Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination
Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination
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DOI：
10.1038/ngeo2943
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发表时间：
2017-06-01
影响因子：
18.3
通讯作者：
Kirchner, James W.
中科院分区：
文献类型：
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作者：
Jasechko, Scott;Perrone, Debra;Kirchner, James W.
地下水易受污染的程度与其年龄密切相关。在全新世之前渗入的地下水在许多含水层中都有记录，并且被广泛认为不受现代污染的影响。然而，这些“化石”地下水在全球的普遍性及其对现代污染物的脆弱性仍然不清楚。在这里，我们分析了来自地球仪周围6,455口威尔斯的地下水碳同位素数据（C-12，C-13，C-14）。我们发现，化石地下沃茨包括一个大的份额（42-85%）的总含水层存储在地壳的上部1公里，和大部分的沃茨泵从威尔斯深250米。然而，在我们的研究中，以化石地下水为主的威尔斯井中有一半也含有可检测水平的氚，这表明存在更年轻的十年期沃茨，并表明当代污染物可能能够到达开采化石含水层的深威尔斯井。我们的结论是，水质风险应考虑沿着与可持续利用时，管理化石地下水资源。
The vulnerability of groundwater to contamination is closely related to its age. Groundwaters that infiltrated prior to the Holocene have been documented in many aquifers and are widely assumed to be unaffected by modern contamination. However, the global prevalence of these 'fossil' groundwaters and their vulnerability to modern-era pollutants remain unclear. Here we analyse groundwater carbon isotope data (C-12, C-13, C-14) from 6,455 wells around the globe. We show that fossil groundwaters comprise a large share (42-85%) of total aquifer storage in the upper 1 km of the crust, and the majority of waters pumped from wells deeper than 250 m. However, half of the wells in our study that are dominated by fossil groundwater also contain detectable levels of tritium, indicating the presence of much younger, decadal-age waters and suggesting that contemporary contaminants may be able to reach deep wells that tap fossil aquifers. We conclude that water quality risk should be considered along with sustainable use when managing fossil groundwater resources.