莱芜市城区街道灰尘重金属含量及其健康风险评价

对莱芜市城区交通干道灰尘中重金属的污染特征及其基本理化性质进行了研究,分析了重金属元素的空间分布及其相关性,并对街道灰尘重金属的健康风险进行了评价.结果表明,街道灰尘中Hg,As,Cr,Pb,Zn和Cu的平均含量分别为0.170、11.7、60.6、52.9、96.3和30.3mg·kg~(-1),街道灰尘呈碱性,pH的平均值为9.40,有机质平均含量为54.06g·kg~(-1),街道灰尘中6种重金属的平均含量均符合土壤环境质量标准(GB 15618-1995)二级标准,除Cr外其他元素平均值均超过山东省土壤背景值.除Pb外,各元素含量均表现为从西向东降低的趋势;Cr、Zn和Cu两两之间具有显著的相关性,Hg和As与其他元素的相关性较弱;交通和工业生产可能是城区街道灰尘重金属的主要来源.健康风险评价的结果表明,不同暴露途径非致癌风险熵均由大到小表现为口摄入途径、皮肤接触途径、吸入途径,口摄入为城区街道灰尘暴露风险的主要途径;各重金属对于人体的非致癌风险由大到小表现为As,Cr,Pb,Cu,Hg,Zn,儿童的非致癌风险大于成人,但均小于风险阈值1;As和Cr形成的致癌风险较低.

Concentrations and health risk assessment of heavy metals in urban street dust of Laiwu City

The dust samples were collected from the main streets in the urban area of Laiwu City.Heavy metals concentrations and the basic physicochemical properties including the pH and organic matter content of street dust were analyzed.The spatial distribution and the correlation between the heavy metals concentrations and the basic physicochemical properties of street dust were discussed.Health risk assessment of heavy metals in the street dust was carried out.The results showed that the mean concentrations of Hg,As,Cr,Pb,Zn and Cu were 0.170,11.7,60.6,52.9,96.3 and 30.3 mg·kg-1 respectively.The street dust was mainly alkaline with the average pH value of 9.40.The organic matter content was 21.49-118.85 g·kg-1 with an average of 54.06 g·kg-1.The concentrations of heavy metals were all in accordance with the second class standard of soil environmental quality standard(GB15618-1995).The mean concentrations of heavy metals except Cr all exceeded the soil background values of Shandong province.Except for Pb,the spatial distribution of heavy metals in the urban area of Laiwu City showed a decreasing trend from the west area to the east area,reflecting the impact of human activity intensity.The significant correlations between Cr,Cu and Zn might suggest the two possible sources of heavy metals in urban street dust;one might be related to vehicle transportation,and the other might be industrial production.However,Hg and As had weak correlations with other heavy metals indicating they might mainly come from other pollution sources.The health risk assessment results showed that the ingestion was the main way contributing to the hazard quotients of heavy metals in urban street dust,followed by the dermal contact and inhalation way.The order of non-carcinogenic hazard risks of heavy metals was as follows:As,Cr,Pb,Cu,Hg,Zn.Non-carcinogenic hazard risks induced by the six heavy metals were higher to children than to adults;however,both of the non-carcinogenic hazard risk was less than the risk threshold i.e.one indicating the health hazard was low or neglectable.As and Cr have very low carcinogenic risk for people who live in the urban area of Laiwu City.