[Pollution and source of atmospheric volatile organic compounds in urban-rural juncture belt area in Beijing].

A method for determining volatile organic compounds (VOCs) by cryogenic dynamic adsorption in solid adsorbent tubes, subsequent thermal desorption with cryofocusing in a cold trap and analysis by gas chromatography and mass spectrometry was adapted. Volatile organic content levels, spatial and temporal distribution and sources were studied. Results indicated that 265 species were detected in atmospheric environment of this area, including alkanes, alkenes, aromatics, halohydrocarbons and oxygenated compounds. The average concentration of VOCs is 431.7 microg x m(-3), followed by aromatics 248.1 microg x m(-3), alkanes 130.5 microg x m(-3) alkenes 11.7 microg x m(-3), halohydrocarbons 22.4 microg x m(-3), oxygenated compounds 18.6 microg x m(-3), respectively. Benzene, toluene, ethylbenzene, xylene and so on have a comparatively high content. Aromatics and alkanes are the most abundant VOCs; Organic pollutants generally occurred at a relatively high level in the morning and evening traffic rush hours. VOCs varied with seasons: winter maximum, followed by autumn, summer minimum. Source analysis showed that atmospheric VOCs mainly come from vehicular exhaust, gasoline evaporation, use of adhesive and solvent and vegetation emission. They accounted for 53.4%, 20.1%, 11.0% and 5.93%, respectively.