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dc.contributor.authorPotter, Jody D.
dc.contributor.authorMcDowell, William H.
dc.contributor.authorMerriam, J. L.
dc.contributor.authorPeterson, Bruce J.
dc.contributor.authorThomas, Suzanne M.
dc.date.accessioned2010-12-29T13:52:18Z
dc.date.available2010-12-29T13:52:18Z
dc.date.issued2010-12
dc.identifier.citationEcological Applications 20 (2010): 2104-2115en_US
dc.identifier.urihttp://hdl.handle.net/1912/4285
dc.descriptionAuthor 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.abstractRapid 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.sponsorshipThis 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.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherEcological Society of Americaen_US
dc.relation.urihttps://doi.org/10.1890/09-1110.1
dc.subjectDenitrificationen_US
dc.subjectN loadingen_US
dc.subjectN2O emissionsen_US
dc.subjectNitrate uptakeen_US
dc.subjectPuerto Ricoen_US
dc.subjectTropical streamsen_US
dc.subjectTropicsen_US
dc.titleDenitrification and total nitrate uptake in streams of a tropical landscapeen_US
dc.typeArticleen_US
dc.identifier.doi10.1890/09-1110.1


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