Geochemical Processes Affecting the Mobility of Dissolved Selenium in Surface Coal Mine Backfill Environments
نویسنده
چکیده
During surface Fadlelmawla', K.J. Reddf, and G.F. Vance3 coal mining, rock material overlying the coal is redistsibuted with respect to its original stratigraphic position. Oxidation of the redistributed backfill material may release dissolved selenium (Se) to groundwater in backfill systems. This study was initiated to examine the chemistry of Se in the groundwater backfill environment. Both backfill core mated and groundwater samples were collected from three sites in Wyoming. Dissolved organic carbon (DOC) from groundwater samples was fractionated into six categories (hydrophobic acids, bases, and neutrals; and hydrophilic acids, bases, and neutrals). pThe DOC was comprised primarily of hydrophobic and hydrophilic acids which were isolated and used in competitive sorption/desorption studies with Se. Core samples were also subjected to precipitation/dissolution studies to determine potential solid phases controlling dissolved Se concentration. Results suggested that coal mine backfill material have a very high sorption capacity for Se. Hydrophilic acids reduced Se sorption by coal mine backfill materials. DOC showed very little effect on Se speciation and potential solid phases controlling dissolved Se. Water extracts from coal mine backfill materials were dominated by MgSe0,O ion pair followed by CaSe030, and Se032species. Dissolved Se concentrations in coal mine backfill environments appeared to be controlled by a Cu,Se solid phase. KEY TERMS: Selenium; sorption/desorption; chemical modeling; precipitation/dissohtion.
منابع مشابه
Effects of Redox Potential on the Speciation of Selenium in Ground Water and Coal-Mine Backfill Materials, Wyoming Katta
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