Diurnal variations of organic molecular tracers and stable carbon isotopic composition in atmospheric aerosols over Mt. Tai in the North China Plain: an influence of biomass burning

Abstract

Organic tracer compounds, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and stable carbon isotope ratios (δ13C) of total carbon (TC) have been investigated in aerosol samples collected during early and late periods of the Mount Tai eXperiment 2006 (MTX2006) field campaign in the North China Plain. Total solvent-extractable fractions were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA) tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs). In early June when the field burning activities of wheat straws in the North China Plain were very active, the total identified organics (2090 ± 1170 ng m^[-3]) were double those in late June (926 ± 574 ng m^[-3]). All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88-1210 ng m^[-3], mean 403 ng m^[-3]) was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude, which could be further transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 24% (up to 64 %) of the OC in the Mt. Tai aerosols was due to biomass burning in early June, followed by the contribution of isoprene SOC (mean 4.3 %). In contrast, isoprene SOC was the main contributor (6.6 %) to OC, and only 3.0% of the OC was due to biomass burning in late June. In early June, δ13C of TC (-26.6 to -23.2 ‰, mean -25.0 ‰) were lower than those (-23.9 to -21.9 ‰, mean -22.9 ‰) in late June. In addition, a strong anti-correlation was found between levoglucosan and δ13C values. This study demonstrates that crop-residue burning activities can significantly enhance the organic aerosol loading and alter the organic composition and stable carbon isotopic composition of aerosol particles in the troposphere over the North China Plain

Anthropogenic and biogenic organic compounds in summertime fine aerosols (PM2.5) in Beijing, China

“…These values are much higher than those reported in Mt. Tai aerosols (LMW/HMW were 1.0 ± 0.80) in Central East China (Fu et al, 2012b) and even higher than those in tropical Indian PM 10 aerosols (5.3 ± 1.8) during summertime . Thus, our results suggest that much more LMW fatty acids are emitted from microbial sources in Beijing in summer, especially at the suburban site.…”

“…Because of their inverse health effects, phthalates have been intensively investigated in both ambient and indoor air (Wang et al, 2006;Fu et al, 2008Fu et al, , 2012bXu et al, 2015). Five phthalates were detected in this study, i.e., dimethyl (DMP), diethyl (DEP), diisobutyl (DiBP), di-n-butyl (DnBP), and di-(2-ethylhexyl) (DEHP) phthalates.…”

Molecular markers of biomass burning, fungal spores and biogenic SOA in the Taklimakan desert aerosols

“…Then, the extracts were reacted with 50 μL of N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA) with 1% trimethylsilyl chloride and 10 μL of pyridine at 70°C for 3 h. The derivatives were diluted with 140 μL of n-hexane containing 1.43 ng μL −1 of the internal standard (C 13 n-alkane) before GC-MS injection. 28 GC-MS Analysis. GC-MS measurements were performed on a Hewlett-Packard model 6890 GC coupled to a HewlettPackard model 5973 MSD.…”

Overview of the Mount Tai Experiment (MTX2006) in central East China in June 2006: studies of significant regional air pollution

“…Tai. , Yamaji et al, (2010), andFu et al (2012), on this issue, similarly report the impact of burning using backward trajectories that passed over hotspots. On 8-10 June, the wind was from the north and thus the influence was small, although hotspots were continuously found south of Mt.…”

“…Tai would be affected by regional emissions when the boundary layer builds up, covering the top of the mountains in the afternoon, as will be described later, the site is believed to be free from local anthropogenic pollution, and is expected to provide regionally representative data. Kanaya et al, 2009;Suthawaree et al, 2010;Inomata et al, 2010), and composition of aerosols including BC/EC (elemental carbon) and OC mass concentrations , molecular composition of organic aerosols Fu et al, 2008Fu et al, , 2010Fu et al, , 2012Kawamura et al, 2013a, b), and ionic composition (Deng et al, 2011;Xu et al, 2009). CO 2 measurements (LI-840, LI-COR biosciences, Lincoln, NE, USA) were made to assist discussion on sources of aerosols and gases.…”