Geochemical studies of low molecular weight organic acids in the atmosphere: sources, formation pathways, and gas/particle partitioning

Abstract

Low molecular weight monocarboxylic acids (LMW monoacids, C 1 –C 10 ) are the most abundant gaseous organic compound class in the atmosphere. Formic or acetic acid is the dominant volatile organic compound (VOC) in Earth’s atmosphere. They can largely contribute to rainwater acidity, especially in the tropical forest, and react with alkaline metals, ammonia, and amines, contributing to new particle formation and secondary organic aerosol production. Gaseous and particulate LMW monoacids were abundantly reported in China. They can be directly emitted from fossil fuel combustion and biomass burring; however, the secondary formation is more important than primary emissions via the photochemical oxidation of anthropogenic and biogenic VOCs. In this paper, we review the distributions of LMW monoacids from urban, mountain, and marine sites as well as from rainwater and alpine snow samples and discuss their sources and formation mechanisms in the atmosphere. We also discuss their importance as cloud condensation nuclei (CCN) and provide future perspectives of LMW monoacids study in the warming world.

Changes in the Size Distributions of Oxalic Acid and Related Polar Compounds Over Northern Japan During Spring

“…Water‐soluble organic compounds make up a significant portion of organic aerosols (OAs) in the atmosphere (Graham et al., 2002; Kanakidou et al., 2005). Dicarboxylic and ω ‐oxocarboxylic acids are most important contributors of water‐soluble organic carbon (WSOC) in atmospheric aerosol particles, in addition to low molecular weight monocarboxylic acids such as formic and acetic acids (Kawamura, 2023). Their contributions to WSOC were estimated in the range of 1%–3% in the urban and semi‐urban sites (Kerminen et al., 2000; Miyazaki et al., 2009; Pavuluri et al., 2010), whereas the values were comparable to or even exceeding 10% in the remote marine locations (Kawamura et al., 1996; Kawamura & Sakaguchi, 1999; Kerminen et al., 1999).…”

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Water-soluble organic compounds make up a significant portion of organic aerosols (OAs) in the atmosphere (Graham et al, 2002;Kanakidou et al, 2005). Dicarboxylic and ω-oxocarboxylic acids are most important contributors of water-soluble organic carbon (WSOC) in atmospheric aerosol particles, in addition to low molecular weight monocarboxylic acids such as formic and acetic acids (Kawamura, 2023). Their contributions to WSOC were estimated in the range of 1%-3% in the urban and semi-urban sites (

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Nitrate formation and iron dissolution in the heterogeneous reactions of NH3 on nano α-Fe2O3

“…They can be released into the atmosphere from primary emissions of biological sources and human activities, or from the photooxidation of volatile organic compounds and the heterogeneous reaction of aldehydes. [28][29][30] Organic acids released into the atmosphere are precursors for aerosol particles that affect cloud growth and the pH of rain. 31,32 Although these ubiquitous acidic gases from a wide range of sources affect the heterogeneous reactions of NH 3 , 33,34 the kinetics and mechanism of their reactions remain elusive.…”

Roles of marine biota in the formation of atmospheric bioaerosols, cloud condensation nuclei, and ice-nucleating particles over the North Pacific Ocean, Bering Sea, and Arctic Ocean

“…These OM types, together with sea salt, are suggested to contribute substantially to the reduction in particle hygroscopicity, especially for fine particles around the CCN activation size range. Additionally, some types of 5 water soluble OM (ĸ~0.3, Petter and Kreidenweis, 2007) such as dicarboxylic acid (i.e., oxalic acid) as secondary biogenic OM and nss-sulfate from high biological activity might also have contributed (Kawamura, 2023). In contrast, during P3 (in the Arctic Ocean) and P4, the CCN activation parameters were characterized by high ĸ values (0.67-0.68) and high CCN AFs (64-76 %), indicating that hygroscopicity and CCN activity were controlled by the highly hygroscopic components from natural sources such as sea salt (ĸ~1.2) and sulfate (ĸ~0.6).…”