University of Michigan, Department of Earth and Environmental Sciences, 1100 N. University Ave., Ann Arbor, MI 48109, USA.
University of Michigan, Department of Earth and Environmental Sciences, 1100 N. University Ave., Ann Arbor, MI 48109, USA.
Sci Total Environ. 2015 Jan 1;502:362-74. doi: 10.1016/j.scitotenv.2014.09.034. Epub 2014 Sep 29.
The anthropogenic emission and subsequent deposition of heavy metals including mercury (Hg) and lead (Pb) present human health and environmental concerns. Although it is known that local and regional sources of these metals contribute to deposition in the Great Lakes region, it is difficult to trace emissions from point sources to impacted sites. Recent studies suggest that metal isotope ratios may be useful for distinguishing between and tracing source emissions. We measured Pb, strontium (Sr), and Hg isotope ratios in daily precipitation samples that were collected at seven sites across the Great Lakes region between 2003 and 2007. Lead isotope ratios ((207)Pb/(206)Pb=0.8062 to 0.8554) suggest that Pb deposition was influenced by coal combustion and processing of Mississippi Valley-Type Pb ore deposits. Regional differences in Sr isotope ratios ((87)Sr/(86)Sr=0.70859 to 0.71155) are likely related to coal fly ash and soil dust. Mercury isotope ratios (δ(202)Hg=-1.13 to 0.13‰) also varied among the sites, likely due to regional differences in coal isotopic composition, and fractionation occurring within industrial facilities and in the atmosphere. These data represent the first combined characterization of Pb, Sr, and Hg isotope ratios in precipitation collected across the Great Lakes region. We demonstrate the utility of multiple metal isotope ratios in parallel with traditional trace element multivariate statistical modeling to enable more complete pollution source attribution.
人为排放和随后沉积的重金属，包括汞 (Hg) 和铅 (Pb)，对人类健康和环境造成了关注。尽管已知这些金属的本地和区域来源对大湖地区的沉积有贡献，但很难从点源追踪到受影响的地点。最近的研究表明，金属同位素比值可能有助于区分和追踪源排放。我们测量了 2003 年至 2007 年间在大湖地区七个地点采集的每日降水样本中的 Pb、锶 (Sr) 和 Hg 同位素比值。Pb 同位素比值 ((207)Pb/(206)Pb=0.8062 至 0.8554) 表明 Pb 沉积受到煤燃烧和密西西比河谷型 Pb 矿床加工的影响。Sr 同位素比值 ((87)Sr/(86)Sr=0.70859 至 0.71155) 的区域差异可能与煤飞灰和土壤尘有关。Hg 同位素比值 (δ(202)Hg=-1.13 至 0.13‰) 也在各站点之间有所不同，这可能是由于煤同位素组成的区域差异，以及工业设施和大气中发生的分馏作用。这些数据代表了首次对大湖地区采集的降水进行的 Pb、Sr 和 Hg 同位素比值的综合特征描述。我们展示了多种金属同位素比值与传统痕量元素多元统计建模并行使用的效用，以实现更完整的污染源归因。
