Mass Absorption Efficiency of Black Carbon from Residential Solid Fuel Combustion and Its Association with Carbonaceous Fractions

Black carbon (BC) emissions, derived primarily from incomplete fuel combustion, significantly affect the global and regional climate. Mass absorption efficiency (MAE) is one important parameter in evaluating the climate impacts of BC. Here, values and variabilities in the MAE of BC (MAE_BC) from real-world residential emissions were investigated from a field campaign covering 163 burning events for different fuel-stove combinations. MAE_BC (average: 12 ± 5 m²/g) was normally distributed and varied greatly by 2 orders of magnitude. Statistically significant differences in MAE_BC were found for various fuels, while no significant differences were observed among different stoves. The fuel difference explained 72 ± 7% of the MAE_BC variation. MAE_BC did not correlate with the modified combustion efficiency but positively correlated with the ratio of organic carbon (OC) to elemental carbon (EC) and negatively correlated with char-EC. The OC/EC ratio was not always lower in coal emissions in comparison to biomass burning emissions. Coal- and biomass-burning emissions had different profiles of carbon fractions. Char-EC, OC, OC/EC, and char-EC/soot-EC can explain 68.7% of the MAE_BC variation, providing the potential for predicting MAE_BC from the carbon fractions, since they are more commonly measured and available.