典型异戊二烯衍生物在大气中由OH引发的氧化降解机理研究.docx

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Title: Mechanistic Studies on the Oxidative Degradation of Typical Isoprene Derivatives by OH in the Atmosphere
Abstract:
Isoprene derivatives, such as isoprene (C5H8), play a significant role in atmospheric chemistry due to their high reactivity towards the hydroxyl radical (OH) and their potential to form various secondary organic aerosols (SOAs) and ozone. This study aims to investigate the mechanistic pathways of the oxidative degradation of typical isoprene derivatives by OH in the atmosphere, focusing on the degradation of isoprene, two-methylbutenes, and methacrolein. Experimental observations, theoretical calculations, and model simulations were utilized to elucidate the reaction mechanisms and explore the impacts on air quality and climate.
Introduction:
Isoprene derivatives are major contributors to the formation of SOAs, which have important implications for air quality and climate change. The reaction of isoprene derivatives with OH initiates a chain of reactions leading to the formation of various products, including peroxy radicals, organic nitrates, and carbonyl compounds. Understanding the atmospheric fate of isoprene derivatives is crucial for accurately predicting the concentrations of key atmospheric species, as well as assessing their impacts on air quality and climate.
Experimental Methods:
Experimental investigations were conducted in a laboratory chamber under controlled conditions to simulate the atmospheric degradation of isoprene derivatives. The detection and measurement of reaction intermediates and products were performed using state-of-the-art analytical techniques, such as proton transfer reaction-mass spectrometry (PTR-MS) and gas chromatography-mass spectrometry (GC-MS). Isotopic labeling experiments were also conducted to provide further insights into reaction mechanisms.
Results and Discussion:
The oxidative degradation pathways of isoprene, two-methylbutenes, and methacrolein by OH were established based on the experimental observations and theoretical calculations. Isoprene reacts rapidly with OH to form isoprene hydroxy peroxy radicals (ISOPOO), which can subsequently react with NO or RO2 radicals, leading to the formation of SOAs and volatile organic compounds (VOCs). Two-methylbutenes undergo similar reactions, resulting in the formation of carbonyl compounds and oxidative products. Methacrolein, an unsaturated aldehyde, reacts with OH primarily through H-abstraction, forming hydroxyl radicals and subsequently leading to the formation of peroxyacyl radicals and volatile organic compounds.
The impacts of the oxidation of isoprene derivatives on air quality and climate were assessed using a chemical transport model. The model simulations indicated that the degradation of isoprene derivatives leads to the formation of secondary organic aerosols, which can contribute to the fine particulate matter () and affect human health. Additionally, the atmospheric degradation of isoprene derivatives results in the formation of organic nitrates, which have implications for nitrogen pollution and tropospheric ozone levels.
Conclusion:
This study provides mechanistic insights into the oxidative degradation of typical isoprene derivatives by OH in the atmosphere. The findings highlight the importance of isoprene derivatives in atmospheric chemistry and their impacts on air quality and climate. Further studies are warranted to understand the intricate interactions between isoprene derivatives and other atmospheric species and to improve the accuracy of model predictions for air pollution control strategies and climate change mitigation efforts.
Keywords: isoprene derivatives, hydroxyl radical, oxidative degradation, secondary organic aerosols, air quality, climate change.