Yearly Variations of Equivalent Black Carbon Concentrations Observed in Krakow, Poland

The evaluation of the equivalent black carbon (eBC) concentration is very important, especially in environmental sciences. Light absorbing carbon (LAC), also presented as equivalent black carbon (eBC), is generated from the partial combustion of fossil fuels and biomass. The scientific interest in eBC is large because its contribution to the PM2.5 fraction is high, especially in urban areas. This study presents yearly variations in eBC concentrations observed in Krakow, Poland. The transmissions of light at different wavelengths were measured by a multi-wavelength absorption black carbon instrument (MABI). Absorption coefficients and concentrations of eBC were calculated. Samples of the PM2.5 fraction were collected from 1 February 2020 to 27 March 2021 every third day in Krakow, Poland. The concentrations of eBC from fossil fuel combustion and biomass burning were in the range of 0.82-11.64 mu g m(-3) and 0.007-0.84 mu g m(-3), respectively. At the same time, PM2.5 concentrations varied from 3.14 to 55.24 mu g m(-3). The eBC contribution was a significant part of PM2.5 mass and we observed a seasonal variation in eBC concentrations during the year, with the peak in winter (5.3 +/- 1.8 mu g m(-3)). The contribution of BC from biomass burning to PM2.5 mass was in the range of 4%-5% with the highest value for winter. The eBC concentration during workdays was 21% higher than during weekend days.