APPENDIX I Toxicity Identification Evaluation Reports for Chollas ...
APPENDIX I Toxicity Identification Evaluation Reports for Chollas ...
APPENDIX I Toxicity Identification Evaluation Reports for Chollas ...
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<strong>Toxicity</strong> <strong>Identification</strong> <strong>Evaluation</strong> of <strong>Chollas</strong> Creek<br />
Stormwater using Hyalella azteca<br />
Results<br />
August 2006<br />
4.1.7 Results of Phase I TIE Per<strong>for</strong>med on February 19, 2006 Sample<br />
Results <strong>for</strong> the TIE per<strong>for</strong>med on the February 19, 2006 sample are summarized in Table 6.<br />
Table 6. Percent Survival of Hyalella azteca in TIE Tests per<strong>for</strong>med on the <strong>Chollas</strong> Creek<br />
Stormwater Sample Collected on February 19, 2006<br />
Test<br />
Stormwater Dilution<br />
Control (Blank)<br />
– Dilution Water<br />
100%<br />
Stormwater<br />
(2X 1 )<br />
Baseline 100 28<br />
Aeration 84 36<br />
pH 6.8 100 16<br />
Filtration 100 100<br />
Solid Phase Extraction<br />
(C- 18 )<br />
92 100<br />
MeOH Eluate 84 52<br />
STS - 10 mg/L 100 12<br />
EDTA - 3 mg/L 96 40<br />
PBO - 0.025 mg/L 100 4<br />
PBO - 0.0007 mg/L 100 28<br />
Carboxyl esterase (0.52<br />
μg/mL)<br />
96 60<br />
BSA (esterase control,<br />
0.52 μg/mL)<br />
100 20<br />
Carboxyl esterase plus<br />
PBO (0.025 mg/L)<br />
96 40<br />
In the Baseline test, toxicity of H. azteca exposed to the 100 percent sample concentration<br />
(28.0% survival) was slightly lower than that in the initial toxicity test (2.5% survival) started on<br />
February 19, 2006. The NOEC was 25%, and the LC 50 was greater than 51.6%. Survival in the<br />
dilution water control was 95%.<br />
The 3.0 mg/L EDTA manipulation did not significantly reduce toxicity in the 100 percent sample<br />
concentration (40% survival) relative to toxicity in the unmanipulated Baseline test (28.0%<br />
survival in the 100 percent sample concentration). Survival in the 3 mg/L EDTA treatment blank<br />
was 96%.<br />
The 10 mg/L sodium thiosulfate (STS) manipulation did not reduce toxicity in the 100 percent<br />
sample concentration (12% survival) relative to toxicity in the unmanipulated Baseline test (28%<br />
survival in the 100 percent sample concentration). Survival in the 10 mg/L STS treatment blank<br />
was 100%.<br />
The Aeration manipulation did not reduce toxicity in the 100 percent sample concentration (36%<br />
survival) relative to toxicity in the unmanipulated Baseline test (28% survival in the 100 percent<br />
Weston Solutions, Inc. 22
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