南、北盘江流域枯水期水化学特征及离子来源分析

Hydrochemical characteristics and sources of Nanpanjiang and Beipanjiang river basins during dry seasons

为进一步了解珠江上游南、北盘江流域水化学现状,对其枯水期36个河水样品进行水化学特征分析,结果表明:枯水期河水pH值在7.85~8.75之间,呈弱碱性,TDS均值为358mg·L^(-1)。河水中阴离子组成以HCO_3^-、SO_4^(2-)为主,当量浓度占比均值达到65%与26%,阳离子中Ca^(2+)和Mg^(2+)是绝对的优势离子,当量浓度占比均值分别为65%和24%。与丰水期相关研究对比分析发现Ca^(2+)、Mg^(2+)、Na^+、SO_4^(2-)、HCO_3^-、Cl^-的枯水期浓度普遍高于丰水期,K^+、NO_3^-丰、枯水期浓度变化不大。Piper图、岩性端元分析以及离子浓度比值分析表明,研究区水化学主要受碳酸和硫酸共同参与下的碳酸盐岩风化控制。南、北盘江流域都受到农业施用的钾肥和氮肥的影响,此外,北盘江主要受到煤炭开采以及燃煤工业的影响,南盘江主要受到源头及上游河段化工企业废水和沿途市县的生活废水的影响。与前人数据对比发现,15年间人为活动对流域水化学的影响加剧。

Water samples were collected in dry seasons to analyze the hydrochemical components of Nanpanjiang and Beipanjiang basins,the upper reaches of the Pearl River.The results show that pH values of the water from the two catchments,ranges from7.85 to 8.75 during dry seasons,slightly alkaline,with an average TDS of 358 mg·L^-1.The anions are dominated by HCO^-3 and SO^2-4 with the mean equivalent concentration accounting for 65% and 26% of the total anions,respectively.The main cations are Ca^2＋and Mg^2＋,accounting for 65%and 24% of the total cations,respectively.Compared with the research about the concentrations of major ions in wet seasons,the concentrations of Ca^2＋,Mg^2＋,Na^＋,SO^2-4,HCO^-3,and Cl^- in dry seasons are higher,while K^＋ and NO^-3 contents almost remain the same.Piper diagrams,end members of lithology and ion concentration ratios collectively indicate that the chemical composition of river water is mainly controlled by carbonate weathering where sulfuric acid and carbonic acid both participate.Nanpanjiang and Beipanjiang are all influenced by agricultural activities.In addition,Beipangjiang is mainly affected by coal mining and coal-combustion industry,while Nanpanjiang is mainly affected by wastewater from industries at upper reach and the cities and towns along the river.Compared with previous data,it is found that the impact of anthropogenic activities on water has increased over the past 15 years.