A research framework for source tracking and quantitative assessment of the Cd anomalies along the Yangtze River Basin.

Cadmium is an cumulative toxic element, which could result in chronic poisoning with an incubation period of as long as 10~30 years. The results of the currently implemented multi-purpose geochemical survey show that there are Cd anomalies spreading along the whole Yangtze River Basin. A preliminary study of the contents of Cd in alluvium on upper, middle and lower reaches of the Yangtze River reveals that these Cd anomalies are mainly caused by natural weathering. On the basis of a unified technical regulation and aiming at the features of the Cd anomalies, we proposed a spatial and temporal variation model for the quantitative assessment of the Cd input flux from tributaries.The model is established by applying the suspended particle matter survey during low-and high-water periods, the stratification sampling of sedimentation column on overbank sediments/floodplain sediments, and the isotopic dating. Thus, the Cd input flux from tributaries could be calculated under a unified regulation and the regional geochemical assessments for the provinces along the Yangtze River could be made under a unified standard, This should create the conditions for a comprehensive study of the mechanics of the Cd anomalies along the Yangtze River.