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Dual Role of Aerosols on Reactive Bromine Recycling in Extrapolar Marine and Continental Regions.

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Title: Dual Role of Aerosols on Reactive Bromine Recycling in Extrapolar Marine and Continental Regions.
Authors: Zhang, Yingnan1 (AUTHOR), Chen, Xiaorui1,2 (AUTHOR), Wang, Tao1 (AUTHOR) tao.wang@polyu.edu.hk, Li, Qinyi1,3 (AUTHOR) qinyi.li@sdu.edu.cn, Xia, Men4 (AUTHOR), Li, Mingxue1 (AUTHOR), Mu, Jiangshan3 (AUTHOR), Shen, Hengqing1,3 (AUTHOR), Herrmann, Hartmut5,6 (AUTHOR), Xue, Likun3 (AUTHOR)
Source: Journal of Geophysical Research. Atmospheres. Dec2024, Vol. 129 Issue 23, p1-12. 12p.
Subject Terms: *Trace gases, *Atmospheric chemistry, *Ozone layer depletion, *Bromine, Chemical models
Abstract: Reactive bromine species play important roles in atmospheric chemistry and influence the abundance of climate‐ and air quality‐relevant trace gases. While extensive studies have focused on bromine chemistry in polar regions, the bromine species in extrapolar regions, particularly regarding pollution‐related bromine recycling, have received less attention. In this study, we examine the factors influencing the bromine recycling at a clean marine site of the North Atlantic (Cape Verde, CVAO), a semipolluted coastal site of the South China Sea (Hok Tsui, HT), and a polluted continental site of North China (Wangdu, WD), using an observation‐based model combined with updated halogen chemistry. Our results indicate that aerosol‐related multiphase processes significantly affect bromine recycling in these extrapolar sites. Nitrate photodissociation efficiently recycled bromide into the gas phase in regions characterized by strong aerosol acidity (HT) or high aerosol concentrations (WD). Concurrently, bromine species are lost from the gas phase toward aerosol surfaces, with this process being more effective at higher liquid water content (WD > HT > CVAO). In semipolluted and polluted sites, the aerosol‐related processes resulted in elevated bromine levels in the daytime compared to nighttime, leading to larger effects of bromine species on ozone than previously thought. Our study suggests the need for a better understanding of the complex effects of aerosols on reactive halogen chemistry. Plain Language Summary: Reactive bromine species significantly influence the abundance of climate‐ and air quality‐relevant trace gases. Over the past decades, the sources and atmospheric impacts of bromine species in polar regions have been extensively studied due to their critical role in the Arctic ozone depletion episodes (ODEs). Both observations and laboratory studies have identified aerosols as crucial players in bromine explosions and subsequent Arctic ODEs. Here, using an observation‐constrained multiphase chemical box model with updates in halogen chemistry, we demonstrate that aerosols can provide a medium for bromine species activation or loss in extrapolar marine and continental regions, depending on their compositions and properties. These aerosol‐related processes are not included in current chemistry climate models, potentially hindering the accurate assessment of the impact of halogen species on climate and air quality. Key Points: We updated bromine‐aerosol interaction mechanisms and improved bromine simulations across extrapolar marine and continental regionsAerosols can provide a medium for bromine species activation or loss, depending on aerosol compositions and propertiesOverlooking aerosol‐related processes may underestimate the effects of bromine species on ozone in semipolluted and polluted regions [ABSTRACT FROM AUTHOR]
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Abstract:Reactive bromine species play important roles in atmospheric chemistry and influence the abundance of climate‐ and air quality‐relevant trace gases. While extensive studies have focused on bromine chemistry in polar regions, the bromine species in extrapolar regions, particularly regarding pollution‐related bromine recycling, have received less attention. In this study, we examine the factors influencing the bromine recycling at a clean marine site of the North Atlantic (Cape Verde, CVAO), a semipolluted coastal site of the South China Sea (Hok Tsui, HT), and a polluted continental site of North China (Wangdu, WD), using an observation‐based model combined with updated halogen chemistry. Our results indicate that aerosol‐related multiphase processes significantly affect bromine recycling in these extrapolar sites. Nitrate photodissociation efficiently recycled bromide into the gas phase in regions characterized by strong aerosol acidity (HT) or high aerosol concentrations (WD). Concurrently, bromine species are lost from the gas phase toward aerosol surfaces, with this process being more effective at higher liquid water content (WD > HT > CVAO). In semipolluted and polluted sites, the aerosol‐related processes resulted in elevated bromine levels in the daytime compared to nighttime, leading to larger effects of bromine species on ozone than previously thought. Our study suggests the need for a better understanding of the complex effects of aerosols on reactive halogen chemistry. Plain Language Summary: Reactive bromine species significantly influence the abundance of climate‐ and air quality‐relevant trace gases. Over the past decades, the sources and atmospheric impacts of bromine species in polar regions have been extensively studied due to their critical role in the Arctic ozone depletion episodes (ODEs). Both observations and laboratory studies have identified aerosols as crucial players in bromine explosions and subsequent Arctic ODEs. Here, using an observation‐constrained multiphase chemical box model with updates in halogen chemistry, we demonstrate that aerosols can provide a medium for bromine species activation or loss in extrapolar marine and continental regions, depending on their compositions and properties. These aerosol‐related processes are not included in current chemistry climate models, potentially hindering the accurate assessment of the impact of halogen species on climate and air quality. Key Points: We updated bromine‐aerosol interaction mechanisms and improved bromine simulations across extrapolar marine and continental regionsAerosols can provide a medium for bromine species activation or loss, depending on aerosol compositions and propertiesOverlooking aerosol‐related processes may underestimate the effects of bromine species on ozone in semipolluted and polluted regions [ABSTRACT FROM AUTHOR]
ISSN:2169897X
DOI:10.1029/2024JD042040