Carla López Lloreda, PhD

Aquatic biogeochemistry | Global change ecology | Science education & outreach

Gradients of Anthropogenic Nutrient Enrichment Alter N Composition and DOM Stoichiometry in Freshwater Ecosystems


Journal article


A. Wymore, P. Johnes, S. Bernal, E. N. J. Brookshire, Hannah M. Fazekas, A. Helton, A. Argerich, R. Barnes, A. Coble, W. Dodds, S. Haq, Sherri L. Johnson, Jeremy B. Jones, S. Kaushal, P. Kortelainen, C. López‐Lloreda, B. Rodríguez-Cardona, R. Spencer, P. Sullivan, C. Yates, W. McDowell
Global Biogeochemical Cycles, 2021

Semantic Scholar DOI
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APA   Click to copy
Wymore, A., Johnes, P., Bernal, S., Brookshire, E. N. J., Fazekas, H. M., Helton, A., … McDowell, W. (2021). Gradients of Anthropogenic Nutrient Enrichment Alter N Composition and DOM Stoichiometry in Freshwater Ecosystems. Global Biogeochemical Cycles.


Chicago/Turabian   Click to copy
Wymore, A., P. Johnes, S. Bernal, E. N. J. Brookshire, Hannah M. Fazekas, A. Helton, A. Argerich, et al. “Gradients of Anthropogenic Nutrient Enrichment Alter N Composition and DOM Stoichiometry in Freshwater Ecosystems.” Global Biogeochemical Cycles (2021).


MLA   Click to copy
Wymore, A., et al. “Gradients of Anthropogenic Nutrient Enrichment Alter N Composition and DOM Stoichiometry in Freshwater Ecosystems.” Global Biogeochemical Cycles, 2021.


BibTeX   Click to copy

@article{a2021a,
  title = {Gradients of Anthropogenic Nutrient Enrichment Alter N Composition and DOM Stoichiometry in Freshwater Ecosystems},
  year = {2021},
  journal = {Global Biogeochemical Cycles},
  author = {Wymore, A. and Johnes, P. and Bernal, S. and Brookshire, E. N. J. and Fazekas, Hannah M. and Helton, A. and Argerich, A. and Barnes, R. and Coble, A. and Dodds, W. and Haq, S. and Johnson, Sherri L. and Jones, Jeremy B. and Kaushal, S. and Kortelainen, P. and López‐Lloreda, C. and Rodríguez-Cardona, B. and Spencer, R. and Sullivan, P. and Yates, C. and McDowell, W.}
}

Abstract

A comprehensive cross‐biome assessment of major nitrogen (N) species that includes dissolved organic N (DON) is central to understanding interactions between inorganic nutrients and organic matter in running waters. Here, we synthesize stream water N chemistry across biomes and find that the composition of the dissolved N pool shifts from highly heterogeneous to primarily comprised of inorganic N, in tandem with dissolved organic matter (DOM) becoming more N‐rich, in response to nutrient enrichment from human disturbances. We identify two critical thresholds of total dissolved N (TDN) concentrations where the proportions of organic and inorganic N shift. With low TDN concentrations (0–1.3 mg/L N), the dominant form of N is highly variable, and DON ranges from 0% to 100% of TDN. At TDN concentrations above 2.8 mg/L, inorganic N dominates the N pool and DON rarely exceeds 25% of TDN. This transition to inorganic N dominance coincides with a shift in the stoichiometry of the DOM pool, where DOM becomes progressively enriched in N and DON concentrations are less tightly associated with concentrations of dissolved organic carbon (DOC). This shift in DOM stoichiometry (defined as DOC:DON ratios) suggests that fundamental changes in the biogeochemical cycles of C and N in freshwater ecosystems are occurring across the globe as human activity alters inorganic N and DOM sources and availability. Alterations to DOM stoichiometry are likely to have important implications for both the fate of DOM and its role as a source of N as it is transported downstream to the coastal ocean.