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Soil and Plant Selenium at a Reclaimed Uranium Mine
Author(s) -
Sharmasarkar Shankar,
Vance George F.
Publication year - 2002
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2002.1516
Subject(s) - environmental chemistry , chemistry , selenate , soil water , selenium , phosphate , bioavailability , ammonium bicarbonate , sorption , dissolution , zoology , adsorption , environmental science , soil science , biology , raw material , bioinformatics , organic chemistry
Selenium (Se) associated with reclaimed uranium (U) mine lands may result in increased food chain transfer and water contamination. To assess post‐reclamation bioavailability of Se at a U mine site in southeastern Wyoming, we studied soil Se distribution, dissolution, speciation, and sorption characteristics and plant Se accumulation. Phosphate‐extractable soil Se exceeded the critical limit of 0.5 mg/kg in all the samples, whereas total soil Se ranged from a low (0.6 mg/kg) to an extremely high (26 mg/kg) value. Selenite was the dominant species in phosphate and ammonium bicarbonate‐diethylenetriamine pentaacetic acid (AB‐DTPA) extracts, whereas selenate was the major Se species in hot water extracts. Extractable soil Se concentrations were in the order of KH 2 PO 4 > AB‐DTPA > hot water > saturated paste. The soils were undersaturated with respect to various Se solid phases, albeit with high levels of extractable Se surpassing the critical limit. Calcium and Mg minerals were the potential primary solids controlling Se dissolution, with dissolved organic carbon in the equilibrium solutions resulting in enhanced Se availability. Adsorption was a significant ( r 2 = 0.76–0.99 at P < 0.05) mechanism governing Se availability and was best described by the initial mass isotherm model, which predicted a maximum reserve Se pool corresponding to 87% of the phosphate‐extractable Se concentrations. Grasses, forbs, and shrubs accumulated 11 to 1800 mg Se/kg dry weight. While elevated levels of bioavailable Se may be potentially toxic, the plants accumulating high Se may be used for phytoremediation, or the palatable forage species may be used as animal feed supplements in Se‐deficient areas.