Determination of Selenium Toxicity for Survival and Reproduction of Enchytraeid Worms in a Sandy Loam Soil
Technical Report,01 Jul 2002,01 May 2006
Army Edgewood Chemical Biological Center Aberdeen Proving Ground
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We investigated toxicity of selenium Se to the soil invertebrate potworm Enchytraeus crypticus using the Enchytraeid Reproduction Test ISO 16387 International Organization for Standardization Geneva, Switzerland, 2004. Studies were designed to generate ecotoxicological benchmarks for developing the ecological soil screening levels Eco-SSLs for risk assessments of contaminated soils. For the present study, we selected aerobic upland soil Sassafras sandy loam SSL, with soil characteristics low levels of clay and organic matter, soil pH adjusted high that support high relative bioavailability of the anionic Se species typically found in soil. Se was amended into SSL soil as sodium selenate. While under ambient greenhouse conditions, the amended SSL soil was subjected to weathering-and-aging by 21 d of alternating cycles of air-drying and rehydration to 6075 of the soil water-holding capacity. Se concentrations that produced 20 and 50 decreases in reproduction for Se weathered-and-aged in SSL soil compared to control response EC20 and EC50 values, respectively were 4.4 and 6.2 mgkg, respectively. Toxicity benchmarks established in the present study have been submitted to the U.S. Environmental Protection Agency Eco-SSL Workgroup, and the EC20 value was used in developing soil invertebrate-based Eco-SSL for Se.