1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 3: ANALYSIS
surviving worms were retrieved. These worms were placed in filtered, flowing seawater for
24 hours to evacuate their digestive tract. Immediately after this process, the soft tissues were
frozen and stored at –20°C (+5°C) pending chemical analysis to estimate bioaccumulation.
The results of this testing showed that there was significant (p < 0.05) bioaccumulation for
several inorganic and organic analytes, as follows:
• Of 15 inorganic analytes, 3 metals (beryllium, silver, and thallium) were not detected in
any of the test animal tissues. Significant bioaccumulation was noted for barium, cobalt,
copper, lead, mercury, nickel, selenium, vanadium, and zinc. Although detected in test
organisms, there was no significant bioaccumulation noted for arsenic, cadmium, or
chromium.
• Of 22 pesticides and PCBs, only 5 compounds (endosulfan sulfate, endrin ketone,
toxaphene, Aroclor 1424, and Aroclor 1260) were not detected in any test animal tissues.
Significant bioaccumulation was noted for BHC (beta and gamma), chlordane (alpha,
gamma, and technical), 4,4’-DDD, 4,4’-DDE, dieldrin, and Aroclor 1254. Although
detected in test organisms, there was no significant bioaccumulation noted for aldrin,
BHC (alpha and delta), 4,4’-DDT, endosulfan (I and II), endrin, and endrin aldehyde.
• Of 17 PAHs, only 5 compounds were detected in animal tissues, and all showed
significant bioaccumulation. These were acenapthene, anthracene, chrysene, pyrene, and
fluorene.
3.2.1.3 Dose-Response Evaluation
Simple linear regression analyses were performed to determine which contaminants in
sediment and pore water best explained amphipod and Mytilus toxicity bioassay results.
Contaminant concentration data were matched by sample locations with toxicity bioassay
results for each bioassay replicate (i.e., chemical data from a given sample location were
repeated for each bioassay replicate from that location). Because the Mytilus bioassay was
performed using replicates within a series of pore water dilutions at each sample location,
chemical data were also repeated for each dilution. Concentrations within each dilution
were estimated by multiplying the concentration in undiluted pore water from each location
by the reported dilution rate. All nondetects were excluded from the analyses.
As described above and in Appendix F, it was necessary to adjust sediment and pore water
to facilitate performing bioassays. As a consequence, samples on which bioassays were
performed were catagorized into four groups:
• wet, salinity not adjusted
• wet, salinity adjusted
• dry, salinity not adjusted
• dry, salinity adjusted
Regression analyses were performed on all groups pooled and by individual groups, to
determine if modification of the test media influenced toxicity.
Prior to analyses, sediment and pore water data were screened to remove observations that
could potentially confound the analyses (see Appendix F tables F-1 through F-4). All data
from samples in which survival did not differ significantly from controls were included in
SAC/143368(003.DOC) 3-31 ERA REPORT
7/31/02