestions,
because the concentrations would be higher in the total digestions. However, the correlations in
Tables 16 and 17 showed only slight differences, and the examination of the scatter plot of the
relationship between urchin fertilization results and tin concentrations showed that the highly
significant negative correlation was driven by the results from just a few samples (Figure 27).
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