Organic and inorganic aerosol compositions in Ulaanbaatar, Mongolia, during the cold winter of 2007 to 2008: Dicarboxylic acids, ketocarboxylic acids, and α‐dicarbonyls

Abstract

[1] To investigate the distributions and sources of water-soluble organic acids in the Mongolian atmosphere, aerosol samples (PM 2.5 , n = 34) were collected at an urban site (47.92°N, 106.90°E, ∼1300 m above sea level) in Ulaanbaatar, the capital of Mongolia, during the cold winter. The samples were analyzed for water-soluble dicarboxylic acids (C 2 -C 12 ) and related compounds (ketocarboxylic acids and a-dicarbonyls), as well as organic carbon (OC), elemental carbon, water-soluble OC, and inorganic ions. Distributions of dicarboxylic acids and related compounds were characterized by a predominance of terephthalic acid (tPh; 130 ± 51 ng m −3 , 19% of total detected organic acids) followed by oxalic (107 ± 28 ng m −3 , 15%), succinic (63 ± 20 ng m −3 , 9%), glyoxylic (55 ± 18 ng m −3 , 8%), and phthalic (54 ± 27 ng m −3 , 8%) acids. Predominance of terephthalic acid, which has not been reported previously in atmospheric aerosols, was mainly due to uncontrolled burning of plastic bottles and bags in home stoves for heating and waste incineration during the cold winter. This study demonstrated that most of the air pollutants were directly emitted from local sources such as heat and power plants, home stoves, and automobiles. Development of an inversion layer (<700 m above ground level) over the basin of Ulaanbaatar accelerated the accumulation of pollutants, causing severe haze episodes during the winter season.

Seasonal variations of water-soluble organic carbon, dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls in Central Himalayan aerosols

“…However, many other polar organic species (e.g., carbohydratelike substances) also can contribute to TC and cannot be ruled out (Stone et al, 2009). The annual average diacid-C/TC ratio at Nainital (1.3 %) is slightly higher than or comparable to those obtained at Asian megacities in Tokyo (0.95 %) (Kawamura and Ikushima, 1993), capital of Mongolia -Ulaanbaatar (0.6 %) (Jung et al, 2010) and Sapporo, Japan (1.8 %) (Aggarwal and Kawamura, 2008). In megacity Chennai, southwest coast of India, a similar annual average value (1.58 %) was obtained by Pavuluri et al (2010), but considerably higher ratios were found during the summer period.…”

“…The diurnal differences were minimum and opposite between the two seasons. The observed lower diacid-C/TC ratios during summer indicate not only less photochemical aging but also the enhanced contribution from hydrophobic carbonaceous aerosols from combustion sources (Aggarwal and Kawamura, 2008;Jung et al, 2010). However, many other polar organic species (e.g., carbohydratelike substances) also can contribute to TC and cannot be ruled out (Stone et al, 2009).…”

“…The annual average diacid-C/OC ratios (1.7±0.7) are comparable to and/or lower than those obtained at Asian megacities like New Delhi, India (1.0 %) (Miyazaki et al, 2009), and in Sapporo, Japan (4.8 %) (Aggarwal and summer: 0.41 %) (Wang et al, 2006a), but comparable to that from biomass burning (daytime: 1.7 %; nighttime: 1.4 %) (Kundu et al, 2010), suggesting that the Nainital aerosols are largely influenced by biomass burning, especially during the winter period. During photochemical production of diacids, contributions of diacid-carbon (diacid-C) to aerosol total carbon (TC) increase in the urban atmosphere (Kawamura and Yasui, 2005;Jung et al, 2010). In the Nainital aerosols the diacid-C/TC ratios during wintertime were 1.7 % and 1.8 % for day and night, respectively, whereas during summertime the contributions were almost halved (0.84 % for day and 0.75 % for night).…”

Measuring and modeling the hygroscopic growth of two humic substances in mixed aerosol particles of atmospheric relevance

“…Levoglucosan, a saccharide that is used as a tracer for biomass burning (Simoneit et al, 1999), was selected to represent category I. Succinic acid, often identified as one of the most abundant dicarboxylic acids in atmospheric aerosol samples (Rogge et al, 1993;Chebbi and Carlier, 1996;Kerminen et al, 2000;Kawamura et al, 2001a, b;Narukawa et al, 2002, Jung et al, 2010Hegde and Kawamura, 2012), was chosen to represent category II. The humic substances Nordic aquatic fulvic acid reference (NAFA) and Fluka humic acid (HA), obtained from the International Humic Substance Society (IHSS), were chosen as model compounds for category III.…”

An enhanced procedure for measuring organic acids and methyl esters in PM&lt;sub&gt;2.5&lt;/sub&gt;

“…Organic acids, including C 6 -C 32 monocarboxylic acids (MCAs), C 2 -C 12 dicarboxylic acids (DCAs), ketocarboxylic acids, and 1-,2-, and 3-substituted aromatic acids (AMAs), are ubiquitous in aerosols (Kawamura, 1993;Sempére and Kawamura, 1994;Fraser et al, 2003;Kawamura and Yasui, 2005;Wang et al, 2006;Li, 2008;Jung et al, 2010), and they can contribute major part of the organic matter in city atmosphere (Satsumabayashi et al, 1989;Huang et al, 2006;Duan et al, 2009). Organic acids can be primary or secondary.…”