不同粒径磷矿粉钝化土壤重金属Cd、Pb的机制研究

采用盆栽试验,研究磷矿粉不同粒径(0.1、1.5、150μm)的3种不同用量(1、2、4 g·kg-1土)钝化土壤重金属Cd和Pb的效应及机制。结果表明,磷矿粉的粒径越小、用量越大,上海青产量越高,叶面积越大,植物体内Cd、Pb的含量越低,土壤中交换态Cd、Pb的含量越低,残渣态Cd、Pb的含量越高。与对照相比,0.1μm磷矿粉高用量(4 g·kg-1土)的处理上海青的产量和叶面积分别显著增加87.3%和147.9%,叶中Cd和Pb含量分别显著降低46.9%和61.9%,根中Cd和Pb含量分别显著降低47.9%和35.3%,土壤交换态Cd和Pb含量分别降低44.8%和44.9%。150μm磷矿粉低用量(1 g·kg-1土)处理叶面积、植物体内Cd、Pb含量与对照都没有达到显著差异。1.5μm磷矿粉处理效果介于0.1μm和150μm磷矿粉处理之间。可见,0.1μm磷矿粉钝化土壤重金属效果最好,其机制是降低了植物容易吸收的交换态Cd和Pb的含量。

Passivation Mechanisms of Soil Heavy Metals Cd and Pb with Different Sizes of Phosphate Powder

Pot experiments were carried out to research on the passivation effects and mechanisms of cadmium(Cd)and lead(Pb)in soil with different sizes(0.1, 1.5, 150 μm)and levels(1, 2, 4 g·kg-1per soil)of phosphate powder. Results showed that the yield and leaf area of rape increased with the level of phosphate powder, but decreased with the size of them. The contents of Cd and Pb in plant and exchangeable Cd and Pb in soil decreased, the soil residual Cd and Pb contents increased, with higher level and smaller size of phosphate powder. In comparison to control without phosphate power, while phosphate powder with 0.1 μm size and 4 g·kg-1per soil was applied, the yield and leaf area of rape significantly increased by 87.3% and 147.9%, respectively. The contents of Cd and Pb in leaves notably decreased by 46.9% and 61.9%, and by 47.9% and 35.3% in roots. The soil exchangeable Cd and Pb contents decreased by 44.8% and 44.9%. None significant difference was found in the phosphate powder with size of 150 μm and dosage of 1 g·kg-1per soil. The effect of 1.5 μm phosphate powder was between 0.1 μm and 150 μm. Therefore, the best passivation effect of them was 0.1 μm phosphate powder, with the reason of decreasing the contents of exchangeable Cd and Pb, which were easily absorbed by rape.