Chemical Fractionation Of Cadmium And The Transformation Of Added Cd And Its Biological Effect In Several Cultivated Soils Of The Hills Of South Hunan

Soil cadmium contamination has become a significant issue with rapid economic development. In this paper, arable soils from hilly areas in Hunan province was collected and speciation of cadmium and its effects were studied. We also investigated that under 50 mg·kg-1 concentration of cadmium affixion, the temporal changing regularity on different parent material types of soils, that under gradient concentration treatment, the biology influence and transformation discipline on cabbage which was planted on different parent material types of red soils.The results showed that (1) cadmium contamination in hilly areas in Hunan province of different parent material types of red soils is far beyond the standard, whereas most cadmium is residua, and exchangeable and carbonate cadmium account for 22%-28% of total cadmium in soil, representing middle level in RAC (risk assessment code); (2) the distribution of cadmium is directly bound up with pH, SOM (soil organic matter) in soil; (3) the adsorbing capacity in different parent material types of red soils after extraneous cadmium affixion followed the series:killas> quaternary> limestone. Exchangeable and carbonate cadmium dominated its distribution in the previous soils. Exchangeable and carbonate cadmium concentration in these soils followed the series:limestone>quaternary>killas, and the tendency of cadmium convert to residue was obvious, and (4) Under gradient concentration of cadmium affixion indicated that carbonate combined cadmium concentration in selected soils followed the series:quaternary> limestone> killas, respectively. Meanwhile, killas red soil represented the minimum biology influence on cabbage while the quaternary maximum. We conclude that cadmium environmental capacity differed from various parent material of red soil.