氯对磷酸盐稳定土壤铅的影响研究

Influence of Chlorine on the Immobilization of Pb with Phosphate in Contaminated Soils

氯对磷酸盐稳定土壤铅具有促进作用。研究的目的是探讨氯的合适用量。在铅冶炼污染土壤(全铅含量为220 mg kg^(-1))中以P∶Pb=6(mol∶mol)加入磷酸二氢钾,同时以Cl∶P=0、0.25、0.33、0.5、1和2(mol∶mol)加入氯,培养后测定土壤性质。结果表明,在氯磷比0.25到2范围内,氯对铅的稳定均有促进作用,当Cl∶P=0.25时,氯的促进效果最为明显,此时土壤DTPA-Pb含量比未加氯处理低3.46%(P<0.05)。土壤镉有效性随着氯用量的增加而增大。较高氯用量时,对土壤铜和锌有效性有一定的促进作用。加氯对土壤磷有效性有一定的促进作用,并导致土壤电导率上升。以上结果说明,在铅污染土壤中加入水溶性磷酸盐时,当磷铅比为6时,可采用0.25的氯磷比达到最佳铅稳定效果。

Chorine（Cl） enhances lead（Pb） immobilization in contaminated soils amended with phosphate. This research was conducted to investigate the optimal dosage of Cl for Pb immobilization in contaminated soils amended with soluble phosphate. A Pb-smelting contaminated soil（total Pb = 250 mg kg^-1） was amended with soluble phosphate at P∶Pb = 6（mol∶mol） and chlorine at Cl∶P = 0, 0.25, 0.33, 0.5, 1 or 2 and incubated for 60 days. The positive enhancing effect of Cl on Pb immobilization existed at Cl∶P = 0.25 to 2. The most significant effect of Cl occurred at Cl∶P = 0.25, the DTPA-Pb concentration of the soil at this dosage was 3.46% lower than the control without Cl amendment（P〈0.05）. The DTPA-Cd concentration increased when the Cl dosage increasing. Higher Cl dosages also increased the availabilities of copper（Cu） and zinc（Zn）, however, this effect was not statistically significant（P〉0.05）. Cl amendment increased the Olsen-P concentration（P〉0.05）. Higher Cl dosage resulted in higher soil electric conductivity. The results suggest that, Cl∶Pb = 0.25 is the optimal dosage of Cl when it is applied into Pb contaminated soil with soluble phosphate at P∶Pb = 6.