The origins of atmospheric methyl mercury

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:214847

Prestbo, E M; Bloom, N S ^[1]

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1. Frontier Geosciences, Inc., Seattle, WA (United States)

Methyl Hg in precipitation shows strong regional patterns, with highest volume weighted mean values (0.4 ng/L) in the Pacific Northwest and lowest values in Florida (<0.01 ng/l). Over most of the North Central region, average values range from 0.05 to 0.2 ng/L. Several potential sources of methyl Hg to the atmosphere have been investigated, including direct anthropogenic emissions, atmospheric methylation of Hg{sup o} or Hg(II), and emissions of methyl or dimethyl Hg from natural surfaces (oceans, bogs, or forests). Direct measurements of major total Hg sources such as coal and waste combustors, and sewage treatment facilities suggest that direct anthropogenic emissions are an insignificant source of methyl Hg to the atmosphere. The gas phase reaction of methyl halides with Hg{sup o} also appears to be an insignificant source of methyl Hg to the atmosphere. Recent laboratory experiments have provided a likely mechanism for atmospheric Hg methylation via a complex reaction involving acetate, sulfite, and iron. From a series of field measurements, another source appears to be the degradation of dimethyl mercury emitted by the upwelling of deep ocean water.

• OSTI ID: 214847
• Report Number(s): CONF-950801--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ATMOSPHERIC PRECIPITATIONS
COMBUSTION PRODUCTS
METHYLATION
METHYLMERCURY
POLLUTION SOURCES