Research On Cd,Pb Fraction Characteristic And Bioavailability In Zhujiang River Delta Vegetable Plot

Through the investigation of vegetable plot in Zhujiang River Delta, sample analysising and data processing, this paper discovered the correlation between the properties of physical and chemical of soil and five fractions of heavy metal Cd, Pb in the soil, and the correlationship between the different fractions Cd, Pb and Cd, Pb content in Brassica Parachinensis. The relationship between soil shortly polluted by various concentration Cd and the dry weight and Cd content of Brassica Parachinensis was proved, Cd fractions change after planting Brassica Parachinensis and the effect of Cd fractions change on Cd content in Brassica Parachinensis through indoor incubation experiments. Through the experiment, the main results were obtained as follows:1 The existence fractions of Cd, Pb and influence factor in soilThe main fraction of Cd is FeMnO_x-Cd, and Pb is RES-Pb in Zhujiang River Delta. Soil available Si and EXC-Cd is negative relevant notably, EXC-Pb is notable negative relevant extremely. OM-Cd is the potential source of EXC-Cd. Soil CEC, OM, Total N, available Ca are the most influence on soil Cd, Pb fractions.2 The relation of Cd , Pb fractions and bioavailability in soilBrassica Parachinensis Cd absorption in Zhujiang River Delta is mainly influenced CA-Cd and FeMnO_x-Cd, the bioavailability of Cd can be evulated by the equation as follow: y = -0.007+1.271X₁+0.589 X₂, And X₁ is EXC-Cd, X₂ is FeMnO_x-Cd;And Brassica Parachinensis Pb absorption in Zhujiang River Delta is mainly influenced EXC-Pb and FeMnO_x-Pb, the bioavailability of Pb can be evulated by the equation as follow: y = -0.01119+0.00413X₁+0.00047X₂, And X₁ is CA—Pb, X₂ is FeMnO_x—Pb.3 The impact on soil Cd fraction and bioavilability by different Cd additonThe dry weight of Brassica Parachinensis is higher than contrast obviously when the soil Cd addition is 1mg/kg soil. The dry weight reduces following the Cd addition increasing when the addition is greater than 1mg/kg soil. The Cd content in BrassicaParachinensis increase following the Cd addition increasing, the equation as follows: y=0.5326x-0J888, R2 = 0.9881**. EXC-Cd, CA-Cd, FeMnOx-Cd in soil reduces, OM-Cd increases, RES-Cd holds the line after planting Brassica Parachinensis. Soil Cd is EXC-Cd as the core after adding Cd in soil, and Cd content in Brassica Parachinensis greatly depends on EXC-Cd, the equation as follow: y=0.015e*9072\ R2=0.9366**.