中文关键词
钝化剂土壤胶体内源铁氧化物铜镉固持机制 | 英文关键词amendmentsoil colloidin-situ iron oxidecoppercadmiumimmobilization mechanism |
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| 中文摘要 |
| 为揭示钝化剂阻控后Cu和Cd二次活化的风险程度，本文采用石灰石（LS）、麦饭石（MF）、生物炭（BC）和铁改性生物炭（Fe-BC）这4种钝化剂，研究其施用后土壤及土壤胶体中Cu和Cd形态变化和内源铁氧化物类型、形貌变化归趋.结果表明，钝化剂对土壤Cu和Cd的固持效果表现为LS>MF>Fe-BC>BC.LS和MF处理后土壤可交换及碳酸盐结合态Cu质量分数分别减少8.19%和2.33%，易还原铁锰结合态Cu质量分数分别增加8.00%和2.69%，二次活化的风险较高；BC和Fe-BC处理后，易还原铁锰结合态Cu质量分数分别减少2.21%和5.90%，有机结合态Cu质量分数分别增加4.75%和3.48%，钝化效果更稳定.LS、MF、BC和Fe-BC处理后，土壤可交换及碳酸盐结合态Cd质量分数分别减少7.64%、8.34%、2.37%和6.73%，残渣态Cd质量分数分别增加8.27%、9.18%、5.73%和9.60%，说明钝化处理后，Cd二次活化的风险较低.胶体中Cu和Cd的含量分别为489.92mg·kg-1和2.57mg·kg-1，远高于土壤中Cu和Cd的含量239.98mg·kg-1和1.93mg·kg-1，且4种钝化剂施用后，土壤胶体中非晶质氧化铁结合态Cu和Cd含量显著增加，说明这是重金属生物有效性降低的主要原因和路径. |
| 英文摘要 |
| Cu and Cd are common pollutants in the soil surrounding copper smelting enterprises. The regional characteristics of southern China results in a high risk of Cu and Cd reactivation in soil after immobilization with soil amendment. To clarify the degree of risk of secondary activation of Cu and Cd, four types of amendments, namely limestone (LS), maifanite (MF), biochar (BC), and iron modified biochar (Fe-BC), were used to study Cu and Cd fraction distribution in soil and soil colloids and the type and fractional changes of in-situ iron oxides. The results showed that the soil amendments were ranked by their immobilizing effect on soil Cu and Cd in the order LS, MF, Fe-BC, and BC; the exchangeable and carbonate-bound fractions of Cu in the soil reduced by 8.19% and 2.33%, and the readily reducible iron- and manganese-bound fractions of Cu increased by 8.00% and 2.69%, respectively, when treated with LS and MF. The risk of secondary activation of heavy metals was higher in soil treated with LS and MF than in soil treated with other amendments. The readily reducible iron- and manganese-bound fractions of Cu reduced by 2.21% and 5.90% and the organic-bound fractions of Cu increased by 4.75% and 3.48% when treated with BC and Fe-BC, respectively. This indicated that the immobilization effect tends to be stable. The exchangeable and carbonate-bound fractions of Cd in the soil decreased by 7.64%, 8.34%, 2.37%, and 6.73%, and the residual fractions increased by 8.27%, 9.18%, 5.73%, and 9.60% respectively, indicating that the amendment treatments resulted in better stability of Cd than Cu. The Cu and Cd contents of soil colloids were 489.92 mg ·kg-1 and 2.57 mg ·kg-1, respectively, which were considerably higher than those in soil (239.98 mg ·kg-1 and 1.93 mg ·kg-1, respectively). The amorphous iron oxide-bound Cu and Cd contents of soil colloids increased significantly with the application of each of the four amendment, which was the main reason and mechanism for the decrease in heavy metal bioavailability. With the extension of aging time, long-term immobilization can be achieved if the heavy metals are further transformed into crystalline iron oxide-bound and residual fractions. |
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