Authigenic carbonates from holocene sediments of Lake Itkul (south of West Siberia) as indicators of climate changes

The results of the study of carbonate-containing bottom sediments from the shallow brackish Lake Itkul (Western Siberia) are presented. The research methods include X-ray diffractometry (XRD), IR spectroscopy, laser granulometry, elemental analysis, etc. By the modeling of XRD carbonate profiles with the Pearson VII function, carbonate phases were identified and their quantitative ratios were determined. By the comparing of carbonate record with lithological, geochemical data in a dated sedimentary section, the evolution of the lake basin in the Holocene caused of climatic changes was reconstructed. Mineralogical signals of the global climatic event known as Bond event 4 in the South of West Siberia have been discovered.

Hydrochemical peculiarities of the Itkul lake ecosystem and its phytoplankton condition

We present the results of the hydrochemical analysis in Lake Itkul, which is the natural monument in the Chelyabinsk Region and an important recreational facility for the population of the Chelyabinsk and Sverdlovsk Regions. The water of Lake Itkul is fresh in terms of chemical composition, has low-alkaline medium reaction, and is very soft and saturated with oxygen. The water content in biogenic substances such as ions of nitrite, nitrate, and phosphate is low. Description and analysis of ecological groups of phytoplankton species of Lake Itkul are provided. The phytoplankton of Lake Itkul comprises eurybiontic and neutral species having wide geographical distributions. Analysis of ion contents of the zinc, copper, manganese, and nickel in the water and organs and tissues of the common roach indicated high residual concentrations of nickel in fish skin and bones, above allowable values. The content of iron, manganese, and other secondary elements in water was significantly lower than their maximum allowable concentrations, reflecting the absence of industrial water discharge within the lake water intake.