拉萨河羊八井剖面水化学特征及水质评价

摘要

为研究拉萨河羊八井剖面水化学特征及存在的水质问题,综合运用图解法、数理统计方法以及Phreeqc软件中反向水文地球化学模拟模块进行水化学特征分析.在此基础上,采用基于遗传算法的投影寻踪模型进行了水质评价.结果表明:研究区水化学类型以低矿化度的Ca·Mg-HCO3·SO4型为主;地下水离子成分主要受溶滤、阳离子交替吸附和脱碳酸作用影响;水质达到Ⅲ级标准的采样点,占总体采样点的87% ,水质整体较好,仅马乡和羊八井电厂排污口附近的水质较差为Ⅳ或Ⅴ级,主要原因是锰矿开采产生的矿业废水和羊八井电厂(一厂)排放的地热废水所致,水体中Fe、Mn、As、F-超标严重.%Aiming at hydro chemical characteristics and water quality of the Yangbajing section in the Lhasa riv-er basin,the chemical characteristics of the water was analyzed by graphical and mathematical statistics and Phreeqc software reverse model.On this basis,projection pursuit model on account of genetic algorithm was used to assess water quality.The results show that chemical type is mainly Ca·Mg-HCO3·SO4.The ionic composition of groundwa-ter was mainly influenced by the action of lixiviation,cation exchange and decarbonation.Due to the water samples attaining grade Ⅲ standard accounting for 87% of the total,the overall water quality is good, only the water quality of Horse township and the sewage outlet of Yangbajing power plant is poor,which is in grade Ⅳ or Ⅴ.The major pollution parameters are Fe,Mn,As and F-,as a result of mining wastewater from manganese mining and geother-mal wastewater from Yangbajing power plant.