高架道路周边建筑物灰尘重金属污染风险:以常州市为例

在常州环城高架道路两侧6个住宅小区不同楼层采集126个灰尘样品,测定Cu、Zn、Pb、Cd、Ni和Cr含量,分析其化学形态和垂直分布特征,采用富集系数和风险评价指数评价其污染程度和生物有效性,并进行潜在生态风险评价和健康风险评价.结果表明,灰尘中Cu、Zn、Pb、Cd、Ni和Cr含量均值分别为181.95、709.99、211.24、2.76、101.59和257.55mg·kg-1,均远大于背景值.灰尘中Cd的富集系数为33.05,富集程度为强烈,Cu、Pb和Zn的富集程度为显著富集,它们可能受到自然源、交通源和区域废气传输的综合影响,Ni和Cr富集系数较低,可能主要受自然源影响.随楼层高度的上升,Cd含量呈增加趋势,Pb和Zn含量呈先增加后降低趋势,Cu含量无显著变化.Zn、Cd、Cu和Pb主要以活性态存在,生物有效性较高,Ni和Cr以残渣态为主,生物有效性较低.改进的潜在生态风险评价结果表明,Cd的潜在生态风险极高,对多元素的潜在生态风险起主导作用,且对高层楼的潜在生态风险较大,其它重金属潜在生态风险为中低级.健康风险评价结果表明,Cr对儿童的致癌风险超过安全阈值,其它重金属对成人与儿童致癌风险及非致癌风险均在安全域之内.

Pollution Risk of Heavy Metals in Dust from the Building Along Elevated Road: A Case Study in Changzhou

Totally 126 samples of windowsill dust were collected from different floors along elevated road in Changzhou. The concentrations of Cu, Zn, Pb, Cd, Ni and Cr were determined, and the vertical distribution and chemical speciation were analyzed. The enrichment factor, bioaccessiblity, potential ecological risk and health risk were evaluated. The results showed that the average contents of Cu, Zn, Pb, Cd, Ni and Cu were 181.95, 709.99, 211.24, 2.76, 101.59 and 257.55 mg·kg^-1 respectively, which were all higher than the background value. The enrichment factor of Cd was 33.05, with enrichment degree of strongly enriched. The enrichment degrees of Cu, Pb and Zn were all significantly enriched. These four heavy metals may come not only from transportation source, but also from natural source and regional industrial polluted gas. The enrichment factors of Ni and Cr were low, which may result from natural source. With the elevation of house height, the concentration of Cd increased, the concentrations of Pb and Zn increased first and then decreased, while Cu showed no significant differences. Zn, Cd, Cu and Pb mainly existed in the active form, while Ni and Cr mainly existed in the residual form. The bioaccessiblity of Zn and Cd was high, while that of other heavy metals was low. The modified potential ecology risk evaluation results showed that the risk of Cd was extremely high, and contributed mainly to the potential risk index of multi-element. The Cd from the windowsill of high height showed higher potential ecological risk. The carcinogenic risk of Cr to children was higher than the threshold value, while the carcinogenic risk and non-carcinogenic risk of other metals to children and adults were all below the safety thresholds.