The specific activities of natural (7Be, 210Pb) and manmade (137Cs) radioisotopes in a suspended matter of snow water have been determined and the density of their fallouts on the surface of the Sherstobitovsky and Ubinsky raised bogs in the Barabinsk forest-steppe has been assessed at the points of snow sampling during the winter period. It has been established that the main concentrator of the 7Be radioisotope is a fine fraction of suspended matter (colloidal particles <0.45 μm in size and dissolved component). For 210Pb, it is a coarse-grain fraction (dust particles >3 μm in size). The first data on the distribution of natural (238U, 210Pb, 226Ra, and 40K) and manmade (137Cs) radioisotopes have been obtained for raised bogs in the forest-steppe zone of Western Siberia. Migration of 137Cs deep down the peat deposit is largely governed by the magnitude of peat water level fluctuations during both the seasonal and long-term cycles and is closely related to the surface microrelief of the bog surface. Moreover, 137Cs, being the geochemical analogue of the biophilic 40K, is absorbed by plant roots from underlying peat horizons and transferred to the upper horizons during the dry seasons. An additional contribution to the high activity of 137Cs in the upper horizons is probably conditioned by its deposition on the surface of the Sherstobitovsky peat bog during its atmospheric transport as a result of peat and forest fires.

The paper presents data on the geochemical processes of postsedimentation transformations of boggy deposits at early diagenesis and the redistribution of chemical elements, including biogenic ones, in the Holocene sections of peat bogs in the Baraba forest-steppe in southern West Siberia. The contents of Fe, Mn, Pb, Hg, Sb, Cd, Cu, and Zn were found out to increase in the upper layers of the peat, whereas the S, N, Ca, and Sr concentrations increase in the middle parts of the peat profiles. The distribution character of various physiological groups of microorganisms in the peat profiles of Ubinskoe and Sherstobitovo peatlands lead to the conclusion that the nitrogen and carbon cycles are more active than that of sulfur. The activity of microorganisms leads to a decrease in pH and Eh in the vertical sections of the peatlands. The high values of $${\text{N}}{{{\text{H}}}_{4}}^{ + }$$ , $${\text{NO}}_{3}^{ - }$$ , TOC, and the chemical oxygen demand in the bog waters of Ubinskoe and Sherstobitovo bogs indicate that active biochemical decomposition and oxidation of organic matter proceed in these bogs. According to their predominant ions, the waters of the bogs belong to the hydrocarbonate class of the calcium group and are characterized by elevated concentrations of Al, Fe, Cu, and Zn, which is caused by the acid composition of the waters. The low pH values of the bog waters and the oxidizing environment facilitated the development of goethite–hydrogoethite mineralization in the upper horizon of peat profiles. The formation of hematite and anhydrite in the middle parts of the peat profiles was probably caused by paleofires. The authigenic minerals formed in the process of early diagenesis are, first of all, pyrite and less often siderite, calcite, and kaolinite. Under reducing conditions, nanoparticles of native Ni and Ni–Cr intermetallic compounds can be formed, and amorphous silica can be deposited at the dissolution of aluminosilicate minerals from the upper peat horizons.

Specific activities of natural (7Be, 210Pb) and technogenic (137Cs) radioisotopes in the suspended matter of snow melted water have been determined and the density of their fallout on the surface of the Sherstobitovo and Ubinskoye peat bogs of the Baraba forest-steppe at the points of snow flow in winter period is estimated. It has been established that the main concentrator of the 7Be radioisotope is a finely dispersed fraction of suspended matter (<0.45 μm), consisting of colloids and dissolved component, 210Pbatm is a coarse-grained fraction (> 3 μm), consisting of dust particles. On the example of vertical profile of the Sherstobitovo peat bog, the first data on the distribution of natural (238U, 210Pb, 226Ra, 40K) and technogenic (137Cs) isotopes were obtained for peat bogs of forest –steppe zone of the Western Siberia. Both 226Ra and 238U show the same pattern of vertical distribution that is also usual for 137Cs and 40K. The increase of activity of these radionuclides is observed in the horizon of 6-12 cm as well as in the lower section part (25-35 cm). According to our assumption it is due to the same processes. Migration of 37Cs deep into peat accumulation is significantly determined by moor water fluctuations in the seasonal and long-term cycle, and it is closely related to the microrelief of bog surface. Besides, 137Cs, being a geochemical analogue of the 40K biophile, is pulled up from the underlying peat horizons by plant roots during the dry season. An additional contribution to the high activity of 137Cs in upper horizons is probably due to the input of 137Cs to the surface of the Sherstobitovo peat bog as a result of peat and forest fires.