不同含磷化合物修复铅污染土壤后的人体健康风险评价

Human health risk assessment for lead contaminated soil after remediation with several phosphate compounds

磷酸盐钝化铅是铅污染土壤的重要修复技术之一.但磷酸盐修复土壤铅污染后,土壤铅对人体的健康风险仍缺乏系统研究.本研究通过向铅污染土壤添加五种不同的含磷化合物(KH2PO4、NH4H2PO4、CaHPO4,植酸和卵磷脂),分析了其对铅污染土壤的钝化效果,运用in vitro和SHIME模型评估修复后土壤铅对人体的健康风险.结果表明,添加含磷化合物30 d后,五种处理均有效降低了铅的DTPA和CaCl2可提取态,分别降低了62.5%—66.5%和27.8%—49.5%,其中植酸和CaHPO4处理效果较好,卵磷脂处理效果较差.5种处理中,铅的生物可给性在胃、小肠和结肠阶段有显著差异,分别为8.67%—9.31%、0.88%—1.55%、2.06%—2.76%,由于受pH的影响,铅在胃阶段生物可给性最高且各处理之间差异不明显,在小肠阶段KH2PO4处理土壤铅的生物可给性最低,卵磷脂处理铅的生物可给性最高,结肠阶段NH4H2PO4处理土壤铅的生物可给性最低,卵磷脂处理铅的生物可给性最高.结肠阶段铅的生物可给性均高于小肠阶段的,可见肠道微生物促进了土壤中Pb的溶出,提高了铅的生物可给性,增加了人体的健康风险.在添加同等含量的含磷化合物修复铅污染土壤后,KH2PO4处理对人体健康风险最小,卵磷脂最大.

The use of phosphate as a stabilizing agent that is widely accepted and capable of lead-contaminated soil remediation.However,there are few studies on the assessment the risk of human health after remediation.In the study,five different phosphorus materials(KH2PO4,NH4 H2PO4,CaHPO4,Phytic acid and Lecithin)were added to lead-contaminated oil,and theirs inactivation of lead was analyzed.In vitro and SHIME models were adopted to evaluate the risk of human health of soil lead after soil remediation.The results showed that,after adding P material for 30 days,the five materials obviously decreases by 62.5%—66.5%DTPA extractable Pb and by 27.8%—49.5%CaCl2 extractable Pb.The Pb inactivation of CaHPO4 and phytic acid was better than the others.Among the five treatments,the Pb bioaccessibility in different phase was quite different,about 8.67%—9.31%in gastric phase,0.88%—1.55%in small intestinal phase and 2.06%—2.76%in colon phase.The Pb bioaccessibility was highest and no significant difference was observed within the five treatments according to the low pH in gastric phase.In small intestinal,the bioaccessibility of soil lead was lowest after adding KH2PO4,highest after adding lecithin.In colon phase,the bioaccessibility of soil lead was lowest after adding NH4H2PO4,highest after adding lecithin.In addition,the bioaccessibility of lead in colon stage was higher than that in small intestine stage,suggested that the human gut microbiota could induced Pb release from soil and increased bioaccessibility,which may resulted in a high risk to human health.After remediation of lead-contaminated soil with the same amount of the five phosphorous materials,the human health risk was the lowest by KH2PO4 and the highest by lecithin.