PW12 Pesticide II
Exhibit Hall
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(PW193) Evaluation of Pesticides in Central Valley Vernal Pools.

Johnson, C1, Schwarzbach, S2, Tjeerdema, R3, 1 U.S. Fish and Wildlife Service, Sacramento, CA, USA2 U.S. Geological Survey, Sacramento, CA, USA3 University of California, Davis, Davis, CA, USA

ABSTRACT- Vernal pools are a unique ephemeral wetland feature of California native landscape which have been heavily impacted over the past century by agricultural and urban development. Current estimates of habitat losses in the Central Valley range from 50% to 85% of pre-settlement acreage. While physical effects have been emphasized in most previous research on vernal pools there is increasing reason to suspect contaminant impacts may also imperil these isolated and vulnerable ephemeral wetlands. Vernal pools often exist within a matrix of agricultural activity in the Central Valley, and even on National Wildlife Refuges they may receive pesticides and other contaminants through aerial deposition. Vernal Pool water was collected for pesticide analysis from the Sacramento National Wildlife Refuge Complex and the San Luis National Wildlife Refuge Complex; representing the northern and southern geography of the Central Valley. Pesticide residues were extracted from the water samples using Solid Phase Micro-Extraction (SPME) confirmed via gas chromatography-mass spectrometry (GC-MS). Analysis on the GC was run in SCAN mode to simultaneously evaluate multiple analytes. Standards from each class were used for retention time confirmatin and quantification. Concentrations of detected analytes include legacy organochlorines (heptachlor), organophosphates (diazinon), organonitrogens (trifluralin) and a number of pthalates.

Key words: vernal, pesticide, pool

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