赤泥及其复合钝化剂对土壤铅、镉和砷的稳定效应

Effects of red mud and the combinations on lead,cadmium,and arsenic availability in contaminated soil

采用土壤培育实验,研究赤泥、酸改性赤泥、沸石、石膏和硫酸亚铁及其复配对复合污染土壤铅、镉、砷有效性的影响。结果表明,赤泥经酸改性处理后铝、钙和铁进一步释放,表面结构发生变化;与对照相比,添加0.5%酸改性赤泥、赤泥与硫酸亚铁复配、酸改性赤泥与沸石复配后,土壤有效态铅含量分别降低1.96%~76.47%、4.94%~75.01%和5.47%~68.44%;加入0.5%酸改性赤泥、赤泥与硫酸亚铁复配后,土壤有效态镉含量分别降低27.78%和15.04%;赤泥与石膏复配和赤泥与硫酸亚铁复配处理降低土壤有效态砷含量效果优于其他钝化材料,培育7、15、30和60 d后砷有效态分别降低0.41%、37.87%、5.41%、3.72%和55.60%、13.81%、37.85%、25.36%;赤泥与硫酸亚铁复配对铅-镉-砷复合污染土壤重金属钝化效果最佳。

The soil incubation experiment was conducted to investigate the effects of red mud,acidmodified red mud,zeolite,gypsum,and ferrous sulfate each and their combinations on the available lead, cadmium, and arsenic concentrations in contaminated soils. The results are showed as follows. In the acid-modified red mud,aluminum,calcium,and iron atoms were further exposed with the changes of surface structures than in the red mud. Additions of 0. 5% acid-modified red mud,the combination of red mud and ferrous sulfate,and the combination of acid-modified red mud and zeolite decreased soil available lead contents by 1. 96% ~ 76. 47%,4. 94% ~ 75. 01%,and5. 47% ~ 68. 44%,respectively,during the incubation. Additions of the 0. 5% acid-modified red mud and the combination of red mud and ferrous sulfate decreased soil available cadmium concentrations with the maximal reductions of 27. 78% and 15. 04%,respectively. The combination of red mud and gypsum and the combination of red mud and ferrous sulfate were more effective than other amendments in reducing the available arsenic,with reductions of 0. 41%,37. 87%,5. 41%,and 3. 72% and 55. 60%,13. 81%,37. 85%,and 25. 36% in 7,15,30,and 60 incubation days,respectively. The overall effect of the combination of red mud and ferrous sulfate was the best for the immobilization of lead,cadmium,and arsenic in heavy metal contaminated soils.