Abstract:

For understanding geochemical behaviors of cadmium (Cd), it is essential to study

the factors that affect the transport of different geochemical species of cadmium in the

pedogenetic process. We focus on the distribution features of cadmium species in paddy soil

profiles in Chengdu agroecosystems in Sichuan Province, in order to discuss the factors

controlling geochemical behaviors of cadmium species, and to assess the ecological safety.

It is known that Cd background values of paddy soils in Minjiang River and Tuojiang River

catchments are 0147 mg·kg-1 and 0215 mg·kg-1, respectively. The inputs of Cd Ion

exchange species and Cd carbonate species into cultivated soils dominate the total Cd

increments, and these cadmium species have limited ability to transfer along the profiles.

The total Cd, pH, total organic carbon (TOC) and clay minerals contents have significant

influence on the transferring of Cd species. The bioavailability index of cadmium for

cultivated paddy soil is very high; it ranges between 059 and 065, which suggests that

the cultivated soils have posed high risk on plant safety.

Key words:

Key words: agroecosystem; cadmium; pedogenetic process; paddy soil profiles