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Atmospheric Nitrogen Deposition Contributions to the Chesapeake Bay Watershed: Maryland Animal NH3 Emissions Sensitivity
Citation:
Bash, J., S. Benish, V. Rao, G. Shenk, L. Linker, K. Foley, S. Napelenok, J. Kelly, Y. Dietrich, AND I. Rumsey. Atmospheric Nitrogen Deposition Contributions to the Chesapeake Bay Watershed: Maryland Animal NH3 Emissions Sensitivity. July 2022 Chesapeake Bay Program’s Quarterly Meeting, NA, NC, July 12, 2022.
Impact/Purpose:
We used the EPA’s Community Multiscale Air-Quality (CMAQ) model version 5.3.3 with Integrated Source Apportionment (ISAM) to explore the impact of animal NH3 emissions from Maryland on reduced nitrogen deposition to the Chesapeake Bay Watershed and tidal waters. CMAQ ISAM simulations were run with EQUATES emissions where Maryland animal sector NH3 emissions were several orders of magnitude lower previous estimates in National Emissions Inventory (NEI) and EPA estimated values comparable to previous estimates NEI estimates. The emission change resulted in large local changes in reduced nitrogen deposition, up to a factor of three, and modest changes in deposition to the watershed and tidal waters of 4.1% and 5.9%, respectively. The updated animal emissions resulted in 1.8% increase in total nitrogen deposition to the Chesapeake Bay Watershed. The highest deposition changes were co-located with emissions changes and resulted in virtually no change in the evaluation against network air-quality and deposition observations due to an insufficient density of observations but is apparent in the model evaluation against satellite NH3 observations.
Description:
We used the EPA’s Community Multiscale Air-Quality (CMAQ) model version 5.3.3 with Integrated Source Apportionment (ISAM) to explore the impact of animal NH3 emissions from Maryland on reduced nitrogen deposition to the Chesapeake Bay Watershed and tidal waters. CMAQ ISAM simulations were run with EQUATES emissions where Maryland animal sector NH3 emissions were several orders of magnitude lower previous estimates in National Emissions Inventory (NEI) and EPA estimated values comparable to previous estimates NEI estimates. The emission change resulted in large local changes in reduced nitrogen deposition, up to a factor of three, and modest changes in deposition to the watershed and tidal waters of 4.1% and 5.9%, respectively. The updated animal emissions resulted in 1.8% increase in total nitrogen deposition to the Chesapeake Bay Watershed. The highest deposition changes were co-located with emissions changes and resulted in virtually no change in the evaluation against network air-quality and deposition observations due to an insufficient density of observations but is apparent in the model evaluation against satellite NH3 observations.