Shotyk William, Krachler Michael, Aeschbach-Hertig Werner, Hillier Stephen, Zheng Jiancheng James
Institute of Earth Sciences, University of Heidelberg, INF 236, D-69120, Heidelberg, Germany.
J Environ Monit. 2010 Jan;12(1):208-17. doi: 10.1039/b909723f. Epub 2009 Sep 14.
Snow samples collected from hand-dug pits at two sites in Simcoe County, Ontario, Canada were analysed for major and trace elements using the clean lab methods established for polar ice. Potentially toxic, chalcophile elements are highly enriched in snow, relative to their natural abundance in crustal rocks, with enrichment factor (EF) values (calculated using Sc) in the range 107 to 1081 for Ag, As, Bi, Cd, Cu, Mo, Pb, Sb, Te, and Zn. Relative to M/Sc ratios in snow, water samples collected at two artesian flows in this area are significantly depleted in Ag, Al, Be, Bi, Cd, Cr, Cu, Ni, Pb, Sb, Tl, V, and Zn at both sites, and in Co, Th and Tl at one of the sites. The removal from the waters of these elements is presumably due to such processes as physical retention (filtration) of metal-bearing atmospheric aerosols by organic and mineral soil components as well as adsorption and surface complexation of ionic species onto organic, metal oxyhydroxide and clay mineral surfaces. In the case of Pb, the removal processes are so effective that apparently "natural" ratios of Pb to Sc are found in the groundwaters. Tritium measurements show that the groundwater at one of the sites is modern (ie not more than 30 years old) meaning that the inputs of Pb and other trace elements to the groundwaters may originally have been much higher than they are today; the M/Sc ratios measured in the groundwaters today, therefore, represent a conservative estimate of the extent of metal removal along the flow path.Lithogenic elements significantly enriched in the groundwaters at both sites include Ba, Ca, Li, Mg, Mn, Na, Rb, S, Si, Sr, and Ti. The abundance of these elements can largely be explained in terms of weathering of the dominant silicate (plagioclase, potassium feldspar, amphibole and biotite) and carbonate minerals (calcite, dolomite and ankerite) in the soils and sediments of the watershed. Arsenic, Mo, Te, and especially U are also highly enriched in the groundwaters, due to chemical weathering: these could easily be explained if there are small amounts of sulfides (As, Mo, Te) and apatite (U) in the soils of the source area. Elements neither significantly enriched nor depleted at both sites include Fe, Ga, Ge, and P.
对从加拿大安大略省锡姆科县两个地点的人工挖掘坑中采集的雪样，采用为极地冰建立的洁净实验室方法分析了主要元素和微量元素。相对于它们在地壳岩石中的自然丰度，潜在有毒的亲铜元素在雪中高度富集，银、砷、铋、镉、铜、钼、铅、锑、碲和锌的富集因子（EF值，以钪计算）在107至1081范围内。相对于雪中的M/钪比值，在该地区两个自流泉采集的水样中，银、铝、铍、铋、镉、铬、铜、镍、铅、锑、铊、钒和锌在两个地点均显著减少，钴、钍和铊在其中一个地点减少。这些元素从水中去除大概是由于诸如有机和矿物土壤成分对含金属大气气溶胶的物理截留（过滤）以及离子物种在有机、金属羟基氧化物和粘土矿物表面的吸附和表面络合等过程。就铅而言，去除过程非常有效，以至于在地下水中发现了明显“天然”的铅与钪的比值。氚测量表明，其中一个地点的地下水是现代的（即不超过30年），这意味着铅和其他微量元素最初向地下水的输入可能比现在高得多；因此，如今在地下水中测量的M/钪比值代表了沿水流路径金属去除程度的保守估计。两个地点的地下水中显著富集的成岩元素包括钡、钙、锂、镁、锰、钠、铷、硫、硅、锶和钛。这些元素的丰度在很大程度上可以根据流域土壤和沉积物中主要硅酸盐（斜长石、钾长石、角闪石和黑云母）和碳酸盐矿物（方解石、白云石和铁白云石）的风化来解释。由于化学风化，砷、钼、碲，尤其是铀在地下水中也高度富集：如果源区土壤中有少量硫化物（砷、钼、碲）和磷灰石（铀），这些就很容易解释。在两个地点既没有显著富集也没有显著减少的元素包括铁、镓、锗和磷。
