Denitrification can Cause Variable No-3 Concentrations in Shallow Groundwater

摘要: The mechanisms regulating NO 3 - concentration and dissimilation in a shallow, spring-fed well were investigated by creating variable flow conditions series of sediment-filled laboratory microcosms. Nitrate concentrations the microcosms reproduced field observations; effluent as high 100% influent when rates high, less than 10% low, intermediate intermediate. NH 4 + (up to 6.9 mg -N L -1 ) did not vary despite changes flow, which indicated that assimilatory dissimilatory reduction inconsequential. Changes consistent with N 2 gas (denitrification) based on following evidence: intermediates denitrification accumulated short retention times (flow > mL min disappeared long 1000 g <400 g) shorten time decreased reduction; sediment pH increased from 7.5 8.5, would occur during denitrification, periods low flow; acetylene caused O accumulate, indicating terminal step was blocked. Forty-seven percent springs, wells, tiles statewide water assessment Kentucky demonstrated concentration. Denitrification appears affect quality year attenuate impacts shallow groundwater.