地球化学工程技术修复江西某Pb超标耕地的应用

摘要

For the purpose of determination of the effect of geochemical materials in soil improvement and heavy metal remediation, three remediation methods were used on a 249 m2 abandoned land in Longnan area of Jiangxi province, where farmland was abandoned due to wastewater pollution from rare earth mining. The technical effectiveness of these three methods was evaluated after one cycle of comparing changes of the easy-migrate-speciation of heavy metals in the soil before and after remediation. The results showed that the element of highest degree of excess was Pb with the amount of 101.50 mg·kg-1, followed by Cd (0.13 mg·kg-1), Hg (0.13 mg·kg-1) and As (2.98 mg·kg-1) which all exceeded the background value of soil in Ganzhou, Longnan. Pb, which exceeded the average soil Pb content in Longnan, was selected as the remediation target. In the soil of this area, the content of available Pb was not significantly correlated with the total amount. Using geochemical engineering technology, the authors detected that the treatment effect was obvious, as shown by the fact that the easy-migrate-speciation of Pb decreased by 3.25%. After one cycle, the repair effect was stable with reduction of Pb easy-migrate-speciation by 1.40% on average. Method C is considered to be the best solution with the reduction of Pb by 3.38 mg·kg-1, and its cost is the cheapest.%为了判别地球化学材料在土壤改良与重金属修复中的作用,本研究以江西龙南某地被稀土采矿废水污染而废弃的农耕地为对象,用黏土矿物等材料组成的三种修复方案对249 km2的废弃地进行修复.一周期后,比较修复前后土壤中重金属生物易迁移态的变化来评价该技术的有效性.结果表明,该地Pb超标程度最重,达101.50 mg·kg-1.Cd、Hg、As次之,分别为0.13 mg·kg-1、0.13 mg·kg-1、2.98 mg·kg-1,均超赣州市土壤背景值含量,超龙南地区土壤Pb的均值,修复目标为Pb.该地土壤中Pb的易迁移态含量与总量不显著相关.经地球化学工程技术修复后,Pb易迁移态降低了3.25%,修复效果明显.一周期后,Pb的易迁移态平均降幅为1.40%,修复效果稳定.修复效果最佳的方案C能使Pb降低幅度达到3.38 mg·kg-1,在经济上体现为最廉价,体现了地球化学工程技术的优势.