Dialkylsulfate formation in sulfuric acid-seeded secondary organic aerosol produced using an outdoor chamber under natural sunlight

摘要: Environmental context Laboratory and field studies have both provided evidence for organosulfate formation by esterification of H2SO4 with organic compounds in aerosols. Using an outdoor chamber, the production dialkylsufate was measured aerosols produced photooxidation various hydrocarbons presence aerosol NOx. The organosulfates influences decrease acidity hygroscopicity. Abstract Secondary (SOA) were volatile (VOCs) isoprene, α-pinene toluene, excess amounts sulfuric acid seed varying NOx concentrations using a large, smog chamber. Aerosol ([H+], μmol m–3) colorimetry integrated reflectance UV-visible spectrometer (C-RUV). C-RUV technique measures changes through neutralisation ammonia dialkylsulfate, diester acid. concentration (μmol dialkylsulfate estimated difference [H+] obtained from particle-into-liquid-sampler ion chromatography (PILS-IC). yield (YdiOS) defined as normalised ammonium-free sulfate ([SO42–]free=[SO42–] – 0.5 [NH4+]) carbon. highest YdiOS appeared isoprene SOA lowest SOA. Under our experimental conditions, more than 50% total sulfates acid-seeded dialkylsulfates. For all SOA, higher observed under conditions (VOC (ppb C)/NO (ppb)<15). Among major functional groups (–COOH, –CO–H, –CHO –ONO2) predicted to be present simple absorptive partitioning model products multiphase system (gas, inorganic aerosol), –ONO2 found correlated YdiOS. In particular, strong correlation between alcohol groups.