含磷材料钝化修复重金属Pb、Cu、Zn复合污染土壤

Immobilization of Pb,Cu,Zn in a Multi-metal Contaminated Soil With Phosphorus Bearing Materials

运用2种含P材料即重过磷酸钙磷肥（TSP）和磷灰石矿尾料（PR）钝化修复Pb、Cu和Zn3种重金属并存的复合污染土壤,通过化学提取和土柱淋溶方法评价修复效果并探讨其可能存在的机理。土壤添加P材料4星期后,所有3种P处理（PR、TSP和PR＋TSP）均有效地降低了毒性提取态的Pb和Cu,其分别下降了15%~70%和10%~18%;水提取态的Pb和Cu分别下降了16%~43%和46%~58%。添加含P材料对土壤中Zn的稳定化影响较小,甚至TSP处理使水提取态的Zn提高了15%。P处理抑制了Pb和Cu在土壤剖面的径向迁移,但对Zn的影响较小。Pb和Cu的固定可能主要是由于形成了磷酸盐沉淀,而Zn的稳定性可能与表面吸附或络合作用有关。P处理未明显改变土壤pH值,尽管总P有所增加,但未观察到其径向迁移的现象。P处理对于稳定P Pb和Cu很有效,对Zn稳定效果有限,甚至有被活化的可能,在实际应用中应关注这一现象。

The chemical Immobilization technique is mainly used for the remediation of the soil Contaminated by single heavy metal.However,the contamination of soil is usually caused by the combination of several heavy metals.This study was designed to determine the effect of phosphate rock（PR） and triple superphosphate fertilizer（TSP） on the immobilization of Pb,Cu,and Zn in the multi-metal contaminated soil.The treatment effectiveness was evaluated by the chemical extraction and column leaching experiments.After 4 weeks,all treatments（TSP,PR,and PR＋TSP） reduced concentrations of Pb and Cu extracted from the Toxicity Characteristic Leaching Procedure（TCLP）by 15%~70% and 10%~18%,respectively,and water soluble Pb and Cu were reduced by 16%~43% and 46%~58%,respectively.However,the P treatments had little effect on the immobilization of Zn in the soil,and on the contrary,the content of water soluble Zn in the soil was increased by 15%.The P treatments inhibited the vertical migration of Pb and Cu in the soil layer,but this technique presented little effect on the migration of Zn.It was presumed that the effective immobilization of Pb and Cu was mainly attributed to the formation of the metal phosphate precipitates.The pH value of the soil was not significantly changed,and no obvious vertical migration of P was observed though the total phosphorus was increased.In summary,the phosphorus treatments was very effective on the immobilization of Pb and Cu.However,it showed limited effect on the stabilization of Zn and even had the potential of activating Zn in the soil,to which more attention should be paid in the practical application.