PW04 Global Atmospheric Transport
Exhibit Hall
8:00 AM - Wednesday
(PW040) The first observations of Asian outflow of mercury species at Cape Hedo, Okinawa.
Prestbo, E.1, Jaffe, D.2, Swartzendruber, P.2, Kato, S.3, Kajii, Y.3, Takami, A.4, Hatakeyama, S.4, Simonich, S.5, Primbs, T.5, Schmedding, D.5, 1 Frontier Geosciences, Seattle, WA, USA2 University of Washington-Bothell, Bothell, WA, USA3 Tokyo Metropolitan University, Tokyo, Japan, Japan4 National Institute for Environmental Studies, Tsukuba, Japan, Japan5 Oregon State University, Corvallis, OR, USA
ABSTRACT- Until recently, atmospheric mercury emissions and impact have been a concern at the national, or at most, continental level. Over the last 20 years, atmospheric mercury emissions have decreased in both North America and Europe. During this same period, atmospheric emissions of mercury in Asia have grown steadily. Currently, estimates suggest that nearly half of the anthropogenic emissions are from Asia, with the large majority coming from the southeastern countries. With new mercury point-source regulations expected for North America, global source input to North America will continue to gain in importance. The research presented is part of an ongoing program to understand the long-range transport and inflow of atmospheric mercury species to North America. In order to better interpret long-range transport events in North America, we recognized the need for an intensive field campaign, at Cape Hedo, on the island of Okinawa, to characterize the outflow of mercury species from Asia. An automated mercury speciation system (Tekran 2537-1130-1135) was used to determine the concentrations of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate-bound mercury (PHg). Mercury measurements were made from 23-March to 2-May, 2004. Also measured continuously at Cape Hedo were O3, CO, NO, NOy, SO2, TEOM, EC/OC, light scatter, chemistry of fine aerosols (AMS), light flux and standard meteorology. The 5-minute resolution mean, median and maximum GEM concentrations during the study were 2.04, 1.99 and 5.47 ng/m3, respectively. These GEM levels agree with recent global models, but are more than 25 percent above the Northern Hemisphere background levels of approximately 1.5 to 1.6 ng/m3. The PHg and RGM mean and maximum values were 3.05, 16.5 and 4.51, 32.5 pg/m3, respectively. These values are below model predictions. A strong diurnal RGM pattern was observed, with peak values coincident with the highest solar insolation. We observed 11 distinct elevated GEM mercury transport events, from various source regions, including industrial pollution, biomass burning and Asian dust episodes. The presentation will focus on a summary of the GEM mercury events with respect to source area, air pollution chemical signature and the behavior of both RGM and PHg.
Key words: Specitation, Mercury, Global, Transport