开封周边地区地表灰尘砷、汞背景值及其应用

Background Values of As and Hg in Surface Dusts in the Vicinity of Kaifeng City and Their Application

在开封市周边地区采集96个地表灰尘样品和49个表土样品,用冷原子荧光法测定样品As、Hg含量,计算灰尘和土壤As、Hg背景值,并以开封城市地表灰尘为例,用地积累指数法(Igeo)和污染负荷指数法(PLI)分别开展基于灰尘和土壤背景值的污染评价.结果表明,开封市附近地区地表灰尘As、Hg背景值分别为8.04 mg·kg-1和22.37μg·kg-1,低于其土壤背景值,也低于我国潮土背景值.同一地区灰尘As、Hg背景值小于土壤,这主要与灰尘和土壤的有机质含量、颗粒大小、农业生产活动有关.基于灰尘背景值的开封城市地表灰尘As、Hg的Igeo和PLI,都大于基于我国潮土背景值的Igeo和PLI.因此,多数学者应用我国潮土背景值开展灰尘污染评价,其污染程度实质上被低估了.

Ninety-six surface dust samples and forty-nine topsoil samples were collected from the vicinity of Kaifeng. Concentrations of As and Hg were determined by cold vapor atom fluorescence spectrometry（AFS） and then the background values of As and Hg were calculated. Geoaccumulation Index（Igeo） and Pollution Load Index（PLI） were used to evaluate the pollution degrees of the surface dust in Kaifeng City based on the background values in dust and soil. The results showed that the background values of As and Hg in surface dust were 8. 04 mg·kg^-1and 22. 37 μg·kg^-1,respectively,lower than those in soil,mainly related to organic matter content,particle sizes and the influence of agricultural activities,and also lower than those in fluvo-aquic soil of China. The values of Igeoand PLI in urban dust of Kaifeng based on the dust background values of the investigation area were higher than those based on the fluvoaquic soil background values of China. Therefore,the pollution degree of dust with heavy metals was actually underestimated if the assessment was based on the fluvo-aquic soil background value.