Multi-model revealing the driving factors of black carbon pollution in Hohhot, the largest city on the Mongolian plateau

There remains a lack of comprehensive and systematic understanding of black carbon (BC) on the Mongolian Plateau. This study investigates the characteristics and sources of BC in Hohhot, the largest city on the Mongolian Plateau, particularly analyzing the impact of COVID-19 lockdown on BC. During the lockdown period (LD), the BC concentration decreased by 38.2% due to reduced emission intensity and improved diffusion conditions. The annal mean concentrations of fossil fuel BC (BCff) and biomass burning BC were 0.50 ± 0.71 μg/m3 and 1.01 ± 1.01 μg/m3, respectively, accounting for 33.1% and 66.9% of BC. The contribution of BCff significantly decreased from pre-lockdown (61.9%) to LD (51.8%). Due to the resumption of transportation activities during post-lockdown, the BCff contribution bounced back to 61.7%. Compared with pre-lockdown, BC concentration decreased by 1.24 μg/m3 during LD. The reduction of anthropogenic emissions (meteorological changes) contributed 0.84 μg/m3 (0.40 μg/m3) to this decrease, accounting for 67.7% (32.3%) of the BC variation. Due to strict transportation restrictions, the fossil fuel BC concentration significantly decreased during LD, contributing to 78.2% of the BC variation. This study provides essential data for the formulation of BC pollution control measures and policies to address climate change in cities on the Mongolian Plateau. [Display omitted] •Prominent temporal variations of black carbon (BC) concentration and sources were observed.•Fossil fuel (BCff) is the main source of BC in Hohhot (66.9%).•Lockdown measures decreased BCff, resulting equal contribution of biomass burning (BCbb) and BCff.•BCff variation contributed 78.2% to the decline of BC during lockdown.•Decline of BCff caused by lockdown measure dominated the decrease of BC.