对我国水利部《水文年鉴》上所载长江、黄河所有水文站自20世纪50年代末至80年代中期的水化学监测数据，以及全球水质监测计划中国站点1979〜1994年的水质监测资料进行分析研究，发现就天然水主要离子组分而言，长江中上游和黄河表现出各自独特的水质变化趋势，即长江水质的酸化趋势和黄河水质的浓化趋势。文章对这两种现象产生的原因进行了探讨。

The trends of water quality change in the Yangtze River and the Yellow River in last 40 years were studied based on monitoring data collected from the Water Year Book of China (from the late 195 to the middle 1990´s) and the UN GEMS/Water program (1979〜1994). The results show that these two rivers each had their own trend of water quality change in respect of the major ions content. The water acidification trend mainly occured in the upper and middle reaches of the Yangtze River, which was caused by serious acid deposition due to the increasing S0₂ emission from coal combustion oxidation of the increasing nitrogenous fertilizer runs from farmland. The water quality concentration trend happened in the Yellow River, which was related to the decreasing of run off and the increasing of irrigation water. The total ion content of river water was increased by the concentration of irrigation water in farmland and its washing effect on soils.