Characterization of water-soluble organic matter in urban aerosol by1H-NMR spectroscopy.
The functional and13C isotopic compositions of water-soluble organic carbon (WSOC) in atmospheric aerosol were determined by nuclear magnetic resonance (1H-NMR) and isotope ratio mass spectrometry (IRMS) in an urban location in the Southern Mississippi Valley. The origin of WSOC was resolved using the functional distribution of organic hydrogen, δ13C ratio, and positive matrix factorization (PMF). Three factors were retained based on NMR spectral bins loadings. Two factors (factors 1 and 3) demonstrated strong associations with the aliphatic region in the NMR spectra and levoglucosan resonances. Differences between the two factors included the abundance of the aromatic functional group for factor 1, indicating fresh emissions and, for factor 3, the presence of resonances attributed to secondary ammonium nitrate and low δ13C ratio values that are indicative of secondary organic aerosol. Factors 1 and 3 added 0.89 and 1.08 μgC m-3, respectively, with the highest contribution in the summer and fall. Factor 2 retained resonances consistent with saccharides and was attributed to pollen particles. Its contribution to WSOC varied from 0.22 μgC m-3in winter to 1.04 μgC m-3in spring.
University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States; University of Alabama at Birmingham, Birmingham, AL 35216, United States.
Marie-Cecile G
MG
Chalbot
States Food and Drug Administration, Jefferson, AR, United States.
Priyanka
P
Chitranshi
States Food and Drug Administration, Jefferson, AR, United States.
Gonçalo Gamboa
GG
da Costa
University of Arkansas Stable Isotope Laboratory, Fayetteville, AR, United States.
Erik
E
Pollock
University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States; University of Alabama at Birmingham, Birmingham, AL 35216, United States.
Ilias G
IG
Kavouras
Biomass burning; NMR; Organic aerosol; Secondary organic aerosol