废弃泡沫混凝土对土壤中镉、砷的赋存形态和油麦菜吸收特征的影响

Effects of waste foam concrete on the passivation of cadmium and arsenic in soil and the total amount of plant enrichment

以废弃泡沫混凝土为原料制备土壤重金属钝化剂,矿山土壤添加钝化剂后进行盆栽实验,探索在不同钝化剂用量下土壤中镉、砷的形态比例变化,以及镉、砷在土壤-油麦菜介质中迁移转化.实验表明,泡沫混凝土中含有大量碳酸盐等水泥水化产物,并含有Fe、Al等元素.随着钝化剂添加量的增大,土壤中镉的交换态比例由97%降至55%,主要转化为碳酸盐态、铁锰氧化态及腐植酸态.油麦菜干重中的镉含量由4.12 mg·kg^-1降至2.15 mg·kg^-1,土壤中砷的腐植酸态比例由33%降至24%,转化为铁锰氧化态及离子交换态.油麦菜中砷含量由0.07 mg·kg^-1提至0.13 mg·kg^-1.研究结果显示废弃泡沫混凝土对土壤中的镉具有一定的钝化作用,可降低植物对土壤中镉的吸收.

Soil samples were collected from the mine soil and planted as lettuce as a hyperaccumulator.Pot experiments were conducted to explore the change of the proportion of cadmium and arsenic in soil and the difference of migration and transformation in soil lettuce.The results show that foam concrete contains a large amount of carbonate and cement hydration products,and contains Fe,Al and other elements.With the increase of the amount of passivator,the ion exchange state of Cd in soil decreased from 97%to 55%,and it was transformed into carbonate state,iron manganese oxide state and humic acid state.The content of Cd in the dry weight of lettuce decreased from 4.12 mg·kg^-1 to 2.15 mg·kg^-1,and the proportion of humic acid state of As in the soil decreased from 33%to 24%,which was transformed into iron manganese oxidation state and ion exchange state.The content of As in the dry weight of lettuce increased from 0.07 mg·kg^-1 to 0.13 mg·kg^-1.Therefore,the waste foam concrete has a certain passivation effect on heavy metals in the soil,which can reduce the migration ability of heavy metals from soil to plants.