Groundwater Nitrate Processing in Deep Stream Sediments

Background/need: Elevated nitrate concentration in ground water is a pressing environmental problem in many regions of the world, including Wisconsin (Browne et al. 2008, Rupert 2008, Saad 2008). The nitrate concentration of ground water in many areas of the Central Sand Ridges
Ecoregion of Wisconsin exceeds the recommended limit for drinking water (10 mg NO₃-N L^-1) set by the Environmental Protection Agency. Current federal policy mandating the use of biofuels (e.g. ethanol produced from corn) and world demands for food may lead to further
increases in nitrate concentrations and loads in groundwater. Identification of hot spots of nitrogen processing will improve the ability of scientists to predict nitrogen retention and loss from watersheds and will aid land and water managers who need to make decisions that balance
nitrogen removal with needs of other stakeholders. The proposed project addresses the following priorities of the University of Wisconsin System: Interactions of groundwater and surface water including chemical transformations in the hyporheic zone.
Objectives: The main objectives of the proposed project were: 1) To determine if nitrogen processing in groundwater associated with deep stream sediments is widespread throughout a river network, 2) To determine if high nitrate concentration in groundwater saturates denitrification in stream sediments.