Long-term black carbon variation in the South-Eastern Baltic Region in 2008-2015

Long-term continuous measurement data of equivalent black carbon (eBC) concentration over a period of 8 years (2008-2015) from the coastal - background site in Preila, Lithuania, have been analysed. The analysis performed with Preila data has shown that the average mean of eBC concentration was 750 ng/m(3). A seasonal pattern was also observed with the highest eBC values (1170 ng/m(3)) in winter gradually declining to the minimum concentration (380 ng/m(3)) in summer. The frequency distribution of the data was fitted with lognormal modes. Cold and warm seasons were parameterised with three and two modes, respectively. Both the parametric and non-parametric trend analysis methods were applied in this research. A positive annual linear trend for the whole period was estimated to range from +1.97% to +5.35% per year. However, the second order trend had a maximum in 2013 and was declining during the last years of the analysed period, or, according to the t-test, had any statistically significant trend. Regional and long-range emissions of coal and biomass combustion are the main sources of the observed eBC in the Preila station during the cold seasons. This study presents the current situation of black carbon trends in the Baltic Sea region and will be helpful for assessing the policies of black carbon emissions in Europe.