Abstract
Secondary inorganic aerosols (SIA) are the predominant components of fine particulate matter (PM2.5) and have significant impacts on air quality, human health, and climate change. In this study, the Community Multiscale Air Quality modeling system (CMAQ) was modified to incorporate SO2 heterogeneous reactions on the surface of dust particles. The revised model was then used to simulate the spatiotemporal characteristics of SIA over China and analyze the impacts of meteorological factors and dust on SIA formation. Including the effects of dust improved model performance for the simulation of SIA concentrations, particularly for sulfate. The simulated annual SIA concentration in China was approximately 10.1 μg/m3 on domain average, with strong seasonal variation: highest in winter and lowest in summer. High SIA concentrations were concentrated in developed regions with high precursor emissions, such as the North China Plain, Yangtze River Delta, Sichuan Basin, and Pearl River Delta. Strong correlations between meteorological factors and SIA pollution levels suggested that heterogeneous reactions under high humidity played an important role on SIA formation, particularly during severe haze pollution periods. Acting as surfaces for heterogeneous reactions, dust particles significantly affected sulfate formation, suggesting the importance of reducing dust emissions for controlling SIA and PM2.5 pollution.
Highlights
The results of field observations and laboratory studies suggest that dust particles can enhance sulfate concentration
We considered the impacts of dust particles to obtain better model performance in the Secondary inorganic aerosols (SIA) simulation, for sulfate concentrations
Based on the estimated dust emissions, the heterogeneous reactions of SO2 on the surface of dust particles were incorporated into the Community Multiscale Air Quality (CMAQ) modeling system
Summary
The results of field observations and laboratory studies suggest that dust particles can enhance sulfate concentration. Numerous laboratory studies have confirmed the existence of heterogeneous reactions of SO2 on the surface of dust particles[14,15,16]. This pathway is not considered in most chemical transport models. To improve the model’s capability to reproduce SIA concentrations, we incorporated the heterogeneous reactions of SO2 on the surface of dust particles into the Community Multiscale Air Quality (CMAQ) modeling system, which is a widely used regional chemical transport model[17,18,19]. The results of this study increase our understanding of the characteristics of SIA pollution in China and provide new insights on air pollution control strategies
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