Molecular characterization of organic aerosols in the Kathmandu Valley, Nepal: insights into primary and secondary sources

Wan, Xin; Kang, Shichang; Rupakheti, Maheswar; Zhang, Qianggong; Tripathee, Lekhendra; Guo, Junming; Chen, Pengfei; Rupakheti, Dipesh; Panday, Arnico K.; Lawrence, M. G.; Kawamura, Kimitaka; Cong, Zhiyuan

doi:10.5194/acp-19-2725-2019

Cited by 42 publications

(19 citation statements)

References 98 publications

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“…Moreover, the level of anhydrosugars (2310 ng m -3 , average) in winter was one order of magnitude higher than other seasons (302 ng m -3 , 171 ng m -3 , 798 ng m -3 for spring, summer and autumn, respectively). Such trends indicated that the haze samples were largely influenced by biomass burning emissions in Beijing, consistent with previous studies in Beijing (Zhang et al, 2017) and other regions such as New Delhi (India), Tasmania (Australia) and Kathmandu (Nepal) (Fu et al, 2010;Reisen et al, 2013;Wan et al, 2019).…”

Section: Anhydrosugarssupporting

confidence: 87%

“…Biomass burning (BB), as a substantial source of particles in the atmosphere, generate plenty of POA (Andreae and Merlet, 2001; Wan et al, 2019;Yan et al, 2015). Levoglucosan, generated by the thermal decomposition of cellulose (Simoneit, 2002;Simoneit et al, 1999), is regarded as the most typical tracer for BB (Simoneit et al, 2004;Simoneit et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

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Molecular markers of biomass burning and primary biological aerosols in urban Beijing: Size distribution and seasonal variation

Xu¹,

Ren²,

Lang³

et al. 2019

Preprint

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Abstract. Biomass burning and primary biological aerosol particles account for an important part of urban aerosols. Floods of studies have been conducted on the chemical compositions of fine aerosols (PM2.5) in megacities where the haze pollution is one of the severe environmental issues in China. However, little is known about their size distributions in atmospheric aerosols in the urban boundary layer. Here, size-segregated aerosol samples were collected in Beijing during haze and clear days from April 2017 to January 2018. Three anhydrosugars, six primary saccharides and four sugar alcohols in these samples were identified and quantified by gas chromatography/mass spectrometry (GC/MS). Higher concentrations of a biomass burning tracer, levoglucosan, were detected in autumn and winter than other seasons. Sucrose, glucose, fructose, mannitol and arabitol were more abundant in the bloom and glowing seasons. Particularly high level of trehalose was found in spring, which was largely associated with the Asian dust outflows. Anhydrosugars, xylose, maltose, inositol and erythritol are mainly existed in the fine mode (<&#8201;2.1&#8201;&#956;m), while the others showed the coarse mode privilege. The concentrations of measured tracers of biomass burning particles and primary biological particles in the haze events were higher than those in the non-hazy days, with an enrichment factor of 2&#8211;10. Geometric mean diameters (GMD) of molecular markers of biomass burning and primary biological aerosols showed that there was no significant difference in the coarse mode (>&#8201;2.1&#8201;&#956;m) between the haze and non-haze samples, while a size shift towards large particles and large GMDs in the fine fraction (<&#8201;2.1&#8201;&#956;m) was detected during the hazy days, which highlights that the stable meteorological conditions with high relative humidity in urban Beijing may favor the condensation of organics onto coarse particles.The contributions of reconstructed primary organic carbon (POC) by tracer-based methods from plant debris, fungal spores, and biomass burning to aerosol OC in the total mode particles were in the ranges of 0.09&#8211;0.30&#8201;% (on average 0.21&#8201;%), 0.13&#8211;1.0&#8201;% (0.38&#8201;%) and 1.2&#8211;7.5&#8201;% (4.5&#8201;%), respectively. This study demonstrates that the contribution of biomass burning was significant in Beijing throughout the whole year with the predominance in the fine mode, while the contributions of plant debris and fungal spores dominated in spring and summer in the coarse mode, especially in the size of >&#8201;5.8&#8201;&#956;m. Our observations demonstrate that the sources, abundance, and chemical composition of urban aerosol particles are strongly size dependant in Beijing, which are important to better understand their environmental and health effects of urban aerosols and should be considered in air quality and climate models.

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Section: Anhydrosugarssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Molecular markers of biomass burning and primary biological aerosols in urban Beijing: Size distribution and seasonal variation

Xu¹,

Ren²,

Lang³

et al. 2019

Preprint

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show abstract

“…S1 in the Supplement). Levoglucosan, a typical tracer of biomass burning, is formed from the thermal decomposition of cellulose during vegetation burning activities, which has been detected in many urban as well as rural areas (Cheng et al, 2013;Chowdhury et al, 2007;Fu et al, 2010;Wang et al, 2006;Yttri et al, 2007). As additional important types of anhydrosugars, mannosan and galactosan, the isomers of levoglucosan, are exclusively derived from the pyrolysis of hemicellulose (Fraser and Lakshmanan, 2000;Simoneit et al, 1999;Simoneit, 2002).…”

Section: Backward Trajectories and Fire Spot Countsmentioning

confidence: 99%

Molecular markers of biomass burning and primary biological aerosols in urban Beijing: size distribution and seasonal variation

Ren

Lang

et al. 2020

Atmos. Chem. Phys.

