||Effect of Sediment Organic Carbon on Survival of 'Hyalella azteca' Exposed to DDT and Endrin.
Nebeker, A. V. ;
Schuytema, G. S. ;
Griffis, W. L. ;
Barbitta, J. A. ;
Casey, L. A. ;
||Corvallis Environmental Research Lab., OR. ;Battelle Pacific Northwest Labs., Richland, WA.
Residual soils ;
Carbon compounds ;
Water quality ;
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Sediment toxicity tests were conducted with the freshwater amphipod Hyalella azteca using sediments ranging in total organic carbon (TOC) concentration from 3 to 11% and spiked with either DDT or endrin. While the toxicity in the DDT-spiked sediment decreased with increasing TOC content, the TOC content of the endrin-spiked sediment had little apparent effect on toxicity. The 10-d sediment dry-weight LC50 for DDT was 11.0 microg/g at 3.0% TOC and 49.7 microg/g at 10.5% TOC. The sediment dry weight LC50s for endrin at 3.0 and 11.2% TOC were 4.4 and 6.0 microg/L, respectively. The results are important in evaluating the carbon normalization theory, which assumes that the availability of nonpolar organic compounds is reduced in the presence of higher concentrations of TOC. The differences in adsorption and toxicity between DDT and endrin are presumably related to the smaller carbon (and octanol/water partition coefficients of endrin.