西南某地区地下水化学及同位素特征研究

Study on Hydrogeochemical and Isotopic Characteristics of Groundwater of an Area in Southwest China

我国西南某地位于汶川地震影响区域，为评价汶川地震对该区水文地质条件的影响，开展了该地区水文地球化学及同位素水文地质研究。地下水化学及同位素测试数据分析表明：研究区地下水 pH 值在7.9～9.48，偏碱性， TDS 多小于500 mg · L -1；水化学组分在垂向上有明显变化，水化学类型以 HCO3 Na 型为主；地下水氢、氧稳定同位素分析表明，该区地下水主要源自当地大气降水补给，氚含量随地下水埋深增大而减小，反映了深部地下水循环交替强度明显小于浅部地下水，也说明区内地下水以垂向交替为主。

The studied area is located within the effected zone of Wenchuan earthquake in southwest China .In order to evaluate the effect of hydrogeological condition w hich caused by the earthquake , the hydrogeochemical and isotopic research was carried out in southwest China .According to the hydrogeochemical and isotopic analysis results ,the pH range of groundwater is from 7.90 to 9.48 ,which is alka-line and the TDS is mostly less than 500 mg·L^-1 .The chemical composition of the groundwater changes obviously in vertical direction and is mainly HCO3-Na type .The analysis of groundwater hydrogen and oxygen stable isotope shows that the groundwater is mainly of meteoric origin .The tritium content decreases with depth increasing ,which reflects the circulation ability of shallow groundwater is stronger than that of deep groundwater system .It also indicates that the groundwater circulation is mainly vertical in the study area .