Limnological characteristics of Northern and Central Yakutian lakes (Siberia) – Physical and chemical properties of surface sediments and water samples

• Main Author: Kausche, Moritz
• Format: Thesis
• Language: unknown
• Published: Humboldt-Universität zu Berlin 2008
• Subjects: taiga; Thermokarst; Yakutia; Siberia
• Online Access: https://epic.awi.de/id/eprint/40402/; https://epic.awi.de/id/eprint/40402/1/Moritz_Kausche_Diplomarbeit.pdf; https://hdl.handle.net/10013/epic.47545; https://hdl.handle.net/10013/epic.47545.d001

Physical and chemical properties of surface sediments and waters of 65 lakes in Northern and Central Yakutia were analysed. The studies included hydrochemical analyses as well as sedimentological, organic and inorganic geochemical analyses, the analysis of stable carbon isotope ratios and the analysis of magnetic susceptibilities. The objectives of this work were a) to characterise Yakutian lakes by their waters and surface sediments. Additionally, the geographical setting, i.e. the climate, vegetation and the morphology were taken into account. b) To explore parameters attributing for the variation in the measured variables using multivariate statistical methods. c) To characterise the relationships between sediments and waters. Most of the sampled lakes originated by thermokarst processes and lack in- and outflows. The ionic composition of the waters is strongly influenced by the continentality of the Lakes. Central Yakutian lake waters have considerably higher ion concentrations and electric conductivities than waters sampled in Northern Yakutia. This reflects the negative water balance (evaporation exceeding precipitation) in that region, which results in evaporation of lake waters. C/N ratios of surface sediments sampled in that regions are higher than those in Northern Yakutia as the bioproductivity is generally higher in Central Yakutia. The influence of the vegetation on the watershed is reflected in elevated Na/K ratios of waters sampled in lakes surrounded by taiga forest or pastures. Statistical analyses identified the elec- VII tric conductivity, ion concentrations and alkalinity of waters as variables controlling the composition of surface sediments. Sediments rich in nutrients, with high concentrations of elements related to lush vegetation on the watershed and high magnetic susceptibilities were encountered in lakes characterised by a) waters with high ionic concentrations and high electric conductivities and b) their geographical setting, i.e. the vegetation on the watershed and the negative water balance in these regions. These results can be of great value to paleolimnological and paleoenvironmental studies, as analysed sediments are being correlated to recent environments.