ABSTRACT

Anthropogenic pollution of groundwater was investigated from the source area to the uppermost densely populated city, Dujiangyan, along the Minjiang River, a tributary of the Yangtze River, in the Sichuan Basin, in China, based on the chemistry of major dissolved ions and stable isotopic ratios (H, O and S). In the source area above 2,900 m, groundwaters were rarely polluted by human activities. Groundwater pollution was found to be limited to populated areas, where the pollutants come mainly from household wastes. The groundwaters in Dujiangyan and the surrounding area were mixtures of waters from the upper streams along the Minjiang River and local precipitation. The groundwater of this area was found to contain high amounts of anthropogenic Cl^-, NO₃^--N, and SO₄^2-. Among these anions, most SO₄^2- was derived from air pollutants. The present study demonstrates that air pollution seriously affects the quality of groundwaters in areas where the Minjiang River emerges from the bottom edge of the Sichuan Basin.