| Abstract [eng] |
The aim of this work was to examine δ34S distribution in atmospheric sulphate aerosol particles and to characterize their sources while applying stable isotope mass spectrometry methods. For this task, the dependence between measurements of atmospheric sulfate aerosol δ34S and particulate sulphate concentration was found. In this work, topics of Sulphur isotopes, their application in stable isotope analysis, δ34S notation and standards used for analysis are discussed. Furthermore, the global sulphur cycle and aerosol terminology is reviewed. It is followed by a description of sulphate aerosol particulate matter formation, natural and anthropogenic sources and their annual global fluxes with typical δ34S values found in nature. In the methodological section, atmospheric aerosol sample collection location and the aerosol sampler instrumentation is described. The sample collection period lasted from 5 March until 6 May, during the year 2020. Also described are the details of sample chemical preparation procedure, stable isotope mass spectrometry equipment, its use for sulphur isotope measurements and normalization of δ34S values. In the experimental section of this work, accuracy of stable isotope mass spectrometer was verified with the use of international reference standards. Afterwards, sample δ34S values together with aerosol sulphate concentrations were determined. By comparing the aerosol sulphate concentrations to air monitoring data it was found that their values change accordingly to the background particulate matter concentrations in Vilnius, however changes in atmospheric SO2 concentrations produced little effect. Subsequently, relationship between δ34S values and aerosol sulphate concentrations was plotted which revealed two possible major sources of sulphate aerosol pollution. These results were then related to atmospheric air parcel trajectory models which were applied in characterizing the pollution sources and their effect on measured δ34S values. The results of this work showed that during the sampling period atmospheric sulphate aerosol δ34S values ranged from 6,1 ‰ to 12,6 ‰. Additionally, it was determined that local pollution sources are represented by lower values of δ34S whereas long range source δ34S values are higher. Finally, two probable dominant sources of atmospheric sulphate aerosol pollution were found. |
