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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2018-336
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
16 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Low-level isoprene observed during summertime at a forested mountaintop site in southern China: implications for strong regional atmospheric oxidative capacity
Daocheng Gong1,*, Hao Wang1,2,*, Shenyang Zhang1, Yu Wang3, Shaw Liu1, Hai Guo3, Min Shao1, Congrong He2,4, Duohong Chen5, Lingyan He6, Lei Zhou1, Lidia Morawska2,4, Yuanhang Zhang7, and Boguang Wang1,2 1Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
2JNU-QUT Joint Laboratory for Air Quality Science and Management, Jinan University, Guangzhou 511443, China
3Air Quality Studies, Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China
4International Laboratory for Air Quality and Health, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia
5State Environmental Protection Key Laboratory of Regional Air Quality Monitoring, Guangdong Environmental Monitoring Center, Guangzhou 510308, China
6Key Laboratory for Urban Habitat Environmental Science and Technology, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China
7State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
*These authors contributed equally to this work.
Abstract. To investigate the atmospheric oxidizing capacity in certain polluted isoprene-rich environments, such as the forests surrounding megacities. Here we present online observations of isoprene and its first-stage oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) in summer 2016 at a remote, high-altitude mountain forest site (1690 m a.s.l.) to the north of the air-polluted Pearl River Delta (PRD) region in southern China. The observed isoprene level was found to be significantly lower in comparison with other forest sites either in China or around the world, although the sampling site was surrounded with subtropical evergreen broad-leaved trees which are strong isoprene emitters. Also, high (MVK+MACR)/isoprene ratio was observed. Based on the observations, we hypothesized that the lower isoprene levels in the study forest might be attributable to a strong atmospheric oxidative capacity in relation to the elevated regional complex air pollution. High daytime OH and nighttime NO3 radical concentrations estimated by using a photochemical box model incorporating Master Chemical Mechanism (PBM-MCM), as well as calculated short atmospheric reaction times of isoprene and long photochemical age, indicated that the isoprene was rapidly and fully oxidized at this aged atmospheric environment, which confirmed our hypothesis. The study suggests that the complex air pollution in the PRD region has significantly elevated the background atmospheric oxidative capacity of the adjacent forests, and most likely does would probably affect the regional air quality and ecological environment in the long term. The feedback of forest ecosystems to the increasing atmospheric oxidation capacity warrants further studies.
Citation: Gong, D., Wang, H., Zhang, S., Wang, Y., Liu, S., Guo, H., Shao, M., He, C., Chen, D., He, L., Zhou, L., Morawska, L., Zhang, Y., and Wang, B.: Low-level isoprene observed during summertime at a forested mountaintop site in southern China: implications for strong regional atmospheric oxidative capacity, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-336, in review, 2018.
Daocheng Gong et al.
Daocheng Gong et al.
Daocheng Gong et al.

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Short summary
The complex air pollution in the air-polluted Pearl River Delta (PRD) region in southern China has significantly elevated the background atmospheric oxidative capacity of the adjacent forests and subsequently lowered the levels of important biogenic volatile organic compounds, such as isoprene, which probably affect the regional air quality and ecological environment in the long term.
The complex air pollution in the air-polluted Pearl River Delta (PRD) region in southern China...
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