Aircraft measurements of polar organic tracer compounds in tropospheric particles (PM<sub>10</sub>) over central China

Abstract

Abstract. Atmospheric aerosol samples were collected by aircraft at low to middle altitudes (0.8-3.5 km a.g.l.) over central East to West China during summer 2003 and spring 2004. The samples were analyzed for polar organic compounds using a technique of solvent extraction/BSTFA derivatization/gas chromatography-mass spectrometry. Biogenic secondary organic aerosol (SOA) tracers from the oxidation of isoprene were found to be more abundant in summer (3.3-138 ng m −3 , mean 39 ng m −3 ) than in spring (3.2-42 ng m −3 , 15 ng m −3 ), while α/β-pinene and β-caryophyllene SOA tracers showed similar abundances between these two seasons. A strong positive correlation (R 2 = 0.83) between levoglucosan and β-caryophyllinic acid was found in the spring samples vs. a weak correlation (R 2 = 0.17) in the summer samples, implying substantial contributions from biomass burning to the β-caryophyllinic acid production in spring. Two organic nitrogen species (oxamic acid and carbamide) were detected in the aircraft aerosol samples, and their concentrations were comparable to those of biogenic SOA tracers. Most of the primary organic aerosol (POA) and SOA tracers were less abundant at higher altitudes, suggesting they are of ground surface origin, either being directly emitted from anthropogenic/natural sources on the ground surface, or rapidly formed through photooxidation of their precursors emitted from the ground surface and then diluted during uplifting into the troposphere. This study demonstrates that primary biological aerosols, biogenic SOA, and organic nitrogen species are important components of organic aerosols in the troposphere over central China during warm seasons.

Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

“…SOA PIN exhibited the lowest concentration in the FT-WES (1.2 ng m −3 ) with a predominance of cis-pinonic acid (Table 2). Aircraft measurements in the FT over central China (Fu et al, 2014) recorded higher concentrations of 3-HGA (8.5 ng m −3 ) and MBTCA (1.9 ng m −3 ) than those measured in the present study (Table 2). Further-generation oxidation products (3-HGA and MBTCA) were higher in the BL (0.51 and 0.24 ng m −3 correspondingly; Table 2), with a statistically significant correlation (r = 0.90, p < 0.01) pointing to a same precursor.…”

“…Secondary products of isoprene oxidation (SOA ISO) evaluated in the present study are 2-methylglyceric acid (2-MGA), 2-methylthreitol (2-MT1) and 2-methylerythritol (2-MT2) (Claeys et al, 2004;Hallquist et al, 2009). Analogous FT concentrations of 2-methylthreitol and 2-methylerythritol were measured in the present study under the SAL (7.3 and 16.8 ng m −3 ; Table 2) and over the central China FT (8 and 17 ng m −3 ; Fu et al, 2014), one of the most important source regions of isoprene emission in the world during summertime (Guenther et al, 1995). Similar SOA ISO concentrations were found in the BL within the SAL and the WES (∼ 17 and ∼ 16 ng m −3 respectively) revealing the emission and subsequent ascending transport of biogenic or anthropogenic compounds, as found in previous studies performed at Izaña, which observed emissions of isoprene during daytime associated with anthropogenic compounds (Salisbury et al, 2006).…”

“…A number of studies have focused on OA speciation in urban areas (Alier et al, 2013;Kawamura and Kaplan, 1987;Puxbaum et al, 2007;Schauer et al, 1996;Simoneit et al, 1991; compared to remote environments. Studies in the free troposphere are less common (Simoneit et al, 2004a;Fu et al, 2008Fu et al, , 2014Wang et al, 2009;Van Drooge et al, 2010;Meng et al, 2014), in spite of the fact that they are of interest due to the long-range transport potential linked to the high wind speeds above the boundary layer.…”

Heterogeneous chemistry and reaction dynamics of the atmospheric oxidants, O3, NO3, and OH, on organic surfaces

“…In addition to highly practical field measurements 152 and atmospheric sampling, 153 future research will continue to focus on deconstructing complex systems into their fundamental components and investigating real-time changes to organic surfaces during exposure to a controlled flux of gas-phase oxidants.…”

Composition of Organic Compounds Adsorbed on PM10 in the Air Above Maribor

“…The daily limits are exceeded mainly in winter due to increased traffic, domestic heating, industrial processes and meteorological phenomena such as inversion or low wind speed. [1][2][3][4][5] Airborne suspended particulate matter can be of natural (forests, pollen, rainfall, storm, vegetation, volcanic ash...) or anthropogenic origin (emissions of industry, transport, burning of fossil fuels, biomass, agriculture...). Primary particles are released into the atmosphere from sources on the Earth's surface.…”