滦河下游河水及沿岸地下水水化学特征及其形成作用

Hydrochemical characteristics and formation mechanism of river water and groundwater along the downstream Luanhe River, northeastern China

了解地表水和沿岸地下水的水化学特征及其形成作用,对地下水水资源保护和可持续开发利用具有重要意义。在系统采集滦河河水及沿岸地下水的基础上,运用描述性统计、相关性分析、阴阳离子三角图、Gibbs图、离子比例系数等方法对水样的离子特征和水化学类型的形成作用进行了分析。研究结果表明:(1)从出山口到入海口,浅层地下水化学类型由HCO3型过渡到HCO3·SO4(SO4·HCO3)型,再逐渐转变为Cl·HCO3型,而阳离子则由Ca(Ca·Mg)向Na·Ca(Na)型转化。(2)浅层地下水化学的形成受地形地貌以及地质结构的控制,在山间盆地和冲洪积扇,溶滤作用是控制地下水水化学变化的主要作用,向下游随着含水介质颗粒变细,地下水径流速度变缓,溶滤作用减弱,蒸发浓缩作用逐渐增强,从出山口到入海口,河水和地下水的钠吸附比(SAR)不断增大,说明溶滤作用逐渐被阳离子交替吸附作用代替。(3)河水的水化学类型主要为HCO3·SO4-Ca·Mg(SO4·HCO3-Ca·Mg)型。水化学形成以蒸发浓缩作用为主,同时受河床中的碳酸盐矿物和硅铝酸盐矿物溶滤作用的影响,在冲积海积平原可能存在蒸发盐岩的溶解。

Understanding of the hydrochemical characteristics and formation mechanism of surface water and groundwater in an unconfined aquifer is important for protection and sustainable utilization of groundwater. In this paper, the exploratory research was done in the Luanhe River watershed using the water samples including river water and groundwater along the Luanhe River. Methods including mathematical statistics, Gibbs figure,Triangle plot and ionic ratios were employed to analyze the hydrochemical characteristics and formation mechanism. The results show that （ 1 ） from the mountain front to the estuary, anion transforms from HCO3 type to HCO3 ~ SO4 （ SOa ~ HCO3） type from north to south, then gradually converted to CI＂ HCO3type. Cation transforms from Ca（Ca-Mg） type to Na＂ Ca（Na） type. （2） The formation of shallow groundwater is constrained by topography and geologic structure. In the district of the intermontane basin and alluvial-proluvial fan, the leaching of halite, carbonate minerals and aluminosilicate is the chief geochemistry action of the shallow groundwater. Along with the runoff pass, the influence of leaching becomes weaker and the effect of evaporation concentration becomes stronger. SAR of river water and shallow groundwater increases from the mountain front to the estuary; and cation exchange and adsorption gradually replaces the leaching. （3） The main hydrochemistry type of the river water is HCO3 - SO4-Ca·Mg （ SO4·HCO3-Ca·Mg） type. Evaporation concentration plays an important role in the formation of the chemical characteristics. In addition, the carbonate minerals and aluminosilicate in the riverbed may be leached by the river water; and the halite may be leached in the marine plain.