平凉地区地震监测台站水化学特征

Hydrochemical characteristics at the seismic stations in Pingliang area

根据水化学组分及氢、氧同位素组成,分析平凉地区9口观测井(泉)水化学类型。采用离子色谱法分析水样中主要离子浓度,用液态水同位素分析仪分析样中氢、氧同位素组成。结果表明,水样的TDS范围为168.6—878.8 mg/L,δD和δ^(18)O值分别为-61.4‰—-84.4‰和-7.8‰—-10.8‰。δD和δ^(18)O指示该区地下水水主要来源于大气降水。水样的水化学类型受含水层岩性控制,以HCO_(3)-Na型为主。该区域地下水中较多的Na^(+)来自盐岩的溶解,HCO_(3)^(-)主要来自灰岩溶解。华亭观测井水样表现出以Mg^(2+)为主要阳离子的特征,归因于该区域菱镁矿的溶解。

The hydrochemical types and origins of underground water in the Pingliang area were discussed based on the hydrochemical composition,δD,andδ^(18)O.The mineralization(TDS)of the water ranged from 168.6 mg/L to 878.8 mg/L.Values of theδD andδ^(18)O ranged from-61.4‰to 84.4‰and from-7.8‰to-10.8‰,respectively.The isotopic data indicated that the water originated from meteorological precipitation.Controlled by the aquifer lithology,the water samples in this area were mainly characterized by the HCO_(3)-Na type.The results will provide a background of hydrochemistry and will be beneficial to monitoring earthquakes and certificating seismicchemical anomalies in the future.