APPENDIX I Toxicity Identification Evaluation Reports for Chollas ...

Toxicity Identification Evaluation of Sweetwater
River Stormwater Using Selenastrum
capricornutum August 2006
4.1.2 Summary of TIE Performed on October 18, 2005 Sample
Table 3: Summary of Growth in TIE tests on Sweetwater Stormwater Sample Collected on October 18, 2005
Test
Control (Blank)
– Dilution Water
Mean Growth – Chlorophyll (RFU)
50% 75%
Stormwater Stormwater
100%
Stormwater
NOEC LC 50
Baseline 113.87 131.75 112.54 69.70 75 >100
C-18 117.4 122.37 86.09 56.8 50 97.32
EDTA 3 92.03 116.02 112.92 85.47 100 >100
EDTA 8 83.91 131.37 131.28 106.96 100 >100
PBO 0.25 87.07 119.17 109.66 83.64 100 >100
PBO 0.50 93.16 137.63 116.7 71.34 100 >100
4.1.3 Statistical Analysis: Differences in Growth Among Stormwater Dilutions
Data was evaluated using one-way, fixed factor ANOVA and Dunnett’s multiple comparisons to
examine the differences in growth of S. capricornutum among the different dilutions of
stormwater. It was determined that regardless of the TIE treatment, significant differences in
growth of S. capricornutum were detected among the different dilutions of stormwater (i.e., 0,
50, 75 or 100%) to which S. capricornutum were exposed (ANOVA, P=0.008). Specifically, as
depicted in Figure 1, growth of S. capricornutum from highest to lowest in the different
stormwater dilutions was as follows: 50%, 75%, 0% (control), and 100%.
Growth of S. Capricornutum (RFU)
160
140
120
100
80
60
40
B
C
A
D
0 50 75 100
Stormwater Dilution (%)
Figure 1. Growth of S. capricornutum exposed to multiple dilutions of a Sweetwater River stormwater
sample. Different letters indicate statistically significant differences among treatments where B>C>A>D.
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