Modeling the Impact of Emissions from Crop Residue Burning on PM2.5 Concentration in Beijing and Its Surrounding Areas

Open biomass burning is an important source of air pollution in North China. The contribution of biomass burning to Beijing and its surrounding areas is quantified using a three-dimensional regional chemical transport model (WRF-Chem) with satellite-detected fire emissions inventory in May 2017 as input. It is found that there were 20 days with dense fires in North China during this month, which exerted great impact on regional air quality. Simulated results show that the biomass burning resulted in PM2.5 concentration increase mainly over major crop production areas in the North China Plain, which are consistent with the distribution of satellite-detected fire spots. Estimation based on model simulation indicates that open biomass burning contributes more than 3 μg/m³ to monthly averaged PM2.5mass concentration over the entire North China with the maximum contribution larger than 11 μg/m³, which accounts for more than 10% of the PM2.5mass concentration in some areas. The simulation also indicates that even if there is almost no fire spot in Beijing and the adjacent areas, biomass burning in the North China Plain and Yangtze River delta can still affect air quality in Beijing through long range transport process. A typical case review suggests that crop residue burning in Henan, Shandong, and Tianjin can significantly affect southeastern portion of Beijing, and leads to PM2.5 concentration increase by more than 17 μg/m³, which is equivalent to larger than 40% increase of the PM2.5 concentration.