Pesticides and PCB contaminants in fish and tadpoles from the Kaweah River Basin, California

The concentrations of t-PCB and selected pesticides in brook trout (Salvelinus fontinalis) and tree frog (Hyla regilla) tadpoles from the Kaweah river basin and in tree frog egg masses from the Lassen Volcanic National Park were determined, and compared with concentrations of these pollutants in trout and frogs from other locations in California. All the t-PCB congeners were analysed by capillary gas chromatography (GC) with electron capture detection and the pesticides by GC-MS. Detection limits were approximately 1 pg for the PCB and 0.13 to 2.3 ng for the pesticides. Concentrations of t-PCB were 4.9 to 8.1 ppb (wet weight) in brook trout, 12.0 to 23.8 ppb in tree frog tadpoles, and 9.1 ppb in tree frog egg masses. Tree frog tadpoles and egg masses showed enhanced concentrations of tri- and tetra-chlorinated biphenyl congeners. Concentrations of p,p'-DDE were 40.1 to 65.7 ppb in brook trout and 9.3 to 9.6 ppb in tree frog tadpoles. Chlorthalonil and chlorpyrifos were found in tree frog tadpoles at concentrations of 33.3 to 47.7 ppb and 10.4 to 17.4 ppb, respectively. Possible sources of the pollutants are discussed. The data suggest that contamination may result from chemical usage in distant locations.