| Abstract: | The work concerns the study of the composition of stable isotopes of oxygen, carbon and hydrogen in the environment of Żabińskie Lake. The research object is unique because its sediment creates annual layers (varves) of extremely high thickness, which allowed for multidisciplinary research. The aim of the work is to determine the factors differentiating the isotopic composition of individual components of the modern lake ecosystem, and then an attempt to reconstruct the qualitative and quantitative climate change for the last millennium. Research on the currently formed carbonate deposit deposited in the Żabińskie Lake showed that its isotopic composition depends on the isotopic composition of atmospheric precipitation. It is also conditioned by the circulation of lake water and reflects changes in the temperature and the amount of precipitation in the summer months. This is when the carbonate in the lake is precipitated in conditions close to equilibrium.
The isotopic composition of oxygen in the sediment deposited in Lake Żabińskie in the years AD 1010-2010 reflects global climate changes, such as Medieval Warming or a Little Ice Age, along with their characteristic minima. Thus, isotopic studies confirmed the sediment chronology developed at the University of Gdańsk. The variability of 518O and 513C in comparison with other tests carried out as part of the Climpol project (Hernandez-Almeida and others 2017), such as change in organic matter content and carbonate content, provided information on changes in hydrology and bioproductivity of the Żabińskie lake during the analysed period. |