PM10-Bound Sugars: Chemical Composition, Sources and Seasonal Variations

Abstract

The presence of anhydrosugars and sugar alcohols in airborne articulate matter <10 µm (PM10) samples collected between December 2018 and June 2019 was studied for two urban environments in Coimbra. Anhydrosugars were used to estimate the biomass burning contribution, and sugar alcohols were investigated regarding biological sources. Anhydrosugars contributed more than sugar alcohols to the total sugars, mainly levoglucosan. Higher levoglucosan concentrations were linked with the use of biomass-fueled heating appliances, mainly during cold periods. A significant contribution from biomass burning smoke was registered, accounting for 20% to 23% of the PM10 mass in the colder period. Xylitol presented higher concentrations in the colder period and was well correlated with levoglucosan, indicating a common origin. Mannitol and arabitol were well correlated with each other but did not present any kind of correlation with anhydrosugars or xylitol, suggesting a natural source. A quantitative estimation based on the concentration of ambient tracers (mannitol) was evaluated, and the results reveal that, for the two sites, the fungal spore relative contribution to PM10 (roadside site: 2.7% to 2.8%; urban background: 1.9% to 2.7%) and OC mass (roadside site: 6.2% to 8.1%; urban background: 3.9% to 7.5%) was significant and always higher in the warmer period.

Organic tracers in fine and coarse aerosols at an urban Mediterranean site: contribution of biomass burning and biogenic emissions

“…The results from this analysis (Table 4 ) suggest that biomass combustion can indeed be considered as a non-negligible source of polyols in the fine mode, particularly for xylitol. This observation is in line with the outcomes of Gonçalves et al ( 2021 ) who also found strong correlations between xylitol and levoglucosan at roadside and urban background sites in Coimbra (Portugal).…”

“…Table 3 presents seasonal concentrations of the analyzed carbohydrates in both PM 1 and PM 10 . The levels of anhydrosugars were maxima in winter and minima during summer, as widely reported in the literature (Cao et al 2022 ; Fu et al 2012 ; Gonçalves et al 2021 ; Jia et al 2010 ; Křůmal et al 2010 ; Marynowski et al 2020 ). The use of wood burning for domestic heating only occurs to a significant extent during the cold season and progressively decreases with increasing temperature, as suggested by the negative correlations between levoglucosan, mannosan, and galactosan, and ambient temperature ( r between 0.70 and 0.76, following a power law).…”

“…The concentrations of sugar alcohols measured in Elche were in general much lower than the values found at other urban sites worldwide, although concentrations show substantial site-to-site differences. For example, Gonçalves et al ( 2021 ) reported concentrations of xylitol in PM 10 ranging from 3 ng m −3 in summer to 20 ng m −3 in winter at an urban background site in Coimbra (Portugal), while mannitol concentrations were around 20 ng m −3 during both summer and winter. In a study performed at different urban sites in Iowa, Rathnayake et al ( 2016 ) also found mannitol levels remarkably higher than the ones registered in Elche (32 ng m −3 ).…”

“…Organic aerosols contain chemical species that can be used as tracers of specific pollution sources. Among these species, sugar compounds (also named carbohydrates or saccharides) have received increased attention in recent years (Gonçalves et al 2021 ; Samaké et al 2020 ; Theodosi et al 2018 ; Zhu et al 2022 ) since they are reliable markers of different biogenic and anthropogenic sources and can provide information on the transport routes of atmospheric particles (Fraser and Lakshmanan 2000 ; Marynowski and Simoneit 2022 ; Rathnayake et al 2016 ; Vincenti et al 2022 ). Anhydrosaccharides (specifically levoglucosan and its isomers mannosan and galactosan) are pyrolytic degradation products of cellulose and hemicellulose (Marynowski and Simoneit 2022 ; Vicente and Alves 2018 ; Vincenti et al 2022 ) and have been widely used as tracers of biomass burning (de Oliveira Alves et al 2015 ; Galindo et al 2021 ; Monteiro et al 2018 ; Zhu et al 2022 ).…”

“…Sugar alcohols mainly come from fungal spores (e.g., mannitol and arabitol; Bauer et al 2008 ) and soil dust (e.g., sorbitol and xylitol; Simoneit et al 2004 ), while primary saccharides, such as glucose and sucrose, can be used as tracers of plant materials (e.g., pollen and plant fragments) and emissions from soils (Fu et al 2012 ; Simoneit et al 2004 ; Vincenti et al 2022 ; Zhu et al 2022 ). Although it has been reported that these last two classes of carbohydrates can also be emitted from biomass burning (Simoneit et al 2004 ; Vincenti et al 2022 ; Yttri et al 2007 ), they have been used to estimate the influence of primary biogenic emissions (i.e., particles released into the atmosphere from the biosphere, including pollen and plant debris, fungal spores, or bacteria) to the levels of organic carbon and PM in a number of previous works (Cao et al 2022 ; Casotto et al 2023 ; Gonçalves et al 2021 ; Jia et al 2010 ; Rathnayake et al 2016 ; Samaké et al 2019a ; Xu et al 2020 ). Despite all this, there are still few studies focusing on the sugar content of atmospheric aerosols in the Mediterranean basin.…”