新疆玛纳斯河流域平原地下水水-岩作用模拟

Water-rock Interaction Simulation of Ground water in the Plain of Manasi River Basin, Xinjiang

玛纳斯河流域平原区地下水化学演化较为复杂,从上游至下游的变化特点主要以Na+、Ca2+、 HCO3-、SO42-含量和TDS值的高低相间交替演化为主。本文对此演化机理进行了水-岩作用模拟研究,模拟结果表明:①矿物相的溶解、析出和蒸发作用、稀释作用共同控制着地下水水化学的演化;②从研究区上游往下,由于地层岩性颗粒逐渐变细,水中矿物相迁入、迁出的数量逐渐增大,水-岩作用逐渐增强;③研究区上游的水-岩作用主要是地表水或灌溉水入渗补给的影响,研究区中下游的水-岩作用主要受蒸发作用的影响;④由于地表水或灌溉水的大量混入,局部的水化学演化往往不符合一般演化规律,甚至于往相反的方向演化,TDS呈下降趋势,产生复杂的过渡水化学类型。

In the plain of Manasi River Basin, chemical evolution is complex comparatively. From upstream to downstream area, the variation characteristics are mainly that the content of Na^＋、Ca^2＋、HCO3^-、SO4^2- and the value of TDS change between high and low by turns. The water-rock interaction simulation has been applied to study the mechanism of it, the simulation results indicate as followes： （1） Dissolution/precipitation of minerals, evaporation and dilution control the chemical evolution of groundwater jointly; （2） In study area, from upstream area to downstream area, because lithology granularity becomes fine gradually, the dissolution/ precipitation amount of minerals in groundwater increases gently, the water-rock interaction becomes intense accordingly; （3） The water-rock interaction in upstream area undergoes the influence of surface water or irrigation water recharge chiefly, and in middle reaches and downstream area undergoes the influence of evaporation mainly; （4） Because of the large recharge of surface water or irrigation water, the chemical evolution in some areas sometimes doesn＇t accord with general orderliness, even changes into reverse direction, TDS Value becomes lower, and produces complex middle chemical types.