INSITU BACTERIAL SELENATE REDUCTION IN THE AGRICULTURAL DRAINAGE SYSTEMS OF WESTERN NEVADA

Dissimilatory in situ selenate reduction to elemental selenium in sediments from irrigated agricultural drainage regions of western Nevada was measured at ambient Se oxyanion concentrations. Selenate reduction was rapid, with turnover rate constants ranging from 0.04 to 1.8 h-1 at total Se concentrations in pore water of 13 to 455 nM. Estimates of removal rates of selenium oxyanions were 14, 38, and 155-mu-mol m-2 day-1 for South Lead Lake, Massie Slough, and Hunter Drain, respectively.