APPENDIX I Toxicity Identification Evaluation Reports for Chollas ...

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Toxicity Identification Evaluation of Chollas Creek Stormwater using Hyalella azteca Results August 2006 MS) in Electron Ionization (EI) mode. It was hypothesized that if the pyrethroids were present at concentrations below detection limits, the pyrethroid synergist PBO might still be measurable. A re-analysis of PBO on the GC-MS demonstrated that concentrations of 630 and 883 ng/L PBO were present in the October and January stormwater samples, respectively, from Chollas Creek. Further examination and re-analysis of the October and January stormwater samples from Chollas Creek on the GC-MS in a different mode (i.e., Negative Chemical Ionization, NCI) also demonstrated that a number a pyrethroids including bifenthrin (14-110 ng/L), cyfluthrin (80- 110 ng/L), cypermethrin (13-53 ng/L), cyhalothrin (48-89 ng/L), and permethrin (116 ng/L) were present in these samples. Because the re-analysis of these stormwater samples occurred on February 21, 2006, the concentrations of pyrethroids measured in Chollas Creek stormwater samples in October of 2005 and January of 2006 may be lower than the actual concentrations due to degradation during this holding time. Chemical analysis of the February stormwater sample also demonstrated significant concentrations of bifenthrin (112 ng/L), cyfluthrin (185 ng/L), cyhalothrin (27 ng/L), and permethrin (484 ng/L). Weston Solutions, Inc. 25
Toxicity Identification Evaluation of Chollas Creek Stormwater Using Hyalella azteca Results August 2006 Table 7. Chemical Analyses of Chollas Creek Stormwater Samples Collected During the 2005-2006 Monitoring Season 10-18- 05 Sample 10-18-05 Sample Reanalyzed on 02-21- 06 Using NICI Mode on GC-MS 1-2-06 Sample Reanalyzed on 2-21-06 Using NICI Mode on GC-MS 1-2-06 2-19-06 Chemical Class Chemical Measurement Fraction Units MDL RL Sample Sample General Chemistry Ammonia-N NA mg/L 0.01 0.05 0.64 0.55 0.48 General Chemistry Dissolved Orthophosphate as P NA mg/L 0.0075 0.01 0.367 General Chemistry Nitrate-N NA mg/L 0.01 0.05 2.75 0.82 1.02 General Chemistry Nitrite-N NA mg/L 0.02 0.05 0.25 0.28 0.3 General Chemistry Total Hardness as CaCO 3 NA mg/L 1 5 122 49.6 45.4 General Chemistry Total Orthophosphate as P NA mg/L 0.01 0.01 0.41 General Chemistry Total Phosphorus NA mg/L 0.016 0.05 0.505 General Chemistry Total Suspended Solids NA mg/L 0.5 0.5 173 217 139 Organophosphorus Pesticides Bolstar (Sulprofos) Total ng/L 10 20
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