This study investigated drivers of denitrification and overall NO3 - removal in an agricultural riparian area in central New York. Denitrification was measured using an in situ push-pull method with 15N-NO3 - as a tracer during summer and fall 2011 at a pair of riparian sites characterized by different hydrologic regimes. Median denitrification rates were 1347 and 703 g N kg soil-1 day-1 for the two study sites. These rates are higher than those reported for other riparian areas, emphasizing the role of some riparian areas as hotspots of NO3 - removal. N2O production was significantly higher at one site, demonstrating that riparian areas can be a greenhouse gas source under certain conditions. Denitrification was negatively correlated with groundwater flux, suggesting that slower flushing of water, and thus longer residence time, promotes denitrification. A mass balance of NO3 - loss revealed that denitrification only accounted for 5-12 % of total NO3 - loss, and production of NH4 + indicated that dissimilatory NO3 - reduction to NH4 + (DNRA) may be occurring at both sites. While both sites were characterized by high NO3 - removal, differences in denitrification rates and NO3 - removal processes demonstrate the need to improve our ability to capture spatial and process heterogeneity in landscape biogeochemical models.
All Science Journal Classification (ASJC) codes
- Environmental Engineering
- Environmental Chemistry
- Ecological Modeling
- Water Science and Technology