漓江流域河流水体离子组成特征及来源

Characteristics and Origin of Major Ions in River Water in the Lijiang River Basin

通过2016年9月至2017年6月在漓江流域采集水样,对其主要离子进行分析,发现了漓江流域水化学主要离子的控制机制、来源及时空变化特征。结果表明,漓江流域的pH值介于6.89~7.79之间,平均值为7.34,EC变化范围在70.6~385.5us·cm^-1之间,平均值为228us·cm^-1,TDS的变化范围为49.42~203.19mg·L^-1,平均值为112.35mg·L^-1。阴、阳离子的浓度顺序为HCO3^->SO4^-2>NO3^->Cl^-,Ca^2+>Mg^2+>Na^+>K^+,水化学类型为HCO3^-Ca型水。Ca^2+、Mg^2+和HCO3^-的变化特征相似,总体呈现中游高,上下游低的特点,Cl^-、Na^+、K^+在中下游的浓度比上游高,季节性差异方面旱季的离子浓度一般大于雨季。离子来源分析表明,Ca^2+、Mg^2+和HCO3^-主要来源于碳酸盐岩的风化,Na^+、K^+和Cl^-除来自岩石的风化外,循环盐对它们也有少量的贡献,NO3^-和SO4^2-也主要来自岩石的风化溶解。

Through collecting water samples in the Lijiang River basin from September 2016 to June 2017,the main ions were analyzed.The control mechanism,sources and temporal and spatial variation characteristics of major ions in water chemistry of the Lijiang River basin were found.The results show that the pH value of the Lijiang River basin is between 6.89 and 7.79,with an average value of 7.34.The range of EC ranged from 70.6 to 385.5 us·cm^-1,with an average value of 228 us·cm^-1.The range of TDS varies from 49.42 to 203.19 mg·L^-1,with an average value of 112.35 mg·L^-1.The concentration order of anion and cation is HCO3^->SO4^2->NO3^->Cl^-and Ca^2+>Mg^2+>Na^+>K^+,indicating that HCO3^-Ca water is the main type.The variation characteristics of Ca^2+,Mg^2+and HCO3-are similar,showing the characteristics of high middle reaches and low upper and lower reaches.The concentrations of Cl^-,Na^+and K^+in the middle and lower reaches are higher than those in the upstream.Seasonal differences in the concentration of ions in the dry season are generally greater than in the rainy season.Ion source analysis shows that Ca^2+,Mg^2+and HCO3^-are mainly derived from the weathering of carbonate rocks.Na^+,K^+and Cl^-are derived from the weathering of rocks,circulating salts also contribute a little to them.NO3^-and SO4^2-are also mainly derived from weathering and dissolution of rocks.