鲁西北阳谷地区浅层高氟地下水化学特征及成因

鲁西北地区是饮水型氟中毒较为突出的地区。选取鲁西北阳谷地区为研究对象,以水文地质调查和取样分析为工作基础,对浅层地下水采用多元统计分析法、地理信息空间分析法及Piper三线图探究了高氟地下水化学特征和赋存特征,结合饱和指数、Gibbs图和氯碱指数以及氟在土壤与地下水的相关关系,从溶解与沉淀平衡、蒸发浓缩和离子交替吸附作用方面分析了氟的来源和高氟地下水成因。结果表明:阳谷地区F^-浓度大于或等于2 mg·L^-1的高氟水分布于地形较高的古河床高地; 地下水F^-浓度由低到高,阳离子则由Ca²⁺、Mg²⁺向Na⁺转变,阴离子则由SO^2-₄和Cl^-向HCO^-₃转变; 阴、阳离子浓度随F^-浓度变化显示不同的规律性,且在F^-浓度大于或等于4 mg·L^-1的高氟水中,这种规律性变化更为明显; 土壤和地下水呈碱性、高HCO^-₃的化学特征以及区域地下水受蒸发浓缩作用影响是高氟水形成的水文地球化学背景条件; 方解石、萤石和石膏的溶解与沉淀平衡以及阴、阳离子交替吸附作用是高氟水形成和分布的主控因素。

Hydrochemical Characteristics and Genesis of High-fluorine Shallow Groundwater in Yanggu Area of the Northwestern Shandong,China

The northwestern Shandong is an area of drinking water fluorosis. Yanggu area in the northwestern Shandong was selected as the research object. Based on the hydrogeological survey and sampling analysis, the hydrochemical and occurrence characteristics of high-fluorine groundwater were studied by using multivariate statistical analysis, geographic information spatial analysis and Piper trilinear diagram. Combining with saturation index, Gibbs diagram, chlor-alkali index and the correlation of fluorine between soil and groundwater, the equilibrium of dissolution and precipitation, evaporation and concentration, alternating adsorption of ions were studied to find the source of fluorine and the genesis of high-fluorine groundwater. The results show that the high-fluorine groundwater with F^- concentration more than or equal to 2 mg·L^-1 in Yanggu area is distributed in the highland of ancient river bed with high topography; F^- concentration in groundwater changes from low to high, and then, the cation changes from Ca²⁺, Mg²⁺to Na⁺, and the anion changes from SO^2-₄ and Cl^- to HCO^-₃; the concentrations of cation and anion show different regularity with F^- concentration, and the variation is more obvious when F^- concentration is more than or equal to 4 mg·L^-1; the chemical characteristics of soil and groundwater are alkaline and high HCO^-₃, and the regional groundwater is affected by evaporation, which is the hydrogeochemical background condition for the formation of high-fluorine groundwater; the dissolution and precipitation balance of calcite, fluorite and gypsum, and the alternate adsorption of anion and cation, are the main factors controlling the formation and distribution of high-fluorine groundwater.