| Summary: | Since EPA measured high concentrations of reactive gaseous mercury (RGM) in emissions from municipal and hospital waste incinerators in 1995, we have been working to elucidate the role of RGM on atmospheric mercury deposition. EPA has recently established automated speciated mercury monitoring sites in Coral Springs, Florida; Cheeka Peak, Washington; Barrow, Alaska; and Mauna Loa, Hawaii. In addition, EPA has conducted over thirty mercury research aircraft sorties off Florida's Atlantic coast and in Barrow, Alaska. In addition to the speciated mercury measurements at each site, fine (<2.5 um) and coarse (2.5 -10 um) particles will be characterized with regard to mass, trace elements and with meteorological back trajectory data source-receptor relationships will be deduced. At each site or study, specific sets of measurements will contribute to our overall understanding of the mechanisms of transformation of Hg0 to RGM and to particulate phase mercury. We will present data from all our studies and discuss the results in terms of homogenous and heterogeneous atmospheric oxidation mechanisms, long-range transport, source receptor relationships and long-term global baseline measurements. This work has been funded wholly or in part by the United States Environmental Protection Agency Office of Research and Development. It has been subjected to peer review and approved for publication.
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