Changes in source-specific black carbon aerosol and the induced radiative effects due to COVID-19 lockdown

The impacts of anthropogenic emissions on the reduction of source-specific equivalent black carbon (eBC) aerosol and their direct radiative effects (DREs) were investigated during the lockdown of coronavirus outbreak in a megacity of China in 2020. Five eBC sources were identified by a newly developed hybrid environmental receptor model. Results showed that biomass burning, traffic-related emissions, and coal combustion were the dominant contributors to eBC. The generalized addictive model indicated that the reduction of traffic-related eBC during the lockdown was entirely attributed to the decrease of emission. The decreased biomass-burning activities and favorable meteorological factors are both important drivers for the biomass-burning eBC reduction during the lockdown. A radiative transfer model showed that the eBC DRE efficiency of biomass burning was the strongest, followed by coal combustion and traffic-related emissions. This study highlights that aggressive reduction in the consumption of residential solid fuels would be effective on climate change mitigation.