Abstract:

Abstract: Fraction and bioavailability of heavy mental in sewage-irrigated soils of XiaoYi were investigated. The results show that the total contents of Ni、Cr、Pb、Cu、Zn and Cd do not exceeded the maximum permissible limits set by State Environmental Protection Agency (SEPA) for soils in China, but the concent of Ni、Cr and Pb has increased compared with the local soil background value. There are significant differences in fractions of heavy metals in sewage-irrigated soils. Further, the residual fraction was the predominant fraction for Ni、Cr and Zn. Pb was dominated by the residual fraction and iron-manganese oxides fraction，and Cu was dominated by organic fraction and residual fraction ,. For cadmium, mainly fraction were exchangeable and carbonate bound forms and the residual form was limited. Compared with the non sewage-irrigated soils , sewage irrigation increased the bioavailability of heavy metals and changed the Chemical fractionation of heavy mental. The availability of heavy metals in sewage-irrigated soil is as order Cd> Pb> Cu > Cr > Zn > Ni, and the mobility followed Pb > Cd> Cu > Cr > Zn> Ni, respectively. The bioavailability of Cd and Pb are much more higher than other heavy metals.