The underappreciated impact of emission source profiles on the simulation of PM2.5 components: New evidence from sensitivity analysis.

The chemical transport model (CTM) is an essential tool for air quality prediction and management, widely used in air pollution control and health risk assessment. However, the current models do not perform very well in simulating PM_2.5 components. Studies suggested that the uncertainties of model chemical mechanism, source emission inventory and meteorological field can cause inaccurate simulation results. Still, the emission source profile of PM_2.5 has not been fully taken into account in current numerical simulation. This study aims to answer (1) Whether the variation of source profile adopted in chemical transport models (CTMs) has an impact on the simulation of PM_2.5 chemical components? (2) How much does it impact? (3) How does the impact work? Based on the characteristics and variation rules of chemical components in typical PM_2.5 sources, different simulation scenarios were designed and the sensitivity of components simulation results to PM_2.5 sources profile was explored. Our findings showed that the influence of source profile changes on simulated PM_2.5 concentration was insignificant, but its impact on PM_2.5 components could not be ignored. The variations of simulated components ranged from 8 % to 167 % under selected different source profiles, and simulation results of some components were sensitive to the adopted PM_2.5 source profile in CTMs. These influences are connected to the chemical mechanisms of the model since the variation of species allocations in emission sources directly affected the thermodynamic equilibrium system. We also found that the perturbation of the PM_2.5 source profile caused the variation of simulated gaseous pollutants, which indirectly indicated that the perturbation of the source profile affected the simulation of secondary PM_2.5 components. Given the vital role of air quality simulation in environment management and health risk assessment, the representativeness and timeliness of source profile should be considered. [ABSTRACT FROM AUTHOR]