中文摘要：

对枯水期乌江及其主要支流河水的硫同位素组成进行了研究。河水SO4^2-的δ^34S值在-15．7‰～18．9‰之间，干流δ^34S值介于-3．7‰～0．0‰之间。主要支流河水的SO4^2-浓度和δ^34S值具有明显的区域性差异：上游碳酸盐岩地区支流河水SO4^2-浓度较高而δ^34S值较低，河水中的SO4^2-来源于煤中还原态硫的氧化、矿床硫化物氧化和大气降水；下游碳酸盐岩夹碎屑岩地区支流河水则相反，具有较低SO4^2-浓度和较高δ^34S值，河水中的SO4^2-来源于硫酸盐蒸发岩溶解、大气降水以及煤中还原态硫的氧化。干流的硫同位素组成显示枯水期河水中的硫酸盐主要来源于碳酸盐岩地区。

英文摘要：

The sulfur isotopic composition of the Wujiang River water and its catchment area water has been measured during low-flow period. The δ^34S values of the river water range from - 15.7‰ to 18.9‰, whereas the δ^34S values of the mainstream show only a narrow range and exhibit negative values from - 3.7‰ to 0.0‰. Spatial variation in SO4^2- concentration and δ^34S of the tributaries over the catchment area is obvious. The upper part of the Wujiang River catchment is dominated by carbonate rocks and coal-bearing formations. The tributaries with depleted ^34S in this area have high SO4^2- concentrations and dominantly originate from rainwater SO4^2-, SO4^2- from oxidation of sulfur in coal and sulfides deposits. Samples from the tributaries of the lower part, which is dominated by carbonate rocks interbedded with clastic rocks, have relatively enriched ^34S and lower SO4^2- concentrations. SO4^2- in these waters appears to result from solution of gypsum, rainwater SO4^2- and oxidation of sulfur in coal. The sulfur isotopic composition of the mainstream indicates that most of the SO4^2- in the Wujiang River water is from the upper part.