Sources of Atmospheric DepositionAtmospheric pollution reaches Maryland from a wide geographic area that results from the movement of air masses into the state. Analyses using U.S. EPA's Regional Acid Deposition Model (RADM) have estimated that approximately 75% of atmospheric nitrogen deposition affecting the Chesapeake Bay watershed originates from outside the immediate Bay drainage. This Chesapeake Bay "airshed" for nitrogen oxide (NOx) extends from Tennessee to Ontario and encompasses an area more than 5.5 times larger than the Bay watershed. Several recent studies have documented that atmospheric deposition is often transported from sources outside Maryland. For example, extensive research into the sources of acidic deposition in Maryland has concluded that regional sulfate (i.e., from sources outside of the state) is the dominant cause of acidification of the state's surface waters. Sources within Maryland, however, may have substantial effects on resources at local scales. Many different activities--including power generation, industry, agriculture, and transportation--contribute pollutants that ultimately may affect Maryland resources through acidification, nutrient enrichment, or toxic effects. |
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 Graphic above: Airshed of the Chesapeake Bay for nitrogen deposition (Source: Dennis 1996) |
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