Temporal and Spatial Trends of Atmospheric Deposition in Maryland and Comparison to Observations of Atmospheric Pollutants in the Chesapeake Bay Watershed

Sarah Benish1, Phil Stratton2, Allison Ring3, Gina Mazzuca4 and Xinrong Ren5

Due to the proximity of heavily polluted urban areas, such as Baltimore, MD and Washington, D.C., the Chesapeake Bay receives an unusually large amount of atmospheric pollutants through deposition. Estimates from the Maryland Department of Natural Resources have found about 27% of nitrogen delivered to the Chesapeake Bay is from the atmosphere. These estimates include direct deposition to the bay’s surface as well as runoff to the watershed. Understanding and quantifying the long-term trends of nitrogen, sulfur, and mercury atmospheric deposition in Maryland is important due to the adverse effects these pollutants have on the local environment. We will assess 40 years atmospheric deposition trends of nitrogen and sulfur in three Maryland locations: Beltsville, located outside of the Washington, D.C. area; Smithsonian Environmental Research Center, situated south of Annapolis, MD near the Bay; and Piney Reservoir in northwestern Maryland. Preliminary results from 2000-2015 show the total nitrogen deposition in Beltsville has decreased by about 50% from 22.72 kg N/ha to 13.76 kg N/ha. Maryland and Mid-Atlantic stations will be compared with national trends of atmospheric pollutants, including mercury, sulfates, and nitrates, to assess relative changes at the local, regional, and national levels. We will use the Environmental Protection Agency’s (EPA) Environmental Monitoring and Assessment Program to compare results from the atmospheric deposition monitors with Mid-Atlantic streams data of nitrate and sulfate to understand how atmospheric and water trends are linked. Additionally, the EPA Continuous Emission Monitoring System will explicate trends in sulfur dioxide and Nox (NO+NO2) from local and upwind power plants. This study will show how atmospheric deposition of pollutants such as sulfates, nitrates, and mercury have decreased over the past several decades in Maryland. Linking these trends to additional datasets will help deepen the understanding between emission reductions from local and upwind regions and the level of nitrates and sulfates present in watersheds, demonstrating improvements to the health of the Chesapeake Bay.

 

1University of Maryland, College Park, sebenish@umd.edu
2University of Maryland, College Park, pstratto@umd.edu
3University of Maryland, College Park, aring1@umd.edu
4University of Maryland, College Park, gmazzuca@umd.edu
5NOAA Air Resources Laboratory & University of Maryland, College Park, xinrong.ren@noaa.gov