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为掌握长江河水化学组成特征及其控制因素,笔者运用Gibbs图、多种离子比例系数法和主成分分析法综合分析了长江流域丰水期河水化学及氢氧同位素特征。结果表明,长江丰水期河水主要来源为大气降水,河水化学类型主要为HCO3·SO4-Ca型,化学成分主要受流域内广泛分布的碳酸盐岩等岩石风化作用控制;河水p H值、浓度沿长江径流方向降低,、Ca2+浓度沿长江径流方向升高。2013年丰水期,长江河水化学组成特征变化的主要影响因子,是易溶盐岩溶解和人类活动(贡献率40%),其次为川贵及长江三角洲地区的酸雨沉降以及人为酸性废水排放促进了流域内石灰岩和富含碳酸盐的三叠系砂页岩溶解(贡献率20%),最后为硅酸盐矿物及其风化产物的溶解(贡献率19%)。为了解长江河水水质状况及其演变趋势,合理评价长江流域水资源提供很好的科学依据。
In order to grasp the characteristics of chemical composition of the Yangtze River and its controlling factors, the author comprehensively analyzed the chemical characteristics of water and hydrogen and oxygen isotopes in the Yangtze River Basin during the wet season by Gibbs plot, multiple ion ratio coefficients and principal component analysis. The results show that the main source of river water during the Yangtze River wet season is atmospheric precipitation, and the chemical type of the river water is mainly HCO3 · SO4-Ca type. The chemical composition is mainly controlled by rocks such as carbonate rocks widely distributed in the river basin. The p H value, Concentration decreases along the runoff of the Yangtze River, and Ca2 + concentration increases along the runoff of the Yangtze River. In the wet season of 2013, the main influencing factors of the chemical composition of the Yangtze River are the dissolution of soluble salt rocks and human activities (contribution rate 40%), followed by the precipitation of acid rain and the promotion of artificial acid wastewater discharge in Sichuan and Guizhou and the Yangtze River Delta The dissolution of limestone and carbonate-rich Triassic sand shale (20% contribution) led to the dissolution of silicate minerals and their weathering products (19% contribution). In order to understand the status of the Yangtze River water quality and its evolution trend, a reasonable scientific basis for evaluating the water resources of the Yangtze River Basin is provided.