The FTMC Department of Nuclear Research has a new Doctor of Natural Sciences. On 28 March, Laurynas Bučinskas earned his PhD after defending his dissertation, "Dynamics and Balance of Sulphur Compounds in Environmental Systems". His academic supervisor was Dr Andrius Garbaras.
Congratulations to our colleague, and best wishes for continued success!
Laurynas' dissertation analyses the activity and transformations of sulphur compounds in the atmosphere. The study employs a combination of stable sulphur (34S/32S) and carbon (13C/12C) isotope ratio measurements, as well as radiocarbon (14C) analysis, to identify key pollution sources affecting air quality in Vilnius. Additionally, it investigates the transformation processes of sulphur compounds in the atmosphere, specifically the oxidation of sulphur dioxide (SO2) with oxygen, and their seasonal variations.
(Photo: Unsplash.com)
"This research covers a crucial topic in environmental science - the identification of pollution sources and the transport of emissions in the atmosphere. Sulphur pollution is particularly significant due to its impact on human health and the climate.
An important characteristic of sulphate aerosols is their ability to scatter solar radiation, which reduces the effect of greenhouse gases on the climate - a beneficial property of these particles. However, excessive sulphur emissions are harmful to both human health and the environment. A negative example of their impact is acid rain, which severely damaged Europe’s natural ecosystems and cultural heritage (such as architectural monuments and statues) in the 1970s and 1980s," says the physicist.
His dissertation research revealed that air quality in Vilnius is influenced primarily by emissions from coal, biomass, and petroleum products. The isotopic analysis used in the study allows for the identification of seasonal pollution sources and the distinction between local and long-range emissions. According to the researcher, the findings could contribute to the development of new emission reduction strategies and improvements in air quality, while the study of sulphur dioxide (SO2) oxidation could enhance climate models.
(Photo: Unsplash.com)
Discussing his findings further, L. Bučinskas also uncovered some unexpected results.
"I was pleased to capture a long-term seasonal variation in the isotopic values of sulphur compounds, which turned out to be the reverse of trends observed in other regions of the world. Our research determined that these variations were driven by changes in pollution sources. Coal is rarely used as a fuel in Lithuania, yet during winter, sulphur emissions from coal combustion were dominant in Vilnius. This indicates that long-range pollution sources from neighbouring countries outweighed local sources. In this sense, Vilnius' environment is quite unique on a global scale, as its sulphur emissions are low and significantly influenced by emissions from neighbouring countries."
Interestingly, one period in the study stood out – when heavy fuel oil (mazut) was used at the Vilnius Heat Plant. This shift was caused by a decrease in natural gas usage across Europe in 2022 due to the changed geopolitical situation.
Mazut contains a high sulphur content (<1%), and during its use, increased local sulphur emissions with unusually negative sulphur isotopic values were recorded in Vilnius. This allowed researchers to evaluate the formation pathways of sulphates in the atmosphere, as SO2 gases undergo oxidation upon entering the air. The study found that SO2 oxidation catalysed by transition metal ions was the dominant reaction, likely enhanced by iron and manganese ions released from coal and mazut combustion emissions," explains the newly qualified PhD of Natural Sciences.
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