Heterogeneous glyoxal oxidation: A potential source of secondary organic aerosol

摘要

Laboratory studies are described that suggest reactive uptake of glyoxal on particulate containing HNO _3 could contribute to the formation of secondary organic aerosol (SOA) in the upper troposphere (UT). Using a Knudsen cell flow reactor, glyoxal is observed to react on supercooled H _2O/HNO _3 surfaces to form condensed-phase glyoxylic acid. This product was verified by derivatization and GC-MS analysis. The reactive uptake coefficient, γ, of glyoxal varies only slightly with the pressure of nitric acid, from γ = 0.5 to 3.0 × 10 ~(-3) for nitric acid pressures between 10 ~(-8) and 10 ~(-6) Torr. The data do not show any dependence on temperature (181-201 K) or pressure of glyoxal (10 ~(-7) to 10 ~(-5) Torr). Using the determined reactive uptake kinetics in a simple model shows that glyoxal uptake to supercooled H _2O/HNO _3 may account for 4-53 of the total organic mass fraction of aerosol in the UT.