Study On The Character Of Heavy Metal Forms In Soil And Its Bioavailability In The Chengdu Plain

Base on the analysis of the content and distribution of heavy metals and its forms in soil in the Chengdu plain, this paper compared the different heavy metal accumulation degrees in different crops, and then discussed the accumulation relationship between heavy metal forms and crops by correlated and grey correlated analysis. Simultaneously, recurred to the relationship between heavy metal forms and mainly physical and chemical properties, analyzing the mainly physical and chemical properties which can affect the validity of heavy metal, then introduced a soil heavy metal forms referenced criterion.The description statistic of the content of different forms (exchangeable, bound to carbonate, bound to Iron and Manganese, bound to organic matter, residue) of heavy metals showed, except Cd in soil was priority to bound to Iron and Manganese oxides, the rest four elements, Pb, Cr, Cu , Zn were priority to residue form. The sequence of different forms of Cd was bound to Iron and Manganese oxides>residue form>bound to carbonate>bound to organic matter form>exchangeable form. The sequence of different forms of Pb, Cr, Cu, Zn was residue form>bound to organic matter>bound to Iron and Manganese>bound to carbonate>exchangeable form. At the same time, the proportion of activity form in total content of five elements was quite different. The proportion of active Cd in total content was highest, and active Cr was lowest. As far as the coefficients of variation of the heavy metal forms were concerned, the bound to carbonate Cd and bound to Iron and Manganese Cu were belonged to intension variation. The range of coefficient of variation of the rest heavy metal forms was 25%～75%, which accorded with moderate variance. The spatial interpolation analysis of active heavy metal showed that, in the north of Chengdu plain (Dujiangyan, Deyang, Pengzhou, Guanghan)the content of the active heavy metal was higher, in the south of Chengdu plain (Shuangliu, Qionglai) the content of the active heavy metal was lower except the active Pb, in the southeast of Chengdu plain the content of the active Cd, Zn, Cu was higher too.The content of Pb, Cd, Cr, Cu, Zn in wheat were respective 0.75, 0.09, 0.74, 6.72, 32.36mg/kg respectively, the content of Pb, Cd, Cr, Cu, Zn in rice were 0.65, 0.11, 0.18, 4.71, 19.71mg/kg respectively, and the content of Cd, Cr, Cu, Pb, Zn in rapeseed were 0.59, 0.11,0.62,5.61, 36.29mg/kg respectively. The limitative criterion of heavy metals in the food, which is awarded by the National...