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Impact of Nitrogen Deposition Reduction on Agriculture Land Nitrogen Budget and Water Quality: Integrated Modeling Assessment in the United States
Citation:
Ran, L., Y. Yuan, R. Mathur, J. Pleim, R. Wang, D. Yang, V. Benson, E. Cooter, AND J. Williams. Impact of Nitrogen Deposition Reduction on Agriculture Land Nitrogen Budget and Water Quality: Integrated Modeling Assessment in the United States. ITM 2019 - 37th International Technical Meeting on Air Pollution Modelling and its Application, Hamburg, GERMANY, September 23 - 27, 2019.
Impact/Purpose:
There is a need for integrated assessment for addressing many aspects of the interdisciplinary science and policy on interactions of air quality with ecosystems.
Description:
Atmospheric nitrogen (N) deposition is an important source which influences ecosystem N cycle, particularly in areas with N limitation. There has been significant N deposition reduction in the United States (US) since 1990 because of tightened standards under the Clean Air Act (CAA) on NOX emissions. Many studies have been conducted to assess the effect of N deposition reduction on air quality and ecosystems. Still, there is a need for integrated assessment for addressing many aspects of the interdisciplinary science and policy on interactions of air quality with ecosystems. In this study, we present an integrated modeling system with agriculture (EPIC - Environmental Policy Integrated Climate), atmosphere (WRF/CMAQ - Weather Research and Forecast model and Community Multiscale Air Quality), and hydrology (SWAT - Soil and Water Assessment Tool) models to assess the interactions among land-air-water processes. This study focuses on assessing the impact of N deposition reduction on agricultural land N budget and water quality. The system is applied for a 12km domain over the conterminous US for 2010, 2011, and 2012. EPIC simulations are conducted using WRF/CMAQ weather and N deposition for these years and adjusted to represent conditions in the early 1990s. SWAT integrated with EPIC and WRF/CMAQ are then applied to the Mississippi River Basin (MRB) to simulate watershed hydrology and water quality for these years under different N deposition conditions. Preliminary results demonstrate that the N budget in agricultural production is sensitive to N deposition. The results demonstrate that increased N fertilization and decreased N loss are in areas with distinct N deposition reduction. In addition, the impact of N deposition reduction on N losses from MRB to the Gulf of Mexico will be analyzed and presented to show the effect of CAA policies on water quality for the largest drainage basin in North America.