徽县铅锌冶炼区土壤中重金属的空间分布特征

采集甘肃省徽县铅锌冶炼区域土壤样品,分析该区域内重金属污染分布规律及污染特征。结果表明,表层土壤中Pb、Cd、Cu、Zn的平均含量分别为214、3.12、25.8、79.5 mg/kg。研究区域内重金属的分布特征显示,污染浓度由冶炼厂中心向四周递减。纵向0~30 cm范围内重金属含量逐渐降低,大部分重金属污染物集中在土壤表层的0~20 cm区域,其中0~2 cm区域内含量较高,Pb和Cd的最高含量分别达到3 877、24.8 mg/kg,与国家土壤环境质量二级标准(p H 6.5~7.5)(GB 15618—1995)相比,分别超标13、82倍,属于重度污染。重金属元素的分布与土壤有机碳含量及p H相关。冶炼厂周围的重金属污染应引起有关部门的高度重视,严格控制污染源,尽快采取措施以防止污染范围进一步扩大。

Study on Transformation of Heavy Metal in Soil from Typical Pb-Zn Smelting Areas

Contamination of trace metals was evaluated in the soil samples collected from Huixian lead-zinc smelting areas, Northwest of China. The results indicated that soil samples from the arable lands surrounding the smelting sites contained high contents of Cd, and Pb. The concentrations of Pb, Cd, Cu and Zn were 214, 3.12, 25.8, 79.5 mg/kg, they were higher than that of element background values in soils of Gansu province and China. The concentrations of heavy metals in topsoil showed a trend in an order: Pb >Zn >Cd >Cu, and heavy metals contents decreased with distance from smelter, moreover, the concentrations of heavy metals was decreased with the depth of soil. High concentrations of Pb, Zn, Cu and Cd were found in many samples taken from surrounding arable lands, indicating a certain extent of spreading of trace metal pollution. The correlation between heavy metals and phys-chemical characteristics showed that Pb, Cd, Cu and Zn were mainly affected by parent rock. The organic matter content was significantly positive correlated with Pb, Cd, Cu, and Zn, however, the pH value was less correlated with the heavy metals. In this study, it can be seen that Pb and Cd pose a potential risk to the local inhabitants. Consequently, some effective measures may be necessary to handle with trace metal contamination in soil.