Million-year-old groundwater revealed by krypton-81 dating in Guanzhong Basin, China.
Million-year-old groundwater revealed by krypton-81 dating in Guanzhong Basin, China.
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DOI：
10.1016/j.scib.2017.08.009
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发表时间：
2017-08
期刊：
影响因子：
18.9
通讯作者：
Jie Li;Z. Pang;Guo‐Min Yang;Jiao Tian;Amin L. Tong;Xiang-yang Zhang;Shui-Ming Hu
中科院分区：
文献类型：
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作者：
Jie Li;Z. Pang;Guo‐Min Yang;Jiao Tian;Amin L. Tong;Xiang-yang Zhang;Shui-Ming Hu
中国科学出版社.由Elsevier BV和Science China Press出版。地下水年龄是指与大气隔离的地下水平均停留时间，对于水资源和工业废物的管理具有重要意义。这对于了解地下污染物的运移和古气候重建也是非常有用的。它是表征含水层水文地质特征的重要参数，包括含水层储存能力、地下水更新速率和流速。对停留时间敏感的环境示踪剂已被证明是估算地下水年龄的有效工具。短寿命的放射性同位素如3 H、85 Kr和3 H/3 He可以指示现代补给，而半衰期长的同位素如14 C、36 Cl、4 He和81 Kr可以用来确定古老地下水的年代。随着核废料处置、碳封存、地热开发等深部地质工程的推进，古地下水定年工作变得越来越重要。最常用的测年方法是14 C。然而，由于它的半衰期是5730年，放射性碳的时间尺度被限制在小于40 ka。目前正在尝试用其他同位素方法测定较老的地下水的年代。氯-36的半衰期为301，000 - 4000年，是一种潜在的工具，超出了放射性碳的限制。然而，36 Cl方法是复杂的初始36 Cl活性和地下输入的稳定氯化物和成核36 Cl的变化。来自地壳沃茨中放射性衰变的氦（4 He）的向内生长提供了一种与36 Cl明显重叠的时间的定性测量。4 He年龄的影响因素，如大气中的氦输入过程中获得的补给和那些从其他地层的He扩散到含水层。
Đ 2017 Science China Press. Published by Elsevier BV and Science China Press. All rights reserved.Groundwater age, defined as the mean subsurface residence time spent isolated from the atmosphere, is of crucial significance for managing water resources and industrial waste. It is also very useful for understanding subsurface contaminant transport, and for paleoclimate reconstruction. It is an important parameter for characterizing aquifer hydrogeology including aquifer storage capacity, the rate of groundwater renewal, and flow velocity. Environmental tracers that are sensitive to residence time have proven to be effective tools for estimating groundwater age. Short-lived radioisotopes such as 3H, 85Kr, and 3H/3He can indicate modern recharge, whereas those with long half-lives such as 14C, 36Cl, 4He, and 81Kr can be used to date old groundwater. With the advance of deep geological engineering such as nuclear waste disposal, carbon sequestration, and geothermal exploitation, dating of old groundwater has become increasingly important. The most routinely applied dating method by far is 14C. However, because its half-life is 5730 years, the radiocarbon timescale is limited to less than 40 ka. Attempts with other isotope methods for dating older groundwater are under way. Chlorine-36, with a half-life of 301,000 ą 4000 years, is a potential tool that extends beyond the limits of radiocarbon. However, the 36Cl method is complicated by variations of the initial 36Cl activity and subsurface input of both stable chloride and nucleogenic 36Cl. The ingrowth of helium (4He) from radioactive decay in crustal waters offers a qualitative measure of time that significantly overlaps with 36Cl. The 4He age is influenced by factors such as atmospheric helium inputs gained during recharge and those from diffusion of He into the aquifer from other strata.