大同市矿区中学地表灰尘重金属粒级效应及健康风险评估

Particle Size Distribution and Health Risk Assessment of Heavy Metal of Surface Dust in Middle School of Mining District in Datong City

以大同市矿区6所中学的地表灰尘样品为研究对象,分析不分粒径的混合样品中Pb、Cd、Cu和Zn的总量,并分别测定其>0.25mm,0.25～0.15mm,<0.15mm团聚体中4种重金属含量,采用EF法和HI法探讨灰尘重金属富集特征和评估中学生的健康风险。结果表明,灰尘中Cu、Zn、Pb和Cd含量的平均值分别为74.67,401.19,68.16,9.46mg/kg,均超过山西省土壤背景值及全国表层土壤背景值;Cu、Zn主要富集在粗颗粒中,而Pd和Cd在不同粒级上的富集无明显差别,4种重金属在不同粒级中富集的质量百分数均不相同;手-口摄入灰尘是重金属暴露的主要途径,4种重金属的健康风险大小顺序为Cu>Pb>Cd>Zn,大同市矿区不同功能区的6所中学的地表灰尘均不存在重金属健康风险。

Samples of surface dust of 6 middle schools were collected from mining district in Datong city, the content of Pb, Cd, Cu and Zn in samples of different particle sizes（〉0.25 ram, 0. 15-0.25 mm, 〈0. 15 mm） and multi-particle-size were assayed. The enrichment characteristics and healthy risk of heavy metals in the surface dust were investigated by means of enrichment factor and HI procedures, and the derivations of heavy metals were tracked via the methods of enrichment factor. The results showed that the average contents of Pb, Cd, Cu and Zn in the surface dust were 68.16, 9.46, 74.67, 401.19 mg/kg, respectively. Cu and Zn usually accumulated affluently in larger coarse particles, while contents of Pb and Cd fluctuated inconspicuously in all particles. The rank of the mass percents of heavy metals in different particle size fractions was coarse particle size（〉0.25 mm） 〉medium particle size（0.15-0.25 mm） 〉fine particle size （〈0.15 mm）. The abundance of Cd in surface dust justified that its origin was from the artificial source, to the contrary, Pb, Cu and Zn accumulated from the natural source. The value of HI was less than 1, which indicated that the health risk of heavy metal in surface dust should be ignored for the researching area.