Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Avenue, Ann Arbor, Michigan 48109, United States.
Environ Sci Technol. 2012 Jan 3;46(1):382-90. doi: 10.1021/es202793c. Epub 2011 Dec 13.
Coal combustion accounts for approximately two-thirds of global anthropogenic mercury (Hg) emissions. Enhanced deposition of Hg can occur close to coal-fired utility boilers (CFUBs), but it is difficult to link specific point sources with local deposition. Measurement of Hg stable isotope ratios in precipitation holds promise as a tool to assist in the identification of local Hg deposition related to anthropogenic emissions. We collected daily event precipitation samples in close proximity to a large CFUB in Crystal River, Florida. Precipitation samples collected in Crystal River were isotopically distinct and displayed large negative δ(202)Hg values (mean = -2.56‰, 1 SD = 1.10‰, n = 28). In contrast, precipitation samples collected at other sites in FL that were not greatly impacted by local coal combustion were characterized by δ(202)Hg values close to 0‰ (mean = 0.07‰, 1 SD = 0.17‰, n = 13). These results indicate that, depending on factors such as powdered coal isotopic composition and efficiency of Hg removal from flue gas, Hg deposited near CFUBs can be isotopically distinct. As this tool is further refined through future studies, Hg stable isotopes may eventually be used to quantify local deposition of Hg emitted by large CFUBs.
煤炭燃烧约占全球人为汞（Hg）排放的三分之二。Hg 可以在靠近燃煤电厂（CFUB）的地方进行增强型沉积，但很难将特定的点源与当地沉积联系起来。测量降水的 Hg 稳定同位素比值有望成为一种工具，帮助识别与人为排放有关的当地 Hg 沉积。我们在佛罗里达州水晶河的一个大型 CFUB 附近收集了每日事件降水样本。在水晶河收集的降水样本在同位素上有明显的区别，并显示出很大的负 δ（202）Hg 值（平均值为-2.56‰，1 SD = 1.10‰，n = 28）。相比之下，在佛罗里达州其他没有受到当地煤炭燃烧严重影响的地点收集的降水样本的 δ（202）Hg 值接近 0‰（平均值为 0.07‰，1 SD = 0.17‰，n = 13）。这些结果表明，根据煤粉同位素组成和从烟道气中去除 Hg 的效率等因素，CFUB 附近沉积的 Hg 可能具有同位素特征。随着这项工具在未来研究中进一步完善，Hg 稳定同位素最终可能被用于量化由大型 CFUB 排放的 Hg 的当地沉积。
