Molecular Composition of Oxygenated Nitrogen-Containing Organic Compounds Emitted from Combustion of the Three Biomass Macro-Components

Abstract. Biomass burning is an important source of oxygenated nitrogen-containing organic compounds, but their formation mechanisms remain unclear. CHON compounds in organic aerosols (OAs) from cellulose, hemicellulose, and lignin combustion at three ignition temperatures (IGT) under full-oxygen conditions were characterized by high-resolution mass spectrometry in negative and positive electrospray ionization modes. Our results indicate that CHON– and CHON+ compounds account for 13–60% and 3.4–32% of OA intensity, respectively, with the composition depending strongly on fuel type and IGT. Lignin-derived CHON compounds had higher aromatic fractions than cellulose- and hemicellulose-derived CHON compounds at low IGT, and all of them had high fractions of reduced-N species with high N contents. With the increasing IGT to 600 °C, the fractions of aromatic CHON increased for OA_cellulose and OA_{hemicellulose} but not for OA_lignin, However, the molecular overlap of CHON compounds among the three OAs elevated, resulting in high similarity in the composition of  nitro-phenolic-like compounds. More reduced-N aromatic compounds were produced at 800 °C for all fuels, but lignin yielded abundant condensed aromatic species. Our findings provide molecular-level insight into CHON chemodiversity across fuel types, and are beneficial for assess the climate and health effects of biomass burning OAs accurately.