Use of Chemical and Isotopic Signatures to Distinguish Between Uranium Mill-Related and Naturally Occurring Groundwater Constituents
Use of Chemical and Isotopic Signatures to Distinguish Between Uranium Mill-Related and Naturally Occurring Groundwater Constituents
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DOI：
10.1111/gwmr.12042
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发表时间：
2014-12-01
影响因子：
1.9
通讯作者：
Morrison, Stan J.
中科院分区：
文献类型：
--
作者：
Kamp, Susan D.;Morrison, Stan J.
在地下水样品中测定化学和同位素特征，以帮助区分新墨西哥州希普罗克附近的三个沙漠河谷和一个埋藏通道（沼泽）的污染源。沼泽和其中一个阿罗约河（Many Devils Wash）的污染以前被归因于一个前铀工厂，因为污染物（硝酸盐、硒、硫酸盐和铀）相似，而且距离很近（0.8公里）。其他两个arroyos远离工厂的网站，并不能收到污染it. Principal成分和聚类分析表明，在沼泽和三个arroyos，对比与地下水化学在处置单元之间的地下水化学的相似性。处置单元地下水的特点是高铀和碳酸氢盐浓度，而在其余的研究领域的特点是高钠和硫酸盐，但较低的铀浓度。Mancos页岩形成了该地区的基岩，含有高浓度的与沼泽和阿罗约地下水相同的化学成分。溶解硫酸盐在阿罗约地下水中耗尽的硫-34，相比之下，更丰富的硫-34来自工厂的硫酸盐。铀-234到铀-238的活性比（AR）接近长期平衡值为1的工厂场地地下水，而AR在所有的阿罗约地下水样品超过2。该厂地下水中的氚活度升高（49至142 pCi/L）是由于该厂在1950年代和1960年代进行原子弹试验期间运行。综合化学和同位素结果表明，地下水在许多魔鬼洗和沼泽可能来自曼科斯页岩，而不是从研磨操作。
Chemical and isotopic signatures were determined in groundwater samples to aid in distinguishing the source of contamination in three desert arroyos and a buried channel (the swale) near Shiprock, New Mexico. The contamination in the swale and one of the arroyos, Many Devils Wash, was previously attributed to a former uranium mill site because of the similar suite of contaminants (nitrate, selenium, sulfate, and uranium) and the close (0.8 km) proximity. The other two arroyos are far removed from the mill site and could not have received contamination from it. Principal component and cluster analysis indicated similarities in groundwater chemistry among the swale and the three arroyos that contrasted with groundwater chemistry at the disposal cell. Disposal cell groundwater is characterized by high uranium and bicarbonate concentrations, whereas that in remaining study areas is characterized by high sodium and sulfate, but lower uranium concentrations. Mancos Shale forms the bedrock in the region and contains elevated concentrations of the same chemical constituents that appear in the swale and arroyo groundwater. Dissolved sulfate in arroyo groundwater was depleted in sulfur-34, in contrast to mill-derived sulfate with more enriched sulfur-34. Uranium-234 to uranium-238 activity ratios (ARs) were near the secular equilibrium value of 1 in mill site groundwater, whereas ARs in all arroyo groundwater samples exceeded 2. Elevated tritium activities present in mill site groundwater (49 to 142 pCi/L) are attributed to the mill being operated during atomic bomb testing in the 1950s and 1960s. The combined chemical and isotopic results indicate that groundwater in Many Devils Wash and the swale was likely derived from the Mancos Shale and not from the milling operation.