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Abstract. Biomass burning and primary biological aerosol particles account for an important part of urban aerosols. Floods of studies have been conducted on the chemical compositions of fine aerosols (PM2.5) in megacities where the haze pollution is one of the severe environmental issues in China. However, little is known about their size distributions in atmospheric aerosols in the urban boundary layer. Here, size-segregated aerosol samples were collected in Beijing during haze and clear days from April 2017 to January 2018. Three anhydrosugars, six primary saccharides and four sugar alcohols in these samples were identified and quantified by gas chromatography/mass spectrometry (GC/MS). Higher concentrations of a biomass burning tracer, levoglucosan, were detected in autumn and winter than in other seasons. Sucrose, glucose, fructose, mannitol and arabitol were more abundant in the bloom and glowing seasons. A particularly high level of trehalose was found in spring, which was largely associated with the Asian dust outflows. Anhydrosugars, xylose, maltose, inositol and erythritol are mainly present in the fine mode (<2.1 µm), while the others showed the coarse-mode preference. The concentrations of measured tracers of biomass burning particles and primary biological particles in the haze events were higher than those in the non-hazy days, with enrichment factors of 2–10. Geometric mean diameters (GMDs) of molecular markers of biomass burning and primary biological aerosols showed that there was no significant difference in the coarse mode (>2.1 µm) between the haze and non-haze samples, while a size shift towards large particles and large GMDs in the fine fraction (<2.1 µm) was detected during the hazy days, which highlights that the stable meteorological conditions with high relative humidity in urban Beijing may favor the condensation of organics onto coarse particles.The contributions of reconstructed primary organic carbon (POC) by tracer-based methods from plant debris, fungal spores and biomass burning to aerosol OC in the total-mode particles were in the ranges of 0.09 %–0.30 % (on average 0.21 %), 0.13 %–1.0 % (0.38 %) and 1.2 %–7.5 % (4.5 %), respectively. This study demonstrates that the contribution of biomass burning was significant in Beijing throughout the whole year with the predominance in the fine mode, while the contributions of plant debris and fungal spores dominated in spring and summer in the coarse mode, especially in sizes >5.8 µm. Our observations demonstrate that the sources, abundance and chemical composition of urban aerosol particles are strongly size dependent in Beijing, which is important to better understand the environmental and health effects of urban aerosols and should be considered in air quality and climate models.

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“…Recently, source-specific tracer methodologies have been introduced to estimate their contribution to aerosol loadings Gosselin et al, 2016;Li et al, 2018;Medeiros et al, 2006b;Verma et al, 2018;. Indeed, atmospheric organic aerosols (OAs) contain specific chemical species that can be used as reliable biomarkers in tracing the sources and abundance of PBOA (Bauer et al, 2008;Gosselin et al, 2016;Holden et al, 2011;Jia et al, 2010;Li et al, 2018;Medeiros et al, 2006b;Wang et al, 2018). For instance, among sugar alcohols, arabitol and mannitol (two common storage soluble carbohydrates in fungi) have been recognized as tracers for airborne fungi, and their concentrations are widely used to estimate PBOA contributions to OA mass Bauer et al, 2008;Buiarelli et al, 2013;Golly et al, 2018;Medeiros et al, 2006b;Samaké et al, 2019;Srivastava et al, 2018;Verma et al, 2018;Weber et al, 2018Weber et al, , 2019.…”

Section: Introductionmentioning

confidence: 99%

Arabitol, mannitol, and glucose as tracers of primary biogenic organic aerosol: the influence of environmental factors on ambient air concentrations and spatial distribution over France

et al. 2019

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The primary sugar compounds (SCs, defined as glucose, arabitol, and mannitol) are widely recognized as suitable molecular markers to characterize and apportion primary biogenic organic aerosol emission sources. This work improves our understanding of the spatial behavior and distribution of these chemical species and evidences their major effective environmental drivers. We conducted a large study focusing on the daily (24 h) PM 10 SC concentrations for 16 increasing space scale sites (local to nationwide), over at least 1 complete year. These sites are distributed in several French geographic areas of different environmental conditions. Our analyses, mainly based on the examination of the short-term evolutions of SC concentrations, clearly show distance-dependent correlations. SC concentration evolutions are highly synchronous at an urban city scale and remain well correlated throughout the same geographic re-Published by Copernicus Publications on behalf of the European Geosciences Union. 11014A. Samaké et al.: Arabitol, mannitol, and glucose as tracers of primary biogenic organic aerosol gions, even if the sites are situated in different cities. However, sampling sites located in two distinct geographic areas are poorly correlated. Such a pattern indicates that the processes responsible for the evolution of the atmospheric SC concentrations present a spatial homogeneity over typical areas of at least tens of kilometers. Local phenomena, such as the resuspension of topsoil and associated microbiota, do no account for the major emissions processes of SC in urban areas not directly influenced by agricultural activities. The concentrations of SC and cellulose display remarkably synchronous temporal evolution cycles at an urban site in Grenoble, indicating a common source ascribed to vegetation. Additionally, higher concentrations of SC at another site located in a crop field region occur during each harvest periods, indicating resuspension processes of plant materials (crop detritus, leaf debris) and associated microbiota for agricultural and nearby urbanized areas. Finally, ambient air temperature, relative humidity, and vegetation density constitute the main effective drivers of SC atmospheric concentrations.

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Molecular characterization of organic aerosols in the Kathmandu Valley, Nepal: insights into primary and secondary sources

Cited by 42 publications

References 98 publications

Molecular markers of biomass burning and primary biological aerosols in urban Beijing: Size distribution and seasonal variation

Molecular markers of biomass burning and primary biological aerosols in urban Beijing: Size distribution and seasonal variation

Molecular markers of biomass burning and primary biological aerosols in urban Beijing: size distribution and seasonal variation

Arabitol, mannitol, and glucose as tracers of primary biogenic organic aerosol: the influence of environmental factors on ambient air concentrations and spatial distribution over France

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