Impact of residential biomass burning emissions on the wintertime particulate pollution in the Guanzhong Basin, China: a case study

Biomass burning (BB) emissions have constituted an important source of ambient air pollution. Previous studies have focused on the impact of open BB (OBB) emissions on the regional air quality and climate, while it remains elusive about the effect of residential BB (RBB) emissions on the particulate matters (PM) pollution and regional climate. The WRF-Chem (Weather Research and Forecast model coupled with Chemistry) model has been used to evaluate the contribution of RBB emissions to the PM pollution in the Guanzhong Basin (GZB) during the persistent air pollution episode from December 14, 2020, to January 6, 2021 in this study. The RBB emission in the GZB is a significant source for primary aerosols under current conditions, with average contribution of 62.8%, 35.9%, and 33.4% for POA (primary organic aerosols), EC (element carbon), and primary PM_2.5 (PM with aerodynamic diameter equal or less than 2.5 µm), respectively. The RBB emissions in the GZB also play an important role in the formation of SOA (secondary organic aerosols), with the average contribution of 52.6% to the SOA during the study period. Additionally, the RBB emissions in the GZB are also responsible for 4.6%, 9.4%, and 8.4% of the sulfate, nitrate, and ammonium, respectively. Therefore, the contribution of RBB emissions in the GZB to the near-surface PM_2.5 mass concentrations during the simulation period is around 29.2% (18.4 μg m^-3) averaged over the GZB. It is noted that the O₃ concentration is slightly decreased by 1.6 μg m^-3 (4.1%) averaged over the GZB with the exclusion of RBB emissions, which is might be resulted from the small decrease in NO₂ concentration (5.9% or 2.0 μg m^-3). Besides, the RBB emissions in the GZB contribute 16.4% (1.0 μg m^-3) to the NH₃ concentrations during the study period. Our results show that the RBB emissions should be considered in the air pollution control strategies for further alleviation of the wintertime PM pollution in the GZB under current conditions.