Soil heavy metal’s form and their enrichment and transfer in plants in the water level fluctuating zone at Yunyang in Three Gorge reservoir area

Caused by water level rise in summer and drop in autumn, 291.1 km2 of water level fluctuating zone (WLFZ) has formed in the region between145 to175 m above sea level from May to October after the Three Gorge Dam being built. Through analyzing on the soil heavy metal’s content and form as well as distribution in the root, stem and leaf of the plants, and on the heavy metal’s enrichment and transfer coefficients from soil to the plant in Yunyang WLFZ, the heavy metal pollution and the enrichment and transfer law are studied in the paper. The results show that there is heavy cadmium pollution in Yunyang WLFZ with the single factor pollution index and Nemerow comprehensive pollution index being 5.02 and 3.637 respectively; that the pollutants cadmium and chromium assume residual form with weak bio-toxicity; the pollutant Cu assumes exchangeable form or combined form with carbonate with relatively strong bio-toxicity; the M n the combined form with iron; and that the distribution ratio of Pb is quite uniform with weak bio-toxicity. The exchangeable form is highly positive correlated with the transfer coefficient and the related coefficient is 0.981.The combined form of organic matter and sulfide is highly positive correlated with the enrichment coefficient and the related coefficient is 0.905. The contribute ratios of the Fe-Mn combined form and the carbonate as well as the residual combined form to the enrichment and transfer coefficients are small. The enrichment and transfer of heavy metals from soil to plant are mainly controlled by the properties of the heavy metals ‘exchangeable form and the combined form of organic matter and sulfide.