Stable Carbon Isotopic Composition of Organic Matter of the Late Pleistocene and Holocene Soils of the Baikal Region

Eurasian Soil Science - The results of studying stable carbon isotopes of the organic matter of Late Pleistocene and Holocene soils of the Baikal region are presented. The δ13С values in...     

Stable carbon and oxygen isotopes in pedogenic carbonate coatings of chernozems in the Southern Cis-Baikalia as indicators of local environmental changes

Carbonate coatings formed on the lower surfaces of pebble inclusions in the Holocene-Late Pleistocene sediments on the Irkutsk-Cheremkhovo Plain have been studied. The coupled analysis of the carbon isotope composition of the soil organic matter and carbonate coatings has indicated the formation of coatings under conditions of phytocenoses with the predominance of C3 plants. A significant effect of the atmospheric CO₂ on the carbon isotope composition in the coatings has been noted, which could be related to their formation under low soil respiration rates. The latter was apparently due to the periodic freezing of the soil, which affected the structure of the coatings and was most manifested in the formation of spherulites in their outer layers. The carbonate coatings consist of two laminae significantly differing in their structure and stable isotope composition, which allows separating two main stages of their formation. The lightening of the carbon isotope composition in the outer (younger) layers of the coatings compared to their inner (older) ones coincides with the increase of the δ¹⁸O values, which points to changes of the environmental conditions in the studied area during the formation of the coatings.     

Carbonate Rhizoliths in Dune Sands of the Belaya River Valley (Upper Angara Region)

Eurasian Soil Science - Results of investigating carbonate rhizoliths formed in the Early Holocene dune sands in the Belaya River valley are presented. Carbonate accumulations are characterized by...     

Reconstruction of Late Glacial and Holocene landscape-climatic changes in the central Selenga Middle Mountains based on the isotopic composition of organic matter

The results of investigation into the composition of stable carbon and nitrogen isotopes of organic matter in the soils developed within soil–sedimentary sequences in the central part of the Selenga Middle Mountains in the Late Glacial and Holocene are presented. In the past 15000 years, the organic matter of the investigated soils has only been formed from the biomass of C3 plants (without the participation of C4 plants). This is confirmed by the of δ¹³С values from–27.00 to–23.35‰. A combined analysis of the parameters of the organic matter (С_org, N_total, C/N, δ¹³С, and δ¹⁵N) of soils formed in different periods makes it possible to assume that the isotopic composition of carbon and nitrogen reflects changes in the climate humidity during the Late Glacial and Holocene periods. The specified intervals of soil formation correspond to the climate humidification and stabilization of the surface owing to the development of dense vegetation. Aridization periods were characterized by the accumulation of sediments that buried soil horizons. The most pronounced stages of climate aridization occurred at the transition from the Late Glacial to the Holocene, from the Boreal to the Atlantic, and from the Atlantic to the Subboreal periods. The optimum soil-forming conditions existed in the periods of 11700–11000, 8800–6900, and 4700–1000 years ago, which is confirmed by the published data on the landscape-climatic changes in the adjacent areas in the past 15000 years.     

Cryoaridic Soils as a Genetic Type in the Russian Soil Classification System: Geography,Morphology, Diagnostics

Eurasian Soil Science - Cryoaridic soils were proposed to be identified as an individual genetic soil type by Vladimir Volkovintser in the 1970s. Volkovintser argued that the specific properties of...