稻壳生物炭对矿区重金属复合污染土壤中Cd、Zn形态转化的影响

Effects of rice-husk-derived biochar on the morphological transformation of Cd and Zn in mining area soils polluted by heavy metals

明确稻壳生物炭的农业生态效应对合理利用其修复矿区重金属复合污染土壤具有重要意义。通过盆栽试验,研究了稻壳生物炭不同施用量(0、5、10、20、50、100 g·kg^(-1))对重金属复合污染土壤p H、CEC和Cd、Zn赋存形态转化的影响。结果表明:与对照相比,稻壳生物炭的添加使土壤p H升高0.18~0.29个单位,CEC提高32.89%(5.68 cmol·kg^(-1));同时,重金属复合污染土壤中弱酸提取态Cd、Zn分别降低21.88%、19.63%,氧化态Cd、Zn分别降低24.12%、18.62%,可还原态Cd、Zn分别降低13.72%、8.97%;而使残渣态Cd、Zn分别升高115.56%、39.45%。综上所述,稻壳生物炭的添加提高了矿区重金属复合污染土壤的p H和CEC,促进了重金属复合污染土壤中Cd、Zn的弱酸提取态、可氧化态和可还原态向化学性质稳定的残渣态转化,降低了土壤重金属的有效性,实现了对重金属复合污染土壤的修复。

Understanding the agroecological effects of rice-husk-derived biochar would provide a reference for its rational application in the remediation of heavy-metal-contaminated soil in mining areas.In the present study,a pot trial was carried out to study the effect of the addition of different concentrations of rice-husk-derived biochar(0,5,10,20,50,100 g·kg-1)on the pH and CEC levels and the morphological transformation of Cd and Zn in heavy-metal-polluted soil.The results indicated that the addition of rice-husk-derived biochar elevated the soil pH and CEC levels by 0.18~0.29 units and 32.89%(5.68 cmol·kg-1),respectively.In addition,the weak-acid-extractable Cd and Zn were reduced by 21.88%and 19.63%,respectively,and the oxidation states of Cd and Zn were reduced by 24.12%and 18.62%,respectively.The reducible fractions of Cd and Zn decreased by 13.72%and 8.97%,respectively,but the residual fractions of Cd and Zn increased by 115.56%and 39.45%,respectively,compared to those of the control treatments.Overall,the application of rice-husk-derived biochar elevated the soil pH and CEC and promoted transformation of the weak-acid-extractable,oxidizable,and reducible fractions of Cd and Zn into chemically stable residual fractions,which could positively reduce the bioavailability of heavy metals in heavy-metal-polluted soil near mining areas.