金矿区高浓度砷污染土壤的稳定化处理

Stabilization treatment of high concentration of As contaminated soils from gold mining area

以粉煤灰、干化污泥、粉碎花生壳、硫酸亚铁(Fe_2SO_4)和磷酸二氢钾(KH_2PO_4)为稳定剂对矿区高浓度As污染土壤进行处理,通过土壤理化性质、重金属形态和浸出浓度变化等综合评估稳定剂对高浓度砷污染土壤的稳定化处理效果。结果表明,添加稳定剂可以提高土壤pH值、有机质含量和阳离子交换量。粉煤灰、干化污泥、粉碎花生壳、硫酸亚铁对土壤中的As有较好的稳定化作用,其中硫酸亚铁对土壤中As的稳定效果最好。同时添加10%粉煤灰、10%干化污泥和1%硫酸亚铁后,土壤中可交换态As、碳酸盐结合态As、铁锰氧化物结合态As、有机结合态As含量显著降低,降幅分别为62.3%、55.2%、29.6%、58.2%,残渣态As含量增加8.1%。添加粉煤灰、干化污泥、硫酸亚铁能显著降低土壤中As的浸出浓度,而添加KH_2PO_4会使土壤中As浸出浓度增加,移动性增强。当同时添加10%粉煤灰、10%干化污泥、1%粉碎花生壳和1%硫酸亚铁后,As浸出浓度最低(0.93 mg·L^(-1)),稳定效果最好,稳定化效率达到了74.8%。土壤中As的浸出浓度与可交换态As和碳酸盐结合态As呈显著正相关,与残渣态As呈显著负相关,可交换态As、碳酸盐结合态As和残渣态-As含量是影响土壤中As浸出浓度变化的主要因素。

In this paper,the fly ash,dried sludge,crushed peanut shells,ferrous sulfate（ Fe2SO4） and potassium dihydrogen phosphate（ KH2PO4） were chosen as stabilizers for stabilization of the high concentrations of As contaminated soil. The effect of stabilizing treatment on high concentrations of As contaminated soil analyzed by changes of soil physical and chemical properties,morphological of As and leaching concentration. The results showed that adding stabilizers could increase soil pH,organic matter content and cation exchange capacity. Fly ash,dried sludge,crushed peanut shells,ferrous sulfate have good stabilization effect to the As,make its transformation from the higher activity,migration patterns of strong to low activity,high stability of the forms,in which ferrous sulfate had the highest stabilization effect. When the addition of 10% fly ash,10% crushed dried sludge and 1% ferrous sulfate,the concentration of EXC-As,CA-As,Fe Mn Ox-As,OM-As were significantly reduced,the decline of 62. 3%,55. 2%,29. 6% and 58. 2% respectively,and RES-As increased by 8. 1%. Adding fly ash,crushed dried sludge,ferrous sulfate can significantly reduce the leaching of As concentration in soil,while adding KH2PO4 will increase the leaching concentration and mobility of As. After added 10% fly ash,10% crushed dried sludge,1% crushed peanut shells and 1% ferrous sulfate,the leaching concentration of As was 0. 93 mg ·L-1,which was the lowest,and the stabilization efficiency reached 74. 8%. The leaching concentration of As had a significant positive correlation with the concentration of EXC-As,CA-As,while had a significant negative correlation with the concentration of RES-As,and they were the main factors affecting the change of As leaching concentration.