城市化进程中长江经济带长江干流水化学演变特征及影响因素

Characteristics and influencing factors of hydrochemical evolution of the mainstream of the Yangtze River in the Yangtze River Economic Belt in the process of urbanization

快速的城市化过程对城市周边水体水化学组成特征产生了诸多影响.为揭示长江经济带城市群发展对长江水化学特征的影响,于2020年10—11月沿长江干流,采集了四川宜宾至上海145个河流水样,并对比了历史水化学数据.同时,运用数理统计、离子比值法等方法探究了长江经济带平水期水化学特征.结果表明:长江河水的主要水化学类型为HCO_(3)·SO_(4)-Ca型,主要受流域内分布的碳酸盐岩等岩石风化作用控制;河水中阳离子以Ca^(2+)为主,阴离子以HCO_(3)^(-)为主,Cl^(-)浓度沿径流方向升高,Ca^(2+)和Mg^(2+)浓度沿径流方向先升高后降低,SO_(4)^(2-)浓度沿径流方向逐渐上升,HCO_(3)^(-)浓度沿径流方向降低;城市化进程中,由于人类活动和工业活动加剧,除HCO_(3)^(-)外,Ca^(2+)、Mg^(2+)、Na~+、K~+、SO_(4)^(2-)和Cl^(-)浓度均升高;沿线工业活动、矿产开发、农业生产活动和生活污水排放可能是SO_(4)^(2-)、NO_(3)^(-)和Cl^(-)的主要来源.

The rapid urbanization has many effects on the characteristics of water chemistry in peri-urban water bodies.To reveal the influence of the development of urban clusters in the Yangtze River Economic Belt(YREB)on the water chemistry characteristics of the Yangtze River,145 river water samples were collected along the mainstream of the Yangtze River from Yibin,Sichuan to Shanghai between October 2020 and November 2020,which were then analyzed and compared with historical water chemistry data.Mathematical statistics and ion ratio method were used to explore the water chemistry characteristics of the Yangtze River economic zone during the flat-water period.The results showed that the water chemistry of Yangtze River(YR)water was dominated by HCO_(3)-SO_(4)-Ca,which was controlled by the weathering of carbonate and other rocks in the basin;Ca^(2+)was the major cation and HCO_(3)^(-) was the major anion in the river water;with the river flow,Cl^(-)concentration increased,Ca^(2+)and Mg^(2+)concentrations increased first and then decreased,SO42-concentration gradually increased,and HCO_(3)^(-)concentration decreased;during urbanization,Ca^(2+),Mg^(2+),Na^(+),K^(+),SO_(4)^(2-)and Cl^(-)concentrations increased except for HCO_(3)^(-),due to the intensified human and industry activities;Mining,agriculture and domestic wastewater discharge along the river may be the sources of SO_(4)^(2-),NO_(3)^(-)and Cl^(-).