John Wiley & Sons, Ltd.

Biokinetic food chain modeling of waterborne selenium pulses into aquatic food chains: Implications for water quality criteria

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We evaluated the use of biokinetic models to predict selenium (Se) bioaccumulation into model food chains following short‐term pulses of selenate or selenite into water. Both periphyton‐ and phytoplankton‐based food chains were modeled, with Se trophically transferred to invertebrates and then to fish. Whole‐body fish Se concentrations were predicted based on (1) the background waterborne Se concentration; (2) the magnitude of the Se pulse; and (3) the duration of the Se pulse. The models were used to evaluate whether the U.S. Environmental Protection Agency's (USEPA's) existing acute Se criteria and their recently proposed intermittent Se criteria would be protective of a whole‐body fish Se tissue‐based criterion of 8.1 µg g−1 dry wt (dw). Based on a background waterborne Se concentration of 1 µg L−1 and pulse durations of 1‐d and 4‐d, the Se pulse concentrations predicted to result in a whole‐body fish Se concentration of 8.1 µg g−1 dw in the most conservative model food chains were 144 and 35 µg L−1, respectively, for selenate and 57 and 16 µg L−1, respectively, for selenite. These concentrations fall within the range of various acute Se criteria recommended by the USEPA based on direct waterborne toxicity, suggesting that these criteria may not always be protective against bioaccumulation‐based toxicity that could occur following short‐term pulses. Regarding the USEPA's draft intermittent Se criteria, the biokinetic modeling indicates that they may be overly protective for selenate pulses, but potentially under‐protective for selenite pulses. Predictions of whole‐body fish Se concentrations were highly dependent on whether the food chain was periphyton‐ or phytoplankton‐based, as the latter had much greater Se uptake rate constants. Overall, biokinetic modeling provides an approach for developing acute Se criteria that are protective against bioaccumulation‐based toxicity following trophic transfer, and is also a useful tool for evaluating averaging periods for chronic Se criteria. This article is protected by copyright. All rights reserved

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