摘要
文章在对1958-1990年期间长江水系191个站点水质监测资料进行统计分析的基础上，研究了长江主要离子的地球化学。结果表明，长江水系各地河水总溶解性固体（TDS）含量的差别达一个数量级（49．7～518．1mg／L），TDS的平均值为205．9mg／L，是全球河流均值的3倍。相比之下，河水TDS含量的季节性变化并不大，尽管河水流量的季节变化很大。长江的主要离子化学主要受岩石风化作用，尤其是碳酸盐矿物的溶解作用所控制。长江中上游的川贵地区酸雨严重。酸雨作用于当地广泛分布的石灰岩和富含碳酸盐的三叠纪砂页岩，导致近半个世纪来长江水质的酸化趋势，使大部分河段SO4^2-和Ca^2＋含量增高，总硬度与总碱度的比值增高。
The geochemistry of major ions （Ca^2＋ , Mg^2＋ , Na^＋ , K^＋ , HCO3^-, SO4^2-, Cl^- and Si^4＋ ） in the Yangtze River was studied, based on the continuously monitoring data at 191 stations in the drainage basin for the period of 1958-1990. The results show that the total dissolved solid （TDS） concentration in the Yangtze River varies over an order of magnitude throughout the basin （49.7-518. 1 mg/L）, with a medium TDS concentration of 205. 9 mg/L, which is about three times the global average. In contrast, the TDS at a given main-channel station varies only slightly in different seasons with a variation factor less than 2.0, despite substantial water dilution in the summer flood season. The major ion geochemistry of the Yangtze River is mainly controlled by rock weathering, with the anion HCO3^- and the cation Ca^2＋ dominating the major ion composition, owing to the abundance of carbonate rock in the basin. A persistently increasing trend has been observed in the concentrations of SO4^2-, Ca^2＋ , and the ratio of total hardness to total alkalinity in the Yangtze River. The water acidification trend mainly occurred in the upper and middle reaches of the Yangtze River and is caused by serious acid deposition owing to the increasing SO2 emission from coal combustion and the oxidation of increasing nitrogenous fertilizer from farmland.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2006年第1期74-85,共12页
Earth Science Frontiers
基金
国家自然科学基金资助项目"中国大河水质变化研究"(49671017)
关键词
长江
水质
主要离子
地球化学
环境变化
Yangtze River
water quality
major ion
geochemistry
environmental change
