生物炭在矿区农田土壤中与镉的纵向共迁移行为

The Vertical Co-Migration Behavior of Biochar and Cd in Farmland Near the Mining Area

以广东韶关大宝山矿山废水污染的农田为研究对象,利用超纯水和甲苯/甲醇提取的溶解性有机质(DOM)的三维荧光光谱平行因子分析(EEM-PARAFAC)技术,追踪荔枝树枝生物炭1年内在土壤层0~100 cm深度范围的迁移行为及其协同重金属镉(Cd)的纵向迁移性质.结果表明:生物炭增加了0~60 cm深土壤层溶解性有机碳(DOC)的质量分数,增加了表层土壤的pH,对深层土壤pH无明显影响;EEM-PARAFAC解析得到3个DOM组分(1个类蛋白和2个类腐殖质组分),生物炭的添加增大了0~60 cm深土壤层类腐殖质的质量分数;并且甲苯/甲醇提取的DOM在0~60 cm深土壤层中均检测出生物炭特有的多环芳烃结构,说明生物炭在1年内发生了明显的纵向迁移;生物炭能够有效降低0~20 cm深土壤中有效态Cd的质量分数,但20~60 cm深土层中有效态Cd与对照组的相比最高增加了148%左右.研究表明:需要特别关注生物炭协同重金属在土壤中纵向迁移行为所带来的环境影响.

Ultrapure water and toluene/methanol were used to extract the dissolved organic matter(DOM)from soils and the three-dimensional fluorescence spectroscopy and the parallel factor(EEM-PARAFAC)technology were employed to track litchi wood biochar within one year in the 0~100 cm soil profiles.The vertical co-migration of Cd in the farmland polluted by the Dabaoshan mine wastewater in Shaoguan,Guangdong,was analyzed.Biochar increased the content of dissolved organic carbon(DOC)in the soil layer of 0 to 60 cm and increased the pH of the topsoil alone.Based on the EEM-PARAFAC analysis,three components of soil DOM(one protein-like component and two humic-like components)were identified.The addition of biochar increased the humic-like content in 0~60 cm soil profiles.Moreover,the unique polycyclic aromatic hydrocarbon structures originated from high temperature pyrolysis of biochar were also detected in soil DOM extracted with toluene/methanol in the 0~60 cm soil profiles,indicating that the biochar underwent a significant vertical migration within one year.In addition,the available Cd decreased in the topsoil with biochar addition but was 148%higher than that in the control group in the 20~60 cm soil profiles.These findings suggest that more attention should be paid to the possible risk of biochar during the remediation of metal-contaminated soils.