The Impact of Terrestrial Nitrogen Inputs on Coastal Eutrophication in Texas

The increased nitrogen inputs influenced by human activities on terrestrial biosphere can cause eutrophication or coastal dead zone in water bodies. The Net Anthropogenic Nitrogen Inputs (NANI) are estimated to measure the human effect on the regional nitrogen cycle. The community Noah land surface model with multi-parameterization options (Noah-MP) is unique in that it recently implements the nitrogen parameterizations from carbon cost theory of the Fixation and Uptake of Nitrogen (FUN) plant model and the Soil and Water Assessment Tool (SWAT) soil nitrogen dynamics. In this study, we reflect anthropogenic nitrogen inputs on the nitrogen dynamics to represent regional nitrogen states/fluxes by replacing nitrogen input parameters of the model with NANI. The model employs atmospheric nitrogen deposition and fertilizer application rate from NANI. The NANI-implemented model simulates within Texas, one of the largest agriculture industries in the Nation. Results show that applying nitrogen fertilizer influences on carbon and water cycles through plant growth and water use, and the impacts on carbon and water cycles depend on the amount of nitrogen inputs. Furthermore, regional differences of nitrogen inputs is expected to influence more on nitrogen state/flux variables simulation than annual differences.