Natural and medical sciences

2020 Issue №4

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Paleoecological conditions of the Gdansk ba­sin in Holocene in the complex analysis of short sediment cores



The article is aimed at reconstructing the paleoecological conditions in the Gdansk Basin of the Baltic Sea in the Late Holocene. The hydrological and hydrochemical conditions of its isolated bottom layer are strongly influenced by water exchange with the North Sea, which in connected to the World Ocean. Information on environmental conditions in the past is necessary to understand the observed changes in the Baltic Sea ecosystem, to identify the natural and anthropogenic components of these changes, as well as to make re­liable forecasts. Changes in natural conditions are reflected in the composition of bottom sediments. Based on the complex study of three short sediment cores, including lithological, micropaleontological and geochemical analysis, the environmental conditions in the Gdansk basin in the Post-Litorina stage of the Baltic Sea were reconstructed. According to the correlation of sediment analysis data with published reconstruction results, the sediments of the stud­ied cores were formed during the last three millennia (from the Roman Warm Pe­riod to the Modern Warm Period). Intensified water exchange between the Baltic and North Seas was recorded before the Roman Warm Period, during the Roman Warm Period itself, the Dark Ages and during the Medieval Cli­mate Optimum. Periods of climate warming, characterized by an increase in surface water productivity and bottom water hypoxia, correspond to the Ro­man Warm Period, the Medieval Climatic Optimum, and the Modern Warm Period.