A TEN YEAR RECORD OF NITRATE RETENTION IN A WISCONSIN STREAM: TEMPORAL VARIATION AT MULTIPLE SCALES
Nitrate retention is an important ecosystem service provided by streams. We measured nitrate retention in a groundwater-fed stream, Emmons Creek, in Central Wisconsin during 2007-2016. We used a two station mass-balance approach based on weekly to biweekly sampling for nitrate in surface water. Groundwater nitrate input was assessed by biweekly to seasonal sampling from a piezometer network. We used time series modelling to generate nitrate concentration time series data that were sensitive to surface water discharge and season. Nitrate concentrations in surface water, but not in groundwater, exhibited strong seasonality. Nitrate retention tended to be highest in spring and autumn, moderate in summer and very low in winter. Groundwater discharge was a strong predictor of nitrate retention within seasons. Our results are consistent with the results of previous research that has demonstrated the importance of shallow groundwater for nitrogen transformation in ecosystems.
Robert Stelzer (Primary Presenter/Author), Department of Biology, University of Wisconsin Oshkosh, firstname.lastname@example.org;
Thomas Parr (Co-Presenter/Co-Author), University of Oklahoma, Thomas.email@example.com;