Unified modeling of the formation and evolution of secondary organic aerosol from oxygenated aliphatic precursors over long-time oxidation

Oxygenated aliphatic compounds are increasingly recognized as an important source of secondary organic aerosol (SOA) in urban air. This class of compounds is diverse, and their complex multi-generation oxidation remains poorly represented in current models, hindering accurate simulation of SOA formation. In this study, we explored efficient and accurate description of SOA formation and evolution from oxygenated aliphatics over long-time oxidation. Here, the oxidation process was separated into first-generation and multi-generation stages: first-generation oxidation was constrained by explicit GECKO-A mechanisms, while multi-generation aging was represented using a two-dimensional volatility basis set (2D-VBS) framework. We constructed and optimized a 2D-VBS model based on experimental data for the oxidation of oxygenated aliphatics, and demonstrated that the whole-set unified parameterization, which uses a single uniform set of parameters to describe the multi-generation aging of all oxygenated aliphatic precursors while explicitly constraining their first-generation oxidation products, can reasonably and efficiently capture SOA formation and aging of diverse oxygenated aliphatics. Estimating real-world SOA formation for several major Chinese urban emission sources via the unified modeling method, we found oxygenated aliphatics contribute approximately 81% of total SOA from cooking emissions. For paint emissions, oxygenated aliphatics rather than aromatics dominate organic component in water-based paints, and the SOA yield (SOA formed per unit of emission) from water-based paints is only 48% of that from solvent-based paints. These results enable more consistent and quantitative attribution of SOA formation from oxygenated aliphatic emissions in real-world urban sources, supporting targeted policymaking and improved public health protection in cities.