Organic atmospheric aerosols: Review and state of the science

Abstract

Abstract. Atmospheric aerosol particles are known to contain organic carbon material in variable amounts, depending on their location. In some parts of the world, organic compounds make up the majority of the total suspended particle mass. This class of particulate matter is important in a wide range of geophysical and environmental problems, ranging from local issues (e.g., pollution toxicity) to the global scale (e.g., climate change). Unfortunately, the richness of organic chemistry and the highly variable physical properties associated with both natural and anthropogenic organic particles lead to great difficulties in sampling and obtaining complete chemical information on these materials. These obstacles result in an incomplete picture of a potentially significant part of atmospheric chemistry and a correspondingly poor understanding of the geophysical and environmental effects of this aerosol. Given the paucity of quantitative molecular data, the purpose of this paper is not to quantitatively describe the importance of organic aerosols in environmental issues, but rather to present a basis for defining what data are needed. With this goal in mind, we begin with an overview of the major environmental issues known to be affected by organic aerosols, followed by a description of the distribution, sources, and chemical and physical properties of organic aerosols as they are currently understood. Methods used to collect and study organic aerosols are provided, followed by a list of outstanding scientific questions and suggestions for future research priorities. mental Protection Agency (U.S. EPA), 1996]. This fraction has been studied extensively, and several models of the geographical distribution and climatic effects of this group of compounds in the aerosol have appeared [IPCC, 1995]. While somewhat less studied, the insoluble inorganic fraction has been analyzed, for example, with nuclear methods, and generally consists of metal oxides, silicates, and clay minerals derived from soil dust. Unlike the salt and soil dust fractions, the organic compounds cover a very wide range of molecular forms, solubilities, reactivities, and physical properties, which makes a complete characterization extremely difficult. The so-called "elemental" carbon (EC) aerosol has been studied extensively, but it is still not clear to what degree it is indeed elemental [graphitic, C(0)] material or high molecular weight refractory organic species or a combination of both. Consequently, there is still no complete inventory of the chemical compounds that compose the fine-particle organic aerosol from any site in the world, and there is only a limited understanding of the sources, sinks, transport, and transformation processes of these particles and their effects. Since organic compounds are usually the second most abundant component of fine aerosol after sulfates [Heintzenberg, 1989; White, 1990; U.S. EPA, 1996], our understanding of the numerous

A monodisperse aerosol dynamics module, a promising candidate for use in long‐range transport models: Box model tests

“…Also the volatile and soluble organic acids may affect the hygroscopic properties of particles as pointed out by Yu [2000] and IPCC [2001]. Besides condensing into particles, organic matter can form a coating on the surface of an inorganic aerosol particle, which may either help or hinder hygroscopic growth depending on the initial particle composition [e.g., Andrews and Larson, 1993;Hansson et al, 1990Hansson et al, , 1998Jacobson et al, 2000].…”

Size-segregated particulate matter and carboxylic acids over urban and rural sites in Londrina City, Brazil

“…Oxalic acid has been detected as the major fraction of water-soluble organic compounds in urban, rural and even in remote areas. [3][4][5][6] Since carboxylic acids are highly water-soluble, they have the potential to modify the hygroscopic properties of atmospheric particles, including their ambient size and cloud condensation nuclei activity. 9,10 Weak organic acids could contribute ca.…”

“…Among them, the oxalic acid has been the main species, followed by succinic and malonic acids. [1][2][3][4][5][6] Mono-and di-carboxylic acids are important groups of organic compounds identified in the atmospheric particles. 7,8 Formic and acetic acids, the dominant species of organic acids in tropospheric aqueous and gaseous phases, are also ubiquitous in aerosol particles.…”

UV-spectroscopy, electronic structure and ozonolytic reactivity of sesquiterpenes: a theoretical study

“…Secondary organic aerosols (SOAs) are ubiquitous components of atmospheric particulate matter which have attracted much attention [8,12,33,34]. Formation of SOAs involves atmospheric reaction of volatile organic compounds and condensation of corresponding products such as polar multifunctional groups over pre-existing particles via gas-to-particle process.…”