In situ emission of BVOCs by three urban woody species

•Plane tree and black locust were strong isoprene emitters.•Late season isoprene emission rate was several fold more than early season.•Large amounts of 2-ethylhexanol was detected late in the season in all trees.

Controlling and monitoring air quality in cities requires understanding anthropogenic sources, but also natural sources must be considered. This is because beneficial Biogenic Volatile Organic Compounds (BVOCs) can exacerbate air pollution by reacting with anthropogenic pollutants. Although these compounds help trees survive, they may have negative effect on human life in polluted cities. In this study we measured terpenoid emissions of urban trees early and late in the growing season, using Solid Phase Micro-extraction (SPME) in a branch enclosure system. Results showed that Robinia pseudoacacia and Platanus orientalis emitted significant amounts of isoprene throughout the season. Isoprene emission early in the season was roughly the same for both species. Late in the season, the standardized emission rate increased to 17.8 and 45 μg g−1 dw h−1 for R. pseudoacacia and P. orientalis, respectively. Furthermore, all trees emitted significant amounts of 2-ethylhexanol late in the season (7.3, 7.9, and 9.2 μg g−1 dw h−1 for Fraxinus rotundifolia, R. pseudoacacia, and P. orientalis, respectively). In conclusion, trees that are typically planted in urban Tehran, emit significant amounts of isoprene. Planting more F. rotundifolia and fewer P. orientalis trees would help improve air quality in Tehran and the cities like Tehran.

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