PW04 Global Atmospheric Transport
Exhibit Hall
8:00 AM - Wednesday

(PW039) The first detection of the long range transport of mercury to North America.

Swartzendruber, P1, Jaffe, D2, Prestbo, E3, Bertschi, I2, Dennison, J2, 1 University of Washington Department of Atmospheric Sciences, Seattle, WA, USA2 University of Washington-Bothell, Bothell, WA, USA3 Frontier Geosciences, Seattle, WA, USA

ABSTRACT- During the Spring of 2004, we measured total Hg, CO, O3, NOx and aerosols at a newly established site on the summit of Mt. Bachelor, Oregon (2.7 km above sea level). As in prior work, we have identified episodes of long range-range transport of pollutants from Asia to North America. However, for the first time, we have measured enhanced Hg during long-range transport. During one significant episode, we observed an enhancement ratio of Hg to CO of 0.006 ng/m3/pppbv which is consistent with the expected emission ratios from coal-fired combustion sources in Asia. This ratio, along with enhancements in ozone, aerosol scatter, and NOx, can be used to help identify the source region. HYSPLIT backtrajectories indicate that the airmasses had arrived from over eastern Asia and support the hypothesis of the industrial regions as being a primary source of Hg to these episodes. The measurement of total atmospheric mercury at Mt. Bachelor was accomplished by thermal reduction at the inlet of any non-elemental gaseous or fine-fraction particulate-bound mercury species. While the speciation of mercury is important for more accurately characterizing the subsequent cycling and fate, the measurement of total Hg and the delta Hg/CO ratio allow for the total flux to North America to be estimated through the CO flux as modeled by the GEOS-CHEM global chemical model. (See presentations by Jaffe et al. and Prestbo et al. for discussions of related measurements in Okinawa, Japan and their relation to the input of Hg the U.S.)

Key words: transport, mercury

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