Hydrologic and biogeochemical drivers of riparian denitrification in an agricultural watershed

Lauren E. McPhillips, Peter M. Groffman, Christine L. Goodale, M. Todd Walter

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

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.

Original languageEnglish (US)
Article number169
JournalWater, Air, and Soil Pollution
Volume226
Issue number6
DOIs
StatePublished - Jun 1 2015

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Environmental Chemistry
  • Ecological Modeling
  • Water Science and Technology
  • Pollution

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