宝鸡市城区灰尘重金属空间分布、来源及健康风险

通过对宝鸡市城区灰尘中Pb、Zn、Cu、Cr、Ni、Co、Cd、As 8种重金属元素含量的测定,采用GIS空间分析、人群健康风险评价方法,对元素含量、空间分布及健康风险进行研究与评估,并借助富集因子法、多元统计分析识别重金属元素的来源。结果表明,宝鸡市城区地表灰尘重金属Cd、Zn、Cu、As含量分别为陕西省背景值的19. 47、4. 77、3. 10和2. 97倍。元素Cd、Zn、Cu的空间分布特征较为相似,高值区出现在车流量极大的市政府以西和代家湾周围; Ni、Cr分别在任家湾火车站、马营镇和虢镇地区出现高值;在陈仓大道东段向北至千河镇的大部分区域,因其种植园施肥及工业污染物排放,出现了As的高值区。健康风险总体较小,致癌重金属风险值均小于10-6,非致癌风险值均小于1。儿童所受非致癌风险大于成人,手-口接触是其主要暴露途径。从空间分布特征来看,人群健康风险指数在城区西部老工业区偏高,低值区出现在东风路、金台大道及滨河公园一带。相关分析、因子分析表明宝鸡市灰尘中重金属主要有3个来源:Zn、Cd、Cu主要源自交通污染; As、Ni、Co源于汽车零部件生产、土壤母质和农药化肥施用的复合污染; Cr主要来源于工业活动。

Distribution, Sources and Health Risk Assessment of Heavy Metals in Dusts of the Urban Area of the Baoji City

The spatial distributions, health risks and sources of trace elements, including Pb, Zn, Cu, Cr, Ni, Co, Cd and As, in dusts of the Baoji City were analyzed by methods of GIS analysis, USEPA health risk assessment model, enrichment factor and multivariate statistical analysis, respectively. It was found that contents of Cd, Zn, Cu and As in dusts of the Baoji city were 19.47, 4.77, 3.10 and 2.97 times bigger than their background values of the Shaanxi province, respectively. The spatial distributions of Cd, Cu and Zn were similar, their high concentration areas were heavy traffic zones like the west of the municipal government and around the Daijiawan district. The high concentration areas of Ni and Cr were the Renjiawan railway station and the Maying Town. The high concentration areas of As were from the east section of the Chencang Avenue to the Qianhe Town, where fertilization and industrial emissions were high. The risk assessment results showed that the risk index of non-carcinogenic elements was less than 10^-6 and the risk index of carcinogenic elements was less than 1, and the non-carcinogenic risk was higher for children than for adults. The health risk index was high at old industrial areas and was low at areas of Dongfeng road, Jintai avenue and Binhe park. The factor and correlation analysis indicated three main sources for heavy metals in dusts of the Baoji city, Zn, Cd and Cu were mainly originated from the traffic pollution, As, Ni and Co were from pollutions of production of automobile parts, palaeosol and applications of pesticide and fertilizer, and Cr was mainly came from industrial activities.