Low-level Summertime Isoprene Observed at a Forested Mountaintop Site in Southern China: Implications for Strong Regional Atmospheric Oxidative Capacity

作者：Daocheng Gong, Hanxi Wang, S. Zhang, Y. Wang, S. C. Liu, Hai Guo, Min Shao, C. He, Dianqiang Chen, Ling He, Luxi Zhou, Lídia Morawska, Yang Zhang, Boguang Wang · 发表于：QUT ePrints (Queensland University of Technology) · 年份：2019 · 研究领域：Atmospheric chemistry and aerosols、Atmospheric Ozone and Climate、Air Quality Monitoring and Forecasting

To investigate the atmospheric oxidative capacity (AOC) in forested high mountain areas adjacent to the photochemistry-active Pearl River Delta (PRD) region in southern China, one-month online observations of isoprene and its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) were conducted at a national background station in Nanling Mountains in summer 2016. The results showed that the observed daytime isoprene levels (377±46pptv) were significantly lower in comparison with other forest sites within and outside China, although the sampling site was surrounded with subtropical evergreen broad-leaved trees which are strong isoprene emitters. Also, high daytime (MVK+MACR)∕isoprene ratios (1.9±0.5) were observed. Based on the observations, we hypothesized that the lower isoprene levels in the study forest might be attributable to a strong AOC in relation to the elevated regional complex air pollution. In further data analyses, high site-level concentrations of daytime OH (7.3±0.5×106moleculescm−3) and nighttime NO3 radicals (6.0±0.5×108</span&...