北京市冬季大气PM_(2.5)中多氯联苯的污染水平与分布

2008年1月同时采集了北京市市区/交通干道(中国地质大学(北京)东门及测试楼顶)、工业区(首钢集团焦化厂、高井热电厂)和背景点(十三陵)大气颗粒物PM2.5样品。依据US EPA1668A方法,采用同位素稀释、高分辨率气相色谱/高分辨率质谱(HRGC/MS)联用技术,对比分析了PM2.5中19种多氯联苯(PCBs)的质量浓度、分布特征及来源。结果表明,5个采样点PM2.5的质量浓度范围为101.85~145.57μg/m3,日均值为119μg/m3,比美国1997年制定的日均标准(65μg/m3)高83%,属严重污染。PM2.5中∑PCBs的质量浓度和毒性当量(TEQ)分别为7.2~16.2 pg/m3(平均值10.9 pg/m3)、8.29~17.81 fgWHO-TEQ/m3(平均值13.58 fgWHO-TEQ/m3),与其他国家和地区比较,北京市大气PCBs的污染处于较低水平。PCBs最高浓度出现在工业区,其次是市区,背景点最低,化石燃料的不完全燃烧是北京市PCBs的主要来源。研究成果将为北京市大气环境中持久性有机污染物(POPs)的污染防治提供科学依据。

Pollution Level and Spatial Distribution of Polychlorinated Biphenyls from Atmospheric Matter PM2.5 in Beijing

In January 2008,PM2.5 was sampled concurrently at five contrasting sites: two urban sites(the east gate of China University of Geosciences(CUGB)and the roof of a testing building within CUGB),two industrial sites(coking plant of Capital Steel Plant and a thermoelectric plant),and a background site(Ming Tombs) in Beijing,China.The concentration and spatial distribution of 19 polychlorinated biphenyls(PCBs) congeners were analyzed with isotope dilution and high resolution gas chromatography/high resolution mass spectrometry(HRGS/HRMS) based on US EPA 1668A method.PM2.5 concentrations were in the range of 101.85-145.57 μg/m3 with mean value of 119 μg/m3,which was 83% higher than the US daily average standard(65 μg/m3),suggesting the atmospheric PM2.5 pollution is very serious in Beijing city.∑19PCBs and ∑TEQ concentrations varied from 7.2-16.2 pg/m3 and 8.29-17.81 fgWHO-TEQ/m3,respectively,with an average concentration of 10.9 pg/m3 and 13.58 fgWHO-TEQ/m3.PCBs levels were lower in Beijing compared to other metropolises in the world.The highest PCBs concentration was observed in industrial sites followed by urban sites and background site,incomplete combustion of fossil fuel were main sources of PCBs in Beijing.The aim of this work was to better understand the overall PCBs levels,to identify the source of PCBs in Beijing city,and to provide the scientific foundation for preventing the atmospheric persistent organic pollutants(POPs) pollution.