TY - JOUR
T1 - Hydrologic and biogeochemical drivers of riparian denitrification in an agricultural watershed
AU - McPhillips, Lauren E.
AU - Groffman, Peter M.
AU - Goodale, Christine L.
AU - Walter, M. Todd
N1 - Publisher Copyright:
© 2015 Springer International Publishing Switzerland.
PY - 2015/6/1
Y1 - 2015/6/1
N2 - 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.
AB - 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.
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U2 - 10.1007/s11270-015-2434-2
DO - 10.1007/s11270-015-2434-2
M3 - Article
AN - SCOPUS:84929144832
SN - 0049-6979
VL - 226
JO - Water, Air, and Soil Pollution
JF - Water, Air, and Soil Pollution
IS - 6
M1 - 169
ER -