额济纳盆地地下水盐化特征及机理分析

 运用水文地球化学方法,分析额济纳盆地不同含水层地下水盐化特征及其机理。结果表明:额济纳盆地地下水受水文地质条件的制约,潜水的盐化自沿河主要补给区到蒸发排泄区具有明显的分带性,由河流主要补给区向北和向东西两侧,至居延海,进素土海子和古日乃湖中心洼地地下水,地下水由淡水,逐渐过渡为微咸水、中度咸水及极度咸水、盐水;承压水属于微咸水。依据地下水中各离子含量的比值特征的分析结果,控制本区地下水盐化的主要因素为硅酸盐矿物溶解和蒸发沉积作用,硅酸盐矿物溶解主要发生在沿河的地下水补给区;蒸发沉积作用主要发生在地下水径流-排泄区。深层地下水埋藏较深,蒸发的作用大大减弱,因而含盐量少,水质较好。

Groundwater Salinization Characteristics and Mechanism in Ejin Basin

Salinization is the most widespread form of water contamination.The areas affected by salinization are mainly located in arid and semi-arid regions.Studying the groundwater salinization can help people recognize the evolution of groundwater environment and make a rational use of the groundwater resource.In this study,with groundwater samples collected from different aquifers in lower reaches of Heihe River,we studied the salinization characteristics and mechanisms of groundwater in the Ejin basin by use of the hydrogeological method.The shallow groundwater salinization within the area from recharge area to discharge area showed zonal distribution characteristic.From the river main recharge area to north,east and west,finally to Juyan lake,Jinsutuhaizi and Gurinai lake depression,groundwater salinization changed from fresh to lightly saline,to moderately saline and to very saline.The confined groundwater belongs to the moderately saline in the study area.From the ionic ratio plot,it was showed that the dominant factors of determining the groundwater salinization in the study area were the silicate rock undergoing dissolving and evaporating-depositing.Dissolution mostly occurred in groundwater recharged area along the river course,evaporation and deposition in running-discharge area.The confined groundwater has low salinity less affected by evaporation due to being deeply buried in rock layer.