||Effects of Freezing on Toxicity of Sediments Contaminated with DDT and ENDRIN.
Schuytema, G. S. ;
Nebeker, A. V. ;
Griffis, W. L. ;
Miller., C. E. ;
||Corvallis Environmental Research Lab., OR.
Hyalella azteca ;
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Two freshwater sediments containing 3 and 11% total organic carbon (TOC) were spiked with DDT and endrin to compare the effects of cold (4 C) and frozen (-20 C) storage of the sediment on toxicity to the amphipod Hyalella azteca in 10-d tests. Toxicity of the DDT-spiked sediment was reduced when it was frozen for 14 d. LC50 values for cold-stored and frozen-stored sediments were 4.2 and 7.3 micro/g DDT (calculated on dry solids basis) at 3% sediment TOC and 11.1 and 23.2 micro/g DDT at 11% sediment TOC, respectively. Toxicity of the 3% TOC endrin-spiked sediment was reduced by freezing; it exhibited LC50s of 5.1 and 7.7 micro/g endrin, respectively, for cold and frozen storage. Toxicity of endrin in two tests in the 11% TOC sediment remained essentially unchanged by freezing. LC50s were 19.6 and 21.7 micro/g endrin for cold and frozen sediments in one test and 10.3 and 9.8 micro/g endrin in the second test.