Spatial and seasonal variations of sugars (alcohol) in China: Emerging results from the CARE-China network

The “Campaign on Atmospheric Aerosol Research” network of China (CARE-China) is a long-term project for the study of the spatio-temporal distributions of physical aerosol characteristics as well as the chemical components and optical properties of aerosols over China. This study presents the size-segregated sugars from the CARE-China network. Sugars associated with size-segregated particulate matter at 8 regions (North China (NC), East China (EC), Northeast China (NE), and Central China (CC), South China (SC), Northwest China (NE), Southwest China (SW) and the Tibetan Plateau (TP)) including 14 sites over China from January 2013 to December 2014 were analyzed via gas chromatography mass spectrometry. Mass concentrations of measured sugars varied considerably with location and season, ranging from 0.20 to 5588 ng m−3, with the majority from levoglucosan (170 ± 207 ngm−3, accounting for 48% of total sugars), followed by sucrose (44.6 ± 39.6 ngm−3, accounting for 11.3% of sugar), and sorbitol (35.5 ± 42.2 ng m−3, accounting for 10.0% of sugars). The highest levels of sugars were observed in urban sites in Central and Southwest China, whereas the lowest concentrations occurred in background and Tibetan Plateau sites. A distinct seasonal variability of sugars was observed, with higher in the winter or autumn and lower during the summer at urban sites. Inconsistent seasonal trends were observed at the background sites located in the higher latitudes, which were characteristic with the highest concentration occurred in spring. Levoglucosan, galactosan and mannosan were found to be dominant in fine size range <1.1 μm, accounting approximately 59% of all size-segregated sugars. Sucrose was enriched in the size range of 3.3–9.0 μm for almost all sampling sites. Concentrations of trehalose and sorbitol in the three size particles were similar. The OC from biomass burning was estimated to be in the range of 0.93–58.7 μg C m−3, with the highest level OCBB% were observed in urban sites in summer and winter. The contributions of biomass burning to OC in the rest of sites were higher in autumn and winter than in spring and summer. Higher OCBB% was observed in spring at the background sites located in Northwest and Northeast China.