Nitrate uptake across biomes and the influence of elemental stoichiometry: A new look at LINX II. Issue 8 (13th August 2016)

• Record Type: Journal Article
• Authors: Wymore, Adam S.; Coble, Ashley A.; Rodríguez‐Cardona, Bianca; McDowell, William H.
• Is Part Of: Global biogeochemical cycles. Volume 30:Issue 8(2016:Aug.)
• Page Start: 1183
• Page End: 1191
• Publication Date: 2016-08-13
• Subjects: nitrate -- LINX II -- stream ecosystems -- elemental ratios -- nutrient additions; Biogeochemical cycles -- Periodicals; Electronic journals; 577.1405
• DOI: 10.1002/2016GB005468
• Languages: English
• ISSNs: 0886-6236

Abstract

Abstract: Considering recent increases in anthropogenic N loading, it is essential to identify the controls on N removal and retention in aquatic ecosystems because the fate of N has consequences for water quality in streams and downstream ecosystems. Biological uptake of nitrate (NO3 − ) is a major pathway by which N is removed from these ecosystems. Here we used data from the second Lotic Intersite Nitrogen eXperiment (LINX II) in a multivariate analysis to identify the primary drivers of variation in NO3 − uptake velocity among biomes. Across 69 study watersheds in North America, dissolved organic carbon:NO3 − ratios and photosynthetically active radiation were identified as the two most important predictor variables in explaining NO3 − uptake velocity. However, within a specific biome the predictor variables of NO3 − uptake velocity varied and included various physical, chemical, and biological attributes. Our analysis demonstrates the broad control of elemental stoichiometry on NO3 − uptake velocity as well as the importance of biome‐specific predictors. Understanding this spatial variation has important implications for biome‐specific watershed management and the downstream export of NO3 −, as well as for development of spatially explicit global models that describe N dynamics in streams and rivers. Key Points: Across biomes NO3 − uptake is best predicted by DOC:NO3 − ratios and photosynthetically active radiation No universal driver of NO3 − uptake was identified Controls on NO3 − uptake vary by biome