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  • Author: Monika Kisiel 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.

Streszczenie

Gleba jest jednym z elementów środowiska przyrodniczego, który często bywa narażony na zanieczyszczenia i degradację. Jednym z głównych źródeł zanieczyszczeń są obiekty gospodarki odpadami, wśród których dominują składowiska odpadów. W Polsce obiekty gospodarki odpadami są zaliczane do przedsięwzięć mogących potencjalnie znacząco oddziaływać na środowisko. Dla większości takich obiektów przeprowadzana jest ocena oddziaływania na środowisko, w ramach której sporządzany jest raport o oddziaływaniu na środowisko. Problematyka ochrony gleb jest jednak często w nim marginalizowana. Celem pracy była analiza jakości wybranych raportów o oddziaływaniu na środowisko obiektów gospodarki odpadami, ze szczególnym uwzględnieniem przeprowadzonej w nich analizy stanu gleb, a także przedstawienie propozycji zakresu prac, niezbędnych do rzetelnej analizy oddziaływania obiektów gospodarki odpadami na gleby. Wyniki przeprowadzonej oceny wskazują na zróżnicowany poziom wykonania w zakresie przedstawienia oddziaływania inwestycji na gleby. Przeważają opracowania ocenione negatywnie jako niezadowalające.

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.