Environmental Sciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA.
Environ Res. 2013 Aug;125:20-9. doi: 10.1016/j.envres.2013.03.013. Epub 2013 Jun 27.
Historical use of liquid elemental mercury (Hg(0)l) at the Y-12 National Security Complex in Oak Ridge, TN, USA, resulted in large deposits of Hg(0)l in the soils. The fate and distribution of the spilled Hg(0) are not well characterized. In this study we evaluated analytical tools for characterizing the speciation of Hg in the contaminated soils and then used the analytical techniques to examine the speciation of Hg in two soil cores collected at the site. These include x-ray fluorescence (XRF), soil Hg(0) headspace analysis, and total Hg determination by acid digestion coupled with cold vapor atomic absorption (HgT). XRF was not found to be suitable for evaluating Hg concentrations in heterogeneous soils containing low concentration of Hg or Hg(0) because Hg concentrations determined using this method were lower than those determined by HgT analysis and the XRF detection limit is 20 mg/kg. Hg(0)g headspace analysis coupled with HgT measurements yielded good results for examining the presence of Hg(0)l in soils and the speciation of Hg. The two soil cores are highly heterogeneous in both the depth and extent of Hg contamination, with Hg concentrations ranging from 0.05 to 8400mg/kg. In the first core, Hg(0)l was distributed throughout the 3.2m depth, whereas the second core, from a location 12m away, contained Hg(0)l in a 0.3m zone only. Sequential extractions showed organically associated Hg dominant at depths with low Hg concentration. Soil from the zone of groundwater saturation showed reducing conditions and the Hg is likely present as Hg-sulfide species. At this depth, lateral Hg transport in the groundwater may be a source of Hg detected in the soil at the deeper soil depths. Overall, characterization of soils containing Hg(0)l is difficult because of the heterogeneous distribution of Hg within the soils. This is exacerbated in industrial facilities where fill materials make up much of the soils and historical and continued reworking of the subsurface has remobilized the Hg.
美国田纳西州橡树岭 Y-12 国家安全综合设施曾大量使用液态元素汞（Hg(0)l），导致土壤中汞（0）大量沉积。泄漏的 Hg(0)的命运和分布尚未得到很好的描述。在这项研究中，我们评估了用于描述污染土壤中 Hg 形态的分析工具，然后使用这些分析技术检查了在该地点采集的两个土壤芯中 Hg 的形态。这些技术包括 X 射线荧光（XRF）、土壤 Hg(0)顶空分析和酸消解结合冷蒸气原子吸收（HgT）测定总 Hg。XRF 不适合评估含有低浓度 Hg 或 Hg(0)的不均匀土壤中的 Hg 浓度，因为使用这种方法测定的 Hg 浓度低于 HgT 分析测定的浓度，且 XRF 的检测限为 20mg/kg。Hg(0)顶空分析与 HgT 测量相结合，可很好地用于检查土壤中 Hg(0)l 的存在及其形态。这两个土壤芯在 Hg 污染的深度和范围方面都高度不均匀，Hg 浓度范围从 0.05 到 8400mg/kg。在第一个芯中，Hg(0)l 分布在 3.2m 的深度范围内，而第二个芯位于 12m 之外，仅在 0.3m 范围内含有 Hg(0)l。连续提取表明，在 Hg 浓度较低的深度，有机结合的 Hg 占主导地位。来自地下水饱和区的土壤显示出还原条件，Hg 可能以 Hg-硫化物的形式存在。在这个深度，地下水的侧向 Hg 迁移可能是在土壤较深部分检测到的 Hg 的来源。总体而言，由于 Hg 在土壤中的不均匀分布，对含有 Hg(0)l 的土壤进行特征描述是困难的。在工业设施中，这种情况更加严重，因为填充物构成了大部分土壤，并且地下的历史和持续再加工使 Hg 重新迁移。
