Chemical Behavior of Cadmium in Wheat Rhizosphere
摘要
The present study deals with some chemical behavior,including Cd extractability,species transformation and adsorption-desorption characteristics,of Cd in the rhizosphere(R) of wheat seedlings grown on both yellow-brown earth(YBE) and red earth (RE).Results indicated an increase of pH about 0.5 unit in the R of the yellow-brown earth and a decrease about 0.4 unit in the R of red earth in comparison with their respective bulk soils(NR).More Cd adsorbed and less Cd desorbed,and hence less Cd extracted in the R of YBE than those in the NR were found.The opposite cases were got for the R of RE.Fractionation experiment showed that in the R of YBE,more Cd was bound to Mn oxides and organic matter,less Cd was in exchangeable form,and little Cd was bound to amorphous and crystal iron oxides.However,little difference of the Cd species between the R and NR of RE was found. Regression analysis indicated that pH was one of the dominant factors affecting the chemical behavior of Cd in rhizosphere.