Mercury Isotopic Evidence for Multiple Mercury Sources in Coal from the Illinois Basin
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- 作者：Liliana Lefticariu ; Joel D. Blum ; James D. Gleason
- 刊名：Environmental Science & Technology
- 出版年：2011
- 出版时间：February 15, 2011
- 年：2011
- 卷：45
- 期：4
- 页码：1724-1729
- 全文大小：834K
- 年卷期：v.45,no.4(February 15, 2011)
- ISSN：1520-5851
文摘
Coal combustion is the largest source of anthropogenic mercury (Hg) emissions to the atmosphere and, thus, has vast environmental implications. Recent developments in Hg stable isotope geochemistry offer a new tool for tracing sources and chemical transformations of anthropogenic Hg in the environment. We present here the first isotopic study of mercury in organic and inorganic constituents of four Pennsylvanian-age coal seams in the Illinois Basin, one of the main coal-producing areas in the USA. We report mass dependent isotopic variations relative to the NIST 3133 standard as 未202Hg and mass independent fractionation as 螖199Hg and 螖201Hg values. The data for Illinois coals show a wide range of 未202Hg (鈭?.75 to 鈭?.68鈥?, 螖201Hg (0.04 to 鈭?.22鈥?, and 螖199Hg (0.02 to 鈭?.23鈥?. In contrast, vein pyrite from two coal seams is isotopically unfractionated relative to NIST 3133. Collectively, these data suggest that isotopically distinct Hg sources contributed to the organic and inorganic fractions of Illinois coals. The 螖201Hg/ 螖199Hg ratio of Illinois coals is 1:1, consistent with isotopic fractionation by photochemical reduction of Hg2+ prior to deposition in coal-forming environments. The isotopic composition of Hg in pyrite is more likely derived from hydrothermal fluids that precipitated reduced sulfur in Illinois coal seams. These results demonstrate, for the first time, the potential of Hg isotopes to discriminate between syngenetic (depositional) and epigenetic (hydrothermal) sources of Hg in coal. Our findings may be useful in distinguishing among various geological processes controlling the distribution of Hg in coal and monitoring the fractions of Hg in emissions associated with organic versus inorganic components of coal.