Isotopic Composition and Fractionation of Mercury in Great Lakes Precipitation and Ambient Air
| Autor: | Joel D. Blum, Laura S. Sherman, Lynne E. Gratz, Gerald J. Keeler |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Air Pollutants
Biogeochemical cycle Trace element chemistry.chemical_element Mineralogy Fresh Water Mercury General Chemistry Fractionation Mercury (element) Deposition (aerosol physics) Isotopes chemistry Environmental chemistry Isotope geochemistry Environmental Chemistry Chemical composition Water Pollutants Chemical Isotope analysis |
| Zdroj: | Environmental Science & Technology. 44:7764-7770 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/es100383w |
| Popis: | Atmospheric deposition is a primary pathway by which mercury (Hg) enters terrestrial and aquatic ecosystems; however, the chemical and meteorological processes that Hg undergoes from emission to deposition are not well understood. Hg stable isotope geochemistry is a growing field used to better understand Hg biogeochemical cycling. To examine the atmospheric Hg isotopic composition in the Great Lakes, precipitation and ambient vapor-phase Hg samples were collected in Chicago, IL, Holland, MI, and Dexter, MI, between April 2007 and September 2009. Precipitation samples were characterized by negative mass-dependent fractionation (MDF) (δ(202)Hg = -0.79‰ to 0.18‰), while most vapor-phase samples displayed positive MDF (δ(202)Hg = -0.59‰ to 0.43‰). Positive mass-independent fractionation (MIF) (Δ(199)Hg = 0.04‰ to 0.52‰) was observed in precipitation, whereas MIF was slightly negative in vapor-phase samples (Δ(199)Hg = -0.21‰ to 0.06‰). Significant positive MIF of (200)Hg up to 0.25‰ was also measured in precipitation. Such MIF of an even-mass Hg isotope has not been previously reported in natural samples. These results contrast with recent predictions of the isotopic composition of atmospheric Hg and suggest that, in addition to aqueous photoreduction, other atmospheric redox reactions and source-related processes may contribute to isotopic fractionation of atmospheric Hg. |
| Databáze: | OpenAIRE |
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