甘肃白银市大气颗粒物PM2.5的地球化学特征研究

Geochemical Characteristics of Atmospheric Particulate Matter from Baiyin City,Gansu Province

2011年8月,横跨白银市区东西向布设12个采样点,间距约1km,采集1.5m高大气颗粒物PM2.5样品,获得了白银市区大气中PM2.5浓度,并测定了大气颗粒物PM2.5中Ag、As、B、Ba、Be、Bi等几十种元素含量。结果发现12个采样点大气颗粒物PM2.5浓度范围为91～277μg/m3,均超过中国环境空气质量二级标准(GB 3095-2012),达二级标准限值(24小时平均值)的1.21～3.69倍。受尾矿堆放及选矿、冶炼企业集中分布的影响,东城区大气颗粒物PM2.5浓度高于工矿企业较少的西城区,污染较为严重。大气颗粒物PM2.5中微量元素浓度与污染源间具有良好的空间对应关系。采用富集系数法和主因子分析法研究大气颗粒物PM2.5元素组成特征,结果表明,白银市大气中PM2.5主要来源为工业废气、矿山与尾矿扬尘及土壤扬尘,三者的贡献率分别为31.2%、28.6%、26.4%。

In order to study the air quality, especially the PM2.5, 12 sample spots across Baiyin City from east to west were set to collect atmospheric particulates in August 2011. The distance from one to another spot is about 1 kilometer, and the sam- pling height is 1.5 meter. PM2.5 in the air over Baiyin City was calculated and about 60 kinds of elements such as Ag, As, and B were tested in the samples. The result showed that the PM2.5 concentrations are within the range of 91-277 μg/m3 at Baiy- in City, approximately 1.21-3.69 times the limit value for the grade two of ambient air quality standards （GB 3095-2012）. Higher PM2.5 was found in the east of Baiyin City than in the west because of more tailings piles and industrial emissions there. The element distribution in PM2.5 was well corresponding with the pollution source. The enrichment factors method and principle composition analysis were used for PM2.5 source analysis. The main pollution sources of PM2.5 at Baiyin City are; industrial waste gas, mine and railings dust, and soil dust, and there contributions are 31.18%, 28.6% and 26.4%, re- spectively.