[Pollution characteristics and ozone formation potential of ambient VOCs in winter and spring in Xiamen].

Air samples were collected at urban and rural sites in Xiamen from January to April 2014. The concentrations of 48 ambient volatile organic compounds (VOC) species were measured by the method of cryogenic pre-concentrator and gas chromatography-mass spectrometry (GC/MS). The ozone formation potential (OFP) of VOCs was also calculated with the method of maximum incremental reactivity (MIR). The results showed that the average mixing ratios of VOCs in winter were 11.13 x 10(-9) and 7.17 x 10(-9) at urban and rural sites, respectively, and those in spring were 24.88 x 10(-9) and 11.27 x 10(-9) at urban and rural sites, respectively. At both sites, alkanes contributed the most to VOCs, followed by aromatics and alkenes. The ratios of B/T showed that vehicle and solvent evaporation were the main sources of VOCs at urban site. While at rural site, transport of anthropogenic sources was another important source of VOCs besides local biomass emissions. Ten main components including propene, n-butane, i-butane, n-pentane, i-pentane, n-hexane, benzene, toluene, ethylbenzene and m/p-xylene accounted for 61.57% and 45.83% of total VOCs at urban and rural sites in winter, respectively, and 62.83% and 53.74% at urban and rural sites in spring, respectively. Aromatics contributed the most to total OFP, followed by alkenes. Alkanes contributed the least to OFP with the highest concentration. C3, C4 alkenes and aromatics were found to be the more reactive species with relatively high contributions to ozone formation in Xiamen. Comparing the average MIR of VOCs at the two sites, it was found that the reactivity of VOCs at rural site was higher than that at urban site.