Long-term observations of levoglucosan in Arctic aerosols reveal its biomass burning source and implication on radiative forcing
Description
Aerosol samples (TSP) were collected from the high latitude Arctic area during the Chinese Arctic expeditions in the summers (July‒September) of 2010, 2012, 2014, 2016, and 2018. Aerosol samples were collected by a high volume air sampler installed on the bow deck of Xuelong. During sampling, the atmosphere was filtered through a glass fiber filter film (burned at 450 C for 4 h before sampling). The sampling time was ~24-48 h, and the sampling volume was approximately 1300 m3. The specific volume is quantified by the flow meter of the large-flow sampler. After collection, the samples were wrapped in aluminum foil, placed in a double-layer dense bag and stored in a refrigerator at -20 C. The extraction of Lev and its isomers from aerosol samples was conducted using an accelerated solvent extraction device (ASE 350, Thermo Fisher Scientific). After extraction, the solution was concentrated and blow-dried with gentle nitrogen gas and subsequently silanized at 70 C for 1 h. An Agilent gas chromatography‒mass spectrometry system (GC‒MS, 7890B-5977B) with electron ionization (EI) mode was used to quantify the target compounds.