磷肥对铅锌矿污染土壤中铅毒的修复作用

Effects of phosphorus fertilizers on remediation of lead toxicity in a soil contaminated by lead and zinc mining

用连续提取法研究了不同磷肥对铅锌矿污染土壤中铅化学形态的影响、磷肥降低铅毒性的机理以及磷肥的有效使用条件.结果表明,3种磷肥都具有显著降低铅的各种非残渣形态含量的作用.磷肥用量在PPb摩尔比为7.0时已经足够修复土壤的铅毒,并且在该磷肥用量水平时,从非残渣形态铅总量的降低幅度上看,3种磷肥修复铅污染的效果顺序为:过磷酸钙(85%)、钙镁磷肥(83%)磷矿粉(16%);把铅的形态与其生物有效性联系起来比较,3种磷肥修复铅污染效果顺序为:钙镁磷肥(94%)、过磷酸钙(92%)>磷矿粉(61%).磷肥具有原位修复铅污染土壤的潜能,其主要机理是通过磷肥中的磷与各种非残渣形态铅反应形成溶解度极小的磷(氯羟基氟)铅矿沉淀,从而降低铅的溶解性的结果,3种磷肥中以磷矿粉最为经济.

The effects of three phosphorus fertilizers （single superphosphate-SSP, calcium magnesium phosphate-CMP, phosphate rock-PR） on chemical fractions of lead （Pb） in a soil contaminated by Pb/Zn mining tailings using a sequential extraction procedure were evaluated. The primary mechanism for decreased lead toxicity in the soil by phosphorus fertilizers and the economic application of phosphorus fertilizers were also discussed. All three phosphorus fertilizers reduced Pb solubility and bioavailability effectively. It was suggested that application dosage of phosphorus fertilizers at the P/Pb molar ratio of 7.0, was enough to remediate Pb toxicity in the soil. At the level of 7.0 molar ratio of P/Pb, the effect of Pb remediation by phosphorus fertilizers followed the order in terms of the sum of decreased nonresidual fractions： SSP（85%）≈CMP（83%）〉〉PR（16%）. If the comparison linking up the chemical fractions of Pb in soil with its bioavailability, the effect of Pb remediation by three phosphorus fertilizers followed the order： CMP（94%）≈SSP（92%）〉 PR（61%）. There was no remarkable difference between SSP and CMP in the reduction of lead toxicity, while both were markedly greater than PR. PR was the most economic amendment in terms of the most bioavailable （exchangeable） fraction of Pb in soil （79%）. h was concluded that PR would be a most cost-effective amendment considering both its effectiveness and price. Lead precipitation as a fluoro-pyromorphite-like mineral in the contaminated soil reacted with phosphorus fertilizer reduced Pb solubility and reduction in the non-residual fractions. The effective conversion indicate a potential of phosphorus fertilizers for in-situ Pb immobilization in soils contaminated by lead and zinc mining railings.