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  • Author: Zbigniew Zagórski x
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Abstract

The aim of the study was to characterize pedogenic iron forms in the sediments of the Lower Triassic (Buntsandstein) in the north-eastern part of the Holy Cross Mountains. These are sediments of continental origin and unique features as the so-called ‘red beds’. Three main types of rocks were studied – sandstones, mudstones and claystones. Chemical forms of iron: Fet (XRF), FeHCl (6M HCl), Fed (dithionite-citrate-bicarbonate, DCB), Feo (ammonium oxalate), Fep (sodium pyrophosphate) were determined. The XRD method revealed the occurrence of goethite in sandstones and hematite in mudstones and claystones. Differential XRD (DXRD) analysis did not show the presence of amorphous iron minerals. The average Fet content in sandstones was 83 g·kg−1, in mudstones 47 g·kg−1, in claystones 55 g·kg−1, while there were lower concentrations of Fed (66 g·kg−1, 13 g·kg−1, 26 g·kg−1, respectively). Feo form content was in the range of 0.3–4 g·kg–1, while there were only traces of Fep. Only Fet and FeHCl occurred in good correlation. In the pedogenic interpretation of the studied rocks, mutual relations between chemical forms of iron were used and their reference to the identified iron minerals. Siltstones and claystones have high resistance to pedogenic factors, which is indicated by low release rates Fed:Fet and very low amorphization index Feo:Fed. The reason is the presence of well crystalline hematite in these rocks. In sandstones, resistance is conditioned by the occurrence of goethite in the matrix. Chemical destruction of iron-carbonate cement promotes the release and amorphization of iron in soils developed from sandstones. The presented results indicate that the specificity of Lower Triassic rocks is important for the proper classification and assessment of properties of soils with a characteristic red colour.

Abstract

The aim of the study was to compare the properties of soils developed from the Lower Triassic Buntsandstein sediments in the north-western part of the Holy Cross Mountains (Poland). These are deposits of continental genesis and unique features such as red beds. Two representative soil pedons - the Bartków profile (pBK) developed from clay and the Góra Czerwona profile (pGC) developed from sandstone were selected for detailed analyzes. The morphology of profiles, their micromorphological features, mineralogical composition, and physico-chemical properties were examined. Most of the properties of the soils are a consequence of the original parent rock lithology. A specific feature of the morphology of the soils are the presence of red color (about 10R by the Munsell color scale) related to the presence of hematite. As shown by the XRD data, hematite is not the product of the current soil-forming processes, but it is a lithogenic component, which was inherited from the parent rock. Under the influence of climatic factors primary rock structure has been transformed into a new pedogenic one. Soils developed from clays have a characteristic angular blocky structure. Micromorphological analysis showed that an important role in the formation of soil structure involves geogenic susceptibility of Triassic clays to specific cuboid disintegration. This is indicated by the pore system of planes as an orthogonal nets visible in thin section. The soils developed from sandstone have a weak (unstable) subangular blocky structure. The main reason is the insufficient dispersion of the clay-ferruginous fraction from the sandstone matrix. Microscopic observations indicate that fine factions occurs as loose microaggregates, which results in a feature that smaller rock fragments and individual quartz grains are not bonded into soil aggregates. The studied soils are characterized by specific physical-chemical properties. Some of them strongly depend on the mineralogical properties of the soil substrate. Strong acidity (pH 3-4) and a very low content of base cations (below 1.0 cmol(+) kg-1) are due to a lack of carbonate minerals in sandstones and weak weathering of aluminium silicate. High exchangeable Al content in clay (16.5 cmol(+) kg-1) should be related to the geochemical properties of the red bed-type rocks such as the Lower Triassic Buntsandstein deposits. Soils developed from the Lower Triassic Buntsandstein clays have a sequence of genetic horizons: Ap, Bw, Bw/C, C and fulfill the criteria assigned to dystrophic typical brown soils (BDt) in the Polish Soil Classification (PSC 2011), whereas in the WRB they were classified as Endoeutric Chromic Cambisols (Loamic). Soils developed from the Lower Triassic Buntsandstein red sandstone can be classified as dystrophic humus brown soil (BDpr) in the PSC (2011). Within the WRB classification that soil can be assigned to Epidystric Chromic Endoleptic Cambisols.

Abstract

The aim of the study was to determine the mineral and chemical composition of technogenic soils (Technosols) developed from fly ash and bottom ash from power plants in which bituminous coal and lignite was combusted. The mineral composition of the “fresh” wastes (i.e. fly ash and bottom ash) and soil samples derived from them was examined by X-ray diffraction (XRD) and using a scanning electron microscope (SEM). The chemical composition (content of major elements) was determined using ICP-AES method. Quartz, mullite, and amorphous substances (glass) predominated in the mineral composition of wastes after bituminous coal combustion. Magnetite was also found there. Soils developed from wastes after bituminous coal combustion contained all above mentioned minerals inherited from fly ash and bottom ash. Moreover, small amounts of secondary calcite were identified. In some soil horizons containing large amounts of inherited magnetite, secondary iron oxides and oxyhydroxides (goethite and lepidocrocite) also occurred. Quartz predominated in the mineral composition of the “fresh” wastes after lignite combustion. Relatively small amounts of iron oxides (magnetite and hematite) were also found there. In “fresh” fly ash, apart from minerals mentioned above, anhydrite and calcium oxide (lime) was identified. Soils developed from wastes after lignite combustion contained inherited quartz, magnetite, and hematite. Furthermore, calcite which sometimes was a predominating mineral in certain soil horizons occurred. Moreover, sulphates (gypsum, bassanite, and ettringite), and vaterite (a polymorph of Ca carbonate) were also found in soils. Silicon predominated among major elements in “fresh” ashes after bituminous coal combustion and soil derived from them followed by Al, Fe, K, Ca, Mg, Ti, Na, P, and Mn. On the other hand, the contents of major elements in the samples (ashes and soils) after lignite combustion can be arranged as follows: Si, Ca, Fe, Al, Mg, Ti, K, Mn, Na, and P. However, in some horizons (i.e. in calcareous materials deposited in the topsoil of some profiles) in soil developed on landfills near TPSs combusting lignite, Ca was a predominating element.

Abstract

The aim of the investigation was to define the extend of pedogenethic processes by analysis of colour changes in groundmass of each genetic horizon. The object of the research were Chromic soils developed from red deposits of Lower Triassic (Buntsandstein) in the Holy Cross Mountains. Micromorphological studies were made with polarization microscopes Olympus BX- 41 and Olympus SZX-10. Image analysis was conducted with software program AxioVision 4.5 with Auto Measure module. The application of advanced methods of digital data analysis allowed for the quantitative compilation of measurement figures in thin sections. On the basis of micromorphometrical data designated objective numerical indicators, which allowed comparison groundmass color between each genetic horizon. Statistical analysis by ANOVA test confirm that groundmass color measured in RGB scale in investigated horizons are almost the same. Obtained results evidence that characteristic red color of soil substrate in analyzed soils developed from Lower Triassic rocks originated from the bedrock color. This fact indicates low extent of the pedogenic processes.