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(70-18) A novel model describing heavy metal concentrations in the earthworm, Eisenia andrei. Saxe, Jennifer1,2, Impellitteri, Christopher1,3, Peijnenburg, Willie4, Allen, Herbert*,1, 1 Department of Civil and Environmental Engineering, Newark, Delaware2 Gradient Corporation, Cambridge, MA3 U.S. Environmental Protection Agency, Cincinnati, Ohio4 National Institute of Public Health and the Environment, Bilthoven, The Netherlands ABSTRACT- We developed a novel model describing Eisenia andrei body concentrations for Cd, Cu, Pb, and Zn as a function of pH, metals, and soluble organic carbon (SOC) in soil extracts for potential use in predicting values in contaminated field sites. Data from seventeen moderately contaminated Dutch field soils in which earthworms were exposed were used in model development. Model parameters quantify biological phenomena important for metal bioavailability, and soil variables quantify relevant soil chemistry characteristics. Earthworm body concentration (EBC) was modeled so that soil metal soluble at bulk soil pH was considered available for dermal exposure, and gut exposure was due to soil metal in solution near neutrally-regulated gut pH. The efficiency parameter values indicated that metals are biologically regulated in the following order (most to least) Zn~Cu>Pb>Cd. The values determined for the exposure-route constant indicate that Cd, Cu, and Pb EBC's are almost exclusively (>96%) due to dermal exposure, and that only 18% of Zn EBC was due to gut exposure. The minimum healthful EBC's determined were Zn>Cu>Pb>Cd, and the values for Pb and Cd were near zero. The Cu model was normalized by soluble organic carbon to be meaningful. The model was most accurate in describing Zn behavior. Key words: earthworm, trace metals, bioaccumulation |
