含铜堆肥施用对红壤及地下水的污染机理研究

Pollution Mechanism of Copper Transported from Compost to Red Soil and Groundwater

城市生活垃圾、畜禽粪便等堆肥原料的重金属污染问题已经非常普遍.因此,研究重金属污染堆肥对土壤及地下水的污染有重要的意义.本文选取了我国南方广泛分布的旱地红壤为供试材料,通过室内土柱模拟降雨实验,探讨不同程度Cu污染堆肥施用到红壤后在土壤中的迁移规律及对地下水的污染机理,揭示堆肥中的Cu在红壤各土层中的形态分布,以及铜的迁移与渗滤液的pH、电导率、可溶性有机质等之间的关系.实验结果表明:在实验8 h时逐渐有Cu随渗滤液流出,在11 h时Cu浓度达到0.015 mg/kg左右.随着Cu在土柱中的迁移,渗滤液pH呈下降趋势,且堆肥中铜的浓度越高,渗滤液pH值下降越大.Cu污染堆肥处理比对照处理的渗滤液中DOM最大浓度渗出时间提前2 h.在模拟降雨完成后,Tessier法测定土柱中的Cu形态在表层、次表层、深层土壤中所占的百分比结果表明:铜在各层中主要以相对稳定的残渣态存在,可交换态、铁锰结合态向有机结合态转化,高铜污染堆肥处理的碳酸盐结合态、有机结合态所占比例比低铜污染堆肥处理的高,且随着土柱的深度而增加.

Abstract： It was very popular of compost materials polluted by heavy metal in municipal solid waste or ani- mal manure. It was important to study the pollution of soil and groundwater by the application of heavy metal polluted compost. In this paper, dryland red soil, widely distributed in South China, was selected to study the pollution mechanism of copper transported from compost to red soil and groundwater in soil column condition. The paper aimed at revealing the heavy metal formation in red soil, the migration of copper from soil column and the relationships of heavy metal concentration in soil or filtrate, pH, electrical conductivity （EC） and dissolved organic matter （DOM） in leachate. Results showed that leaching of Cu from soil columns began at 8th hour and reached a peak of 0. 015 mg/kg at llth hour. pH decreased with the migration of copper in the water phase, pH was lower in treatment with higher concentration of copper than in treatment with lower concentration of copper. The highest concentration d DOM in leachate occurred 2 h earlier in treatment with copper than in control. After simulated rainfall, Tessier method was used to determine the residue of five copper formations in the surface layer, middle layer and deep layer. Residual formation was the main component of copper. Formations of exchangeable and bound to iron and manganese oxides were transformed to formation bound to organic matter. Formation bound to organic matter increased with the increase of copper in compost, and increased with the soil column depth.