Dissimilatory Nitrate Reduction in a Waste‐Water Contaminated Aquifer

Publisher Website
Google Scholar
Abstract
Ground water beneath the McVille, North Dakota Municipal Waste‐Stabilization Ponds was studied to determine the chemical effects of seepage on a shallow unconfined aquifer. Relatively coarse‐grained glaciofluvial sediments underlie the site and facilitate transport of partially treated waste water to the water table, altering the local ground‐water chemistry.The plume resulting from infiltration contains elevated levels of dissolved organic carbon (DOC) and ammonium in areas of low redox potential. The presence of nutrients in waters of low redox potential promotes the growth of anaerobic bacteria. Ground water containing high nitrate concentrations, due to leachate from an adjacent abandoned landfill, occurs upgradient of the ponds. These high nitrate waters, traveling downgradient, mix with the low redox potential ground water beneath and downgradient of the lagoon. Ammonium concentrations, downgradient of the waste‐stabilization ponds, are greater than ammonium levels within the ponded waste water. The abundant microbial population appears to utilize DOC and nitrate as nutrients for growth and energy. The utilization of nutrients occurs in a redox reaction, in which nitrate is apparently reduced to ammonium and carbon is oxidized. The increase in ammonium levels and decrease in nitrate levels suggests nitrate is not assimilated into cell tissue, but instead dissimilatory nitrate reduction to ammonium takes place. Dissimilatory reduction refers to reduction of a compound for its energy yield, without conversion of the compound to biomass (Ceazan et al, 1984).

This publication has 11 references indexed in Scilit: