Organic carbon content in the late Pleistocene and Holocene fossil soils (reconstruction for Eastern Europe)

The organic carbon content of soil and paleosols in the region of the East European plain (EEP) is examined in this study to assess the mass of carbon stored in paleosols formed during three intervals in the past: Holocene (6–7 ka BP), Valday glaciation (18–20 ka BP) and Eemian interglaciation (Mikulino, 120–125 ka BP). For the main part of the EEP, reconstructions of soil cover are primarily based on results of actual paleosol profile studies and their geochemical properties. In regions where fossil soils are not well preserved, the reconstructions are based on the correlation between soil characteristics and vegetation cover. The cartographic reconstruction of the soil type distribution served as a basis for the estimation of humus carbon stocks in the fossil soils. The humus carbon content in 1-m layer of the soils, which represent modern analogues of paleosols, was used to estimate the carbon content of paleosols. The geographical location of soil zones and their areas differ from the present-day ones in all the cases. Estimations of humus carbon storage in the past soils were made within the limits of the key region (polygon) of the East European plain (between 46°N and 65°N and 25–30°E and 55°E), using an equal-area projection. The key area covers 3.2×106 km2. For the present day total quantity of soil humus carbon storage within the limits of the key-region is 41 Gt, that for the Eemian (Mikulino) interglacial maximum 56 Gt (137% of the present day value), for the Last Glacial maximum 6 Gt (15%), and for the Holocene optimum 49 Gt (120%).