铅锌冶炼厂渣堆场周边土壤铅污染特征

金属冶炼过程留下的废渣经过雨水冲刷及渗滤液等的作用使残留在废渣中的重金属发生迁移转化，导致渣堆场下及周边土壤受到重金属污染。了解冶炼厂渣堆场下及周边土壤重金属污染状况对场地修复及土地利用规划均有重大意义。本研究调查了湖南某铅锌冶炼厂渣堆场0~4 km内三个采样区0~20 cm表层土壤及0~100 cm深度土壤中铅的污染状况，采用单项污染指数法进行铅污染评价，并分析了铅纵向迁移随深度变化和横向迁移随距离变化的分布特征。结果表明，铅锌冶炼厂渣堆场下及周边0~1 km范围内土壤受到了铅污染，渣堆场下、距渣堆场10 m处及1 km处表层土壤中重金属铅的质量分数分别可达775.25、645.33和309.80 mg·kg^-1，超过了当地土壤中铅的背景值，也超过了土壤二级质量标准甚至三级质量标准。三个采样区的铅污染指数分别为2.6、2.1及1.03，污染等级均为Ⅱ级，污染程度为轻度污染。三个采样区土壤中铅污染主要集中于0~20 cm土壤层中，铅的质量分数分别达775.25，645.33和309.80 mg·kg^-1，20~100 cm土壤层中铅的质量分数低于0~20 cm的，分别在88.48~120.96 mg·kg-1、235.01~380.16 mg·kg^-1及309.80~59.32 mg·kg^-1之间。渣堆场下土壤中的铅从0~20cm土壤层往下至20~100cm土壤层迁移量远小于距渣场10 m处及1 km处的。三个采样区表层0~20 cm土壤层中铅的变化规律为距渣堆场0 m（渣堆场下）〉距渣堆场10 m〉距渣堆场1 km〉距渣堆场4 km，质量分数随距离增加而降低。20~40 cm及40~60 cm土壤层中铅的变化规律为距渣堆场10 m〉距渣堆场1 km〉距渣堆场0 m处（渣堆场下）〉距渣堆场4 km，60~80 cm及80~100 cm土壤层的变化规律为距渣堆场10 m〉距渣堆场0 m处（渣堆场下）〉距渣堆场1 km〉距渣堆场4 km，铅的质量分数随距离的增加先升高后降低。

The Characteristics of lead pollution in the soil around the slag yard in lead and zinc smeltery

The soils around the slag yard in smeltery are contaminated by heavy metals which in smelting waste are transfered and transformed by rain washing and filtrating. Survey the soil contamination characteristics has great significance to remediation and utilization. Lead pollution in the soil around the slag yard in lead and zinc smeltery in hunan province was surveyed. The survey fields include the 0~100 cm depths soil in the range of 0 to 4 km distance from the slag yard. Lead pollution was assessed by the single pollution index method. The distribution characteristics of lead pollution changing with the level distance and the vertical distance were analyzed. The result indicates that the soil in the range of 0 to 1 km distance from the slag yard is polluted by lead, The lead concentrations in the soil under the slag yard, 10 m and 1 km from the slag yard reached 775.25, 645.33 and 309.80 mg·kg^-1. The concentrations were much higher then the values of the soil background and also much higher than the values of soil quality standard of grade two and three. The lead pollution indexes in the three sampling regions are 2.6, 2.1 and 1.03. The pollution levels are all grade Ⅱ, those belong to light pollution. In the three sampling regions, the lead concentrate in the 0~20 cm depths soil layers, the lead mass fraction reached 775.25, 645.33 and 309.80 mg·kg-1, respectively. The lead in the 20~100 cm depth soil layer are less than those in the 20~100 cm depth soil layer, the lead mass fraction are only about 88.48~120.96, 235.01~380.16 and 309.80~59.32 mg·kg^-1. The lead transport quantities from 0~20 cm depth soil layer to the 20~100 cm depth soil layer under the slag yard are much less than those in 10 m and 1 km distance from the slag yard. The lead mass fractions of the 0~20 cm depth soil layer in the three sampling regions reduce with the increasing distance, the change law is 0 m distance from the slag yard（under the slag yard）〉10 m distance from the slag yard〉1 km distance from the slag yard〉4 km distance from the slag yard. The lead mass fractions of 20~40 cm and 40~60 cm depth soil layer increase firstly and then reduce, the change law is 10 m distance from the slag yard 〉 1 km distance from the slag yard〉0 m （under the slag yard） distance from the slag yard〉4 km distance from the slag yard. The lead mass fractions of 60~80 cm and 80~100 cm increase firstly and then reduce with the increasing distance, the change law is 10 m distance from the slag yard〉0 m distance from the slag yard （under the slag yard）〉1 km distance from the slag yard〉4 km distance from the slag yard.