生物炭-凹凸棒土复合材料对水稻土锌镉的钝化及土壤养分和酶活性的影响研究

为了比较生物炭、凹凸棒土以及生物炭-凹凸棒土复合材料3种钝化剂对锌镉复合污染水稻土的钝化修复效果,本研究利用傅立叶红外光谱(FT-IR)、X射线衍射(XRD)、比表面积表征(BET)和扫描电镜(SEM)等技术手段对稻壳生物炭和凹凸棒土样品进行表征,并采用土培试验研究稻壳生物炭、凹凸棒土及生物炭-凹凸棒土复合材料对实际重金属锌(Zn)、镉(Cd)污染水稻土钝化效果及理化性质的影响。结果表明,凹凸棒土比稻壳生物炭具有更大的比表面积,且表面更不规则、更粗糙。土培试验表明,3种钝化剂均降低了水稻土中Cd和Zn的生物有效性,并在不同程度上改善了土壤理化性质。单独添加2.0%凹凸棒土和2.0%稻壳生物炭处理,分别使土壤Zn有效态含量降低了86%和51%,Cd有效态含量降低了25%和8%。2.0%生物炭-凹凸棒土复合材料施加后,土壤中Zn和Cd有效态含量分别降低了83%和23%,且土壤pH值提高至5.8,有机碳含量提高了39%。说明稻壳生物炭-凹凸棒土复合材料比单独使用凹凸棒土和生物炭更能有效地固定Cd和Zn,同时能改善复合污染水稻土的理化特性。因此,生物炭-凹凸棒土复合材料具有作为一种新型钝化材料用于土壤修复的潜力,为土壤重金属原位钝化修复提供了一种新思路。

Effects of Biochar-Attapulgite Composite on Zinc and Cadmium Passivation of Paddy Soil and Soil Nutrient and Enzyme Activities

In order to compare the remediation effect of biochar, attapulgite and attapulgite-biochar composite. FTIR, XRD, BET and SEM were used to characterize rice husk biochar and attapulgite samples, and soil incubation experiments were conducted to study the effects of rice husk biochar, attapulgite and attapulgite-biochar composites on the passivation effect and physicochemical properties of Zinc and Cadmium contaminated soil. The incubation results showed that these three passivation agents reduced the bioavailability of Cd and Zn, meanwhile improved the soil properties to varying degrees. Zn content was reduced by 86% and 51%, and Cd content was reduced by 25% and 8% for the treatment of 2.0% attapulgite and 2.0% biochar, respectively. The availabe content of Zn and Cd in the soil was reduced by 83% and 23%, respectively, the soil pH was increased to 5.8, and the organic carbon content increased by 39%. after the application of 2.0% biochar-attapulgite composite. Compared with individual applications of attapulgite and biochar, rice husk biochar-attapulgite composite could efficiently immobilize Cd and Zn, and improve physicochemical properties in Zinc and Cadmium contaminated paddy-growing soil. Therefore, attapulgite-biochar composite could be a potential new passivation agent for soil remediation providing some new ideas for soil heavy metal remediation.