中文摘要：

土壤地球化学调查显示，长江沿岸，尤其湖南洞庭湖流域存在以镉为主的重金属高值带。为进一步确定As和Cd等重金属元素在河流中的存在形式、迁移方式和通量等地球化学特征，本研究在洞庭湖水系主要干支流的关键位置布置采样点，分夏季丰水期和冬季枯水期两次，采集了原水、0．45μm过滤水和0．20μm过滤水等水样品，以及悬浮物固体样品，分析了水和悬浮物样品中As和Cd、Ph等重金属元素含量。结果发现，As元素在湘江、资水、湘江上游支流西河和耒水中含量最高，耒水、西河及湘江的Pb、Zn含量相对偏高，Cd在湘江、耒水及泪罗江的含量也明显高于其他河流；研究区河水中As、Ni、Cd和Zn等元素在水中离子态比例较大，其溶解态含量受河水pH和温度的控制，湘江、西河、耒水和泪罗江中悬浮物As、Zn、Cu、Cd、Ph和Cu等元素含量远高于其他水系悬浮物，这与这些流域内存在多金属矿区密切相关；不同元素在河水中迁移途径有很大差别，As以溶解态和胶体态为主要迁移形式，Ph、Zn、Cu、Cd和Ni等重金属元素以悬浮物形式迁移的比例最大；主要人湖河流中，湘江输入洞庭湖的As、Zn、Cu和Cd总量最大，年通量分别为961．43t、478．90t、101．67t、59．58t。

英文摘要：

A Cd anomaly was found around the Dongting Lake in Hunan Province by previous soil geochemical survey. In order to investigate the formation, ways of transportation and fluxes of As and heavy metals such as Cd, sampling points were designated at the key locations in the Dongting Lake water system. Samples of raw water, water filtrated by 0. 45 μm filters and 0. 20 μm ones, and filtrated suspended sediments were collected at each sampling location. As and heavy metals such as Cd, Pb etc. in the water and sediment samples were ana- lyzed. As was found concentrated at Zishui, Xiangjiang and its upstream branches like Xihe and Leishui; Pb, Zn were concentrated at Xiangjiang, Xihe and Leishui; and Cd concentrated at Xiangjiang, Leishui and Miluojiang. Dissolved forms were found to be the dominant of the total contents for As, Ni, Cd and Zn. The proportion of dissolved to the total was controlled by pH and temperature of the water. As, Zn, Cu, Cd, Pb and Cu contents in the suspended sediments from Xiangjiang, Xihe, Leishui and Miluojiang were higher than in the oth- er water systems due to the mining activities for metals at the drainage basins. As was transported more in the form of the dissolved form than in the particulate one, but Pb, Zn, Cu, Cd and Ni were more transported in the form of the particulate. Xiangjiang is the biggest source of As, Zn, Cu and Cd for the Dongting Lake with the annual fluxes of 961.43 t, 478.90 t, 101.67 t and 59.58 t respectively.