Aircraft measurements of polar organic tracer compounds in tropospheric particles (PM10) over central China

摘要

Atmospheric aerosol samples were collected by aircraft at low to middlealtitudes (0.8–3.5 km a.g.l.) over central East to West China during summer2003 and spring 2004. The samples were analyzed for polar organic compoundsusing a technique of solvent extraction/BSTFA derivatization/gaschromatography–mass spectrometry. Biogenic secondary organic aerosol (SOA)tracers from the oxidation of isoprene were found to be more abundant insummer (3.3–138 ng m, mean 39 ng m) than in spring (3.2–42 ng m,15 ng m), while α/β-pinene and β-caryophyllene SOA tracers showed similar abundances between these twoseasons. A strong positive correlation ( = 0.83) betweenlevoglucosan and β-caryophyllinic acid was found in the springsamples vs. a weak correlation ( = 0.17) in the summersamples, implying substantial contributions from biomass burning to theβ-caryophyllinic acid production in spring. Two organic nitrogenspecies (oxamic acid and carbamide) were detected in the aircraft aerosolsamples, and their concentrations were comparable to those of biogenic SOAtracers. Most of the primary organic aerosol (POA) and SOA tracers were less abundant at higheraltitudes, suggesting they are of ground surface origin, either beingdirectly emitted from anthropogenic/natural sources on the ground surface,or rapidly formed through photooxidation of their precursors emitted fromthe ground surface and then diluted during uplifting into the troposphere.This study demonstrates that primary biological aerosols, biogenic SOA, andorganic nitrogen species are important components of organic aerosols in thetroposphere over central China during warm seasons.