METHODS AND OBJECTS OF CHEMICAL ANALYSIS ISSN title: "Metody i obʺekty himičeskogo analiza" An international journal devoted to all aspects of Analytical chemistry ISSN 2413-6166 (Online), ISSN 1991-0290 (Print)
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Peculiarities of the diatom valve chemical composition (inorganic components) study by electron probe X-Ray Microanalysis

L.A. Pavlova, L.L.Tkachenko, A.V. Goreglyad, M.I. Kuzmin

A. P. Vinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, 664033, Irkutsk, Favorsky str. 1A.

Authors have studied diatom valves from Hovsgol (Mongolia) and Baikal (Russia) lakes by electron-probe microscopy and electron probe x-ray microanalysis (EPMA). The procedure to determine chemical composition of diatoms via wave and energy-dispersive spectrometers has been developed. The obtained composition of diatoms from Lake Baikal indicates that Al, Fe, Mg and Ca contents vary down core following the variations of biogenic, while aluminum contents increases with the age of sediment. The composition of diatoms from Hovsgol Lake depends on their preservation. Some elements show that the diatoms with a good preservation contain less inorganic components while the valves with poor preservation the elemental concentrations increase. Intervals with a poor preservation are thin (1-3 cm thick) resulting most likely from short-term periods of climatic instability. Silica content shows smooth transitions from periods with satisfactory diatom preservation to the periods marked by a poor preservation of diatom valves. The number of intervals with a poor preservation increases with the depth. Our results well agree with literature data of spore-pollen analysis. Such a correlation cannot be random but confirms that the given method is promising. The element concentrations in diatom valves can be used for paleoclimatic reconstructions, as the composition of diatoms is related to the environment.

Key words: diatom valves, chemical composition, electron probe x-ray microanalysis

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