Publications by Colleges and Departments (MSU - Bozeman)
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Item Selenate bioreduction in a large in situ field trial(Elsevier BV, 2024-04) Hendry, M. Jim; Kirk, Lisa; Warner, Jeff; Shaw, Shannon; Peyton, Brent M.; Schmeling, Erin; Barbour, S. LeeRemoving selenium (Se) from mine effluent is a common challenge. A long-term, in situ experiment was conducted to bioremediate large volumes (up to 7500 mc d−1) of Se(VI)-contaminated water (mean 87 μg L−1) by injecting the water into a saturated waste rock fill (SRF) at a coal mining operation in Elk Valley, British Columbia, Canada. To stimulate/maintain biofilm growth in the SRF, labile organic carbon (methanol) and nutrients were added to the water prior to its injection. A conservative tracer (Br−) was also added to track the migration of injected water across the SRF, identify wells with minimal dilution and used to quantify the extent of bioreduction. The evolution of the Se species through the SRF was monitored in time and space for 201 d. Selenium concentrations of <3.8 μg L−1 were attained in monitoring wells located 38 m from the injection wells after 114 to 141 d of operation. Concentrations of Se species in water samples from complementary long-term (351–498 d) column experiments using influent Se(VI) concentrations of 1.0 mg L−1 were consistent with the results of the in situ experiment. Solid samples collected at the completion of the column experiments confirmed the presence of indigenous Se-reducing bacteria and that the sequestered Se was present as insoluble Se(0), likely in Se-S ring compounds. Based on the success of this ongoing bioremediation experiment, this technology is being applied at other mine sites.Item Growth of Coal Mining Operations in the Elk River Valley (Canada) Linked to Increasing Solute Transport of Se, NO3–, and SO42– into the Transboundary Koocanusa Reservoir (USA–Canada)(American Chemical Society, 2023-11) Storb, Meryl B.; Bussell, Ashley M.; Caldwell Eldridge, Sara L.; Hirsch, Robert M.; Schmidt, Travis S.Koocanusa Reservoir (KOC) is a waterbody that spans the United States (U.S.) and Canadian border. Increasing concentrations of total selenium (Se), nitrate + nitrite (NO3–, nitrite is insignificant or not present), and sulfate (SO42–) in KOC and downstream in the Kootenai River (Kootenay River in Canada) are tied to expanding coal mining operations in the Elk River Watershed, Canada. Using a paired watershed approach, trends in flow-normalized concentrations and loads were evaluated for Se, NO3–, and SO42– for the two largest tributaries, the Kootenay and Elk Rivers, Canada. Increases in concentration (SO42– 120%, Se 581%, NO3– 784%) and load (SO42– 129%, Se 443%, NO3– 697%) in the Elk River (1979–2022 for NO3–, 1984–2022 for Se and SO42–) are among the largest documented increases in the primary literature, while only a small magnitude increase in SO42– (7.7% concentration) and decreases in Se (−10%) and NO3– (−8.5%) were observed in the Kootenay River. Between 2009 and 2019, the Elk River contributed, on average, 29% of the combined flow, 95% of the Se, 76% of the NO3–, and 38% of the SO42– entering the reservoir from these two major tributaries. The largest increase in solute concentrations occurred during baseflows, indicating a change in solute transport and delivery dynamics in the Elk River Watershed, which may be attributable to altered landscapes from coal mining operations including altered groundwater flow paths and increased chemical weathering in waste rock dumps. More recently there is evidence of surface water treatment operations providing some reduction in concentrations during low flow times of year; however, these appear to have a limited effect on annual loads entering KOC. These findings imply that current mine water treatment, which is focused on surface waters, may not sufficiently reduce the influence of mine-waste-derived solutes in the Elk River to allow constituent concentrations in KOC to meet U.S. water-quality standards.