Total Chemical Composition of Anthropogenically Transformed Soils of the Sirius Federal Territory

Introduction. Anthropogenically transformed soils of the Sirius Federal Territory were formed followingof large-scale engineering levelling carried out during preparation for the 2014 Olympics and subsequent urban development of the Imeretinskaya Lowland. The surface horizons of these soils are composed of imported material from the dark-humus horizon (AU) of Halpic Chernozem, which, under the humid subtropical climate, undergoes transformation atypical of chernozems. The aim of the study is to assess the features of the bulk chemical composition of the anthropogenically transformed soils of the Sirius Federal Territory and the nature of the early stage of transformation of the chernozem material using geochemical indices of weathering and pedogenesis.

Materials and Methods. The study objects are anthropogenically transformed soils of the Sirius Federal Territory that have been functioning for 10–12 years. The reference objects are the AU and Cca horizons of Halpic Chernozem. The bulk content of macroelements was determined by X-ray fluorescence (XRF) analysis using a portable MetallTest ana-lyzer. The CIA, Ki, and Kr indices were used for interpretation.

Research Results. A statistically significant decrease in SiO2 along with a simultaneous increase in Al2O3 and Fe2O3 was established in the reclamation–humus horizon RAT compared with the genetically homogeneous AU horizon. No significant differences were detected for CaO, MgO, and K2O. For all integral coefficients and most macroelements, significant RAT–Cca differences were found, which confirms the substantial transformation of the chernozem material over 10–12 years.

Discussion and Conclusion. The observed shift reflects the early stage of subtropical hypergenesis: decarbonatization, leaching of bases, and relative accumulation of sesquioxides under a leaching water regime, while preserving the car-bonate–alkaline reserve inherited from the original Halpic Chernozem. The results obtained substantiate the need for regular geochemical monitoring of urban soils of the Sirius Federal Territory and can be used in the development of reclamation regulations for humid subtropical zones.

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