气候变化领域集成服务门户(CCPortal): Biodegradation by bacteria in clouds: An underestimated sink for some organics in the atmospheric multiphase system

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DOI	10.5194/acp-21-3123-2021
	Biodegradation by bacteria in clouds: An underestimated sink for some organics in the atmospheric multiphase system
	Khaled A.; Zhang M.; Amato P.; Delort A.-M.; Ervens B.
发表日期	2021
ISSN	1680-7316
起始页码	3123
结束页码	3141
卷号	21 期号:4
英文摘要	Water-soluble organic compounds represent a significant fraction of total atmospheric carbon. The main oxidants towards them in the gas and aqueous phases are OH and NO3 radicals. In addition to chemical solutes, a great variety of microorganisms (e.g., bacteria, viruses, fungi) have been identified in cloud water. Previous lab studies suggested that for some organics, biodegradation by bacteria in water is comparable to their loss by chemical processes. We perform model sensitivity studies over large ranges of biological and chemical process parameters using a box model with a detailed atmospheric multiphase chemical mechanism and biodegradation processes to explore the importance of biodegradation of organics in the aqueous phase. Accounting for the fact that only a small number fraction of cloud droplets ( 0:0001 0.001) contains active bacterial cells, we consider only a few bacteria-containing droplets in the model cloud. We demonstrate that biodegradation might be most efficient for water-soluble organic gases with intermediate solubility ( 104 - KH.eff/ [M atm-1] - 106, e.g., formic and acetic acids). This can be explained by the transport limitation due to evaporation of organics from bacteriafree droplets to the gas phase, followed by the dissolution into bacteria-containing droplets. For cloud condensation nuclei (CCN)-derived compounds, such as dicarboxylic acids, the upper limit of organic loss by biodegradation can be approximated by the amount of organics dissolved in the bacteria-containing droplets (> 0:1 %). We compare results from our detailed drop-resolved model to simplified model approaches, in which (i) either all cloud droplets are assumed to contain the same cell concentration (0.0001 0.001 cell per droplet), or (ii) only droplets with intact bacterial cells are considered in the cloud (liquid water content 10-11 vol = vol). Conclusions based on these approaches generally overestimate the role of biodegradation, particularly for highly water-soluble organic gases. Our model sensitivity studies suggest that current atmospheric multiphase chemistry models are incomplete for organics with intermediate solubility and high bacterial activity. © 2021 Copernicus GmbH. All rights reserved.
语种	英语
scopus关键词	atmospheric chemistry; atmospheric sink; bacterium; biodegradation; carbon; cloud; droplet; organic compound; radical; reaction kinetics; solubility; Bacteria (microorganisms)
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/247100
作者单位	Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, Clermont-Ferrand, 63000, France
推荐引用方式 GB/T 7714	Khaled A.,Zhang M.,Amato P.,et al. Biodegradation by bacteria in clouds: An underestimated sink for some organics in the atmospheric multiphase system[J],2021,21(4).
APA	Khaled A.,Zhang M.,Amato P.,Delort A.-M.,&Ervens B..(2021).Biodegradation by bacteria in clouds: An underestimated sink for some organics in the atmospheric multiphase system.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(4).
MLA	Khaled A.,et al."Biodegradation by bacteria in clouds: An underestimated sink for some organics in the atmospheric multiphase system".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.4(2021).