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Denitrification and total nitrate uptake in streams of a tropical landscape

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dc.contributor.author Potter, Jody D.
dc.contributor.author McDowell, William H.
dc.contributor.author Merriam, J. L.
dc.contributor.author Peterson, Bruce J.
dc.contributor.author Thomas, Suzanne M.
dc.date.accessioned 2010-12-29T13:52:18Z
dc.date.available 2010-12-29T13:52:18Z
dc.date.issued 2010-12
dc.identifier.citation Ecological Applications 20 (2010): 2104-2115 en_US
dc.identifier.uri http://hdl.handle.net/1912/4285
dc.description Author Posting. © Ecological Society of America, 2010. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 20 (2010): 2104-2115, doi:10.1890/09-1110.1. en_US
dc.description.abstract Rapid increases in nitrogen (N) loading are occurring in many tropical watersheds, but the fate of N in tropical streams is not well documented. Rates of nitrate uptake and denitrification were measured in nine tropical low-order streams with contrasting land use as part of the Lotic Intersite Nitrogen eXperiment II (LINX II) in Puerto Rico using short term (24-hour) additions of K15NO3 and NaBr. Background nitrate concentrations ranged from 105 to 997 μg N/L, and stream nitrate uptake lengths were long, varying from 315 to 8480 m (median of 1200 m). Other indices of nitrate uptake (mass transfer coefficient, Vf [cm/s], and whole-stream nitrate uptake rate, U [μg N·m−2·s−1]) were low in comparison to other regions and were related to chemical, biological, and physical parameters. Denitrification rates were highly variable (0–133 μg N·m−2·min−1; median = 15 μg N·m−2·min−1), were dominated by the end product N2 (rather than N2O), and were best predicted by whole-stream respiration rates and stream NO3 concentration. Denitrification accounted for 1–97% of nitrate uptake with five of nine streams having 35% or more of nitrate uptake via denitrification, showing that denitrification is a substantial sink for nitrate in tropical streams. Whole-stream nitrate uptake and denitrification in our study streams closely followed first-order uptake kinetics, indicating that NO3 uptake is limited by delivery of substrate (NO3) to the organisms involved in uptake or denitrification. In the context of whole-catchment nitrogen budgets, our finding that in-stream denitrification results in lower proportional production of N2O than terrestrial denitrification suggests that small streams can be viewed as the preferred site of denitrification in a watershed in order to minimize greenhouse gas N2O emissions. Conservation of small streams is thus critical in tropical ecosystem management. en_US
dc.description.sponsorship This research was part of the Lotic Intersite Nitrogen eXperiment II (LINX II) funded by the National Science Foundation (DEB-0111410). Additional support was provided by the National Science Foundation to the Institute of Terrestrial Ecology at the University of Puerto Rico and the International Institute of Tropical Forestry (DEB-0218039 and DEB-0620919) through the Luquillo Long Term Ecological Research (LUQ LTER) program. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher Ecological Society of America en_US
dc.relation.uri http://dx.doi.org/10.1890/09-1110.1
dc.subject Denitrification en_US
dc.subject N loading en_US
dc.subject N2O emissions en_US
dc.subject Nitrate uptake en_US
dc.subject Puerto Rico en_US
dc.subject Tropical streams en_US
dc.subject Tropics en_US
dc.title Denitrification and total nitrate uptake in streams of a tropical landscape en_US
dc.type Article en_US
dc.identifier.doi 10.1890/09-1110.1


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