长江流域四川段Cd异常源追踪

在成都经济区区域生态地球化学调查基础上,重点研究长江各支流重金属元素Cd的来源与分布、分配特征,定量估算金沙江等四大支流Cd的输出通量。结果表明,该区早期及现代沉积物、悬浮物中Cd均为高背景值,其质量分数达0.2×10-6;水系沉积物及悬浮物中Cd的高值点明显受到流域内分布的铅锌矿、金矿等多金属硫化物矿床或矿点影响;区内各水系Cd的输出通量明显增加,岷江、沱江Cd的输出通量占流域总通量的比例上升,嘉陵江所占比例下降,金沙江略有变化;水体中Cd的输出通量所占比例在泥沙中减少,在悬浮态和溶解态中增加。

Tracing of Cd anomalous source along the Sichuan section of the Yangtze valley in China

On the basis of the regional eco-geochemical investigation in the Chengdu economic zone, this article studies the origin, the composition and the distribution characteristics of the heavy metal element Cd estimates quantitatively the output flux of Cd along four big branches of Yangtze River such as the Jinshajiang River. The result indicates that Cd in suspended loads of the modern and earlier sediments possesses the high background with the mass fraction of 0.2×10~(-6);The high value of Cd in the stream sediments and the suspended loads is obviously influenced by poly-metallic sulphide deposits or the mineralization points distributed over the basin including lead-zinc mine, gold mine, and so on, Cd output flux in various streams in the Sichuan section of the Yangtze valley is obviously increasing, the proportion of Cd output flux in Minjiang River and Tuojiang River to the total flux is increasing, and in Jialinjiang River is reducing and in Jinshajiang River slightly changes. The proportion of Cd output flux in silts (sand) along the branches is reducing, however in a suspension state and dissolution state, it is increasing.