Influence of organic aerosol molecular composition on particle absorptive properties in autumn Beijing

Abstract. Organic aerosol (OA) is a major component of fine particulate matter (PM), affecting air quality, human health, and the climate. The absorptive reflective behavior OA components contributes to determining particle optical properties thus their effects on radiative budget troposphere. There limited knowledge influence molecular composition in polluted urban environment. In this study, we characterized oxygenated collected filter samples autumn 2018 Beijing, China, with inlet for gases aerosols coupled high-resolution time-of-flight chemical ionization mass spectrometer (FIGAERO–CIMS). Three haze episodes occurred during our sampling period daily maximum concentrations 50, 30, 55 µg m?3. We found that signal intensities dicarboxylic acids sulfur-containing compounds increased two more intense episodes, while relative contributions wood-burning markers other aromatic were enhanced cleaner periods. further assessed by combining detailed measurements collocated light absorption measurements. show enhancement (Eabs) black carbon (BC) was mostly related (e.g., acids), likely formed aqueous-phase reactions periods higher humidity, speculate they might contribute lensing effects. Aromatics nitro-aromatics nitrocatechol its derivatives) high coefficient (babs) consistent light-absorbing (brown) (BrC). Our results provide information at level associated BrC BC can serve as basis studies anthropogenic forcing