| Abstract [eng] |
Sulfur compounds play a crucial role in Earth’s climate system, significantly affecting air quality and human health. Sulfate aerosols contribute to climate cooling by scattering solar radiation, with their radiative forcing properties dependent on SO2 oxidation pathways. Thus, accurately identifying sulfur pollution sources and understanding atmospheric oxidation mechanisms is essential for assessing their environmental and climatic effects. The results of this study revealed distinct seasonal trends in the isotopic compositions of atmospheric sulfur compounds, with higher δ34S values in the summer months and lower δ34S values in the winter months, driven by shifts in predominant pollution sources and oxidation pathways. By integrating stable sulfur (34S) and carbon (13C) isotopes with radiocarbon (14C) analysis, the research identified that the main anthropogenic pollution sources in Vilnius were biomass burning, coal combustion emissions from neighboring countries, and, during the 2022 – 2023 heating season, emissions from heavy fuel oil, which became a significant contributor during this period. Furthermore, isotopic composition data from synchronously collected SO2 and sulfate aerosol samples enabled a quantitative assessment of the main SO2 oxidation pathways. The findings showed that transition metal ion-catalyzed oxidation was the prevailing mechanism for sulfate formation in Vilnius during winter, while oxidation by H2O2 and OH played a lesser role. |
