| Abstract [eng] |
In this work, the dynamics of the mass concentration of aerosol black carbon (BC) (formed during the combustion process of fossil and biomass fuels) was analysed and the contribution of the pollution sources was quantified. The aim of the work was to perform BC source apportionment using the “Aethalometer model” and to evaluate their contribution to the dynamics of the BC mass concentration in Vilnius city. BC mass concentration and optical parameters were calculated using a 7-wavelength aethalometer, other organic aerosol components were determined at urban background pollution environment in 2014, 2017, 2020 using an aerosol chemical speciation monitor and aerosol mass spectrometer. Spatial measurements of BC mass concentration were performed using a micro-aethalometer while traveling via pedestrian and bicycle paths within different micro-environments of Vilnius. The BC source apportionment is based on a different wavelength absorption defined by the absorption Angstrom exponent value. Based on the “Aethalometer Model”, pollution sources were separated into two: fossil fuel combustion (AAEtr) and biomass combustion (AAEwb). The most suitable combination of 0.9 (AAEtr) and 2.2 (AAEwb) values was selected. It was based on the strong correlations of BCtr and BCwb with HOA (hydrocarbon-like organic aerosol), NO2 and BBOA (biomass burning organic aerosol). The results of the source apportionment analysis showed that the dominant source of BC pollution in Vilnius is fossil fuel combustion. The analysis of the absorption coefficient spectra showed that during the study period between 2014 and 2020. the value of the BCtr absorption coefficient associated with fossil fuel combustion increased 3.6 times. Spatial measurements performed at different micro-environments of Vilnius showed that the mass concentration of BC varies in a wide range from 0.5 to 9.9 µg·m–3. Using the determined combination of AAEtr and AAEwb values, it was found that transport-related BCtr has the largest contribution (~ 49 - 96%) to air quality in pedestrian and cycling areas. These findings highlight the problem of local air pollution caused by transportation, the impact of BC on the thermal balance of the atmosphere and raise concern for public health. |
