Oxidation of VOCs Effect on Product of Atmospheric Photochemical Reaction with Different Elevation

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Plant-driven biological volatile organic compounds (BVOC), important precursors for ozone and secondary organic aerosol (SOA) formations in the atmospheric oxidation processes, are accounted for more than 50% of total VOCs emissions in Taiwan. However, BVOCs oxidation processes in the atmosphere have never been fully investigated. The major objectives of this study were to understand the levels of BVOCs and new particle formation (NPF) process in a middle-altitude forest recreation area (Xitou); and to understand the vertical distribution of atmospheric VOCs, carbonyls and other pollutants between Xitou and Zhushan (a low-altitude town). Interaction of anthropogenic and biogenic emissions and subsequent atmospheric oxidation processes were also evaluated in this study. The results show that the levels of isoprene, benzene, toluene, xylenes (IBTX) in summer Xitou (0.69±0.5, 0.18±0.19, 0.29±0.26 and 0.23±0.26 ppb, respectively) were lower than that in summer Zhushan (1.78±0.95, 0.38±0.09, 1.38±1.07 and 0.26±0.10 ppb, respectively). The levels of formaldehyde and acetaldehyde in Summer Xitou (5.24±3.0 and 3.08±1.85 ppb) were both higher than that in summer Zhushan (2.53±0.96 and 1.20±0.37 ppb). On the contrary, The levels of formaldehyde and acetaldehyde in winter Xitou (4.32 ±2.66, 2.62 ±3.36 ppb) were both lower than that in winter Zhushan (6.44 ±2.86 and 4.38 ±5.92 ppb). The levels of primary emissions of formaldehyde and acealdehyde in Xitou were less than that in Zhushan. The major formaldehyde and acetaldehyde in summer Xitou may be contributed by the oxidations of BVOCs in the middle-altitude forest area. Results from Xitou chamber study show that the NPF processes usually occurred in the sunny mornings.