An investigation was conducted to identify the characteristics of heavy metals in orange ecosystem in three areas in the Three Gorge Reservoir Region by using the modified Tessier sequential extraction procedure.The contents of Cu and Pb in different speciation fractions of the soils can be ordered as the Residual(F6)>Reducible(F4)>Oxidable(F5)>Water soluble(F1)>Carbonate(F3)>Exchangeable(F2),and the contents of Zn and Ni follow the order of the Residual(F6)>Oxidable(F5)>Reducible(F4)>Water soluble(F1)>Carbonate(F3)> Exchangeable(F2),and those of Cd follow the order of the Reducible(F4)>Oxidable(F5)>Exchangeable(F2)> Carbonate(F3)>Residual(F6)>Water soluble(F1).The concentrations of Cu in the different organs of oranges follow the increasing sequence of pulp>leaf>pericarp,those of Zn and Ni following the increasing sequence of leaf >pulp>pericarp,and those of Pb and Cd follow the increasing sequence of leaf>pericarp>pulp.Correlation degrees of different forms of same heavy metals in soils are according to the order of Cu>Zn>Cd>Pb>Ni.Correlation degrees of different heavy metals in same forms are according to the order that the forms of Reducible(F4),Oxidable(F5) and Residual(F6) are higher than the forms of Water soluble(F1),Exchangeable(F2) and Carbonate(F3).There are either positive or negative correlations between heavy metals in leaves and in pulp,while there are all positive correlations between heavy mentals in leaves and in pericarp.There are significant correlations between the concentrations of some heavy metals in leaves,pericarp or pulp,and those in speciation fractions in the soils.
LI QilinWEI ChaofuHUANG YunWANG LiweiWANG Dingyong
