西北典型工矿型绿洲土壤重金属污染及健康风险评价

The Soil Heavy Metal Pollution and Health Risk Assessment in Typical Industrial and Mining Oases in Northwest China

对白银市不同区域土壤中主要的重金属污染物进行采样分析,结果表明矿区土壤重金属含量最高,东大沟和西大沟污水灌溉区土壤重金属含量也显著高于甘肃省土壤背景值。地质积累指数结果表明,矿区、西大沟和东大沟区域土壤受铜、铅、锌三种重金属中度至重度污染的占比较高,而五个区域土壤样品中镉的I_(geo)值均较高。化学连续提取结合铅同位素组成的分析结果表明白银地区有色金属采矿、冶炼活动所释放进入土壤的重金属其活性较高,可能通过食物链进入人体内,存在较高的生态风险。不同区域土壤中重金属的非致癌风险为矿区>东大沟>西大沟>东大沟与西大沟之间>黄河水灌溉区,铅是当地居民非致癌风险的主要贡献者。矿区的HI值>1,为3.12,其余区域均小于1,说明矿区土壤中的重金属对儿童存在较高的非癌症健康风险,而其余四个区域可能不会对儿童造成重大的非癌症健康风险。

In this paper,the main heavy metal pollutants in soils in different regions of Baiyin City were sampled and analyzed.Results showed that the soil heavy metal contents in mining area was the highest,the soil heavy metal contents in Dongdagou and Xidagou sewage irrigation area was also significantly higher than the background value of Gansu soil.The results of index of geo-accumulation(I_(geo))showed that the soils in the ore district,Xidagou and Dongdagou were heavily polluted by Cu,Pb and Zn,and the I geo values of Cd in the soil samples from that five regions were all high.The analysis results of chemical sequential extraction combined with Pb isotopic compositions show that the heavy metals released into the soil by nonferrous metal mining and smelting activities in Baiyin area have high activity,which may enter the human body through the food chain,with high ecological risk.The non-carcinogenic risk of heavy metals in soil of different regions in Baiyin in order to sort as follow:ore district>Dongdagou>Xidagou>Area between Dongdagou and Xidagou>Yellow River irrigation area,and Pb is the main contributor to the non-carcinogenic risk of local residents.The HI value in the mining area is 3.12 which is greater than 1,while that values all less than 1 in the other areas,indicating that heavy metals in the soil of the ore district pose a high non-cancer health risk to children,while the other four areas may not pose a significant non-cancer health risk to children.