武清凹陷浅层含氟地下水演化特点及成因分析

选取武清北水源地所在Ⅳ级构造单元——武清凹陷为研究区,共布设地下水取样点95个。以第一含水组地下水中氟为研究对象,在水文地质调查及取样分析测试基础上,运用水化学图解、统计分析、水文地球化学模拟等方法,分析武清凹陷浅层地下水中F-含量空间分布特征、演化特点及成因。结果表明:研究区浅层地下水F-质量浓度总体较高,分布趋势为以WN—ES为轴线浓度最高,向两侧浓度逐渐降低;高氟地下水的水化学类型较复杂,总体具有弱碱性、高钠、低钙的特征;高氟水形成主要受控于该地区强烈的蒸发浓缩作用、萤石溶解作用、方解石—白云石沉淀作用和F-解吸作用等。

Evolution characteristics and genesis of shallow fluorine-bearing groundwater in Wuqing Sag

In this paper,the Wuqing Sag,a fourth-level tectonic unit where the water source in the north of Wuqing is located,was selected as the research area,and 95 groundwater sampling points were set up.Fluoride groundwater in the first aquifer was taken as the study object.Based on hydrogeological survey and sample analysis,the authors investigated spatial distribution of F-concentrations as well as evolution feature and genesis of fluoride groundwater in shallow aquifer from Wuqing Sag by means of hydrogeochemical plot,statistic analysis and geochemical modeling.The results show that the mass concentration of F-in shallow groundwater in the study area is generally high,the distribution trend is that the concentration in the NW-SE direction is the highest,and the concentration gradually decreases toward both sides,that hydrogeochemical types of groundwater with high F-concentration are relatively complex,and have the characteristics of weak alkali,high sodium and low calcium,and that the formation of high-fluorine water is mainly controlled by the strong evaporation and concentration,fluorite dissolution,calcite-dolomite precipitation,and F-desorption in this area.