铅锌冶炼废渣堆场土壤重金属污染特征研究

Study of the Characteristics of Heavy Metal Pollution at Pb/Zn Smelting Slag Site

在铅锌冶炼过程中产生了大量含重金属的废渣,这些废渣未经有效处置堆放于空旷地,由于风化、淋洗等作用导致废渣中重金属进入废渣堆场及周边土壤中.采用野外取样调查、室内化学分析及污染评价等方法,研究了湖南某铅锌冶炼厂冶炼废渣堆场及周边土壤中重金属的含量和分布规律.研究结果表明：废渣堆场表层土壤中各重金属的质量分数分别为Pb1 889.60 mg·kg^-1、Zn 5 682.00 mg·kg^-1、Cd 48.40 mg·kg^-1 和Cu 1 848.60 mg·kg^-1,此值已超出国家规定的二级标准值（GB 15618─1995）,其中Pb 超出5.40 倍,Zn 超出18.94 倍,Cd 超出80.67 倍,Cu 超出18.49 倍.距渣场10 m 远处表层土壤中Pb、Zn、Cd 和Cu 的质量分数分别为641.01、1 509.61、38.45 和1 240.10 mg·kg^-1,10 m 远处表层土壤中Pb、Zn、Cd 和Cu 相对国家二级标准值的超标倍数分别为2.14、6.04、128.17 和12.40 倍.1 000 m 远处表层土壤中Pb、Zn、Cd 和Cu 的质量分数分别为309.80、685.71、8.81 和875.13 mg·kg^-1,1 000 m 远处表层土壤中Pb、Zn、Cd 和Cu 各超标1.03 倍、2.74 倍、29.33倍和8.75 倍.由此可见,废渣堆场周边土壤同样遭受重金属Pb、Zn、Cd 和Cu 不同程度的污染.纵向上,废渣堆场土壤重金属Pb、Zn、Cd 和Cu 在表层（0-20 cm）土壤中的质量分数均大于其在表层以下各土层中的质量分数,其中在40-60 cm土层中的质量分数又高于20-40,60-80 和80-100 cm 等土层,但其分布总体上呈现出随土层深度增加而减少的规律;横向上,废渣堆场各土壤剖层重金属Pb、Zn、Cd 和Cu 的质量分数均高于渣场外10 和1 000 m 远处各土层的质量分数,即土壤中重金属含量随距污染源距离的增加而逐渐减少.因此,冶炼废渣的大量堆置已使周围环境遭受了重金属的严重污染,相关部门有必要加强对冶炼废渣的处置和管理.

A large amount of slags rich in heavy metals had been produced during nonferrous smelting process. These smelting slags were directly piled and no recycling technology was used on them, thus heavy metals entered into the soil under the weathering and leaching of rain. Heavy metal content and distribution at or around Pb/Zn smelting slag site were studied applying sampling investigation, chemical analysis and assessment in the paper. The conclusion shows:The weight of Pb, Zn, Cd and Cu is 1 889.60, 5 682.00, 48.40 and 1 848.60 mg·kg-1 individually in the surface soil (0~20 cm) at Pb/Zn smelting slag site, the content is far beyond the national standard (GB 15618─1995), Pb content is 5.40 times of the national standard, Zn、Cd and Cu is 18.94, 80.67 and 18.49 times of the national standard individually. So heavy metals such as Pb, Zn, Cd and Cu are severely polluted the surface soil at Pb/Zn smelting slag site. At the site of 10 m far away from the slag field,the weight of Pb, Zn, Cd and Cu is 641.01, 1 509.61, 38.45 and 1 240.10 mg·kg-1 individually, which is 2.14, 6.04, 128.17 and 12.40 times of the national standard. Pb, Zn, Cd and Cu weight is individual 309.80, 685.71, 8.81 and 875.13 mg·kg-1 at the site of 1 000 m far away from the slag field, and Pb content is 1.03 times of the national standard, Zn is 2.74 times of the national standard, Cd is 29.33 times of the national standard, Cu is 8.75 times of the national standard. Thus the surface soil around Pb/Zn smelting slag site is also polluted inordinately. In vertical, the content of Pb, Zn, Cd and Cu decreased with the increasing of the soil depth, e.g. Pb, Zn, Cd and Cu content in the surface soil is higher than under the surface soil. In horizon, Pb, Zn, Cd and Cu content at Pb/Zn smelting slag site is higher than both 10 m far away from and 1 000 m far away from Pb/Zn smelting slag site. So with the increasing of the distance from pollution sources, Pb, Zn, Cd and Cu content is decreased. Smelting slags of stacking results in the pollution of environment so that it is necessary to strengthen the management and disposal of smelting slag.