Sulfate Reduction in Freshwater Sediments Receiving Acid Mine Drainage

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Abstract
One arm of Lake Anna, Va., receives acid mine drainage (AMD) from Contrary Creek (SO 4 2− concentration = 2 to 20 mM, pH = 2.5 to 3.5). Acid-volatile sulfide concentrations, SO 4 2− reduction rates, and interstitial SO 4 2− concentrations were measured at various depths in the sediment at four stations in four seasons to assess the effects of the AMD-added SO 4 2− on bacterial SO 4 2− reduction. Acid-volatile sulfide concentrations were always an order of magnitude higher at the stations receiving AMD than at a control station in another arm of the lake that received no AMD. Summer SO 4 2− reduction rates were also an order of magnitude higher at stations that received AMD than at the control station (226 versus 13.5 mmol m −2 day −1 ), but winter values were inconclusive, probably due to low sediment temperature (6°C). Profiles of interstitial SO 4 2− concentrations at the AMD stations showed a rapid decrease with depth (from 1,270 to 6 μM in the top 6 cm) due to rapid SO 4 2− reduction. Bottom-water SO 4 2− concentrations in the AMD-receiving arm were highest in winter and lowest in summer. These data support the conclusion that there is a significant enhancement of SO 4 2− reduction in sediments receiving high SO 4 2− inputs from AMD.