Sectoral Size-Resolved Particle Number Emissions With Speciation: Emission Profile-Based Quantification and a Case Study in the Yangtze River Delta Region, China

Sizes and number concentrations are critical parameters for the impact of atmospheric particles on climate and human health. However, comprehensive studies focusing on size-resolved particle number (PN) emissions from various sectors are scarce. This study aims to fill this research gap by developing sectoral size-resolved PN emissions for major species including sulfate, organic mass (OM), and black carbon (BC). The size-resolved emission profiles derived from various measurements in the literature were integrated with a particle mass emission inventory (EI) for 13 major sectors in the Yangtze River Delta region of China as a case study. The particle number size distribution (PNSD) of emitted particles exhibited two distinct peaks: one at approximately 10 nm and the other in the range of 40–60 nm. The primary contributors to PN emissions in the region in 2017 were power plants, gasoline vehicles, diesel vehicles, and cooking sources. In terms of species, OM dominated PN emissions, followed by primary sulfate and then BC. A regional size-resolved aerosol model employing the size-resolved PN EI developed here (referred to as the BIN-SPE experiment) provided reasonably accurate temporal variations of the total PN concentration and captured the PNSD within the size range of 10–300 nm. Uncertainty analysis of sectoral PN emissions across size ranges was carried out and the performance of the BIN-SPE experiment was compared with those of three commonly used PN emission parameterizations. Our model evaluations highlight future needs for in-depth investigations into more advanced size-resolved emissions and secondary OM formation mechanisms.