煤矸石土壤重金属污染对3种叶菜食用安全性的影响初探

Effect of the heavy metal pollution in gangue soil on food security of three leafy vegetables

按照广东土壤背景值和国家土壤环境二级标准,采用单因子污染指数法、内梅罗综合污染指数法和潜在生态危害指数法评价明山煤矸石粉与黄土混合而成的5种不同比例的土壤的污染程度和潜在生态危害,结果表明：5种土壤的Zn、Cu、Cd、Mn4种重金属含量均较高,且含量从高到低依次为Mn〉Zn〉Cu〉Cd,Pb未达原子吸收光谱仪的检测限;煤矸石所占比例越大,4种重金属含量越高。单因子污染指数和综合污染指数指数大小排序为Cd〉Zn〉Cu,潜在生态风险指数排序为Cd〉Cu〉Zn,说明Cd是主要的土壤污染因子和生态风险因子;Mn含量超过土壤中Mn含量的适中标准值170~1 200 mg/kg。5种比例土壤均未达到种植食用作物的要求。5种混合土壤所种植的3种叶菜中,叶中Pb含量未达原子吸收光谱仪的检测限,Zn、Cu、Cd、Mn 4种重金属含量在绝大多数样品中均超过它们在作物中的限量标准值,且单因子污染指数和综合污染指数多数均在重污染水平,Cd是主要的污染元素。

Based on Guangdong soil background value and the national grade-two standard of soil environment,the contamination extent and potential ecological risk of five kinds of soil mixed with different proportions of coal gangue powder and loess in Mingshan were evaluate by the method of single-factor pollution index,Nemerow pollution index and potential ecological risk index.The results showed that： the heavy metal contents of Zn,Cu,Cd and Mn were high relatively in the five kinds of soil mixtures with MnZnCuCd,while the content of Pb was below the detection limit of atomic absorption spectrometer.The greater the proportion of coal gangue was,the higher the contents of the 4 kinds of heavy metals would be.The single-factor pollution index,Nemerow pollution index and potential ecological risk index were ranked as follows： CdZnCu,CdZnCu and CdCuZn,respectively,which suggested that Cd was the main soil pollution factor and ecological risk factor;the content of Mn in these soil mixtures exceeded the moderate standard amount of 170~1 200 mg/kg in soil.Therefore,the soil mixtures in the trials were not suitable for cultivating edible crops.In addition,the content of Pb in 3 kind of leafy vegetables grown in the mixed soils was lower than the detection limit of atomic absorption spectrometer,and the heavy metal content of Zn,Cu,Cd and Mn in most samples were above the limit standard of crops,which indicated that the single-factor and integrated pollution index reached severe pollution level,and Cd was the main pollution element.