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Titel (primär) Disaggregating landscape‐scale nitrogen attenuation along hydrological flow paths
Autor Jawitz, J.W.; Desormeaux, A.M.; Annable, M.D.; Borchardt, D.; Dobberfuhl, D.;
Journal / Serie Journal of Geophysical Research-Biogeosciences
Erscheinungsjahr 2020
Department ASAM;
Band/Volume 125
Heft 2
Sprache englisch;
POF III (gesamt) T31;
Abstract Evaluating how nitrogen (N) sources are attenuated throughout the landscape is critical to further our understanding of catchment‐scale N budgets. We developed a catchment‐scale N budget for a mixed land‐use karst springshed using in situ measurements (nitrate leaching fluxes and attenuation) and long‐term records (surface N inputs and spring exports) to estimate 20‐year average landscape‐scale N loading, attenuation, and export. We introduce a conceptual model framework to compute N export that can be applied consistently for point or nonpoint sources. The model is based on the product of only four components for each N source: population density or proportion of land cover, P, specific load, L, anthropogenic attenuation, A, and natural attenuation, N. The product of these components is computed for each N source and then integrated at the basin scale. The concise PLAN model framework predicted attenuation of 90%±3% of N inputs, in close agreement with the estimate based on measured spring mass discharge (87%±3%). Further, when this attenuation is disaggregated along the hydrological flow path, we estimate that 64% of inputs are lost in the surface soil, 20% in the vadose zone, and 6% in the aquifer. Livestock and human wastes were estimated to be the dominant contributors to spring N export, which was independently supported by isotopic data. The PLAN model is a simple, transferable framework that supports systematically computing N export based on proportioning of load and attenuation. Identifying the main sources of N ultimately contributing to discharged N loads is a critical step towards source‐related water quality management.
ID 22723
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Jawitz, J.W., Desormeaux, A.M., Annable, M.D., Borchardt, D., Dobberfuhl, D. (2020):
Disaggregating landscape‐scale nitrogen attenuation along hydrological flow paths
J. Geophys. Res.-Biogeosci. 125 (2), e2019JG005229