title: Effectiveness of Emission Controls to Reduce the Atmospheric Concentrations of Mercury.
abstract: Coal-fired power plants in the United States are required to reduce their emissions of mercury (Hg) into the atmosphere to lower the exposure of Hg to humans. The effectiveness of power-plant emission controls on the atmospheric concentrations of Hg in the United States is largely unknown because there are few long-term high-quality atmospheric Hg data sets. Here, we present the atmospheric concentrations of Hg and sulfur dioxide (SO2) measured from 2006 to 2015 at a relatively pristine location in western Maryland that is several (>50 km) kilometers downwind of power plants in Ohio, Pennsylvania, and West Virginia. Annual average atmospheric concentrations of gaseous oxidized mercury (GOM), SO2, fine particulate mercury (PBM2.5), and gaseous elemental mercury (GEM) declined by 75%, 75%, 43%, and 13%, respectively, and were strongly correlated with power-plant Hg emissions from the upwind states. These results provide compelling evidence that reductions in Hg emissions from power plants in the United States had their intended impact to reduce regional Hg pollution.
authors.affiliation: Appalachian Laboratory, University of Maryland Center for Environmental Science , 301 Braddock Road, Frostburg, Maryland 21532, United States.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Castro
authors.affiliation: Power Plant Research Program, Maryland Department of Natural Resources , Annapolis, Maryland 21401, United States.
authors.forename: John
authors.initials: J
authors.lastname: Sherwell
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000517:prevention & control*; D001272:Atmosphere; D004784:Environmental Monitoring / Q000379:methods; D008396:Maryland; D008628:Mercury / Q000032:analysis*; D009820:Ohio; D052638:Particulate Matter / Q000032:analysis; D010414:Pennsylvania; D011210:Power Plants; D013458:Sulfur Dioxide / Q000032:analysis; D014903:West Virginia
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D008628:Mercury