关中盆地大荔地区地下水氟水文地球化学规律

Hydrogeochemistry of the fluoride in groundwater in the Dali area of the Guanzhong Basin

为了研究关中盆地大荔地区氟的水文地球化学规律,采集239个地下水样品及35个土壤样品,分析了水化学类型和水化学组分对氟的影响,结果表明在弱碱性环境下,重碳酸钠型是促进氟富集并增强围岩向地下水中转化的主要因素;硫酸钙镁型的地下水抑制氟富集。水化学组分中Na+、Cl-、HCO3-、pH与氟呈正相关,而Ca2+则抑制水溶液中氟含量增加;迁移系数与HCO3-、pH呈正相关关系,与其他主要离子呈负相关关系。利用Preeqic软件分析了饱和指数和Ca2+、F-的离子活度,得出萤石的平衡控制着氟和钙的水文地球化学行为,F-可能来源于萤石和方解石的分解。

In order to study hydrogeochemistry of the fluoride in groundwater in the Dali area of the Guanzhong basin, 239 groundwater samples and 35 soil samples were analyzed. The influence of water type and compositions on fluoride in groundwater was examined by using the Piper diagram and Durov diagram, combining with the box diagram. The results show that in the alkalescence environment, saleratus type water is the main factor of promoting fluoride richment and building up fluoride transfer from wall rock to groundwater. Calcium （magnesium） sulphate type water counterworks fluoride to enrich. Sodium, chloride, bicarbonate and pH have active function to enrich the fluoride in the groundwater, but calcium contents is negative correlative to fluoride content. The Migration coefficient is in a positive relation with bicarbonate and pH and in a negative relation with other main chemiscal ions. Groundwater circulation condition is the motive of the fluoride enrichment and transfer. Using the Phreeqci software to analyze saturated index and calcium and fluorine ion activity, we found that fluorite and calcite control water chemical compositions which have some relations with fluoride in groundwater.