MAGNETIC MINERALOGY OF SEDIMENTS AND SOIL OF KHORTYSYA RESERVE МАГНІТНА МІНЕРАЛОГІЯ ДОННИХ ВІДКЛАДІВ ТА ҐРУНТІВ ЗАПОВІДНИКА "ХОРТИЦЯ"

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Menshov O., Horoshkova L., Smyrnyy M., DİNDAROĞLU T., Horoshkov S.

Visnyk of Taras Shevchenko National University of Kyiv. Geology, cilt.1, sa.112, ss.17-24, 2026 (ESCI, Scopus)

Özet

Background. The territory of the Khortytsia Nature Reserve is suitable for retrospective investigations of the accumulation of magnetic material, heavy metals, and clastic particles of various origins in soils and bottom sediments. Their analysis makes it possible to reconstruct the relative contributions of natural and anthropogenic factors that have shaped the condition and transformation of the reserve's ecosystems over several centuries. The aim of this paper is to study the magnetic mineralogy of soils and lake sediments in order to identify the key natural and technogenic factors that, both in a retrospective context and under present-day conditions, determine the state of the protected natural environment. Methods. The magnetic research methodology included the measurement and calculation of mass-specific magnetic susceptibility (χ), frequency-dependent magnetic susceptibility (χfd) as an indicator of the relative content of superparamagnetic (SP) and multidomain (MD) fractions in the total magnetic susceptibility signal. Anhysteretic remanent magnetization (ARM) and saturation remanent magnetization (Mrs) were also measured, and anhysteretic magnetic susceptibility (χARM) was calculated. Thermomagnetic analysis was performed. Results. For all study sites, χfd values range between 1–2%, indicating a pronounced dominance of coarse-grained multidomain material over superparamagnetic and single-domain particles of pedogenic origin. The generally accepted threshold for MD grain predominance is χfd values of approximately 3–4%. The χARM/χ ratio varies between 0.70 and 2.13. This indicates that samples collected from burned areas and forest sites still contain single-domain grains, although in smaller quantities compared to multidomain (MD) particles. In contrast, lake bottom sediments (with the exception of Lake Prohnii) show a clear dominance of the multidomain fraction, as evidenced by χARM/χ values <1. Conclusions. The results of magnetic mineralogical investigations of soil and lake sediment samples from Khortytsia demonstrate that the principal ferrimagnetic mineral is multidomain magnetite of lithogenic origin, with possible admixtures of technogenic multidomain magnetite. In addition, stable single-domain grains of pedogenic genesis represented by maghemite were identified. Hematite was also detected and may have either pedogenic or technogenic origin. The presence of iron sulfides in bottom sediments, primarily pyrrhotite, is likely associated with the input of this component through weathering processes of bedrock.