The characteristics, seasonal variation and source apportionment of VOCs at Gongga Mountain, China

The mixing ratio, composition and variability of volatile organic compounds (VOCs) were measured from 2008 through 2011 at Gongga Mountain Forest Ecosystem Research Station (102°00′E, 29°33′N, elevation 1640 m), a remote station in southwest China. Weekly samples were collected in the Gongga Mountain area and were analyzed using a three-stage preconcentration method coupled with GC-MS. An advance receptor model positive matrix factorization (PMF) was applied to identify and apportion the sources of VOCs. The results show that the measured VOC mixing ratio at Gongga Mountain is dominated by aromatics (35.7%) and alkanes (30.8%), followed by halocarbons (21.6%) and alkenes (11.9%). The general trend of seasonal variation shows higher mixing ratios in spring and lower mixing ratios in autumn. The effect of alkanes and aromatics on the seasonal variation of total volatile organic compounds (TVOCs) is significant. Five sources were resolved by the PMF model: (1) gasoline-related emission (the combination of gasoline exhaust and gas vapor), which contributes 35.1% of the measured VOC mixing ratios; (2) solvent use, contributing 21.8%; (3) fuel combustion, contributing 29.1%; (4) biogenic emission, contributing 5.2%; and (5) industrial, commercial and domestic sources, contributing 8.7%. The effect on this area of the long-range transport of air pollutants from highly polluted areas is significant.