Influence Of Stove, Fuel, And Oxidation Flow Reactor Conditions On Aging Of Laboratory-Generated Cookstove Emissions

Oxidation flow reactor (OFR) experiments are a useful way to explore secondary organic aerosol (SOA) production during photochemical aging of biomass combustion emissions. Here, we extend previous work by studying SOA formed by emissions from three cookstoves used in low-income settings (Philips, Chulika, and three-stone fire (TSF)) while varying the fuel type (red Oak and loblolly Pine) and OFR operating conditions. Differences in SOA formation across fuel types were relatively minor, with SOA formation increases of <30% for Oak vs Pine experiments. Mass spectral fragments (f(44), f(43), and f(60)) from aged Oak and Pine emissions generally spanned the same continuum with combustion technology playing a larger role in dictating aged OA evolution than the fuel type. Combustion technology also has a much greater influence on net aerosol climate forcing relative to interfuel differences. The OFR was operated under "wet" and "dry" conditions, to study the impacts of more or less tropospherically relevant oxidation conditions on SOA formation, respectively. SOA formation did not vary dramatically across OFR conditions and was larger by up to 27% for the TSF and 5% for the Philips for "wet" operation. OA spectral differences were greater, with f(44) up to 28% greater for "wet" operating conditions at similar levels of aging. Overall, changes in reactor operation were not sufficient to alter major conclusions from previous work where the OFR was operated under conditions similar to the "dry" conditions applied here. Positive matrix factorization analyses on SOA spectra identified two factors, a transient oxidation factor and a uniformly aged factor, which were similar across experiments.