Department of Geography, Hong Kong Baptist University, Hong Kong 999077, China.
Thrust of Earth, Ocean and Atmospheric Sciences, Hong Kong University of Science and Technology (Guangzhou), Guangzhou 511455, China.
Environ Sci Technol. 2024 Nov 12;58(45):20081-20090. doi: 10.1021/acs.est.4c05656. Epub 2024 Nov 1.
Oxygenated volatile organic compounds (OVOCs) significantly modulate atmospheric chemistry, but the sources and air quality impacts of OVOCs in aged urban outflows remain to be elucidated. At a background site in South China, the ozone formation potential of six nonformaldehyde OVOCs studied was equivalent to that of 3.56 ppbv of formaldehyde, more than half of which was contributed by acetaldehyde. Source apportionment incorporating photochemical age revealed that considerable fractions (52.7%-62.6%) of the OVOCs were of biogenic origin, except for ethanol, which was primarily derived from anthropogenic emissions. The oxidation of -/-2-butene explained 71.1% of the in situ acetaldehyde formation. In contrast, α/β-pinenes and isoprene contributed 73.8% and 28.4% to acetone and methylglyoxal formation, respectively. An average of 12.4% of net in situ ozone (O) production rate was attributed to the OVOCs studied, where the biogenic fractions accounted for 59%. The changes in the O production rate and hydroxyl radical (OH) concentration caused by OVOCs were mainly affected by ozone formation sensitivity. The effects of primary acetaldehyde and acetaldehyde-led O on secondary acetaldehyde formation were weak at this background site; however, they cannot be ignored in polluted areas. This study provides a scientific basis for mitigating O pollution driven by biogenic emissions and OVOCs.
含氧挥发性有机化合物（OVOCs）对大气化学有显著的调节作用，但老化城市流出物中 OVOCs 的来源和空气质量影响仍需阐明。在中国南方的一个背景站点，研究的六种非甲醛 OVOCs 的臭氧形成潜力相当于 3.56ppbv 甲醛，其中一半以上来自乙醛。结合光化学年龄的源分配表明，相当大的分数（52.7%-62.6%）的 OVOCs 具有生物源，乙醇除外，其主要来自人为排放。-/-2-丁烯的氧化解释了 71.1%的原位乙醛形成。相比之下，β-蒎烯和异戊二烯分别对丙酮和甲基乙二醛的形成贡献了 73.8%和 28.4%。平均有 12.4%的净原位臭氧（O）生成速率归因于研究中的 OVOCs，其中生物源分数占 59%。OVOCs 引起的 O 生成速率和羟基自由基（OH）浓度变化主要受臭氧形成敏感性的影响。在这个背景站点，原始乙醛和由乙醛引发的 O 对二次乙醛形成的影响较弱；然而，在污染地区，它们不能被忽视。本研究为减轻生物排放和 OVOCs 驱动的 O 污染提供了科学依据。
