Abstract. The atmospheric processes under polluted environments involving interactions of anthropogenic pollutants and natural emissions lead to the formation of various and complex secondary products. Therefore, the characterization of oxygenated organic compounds in urban areas remains a pivotal issue in our understanding of the evolution of organic carbon. Here, we describe measurements of an iodide chemical ionization
time-of-flight mass spectrometer installed with a Filter Inlet for Gases and
AEROsols (FIGAERO-I-CIMS) in both the gas phase and the particle phase at an urban
site in Guangzhou, a typical megacity in southern China, during the autumn
of 2018. Abundant oxygenated organic compounds containing two to five oxygen atoms
were observed, including organic acids, multi-functional organic compounds
typically emitted from biomass burning, oxidation products of biogenic
hydrocarbons and aromatics. Photochemistry played dominant roles in the
formation of gaseous organic acids and isoprene-derived organic nitrates,
while nighttime chemistry contributed significantly to the formation of
monoterpene-derived organic nitrates and inorganics. Nitrogen-containing
organic compounds occupied a significant fraction of the total signal in
both the gas and particle phases, with elevated fractions at higher
molecular weights. Measurements of organic compounds in the particle phase
by FIGAERO-I-CIMS explained 24 ± 0.8 % of the total organic aerosol
mass measured by aerosol mass spectrometer (AMS), and the fraction increased
for more aged organic aerosol. The systematical interpretation of mass
spectra of the FIGAERO-I-CIMS in the urban area of Guangzhou provides a
holistic view of numerous oxygenated organic compounds in the urban
atmosphere, which can serve as a reference for the future field measurements
by FIGAERO-I-CIMS in polluted urban regions.
Automated Analysis of Persistent Organic Pollutants in the Gas Phase by Laser Ionization Mass Spectrometry
