九江庐山地区地下水水文地球化学特征及成因

Hydrogeochemical Characteristics and Genesis of Groundwater in Lushan Area of Jiujiang

分析九江环庐山地区观测井水、大气降水、冷泉水、地热温泉水及地表水水样的常量化学组分和氢氧同位素及氚活度,结果表明,庐山地区地下水主要分为西北、东南两个水文地质单元,西北侧以九江台2号井井水、东林寺泉水为代表,水化类型为HCO_(3)-Ca;东南侧以地热温泉井水、观音桥泉水为代表,水化类型为HCO_(3)-Na,离子组分主要来自风化壳岩石风化。氢氧同位素显示,九江庐山地区地下水均属于降水成因型,部分井泉具有深循环的特征;氯离子估算结果显示,大气降水直接补给率约为4.5%~33.27%。大气降水下渗补给形成裂隙承压自流井泉是庐山地区地下水主要成因,另有部分为降水经长时间深循环形成地热温泉水,而九江台2号井既有浅表水特征又有深循环水的特征,暗示两个不同补给源的含水层通过不同循环路径上升到浅表地层,携带有部分深部构造活动信息,有利于获取地震前兆异常信息。

We analyze the constant chemical composition and hydrogen,oxygen isotope and tritium activity data of observation well water,atmospheric precipitation,cold spring water,geothermal hot spring water and surface water samples in the Lushan area around Jiujiang.We show that the groundwater in the Lushan area is mainly divided into two hydrogeological units in the northwest and southeast.The hydration type represented by Jiujiangtai No.2 well water and Donglin Temple is HCO3-Ca type on the northwest side,while the hydration type represented by geothermal spring well water and Guanyinqiao spring is HCO3-Na type on the southeast side;the ion component mainly comes from weathering of crust rocks.Hydrogen and oxygen isotopes indicate that the groundwater in the Lushan area of Jiujiang belongs to the cause of precipitation,and some confined fractured well springs have deep circulation characteristics.Estimating the chloride ion indicates that the direct recharge rate of atmospheric precipitation is about 4.5%-33.27%.The formation of fissures and pressured artesian wells by infiltration recharge under atmospheric precipitation is the main cause of groundwater in Lushan area,a part of which is the formation of geothermal hot spring water through long-term and deep circulation of precipitation.The characteristics of Jiujiangtai No.2 well has both shallow surface water and circulation water,suggesting aquifers of two different recharge sources rise to the shallow bottom through different circulation paths,contributing to carrying part of the information of deep tectonic activity,is helpful to obtain seismic precursor anomaly information.