Measurement report: Saccharide composition in atmospheric fine particulate matter during spring at the remote sites of southwest China and estimates of source contributions

Abstract

Abstract. Based on source-specific saccharide tracers, the characteristics of biomass burning (BB) and biogenic emissions of saccharides were investigated in three rural sites at Lincang, which is 65 % covered with forest in the southwest border of China. The total saccharides accounted for 8.4 ± 2.7 % of organic carbon (OC) and 1.6 ± 0.6 % of PM2.5. The measured anhydrosugars accounted for 48.5 % of total saccharides, among which levoglucosan was the most dominant species. The high level of levoglucosan was both attributed to the local BB activities and biomass combustion smoke transported from the neighboring regions of Southeast Asia (Myanmar) and the northern Indian subcontinent. The measured mono- or disaccharides and sugar alcohols accounted for 24.9 ± 8.3 % and 26.6 ± 9.9 % of the total saccharides, respectively, and both proved to be mostly emitted by direct biogenic volatilization from plant material or surface soils rather than byproducts of polysaccharide breakdown during BB processes. Five sources of saccharides were resolved by non-negative matrix factorization (NMF) analysis, including BB, soil microbiota, plant senescence, airborne pollen, and plant detritus with contributions of 34.0 %, 16.0 %, 21.0 %, 23.7 %, and 5.3 %, respectively. The results provide information on the magnitude of levoglucosan and contributions of BB, as well as the characteristic of biogenic saccharides, at the remote sites of southwest China, which can be further applied to regional source apportionment models and global climate models.

Measurement report: Characterization of sugars and amino acids in atmospheric fine particulates and their relationship to local primary sources

“…4). Averages of the sum of mannitol and arabitol concentrations measured in the three sampling locations (75 ng m −3 ) were higher than those reported in the megacity of Beijing (21 ng m −3 ) (Kang et al, 2018) and the rural site of Lincang, China (21.5 ng m −3 ) (Wang et al, 2021). Since these sugar polyols are reported to be abundant in fungi, trees, branches, and leaves (Wang et al, 2021;Fu et al, 2008), the high abundance of mannitol and arabitol found in this study can be attributed largely to a biological origin.…”

“…To accurately qualify the BB source in different locations, nss-K + has also been used as a typical tracer of BB in previous studies (Kunwar and Kawamura, 2014). However, previous studies also indicated that soil dust could be another source of water-soluble nss-K + in aerosols (Urban et al, 2012(Urban et al, , 2014Wang et al, 2021). The nss-K + concentrations averaged 633.1 ng m −3 in the urban area, which was higher than those observed in the rural (549.6 ng m −3 ) and forest (590.2 ng m −3 ) areas.…”

“…The sources of these two sites were proved to be attributed mainly to wood burning (Urban et al, 2012). The ratio of lev/K + was used to characterize the type of biomass burned (Wang et al, 2021). Cheng et al (2013) found that the levoglucosan to K + ratio in emissions from the combustion of crop residuals was below 1.0, which is much lower than the ratio for hardwood burning (average = 25.69 ± 9.11) and softwood burning (average = 105.58±102.60).…”

“…Levoglucosan / mannosan (L/M) ratios have been employed to identify specific burning substrates in numerous studies (Fabbri et al, 2009;Fan et al, 2020;Zhu et al, 2015). L/M ratios for smoke particles from the burning of crop residues (∼ 40 to 55.7) were high, while L/M ratios for the burning of hardwood (15-33) and softwood (3-10) were low (Engling et al, 2009(Engling et al, , 2014Sheesley et al, 2003;Wang et al, 2021). Besides that, recent studies demonstrate that levoglucosan is also present in lignite smoke particle matter (Rybicki et al, 2020a).…”

“…For instance, plant-debris-derived aerosol organic carbon was estimated based on the relationship of glucose and plant debris (Fan et al, 2020). Sucrose have been widely employed to indicate airborne pollen grains (Wang et al, 2021;Fu et al, 2012;Yan et al, 2019). The sugar alcohols arabitol and mannitol are found to be produced by fungi, lichens, soil biota, and algae to overcome environmental stress (Medeiros et al, 2006).…”