张家口宣化区土壤和粉尘中重金属分布、来源解析与污染评价

为研究张家口市土壤和粉尘中重金属的污染状况,选择张家口宣化区为研究区,采集22个表土样、10个粉尘样,测试其中As、Hg、Cd、Pb、Zn、Cu和Ni 7种重金属的含量,采用多元统计方法探究了研究区土壤和粉尘中重金属污染的来源及空间分布特征,并对土壤和粉尘中重金属污染进行了评价。结果表明:在粉尘样中,重金属Zn含量的最大值达到了341.2 mg/kg,是农用地土壤污染风险筛选值的3.41倍,说明重金属Zn在燃煤企业周围粉尘中出现了一定的累积,而在表土样中,重金属Hg、Cd、Pb、Zn、Cu和Ni含量的平均值均大于当地土壤背景值,其中表土样中重金属Zn和Cu含量的最大值分别达到了718.8 mg/kg和151.7 mg/kg,是农用地土壤污染风险筛选值的1.52倍和2.40倍,说明重金属Zn、Cu在研究区表土中严重累积,重金属Cd、Pb和Hg在研究区表土中一定范围内累积;在粉尘样中,重金属Cd、Cu、Ni主要来源于汽车交通运输,重金属Zn、Pb、As、Hg主要来源于燃煤活动,而在表土样中,重金属Cd、Pb、Hg、Zn主要来源于交通、燃煤和污水灌溉,重金属As主要受土壤母质的影响;但土壤中重金属Zn在一定比例上处于轻度污染水平,总体上研究区土壤处于安全水平。

Distribution,Source Analysis and Pollution Assessment of Heavy Metals in Xuanhua District of Zhangjiakou City

To study the heavy metal pollution in Zhangjiakou City,this paper collects 22 samples from surface soils and 10 samples from dusts in Xuanhua District,Zhangjiakou City,and determines the contents of 7 heavy metals including As,Hg,Cd,Pb,Zn,Cu and Ni.The paper applies multivariate analysis to researching the sources and spatial distribution of heavy metals in soil and dust,and assesses the pollution of heavy metals.The maximum concentration of Zn which is 3.41 times of risk intervention values for soil contamination of agricultural land reaches 341.2 mg/kg in dust,and the accumulation of Zn appears around coal-fired industry.The average concentrations of Hg,Cd,Pb,Zn,Cu and Ni in soils are higher than the background ones of Zhangjiakou.The maximum values of Zn and Cu which are1.52,2.40 times of risk intervention values for soil contamination of agricultural land reach 718.8 mg/kg and 151.7 mg/kg,indicating the serious accumulation of Zn and Cu in soil,and accumulation of Cd,Pb and Hg in certain range of the study area.The results show that Cd,Cu,Ni in dust mainly come from traffic,and Zn,Pb,As.Hg from coal combustion.Cd,Pb,Hg,Zn in soil are from traffic,coal combustion and wastewater irrigation.As in soil is affected by soil parent materials.In general,the study area is at a safe level,in which zinc is at a slight pollution level in a certain proportion,while other heavy metal elements are not polluted.