Former mining activities lasting 140 years in the Ducktown Mining District, Tennessee, USA, has contaminated the streams draining the district with acid-mine drainage (AMD). North Potato Creek and its major tributary, Burra Burra Creek, are two of the most heavily AMD-impacted streams in the district. The removal of dissolved metals from the water in these creeks is largely attributable to the sorption of Cu, Zn, Co, Al, and Mn on suspended hydroxide precipitates of Fe. The fraction of trace metals remaining in solution decreases with increasing pH in the sequence Pb<Cu<Zn<Co. The concentration of Fe in solution also decreases with increasing pH due to the formation of ferric hydroxide precipitates which accounted for up to 81.4% by weight of the total suspended sediment. The concentration of suspended sediment substantially decreases as the water of North Potato Creek flows through a large settling basin, where 1.3 (±0.3)×106 kg/year of trace-metal-laden suspended sediment would be annually deposited. In spite of this attempt to purify it, the water discharged into the river is acidic (pH 3.6) and still contains high concentrations of dissolved trace metals, which would resorb on to suspended sediment and be ultimately transported to a downstream reservoir, Ocoee No. 3 Lake.
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Acknowledgments The authors express gratitude for valuable discussions to Jerry M. Bigham on the characterization of suspended sediment and to Douglas E. Pride on the history and the mines of the Ducktown Mining District. This work was supported by the Graduate Student Alumni Research Award of the Graduate School of The Ohio State University and the Korean Research Foundation (KRF-2005-070-C00137).
All Science Journal Classification (ASJC) codes
- Environmental Engineering
- Environmental Chemistry
- Ecological Modelling
- Water Science and Technology