Mercury isotopic evidence for multiple mercury sources in coal from the Illinois basin.
Mercury isotopic evidence for multiple mercury sources in coal from the Illinois basin.
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DOI：
10.1021/es102875n
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发表时间：
2011-01
影响因子：
11.4
通讯作者：
L. Lefticariu;J. Blum;J. Gleason
中科院分区：
文献类型：
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作者：
L. Lefticariu;J. Blum;J. Gleason
煤炭燃烧是人为向大气排放汞 (Hg) 的最大来源，因此具有巨大的环境影响。汞稳定同位素地球化学的最新发展为追踪环境中人为汞的来源和化学转化提供了新工具。我们在这里首次对伊利诺伊州盆地（美国主要产煤区之一）四个宾夕法尼亚时代煤层的有机和无机成分中的汞进行同位素研究。我们将相对于 NIST 3133 标准的质量相关同位素变化报告为 δ(202)Hg，将质量无关的分馏报告为 Δ(199)Hg 和 Δ(201)Hg 值。伊利诺伊州煤炭的数据显示 δ(202)Hg（-0.75 至 -2.68‰）、Δ(201)Hg（0.04 至 -0.22‰）和 Δ(199)Hg（0.02 至 -0.23‰）的范围很广。相比之下，相对于 NIST 3133，来自两个煤层的脉状黄铁矿在同位素上未分级。总的来说，这些数据表明同位素不同的汞源对伊利诺伊州煤炭的有机和无机部分有贡献。伊利诺斯州煤炭的 Δ(201)Hg/ Δ(199)Hg 比率为 1:1，与在成煤环境中沉积之前通过光化学还原 Hg(2+) 进行的同位素分馏一致。黄铁矿中汞的同位素组成更可能来自伊利诺伊州煤层中沉淀还原硫的热液。这些结果首次证明汞同位素具有区分煤中汞的同生（沉积）来源和表观（热液）来源的潜力。我们的研究结果可能有助于区分控制煤炭中汞分布的各种地质过程，并监测与煤炭有机成分和无机成分相关的排放物中汞的比例。
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 δ(202)Hg and mass independent fractionation as Δ(199)Hg and Δ(201)Hg values. The data for Illinois coals show a wide range of δ(202)Hg (-0.75 to -2.68‰), Δ(201)Hg (0.04 to -0.22‰), and Δ(199)Hg (0.02 to -0.23‰). 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 Δ(201)Hg/ Δ(199)Hg ratio of Illinois coals is 1:1, consistent with isotopic fractionation by photochemical reduction of Hg(2+) 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.