Abstract
Air samples were collected from six locations during the periods of February, 2011–March, 2012 in Beijing city. Samples were analyzed using HRGC-HRMS according to HJ 77. 2-2008. The concentrations, congener profiles, seasonal variation, spatial distribution, and sources identified were investigated. The mass concentrations of 2,3,7,8-substituted PCDD/Fs is 1750 to 10380 fg/m3 with an average of 3670 fg/m3. The highest concentration was observed at site DS in February 2011 and the lowest was at site NS in July 2011. The TEQ concentrations of PCDD/Fs ranged from 35.0 to 751 fg I-TEQ/m3, with an average of 251 fg I-TEQ/m3. The dominant contributor to total TEQ value is 2,3,7,8-PeCDFs, with an average contribution of 40%. Low-chlorinated PCDDs were observed in all samples in winter. The concentration and profiles exhibit obvious seasonal variation. The PCDD/Fs at six sampling sites did not show obvious spatial variation. Seasonal variation of PCDD/F concentrations indicated that the emission sources may be different. Fossil fuel combustion and automobiles may be the main dioxins emission sources during the heating period, whereas, in non-heating period, the automobiles alone are the main emission sources.
Highlights
Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) have aroused big concerns of the public and government for a few decades
The highest concentration was observed at site Dongsi Road (DS) in February 2011 and the lowest was at site Nansi Road (NS) in July 2011
The highest concentration were observed at site DS in February2011 and the lowest was at site NS in July 2011
Summary
Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) have aroused big concerns of the public and government for a few decades. Many countries (including China) have conducted PCDD/Fs monitoring studies in ambient air (Bakoglu et al, 2005; De Assunção et al, 2005; Coutinho et al, 2007; Kim et al, 2007; Ren et al, 2007; Li et al, 2008 a, b). Beijing is the capital of China, located on Huabei plain with area of 16,410 km2 It is the biggest city throughout the country. This study was the first one conducted after Olympic Games in 2008, and the goal is to monitor the 2,3,7,8substituted PCDD/Fs at six different functional zones in urban of Beijing and to evaluate the emission sources after the strict control measures for Olympic Games. PCDD/Fs concentrations, profiles and their relationship with meteorological conditions, seasonal variations, as well as the potential emission sources are discussed
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