The remediation of ammonium-containing groundwater discharged from uranium mill tailing sites is a difficult problem facing the mining industry. The Monument Valley site is a former uranium mining site in the southwest US with both ammonium and nitrate contamination of groundwater. In this study, samples collected from 14 selected wells were analyzed for major cations and anions, trace elements, and isotopic composition of ammonium and nitrate. In addition, geochemical data from the U.S. Department of Energy (DOE) database were analyzed. Results showing oxic redox conditions and correspondence of isotopic compositions of ammonium and nitrate confirmed the natural attenuation of ammonium via nitrification. Moreover, it was observed that ammonium concentration within the plume area is closely related to concentrations of uranium and a series of other trace elements including chromium, selenium, vanadium, iron, and manganese. It is hypothesized that ammonium-nitrate transformation processes influence the disposition of the trace elements through mediation of redox potential, pH, and possibly aqueous complexation and solid-phase sorption. Despite the generally relatively low concentrations of trace elements present in groundwater, their transport and fate may be influenced by remediation of ammonium or nitrate at the site.

中文翻译：

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前铀厂尾矿场铵的运输和归宿及其对铀和其他微量元素的影响

铀厂尾矿场排放的含铵地下水的治理是采矿业面临的难题。纪念碑谷遗址是美国西南部的一个前铀矿开采场，地下水受到铵和硝酸盐的污染。在本研究中，从 14 个选定井中收集的样品分析了主要阳离子和阴离子、微量元素以及铵和硝酸盐的同位素组成。此外，还分析了来自美国能源部 (DOE) 数据库的地球化学数据。结果显示有氧氧化还原条件以及铵和硝酸盐的同位素组成的对应关系证实了铵通过硝化作用的自然衰减。而且，据观察，羽流区域内的铵浓度与铀和一系列其他微量元素（包括铬、硒、钒、铁和锰）的浓度密切相关。据推测，硝酸铵转化过程通过调节氧化还原电位、pH 值以及可能的水络合和固相吸附来影响微量元素的分布。尽管地下水中存在的微量元素的浓度通常相对较低，但它们的迁移和归宿可能会受到现场铵或硝酸盐修复的影响。以及可能的水络合和固相吸附。尽管地下水中痕量元素的浓度通常相对较低，但它们的迁移和归宿可能会受到现场铵或硝酸盐修复的影响。以及可能的水络合和固相吸附。尽管地下水中存在的微量元素的浓度通常相对较低，但它们的迁移和归宿可能会受到现场铵或硝酸盐修复的影响。