An online continuous monitoring system was used to determine the volatile organic carbons (VOCs) in the ambient air of a typical petrochemical industrial park in autumn (Sep., Oct., Nov.) of 2014. The composition, photochemical reactivity, temporal variation, and source of VOCs were analyzed. The results indicated that the mixing ratio of VOCs in autumnal ambient air of the study area was higher than those of other cities and industrial areas. Alkanes were the most abundant group in the VOC mixing ratio, and no significant temporal difference was observed among the three months studied. However, the alkanes, alkenes, and aromatics presented obvious diurnal variation, with single peak and trough values, while the acetylene exhibited "W"-shaped variation, with two minimum and one maximum values. Source apportionment using positive matrix factorization (PMF) indicated that the sources of VOCs in the study area of natural gas transportation and solvents, such as from leakage or volatile oil refinery processing, followed by other traffic sources and asphalt have some contribution. Alkenes and alkanes were the dominant groups of the source apportionment composition, as expressed by the propylene-equivalent (Propy-Equiv) and maximum incremental reactivity (MIR) methods, respectively.
Keywords: composition; photochemical reactivity; source apportionment; variation trend; volatile organic carbons (VOCs).