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Saint Petersburg, Russia

Vodyanitskii Y.N.,Russian Academy of Agricultural Sciences
Eurasian Soil Science | Year: 2010

Iron hydroxides are subdivided into thermodynamically unstable (ferrihydrite, feroxyhyte, and lepidocrocite) and stable (goethite) minerals. Hydroxides are formed either from Fe3+ (as ferrihydrite) or Fe2+ (as feroxyhyte and lepidocrocite). The high amount of feroxyhyte in ferromanganic concretions is proved, which points to the leading role of variable redox conditions in the synthesis of hydroxides. The structure of iron hydroxides is stabilized by inorganic elements, i. e., ferrihydrite, by silicon; feroxyhyte, by manganese; lepidocrocite, by phosphorus; and goethite, by aluminum. Ferrihydrite and feroxyhyte are formed with the participation of biota, whereas the abiotic formation of lepidocrocite and goethite is possible. The iron hydroxidogenesis is more pronounced in podzolic soils than in chernozems, and it is more pronounced in iron-manganic nodules than in the fine earth. Upon the dissolution of iron hydroxides, iron isotopes are fractioned with light-weight 54Fe atoms being dissolved more readily. Unstable hydroxides are transformed into stable (hydr)oxides, i. e., feroxyhyte is spontaneously converted to goethite, and ferrihydrite, to hematite or goethite. © 2010 Pleiades Publishing, Ltd. Source


Vodyanitskii Y.N.,Russian Academy of Agricultural Sciences
Eurasian Soil Science | Year: 2012

In line with the present-day ecological and toxicological data obtained by Dutch ecologists, heavy metals/metalloids form the following succession according to their hazard degree in soils: Se > Tl > Sb > Cd > V > Hg > Ni > Cu > Cr > As > Ba. This sequence substantially differs from the succession of heavy elements presented in the general toxicological GOST (State Norms and Standards) 17.4.1.02-8, which considers As, Cd, Hg, Se, Pb, and Zn to be strongly hazardous elements, whereas Co, Ni, Mo, Sb, and Cr to be moderately hazardous. As compared to the general toxicological approach, the hazard of lead, zinc, and cobalt is lower in soils, and that of vanadium, antimony, and barium is higher. The new sequence also differs from that of the metal hazard in soils according to the Russian standard on the maximal permissible concentration of mobile metal forms (MPC mob): Cu > Ni > Co > Cr > Zn. Neither an MPC mob nor an APC mob has been adopted for strongly hazardous thallium, selenium, and vanadium in Russia. The content of heavy metals in contaminated soils is very unevenly studied: 11 of them, i. e., Cu, Zn, Pb, Ni, Cd, Cr, As, Mn, Co, Hg, and Se, are better known, while the rest, much worse, although there are dangerous elements (Ba, V, Tl) among them. © 2012 Pleiades Publishing, Ltd. Source


Tursina T.V.,Russian Academy of Agricultural Sciences
Eurasian Soil Science | Year: 2012

A methodology for the analysis and diagnosis of soil polygenesis is discussed. It is based on the successive and complementary stages of soil examination: (1) the field stage, during which the morphological analysis of a soil profile is combined with the study of the spatial behavior of the major soil horizons in order to reveal the degree of their genetic interdependence or their stratigraphic independence and (2) the stage of the careful morphological description of the soil profile at different levels (from the macrolevel to the micro- and submicrolevels) by the methods of soil morphology in combination with the methods of paleogeography, mineralogy, cryolithology, microbiomorphology, and other sciences. As a result, we distinguish between the modern and relict (inherited) soil features; the latter are subdivided into the lithogenic soil features (lithorelics) and pedogenic soil features (pedorelics, traces of the former stages of the soil development). Two groups of models of soil polygenesis can be distinguished: (1) simple models, according to which the changes in the character of the pedogenesis and in the environmental conditions are recorded in the same lithological matrix, and (2) complex models, according to which the changes in the cycles of the soil formation are complicated by the processes of sedimentation so that they are recorded in the changing lithological matrix. © 2012 Pleiades Publishing, Ltd. Source


Khitrov N.B.,Russian Academy of Agricultural Sciences
Eurasian Soil Science | Year: 2012

On the basis of soil studies along routes and on key plots, 35 new areas of soils with definite features of vertigenesis have been identified in Belgorod and Voronezh oblasts and in the northern part of Volgograd oblast (in the Don River basin). Earlier, vertic soils were not noted for these areas. In the studied region, their portion in the soil cover is much less than 1%. All the delineated areas of vertic soils are confined to the outcrops of swelling clay materials of different origins (marine, lacustrine, glacial, and colluvial sediments) and ages (Quaternary or Tertiary) that may be found in four landscape positions: (1) in the deep closed depressions within vast flat watersheds; (2) in the bottoms of wide hollows on interfluvial slopes and, sometimes, on steeper slopes of local ravines; (3) in the hydromorphic solonetzic soil complexes, and (4) on steplike interfluvial surfaces with the outcrops of Tertiary clays. Within the studied areas, soils with different degrees of expression (six grades) of vertic properties are present. These soils belong to the type of dark vertic soils proper and to vertic subtypes of different soil types according to the Russian soil classification system; according to the WRB system, they belong to Vertisols proper and to reference soil units with a Vertic prefix in the groups of Chernozems, Phaeozems, and Solonetzes. Statistical data on the morphometric indices of the vertic properties (the depth and thickness of the soil horizons with slickensides, a wedge-shaped structure, and cracks filled with material from the upper horizons) and the depth and thickness of the Vertic horizon are analyzed. © N.B. Khitrov, 2012. Source


Khitrov N.B.,Russian Academy of Agricultural Sciences
Eurasian Soil Science | Year: 2012

A methodology for creating detailed soil maps on the basis of a dense grid of soil testing points and the numerical interpolation of experimental data on the soil properties is discussed. The study of the soil cover patterns combines regular sampling grids with equal spacing and additional sampling points chosen with due account for the soil cover specificity in particular areas. Soil diagnostics are performed at each of the points, and the diagnostic features of the soils are recorded in the field. In a laboratory, these data are arranged into a database, and a legend to the soil map is created. The necessary and sufficient set of the quantitative soil characteristics is selected, and quantitative criteria of the boundaries between the separate soil polygons are determined on the basis of numerical interpolation. Algorithms to delineate soil polygons on the basis of the selected indices are developed. Separate thematic map layers are produced for each of the selected soil characteristics. An integral soil map for the investigated area is obtained via the superposition of these layers. The thickness and/or the depths of the upper/lower boundaries of the soil layer with definite diagnostic characteristics making it possible to distinguish the given soil from its neighbors are used as the criteria for delineating the boundaries between soil polygons. Special criteria based on the proportions between the thicknesses or depths of several layers can also be applied for this purpose. The creation of a detailed soil map of a plot on the Kamennaya Steppe is discussed as an example of the practical application of this methodology. © 2012 Pleiades Publishing, Ltd. Source

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