赤水河上游流域水化学变化与离子成因分析

Analysis of Hydro-chemical Changes and Genesis of Major Ions in Upper Reach of Chishui River

选取赤水河上游流域的河水为研究对象,研究分析了河水的水化学特性沿流域空间变化以及主要离子特别是SO42-的来源等内容。结果显示:赤水河水质属低矿化度硬水,HCO3-和Ca2+为河水中的主要阴阳离子,赤水河是典型的碳酸盐岩河流。以白沙河为界,上段河流水化学组成变化平稳,离子主要来源于天然环境的输入,白沙河下游河流各化学组分差异显著,分析是受一定人为因素的影响。SO42-为次要阴离子,占阴离子总量的30%,发现SO42-与Ca2+、HCO3-与Mg2+相关性较好,HCO3-与Ca2+相关性差,推断SO42-来源于石膏的溶解。但石膏的溶解还不能完全解释SO42-的来源问题,经分析环境酸化也是一种影响河水中SO42-含量的重要方式。

Selecting the upper reach of the Chishui River as study object, its spatial variation of hydro-chemical characteristic and 2- sources of major ions （especially SO4 ）were analyzed. The results show that the Chishui River belonged to low salinity and hard water in water quality. HCO3- and Ca2＋ are the dominant anion and cation, and the Chishui River is a typical carbonate river. Bordered by the Baisha River, the hydro-chemical composition of the upper river changed in smooth, major ions came mainly from the input of natural 2- environment. Because of the effect of human factors, the volatility of hydro-chemical composition has appeared in the lower river. SO4 is the secondary anion, accounting for 30% of the total anion. The correlation of SO42- and Ca2＋, HCO3 and Mg2＋ are good, while those of HCO3 2＋ 2- and Ca are poor. So, we inferred that the SO4 is from the dissolution of gypsum. However, the dissolution of gypsum can not fully explain the source of SO4 , acidification is also an important way affecting the content of SO4 in the river.