Isoprene Emissions, Oxidation Chemistry and Environmental Impacts

Isoprene emissions can affect the oxidizing capacity of the atmosphere and are likely to increase with an increase in the world’s biomass. The emission of isoprene is strongest in tropical forested regions, suggesting a major portion of tropospheric chemistry occurs in the tropics. As well as defore...

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Bibliographic Details
Main Authors: M. Anwar H. Khan, Rayne Holland, Charlotte Mould, Asan Bacak, Carl J. Percival, Dudley E. Shallcross
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Atmosphere
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Online Access:https://www.mdpi.com/2073-4433/16/3/259
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Summary:Isoprene emissions can affect the oxidizing capacity of the atmosphere and are likely to increase with an increase in the world’s biomass. The emission of isoprene is strongest in tropical forested regions, suggesting a major portion of tropospheric chemistry occurs in the tropics. As well as deforestation and reforestation having a direct impact on the world’s climate through land cover, there is also an indirect environmental impact (e.g., global warming, air pollution) through the resulting change in isoprene emissions. Previously, incomplete understanding of isoprene oxidation chemistry caused a model-measurement breakdown for concentrations of HO<sub>x</sub> radicals observed over certain low-NO<sub>x</sub> regions, such as the pristine Amazon rainforest. Over the last decade, however, understanding of isoprene oxidation chemistry has been vastly improved. Numerous research studies have provided evidence for the involvement of 1,6-H and 1,5-H shift reactions in the isoprene oxidation mechanism, which increases the level of HO<sub>x</sub> recycling that occurs. As well as helping to reduce the model-measurement breakdown observed, the updated isoprene oxidation mechanism affects the tropospheric burdens of other species, including carbon monoxide (CO), methane (CH<sub>4</sub>), ozone (O<sub>3</sub>), organic peroxides (ROOH), secondary organic aerosol (SOA), and organic nitrates (RONO<sub>2</sub>). There are still gaps in the understanding of the impacts and oxidation chemistry of isoprene emissions, which this literature review identifies and discusses. In the future, there is still much scope for further research, including modeling future reforestation scenarios with isoprene emissions and their impacts on both global and regional scales.
ISSN:2073-4433