Denitrification and total nitrate uptake in streams of a tropical landscape
Potter, Jody D.
McDowell, William H.
Merriam, J. L.
Peterson, Bruce J.
Thomas, Suzanne M.
MetadataShow full item record
KeywordDenitrification; N loading; N2O emissions; Nitrate uptake; Puerto Rico; Tropical streams; Tropics
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.
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.
Showing items related by title, author, creator and subject.
Effects of experimental warming and carbon addition on nitrate reduction and respiration in coastal sediments Brin, Lindsay D.; Giblin, Anne E.; Rich, Jeremy J. (2015-04)Climate change may have differing effects on microbial processes that control coastal N availability. We conducted a microcosm experiment to explore effects of warming and carbon availability on nitrate reduction pathways ...
Intracellular isotope localization in Ammonia sp. (Foraminifera) of oxygen-depleted environments : results of nitrate and sulfate labeling experiments Nomaki, Hidetaka; Bernhard, Joan M.; Ishida, Akizumi; Tsuchiya, Masashi; Uematsu, Katsuyuki; Tame, Akihiro; Kitahashi, Tomo; Takahata, Naoto; Sano, Yuji; Toyofuku, Takashi (Frontiers Media, 2016-02-19)Some benthic foraminiferal species are reportedly capable of nitrate storage and denitrification, however, little is known about nitrate incorporation and subsequent utilization of nitrate within their cell. In this study, ...
Origin of the deep Bering Sea nitrate deficit : constraints from the nitrogen and oxygen isotopic composition of water column nitrate and benthic nitrate fluxes Lehmann, Moritz F.; Sigman, Daniel M.; McCorkle, Daniel C.; Brunelle, Brigitte G.; Hoffmann, Sharon S.; Kienast, Markus; Cane, Greg; Clement, Jaclyn (American Geophysical Union, 2005-10-12)On the basis of the normalization to phosphate, a significant amount of nitrate is missing from the deep Bering Sea (BS). Benthic denitrification has been suggested previously to be the dominant cause for the BS nitrate ...