Geochemical characteristics of cadmium in soils and stream sediments in the Three Gorges reservoir area,China

The cadmium distribution characteristics in different media in the Yangtze Gorges reservoir area and distribution characteristics of elements in sediments of the Yangtze River at the perpendicular and cross sections have been studied. The study shows that there is appreciable difference between the cadmium abundance in eluvial soils of the area and that of the Yangtze River sediments. The stream sediments have a notably higher Cd anomaly,and the Cd anomaly occurs in stream sediments of all the depositional stages. Cd from the upstream source is the main factor responsible for a higher anomaly in the stream sediments of the reservoir area. Human activities influence the cadmium content of the soils and stream deposits obviously. The Cd contents of soils in factories,docks and household refuse places are far higher than that in other places. The cadmium content in sediments formed by the urban sewage system is also higher than that in sediments of the main water system of the Yangtze River. Therefore,the natural source is the root cause for the prevalence of cadmium anomaly in the Yangtze River,while the anthropogenic source is likely to be responsible for high Cd anomalies in large and intermediate-sized cities along the Yangtze River.