Hydrochemical and stable isotopes (δ2H and δ18O) changes of groundwater from a spring induced by local earthquakes, Northwest China
Hydrochemical and stable isotopes (δ2H and δ18O) changes of groundwater from a spring induced by local earthquakes, Northwest China
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DOI：
10.3389/feart.2022.1100068
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发表时间：
2023-01
期刊：
影响因子：
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通讯作者：
Yang Xiang;S. Peng
中科院分区：
文献类型：
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作者：
Yang Xiang;S. Peng
据报道，地震会引起地下水化学成分和同位素的变化，而这些变化大多发生在水井或温泉中；然而，局部小地震引起的冷泉变化较少受到关注。本文收集了2018年9月至2019年12月X10泉的连续监测数据，采用水化学分析和同位素方法研究了X10泉的水文地球化学特征。结果表明：①X10春季主要化学离子浓度具有冬高夏低的年动态变化特征，这种变化可能与融雪的季节效应有关；2)泉水来源于远距离大气降水、融雪和基岩裂隙水，并受岩石风化和蒸发的影响；3)地下水中氢、氧稳定同位素比值和HCO3−浓度对局部小地震活动敏感。我们认为小地震可以改变断裂带或含水层的渗透率，导致不同化学成分和同位素的地下水混合。研究表明，氢、氧稳定同位素比常用化学成分对地震活动更敏感，且敏感成分在不同的观测井或井中有所不同；因此，未来应考虑同位素与水化学的联合监测，以捕捉地震引起的水文地球化学前兆信号。
It has been well reported that earthquakes can cause changes in groundwater chemistry and isotopes, and much of those changes were occurred in wells or hot springs; however, changes in cold spring caused by local small earthquakes have received less attention. Here, we collected continuous monitoring of the X10 spring (September 2018 to December 2019), investigated the hydrogeochemical characteristics of the spring by using water chemistry analysis and isotope methods. We compared the changes in water chemical ion concentrations and hydrogen-oxygen isotope ratios with the surrounding seismic activity, and the results show that 1) major chemical ion concentrations in X10 springs have an annual dynamic pattern of being high in winter and low in summer, and this change may be related to the seasonal effect of snowmelt; 2) the spring water originates from long-distant meteoric water, snowmelt, and bedrock fissure water and is affected by rock weathering and evaporation; 3) the hydrogen and oxygen stable isotope ratios and HCO3 − concentration in groundwater are sensitive to local small seismic activity. We considered that small earthquakes can change the permeability in fault zones or aquifers, leading to mixing of groundwater with different chemical composition and isotopes. Our study demonstrates that the hydrogen and oxygen stable isotopes are more sensitive to seismic activity than the commonly used chemical constitutents, and that the sensitive constitutents vary in different observation wells or springs; therefore, combined monitoring of isotopes and water chemistry should be considered in the future to capture hydrogeochemical precursor signals caused by earthquakes.