Micromorphological diagnostics of soil, aeolian and deluvial processes according to the peculiar fabric of crusty horizons in different-aged extreme aridic soils of Mongolia

Lebedeva (Verba), M.P.; Golovanov, D.; Abrosimov, K.

Авторы: Lebedeva (Verba) M.P., Golovanov D., Abrosimov K.
Сборник: Abstract Book “Soil-Forming Processes and their Rates”, Workshop and Field Trip in the Mojave Desert
Тезисы
Год издания: 2014
Место издания: USA, RAISIN
Первая страница: 26
Последняя страница: 31
Аннотация: Micromorphological diagnostics of soil, aeolian and deluvial processes according to the peculiar fabric of crusty horizons in different-aged extreme aridic soils of Mongolia Marina Lebedeva1, Dmitrii Golovanov2, Konstantin Abrosimov1 1V.V. Dokuchaev Soil Science Institute, Moscow, Russia, 2Lomonosov State University, Moscow, Russia At present, the ever increasing attention to the peculiar fabric of the crusty horizon in desert soils is necessitated by an objective diagnostics of well-expressed desert properties and the role of the crusty horizon in their development. Being highly porous, the crusty horizon reveals the low water permeability and causes the soil drying to be a hinder for moisture penetration into the deeper horizons (Turk, Graham, 2011). This study is aimed at specifying peculiar features of extreme arid soils in Mongolia. The objects of research are the surface horizons in profiles of the young soil developed at the place of blown solonchak in central part of Eihen-Gol oasis subjected to desertification due to shallow groundwater, and the well-developed soil (Yermic-Gypsic Regosol) in piedmont plains of the south in Mongolia. The topsoil of these profiles reveals a stony pavement with desert rind, underlying by a crusty horizon 2-5 cm thick, whose diagnostic features are the vesicular porosity and a compact, blocky, vertically cracked, textural-metamorphic horizon sharply underlain by the horizon with gypsum. The basic methods are microtomographic (SkyScan 1172 with resolution of 5 mkm/piksel) and micromorphological (microscope Olympus BX51 with video-camera Olympus DP26) investigations carried out at the V.V. Dokuchaev Soil Science Institute. The software nRecon and ctAn was used to interpret tomographic data and to analyze the obtained images. The tomographic investigations permitted to simulate the pore space in central zone of every soil sample as based upon the analysis of more than two thousand flat tomographic sections. It was established that the pore space in each crusty horizon has specific peculiar features, but the regularity is that the crust horizon with vesicular porosity is clearly expressed in the course of the soil development. The tomographic data showed a great amount of ferruginous pedofeatures especially in the developed soil. Micromorphological investigations showed that the crusty horizons display a clearly expressed vertical texture differentiation and the void pattern in the crust of the well-developed soil. When judging about the fabric elements, it may be explained by periodical input of deluvial clay and aeolian depositions. The upper part of the crust composes of the silt-clayey material with isolated vesicular voids. They have clayey aeolian infillings - sandy particles are represented by silicates, clay particles – by micrit calcite. In zones there is a great amount of ferruginous pedofeatures – micro-segregations what is evidenced by results of microtomographic investigations. A higher interaggregate porosity in the young extreme arid soil is conditioned by the sandy composition, granular microstructure due to the salt coagulation of the fine earth. In the well-developed the structural change in the carbonate material is observed as associated with the soil frost resulting in the formation of subparallel oriented voids under the vesicular porous layer. Thus, the study of crusty horizons in desert soils of Mongolia using the tomographic method allowed specifying the closed rounded voids and separating them from the root channels in soil thin sections. The formation of rounded voids is connected with the soil gas emission during physical, chemical and microbiological processes (Lebedeva (Verba), Kutovaya, 2013). As a result of this study, the intense aeolian input of silicate and carbonate materials to the soil is observed in vesicular voids. In the evolution row of extreme arid soils – from young to well-developed ones – the amount of ferruginous pedofeatures is increasing to be a peculiar feature of the present iron mobility conditioned by a low filtration capacity of the crusty horizon in desert soils as well as the outbreak of microbiological activity. The complex micromorphological and microtomographic investigations of crusty horizons permit to determine the ratio between aeolian and deluvial depositions and their quantity, the manifestation degree of soil formation processes to assess their water-physical and ecological functions as well as to be conductive to a better understanding of their genesis. This study was supported by Russian Foundation of Fundamental Investigations, project no. 14-27-00133.
Добавил в систему: Голованов Дмитрий Леонидович

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Micromorphological diagnostics of soil, aeolian and deluvial processes according to the peculiar fabric of crusty horizons in different-aged extreme aridic soils of Mongoliaтезисы доклада

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