Franz Ottner

Mineralogical and geochemical indicators of the polygenetic nature of terra rossa in Istria, Croatia

Abstract Terra rossa in Istria is situated on the Jurassic–Cretaceous–Paleogene carbonate plain and is considered a polygenetic reddish soil which bears typical terra rossa Fe-oxide characteristics (e.g., Fe d and Fe d /Fe t ). The difference in particle size, mineralogy and geochemistry observed between terra rossa and the insoluble residue of limestones and dolomites clearly indicates that the additions of external materials might have diminished the influence of insoluble residue of limestones and dolomites as the primary parent material of terra rossa in Istria. Terra rossa is clay and silty clay composed of quartz, plagioclase, K-feldspar, micaceous clay minerals (illitic material and mica), kaolinites (Kl D and Kl), chlorite, vermiculite, low-charge-vermiculite or high-charge smectite, mixed-layer clay minerals (other than illitic material), hematite, goethite and XRD-amorphous inorganic compound. Calcite, dolomite and boehmite are sporadically present and are of local importance. Kaolinites and illitic material are dominant clay mineral phases in the clay fraction of all terra rossa from Istria. Kaolinite which does not form intercalation compounds with dimethylsulfoxide (DMSO) is the dominant mineral phase in fine clay and is considered predominantly authigenic rather then inherited from parent materials. Neither the content and particle size distribution nor the bulk and clay mineralogy of the insoluble residue of limestone and dolomite support development of terra rossa entirely by dissolution of carbonate rock. If terra rossa has developed only from the insoluble residue of limestone and dolomite, its clay content, due to weathering should be higher than that in the insoluble residues which is not the case. Plagioclase was found only in one insoluble residue while all terra rossa samples contain this mineral. Moreover, insoluble residues do not contain vermiculite which was observed in small amounts in clay fraction of all terra rossa samples. (Na 2 O/K 2 O)×100, Zr/Nb and (Zr/Ti)×1000 ratios in the majority of terra rossa samples are much higher than in the insoluble residue of limestones and dolomites which also supports external material influence in the genesis of terra rossa. Materials other than the insoluble residue of limestones and dolomites which might have contributed to terra rossa are loess sediments, whose deposition was very important recurrent process in Istria probably since the early Middle Pleistocene, and flysch sediments which extended much more southwards from its present position. Analyses performed indicate that both loess older than that of the Upper Pleistocene age and flysch might have contributed in the genesis of terra rossa.

Results of an inter-laboratory comparison of methods for quantitative clay analysis

Abstract In a comparison of analytical methods in clay mineralogy, two clay samples (from Hennersdorf and Freydegg) of different clay composition were analyzed by 19 laboratories mainly by XRD. Participants used different methods of pre-treatment, preparation, analysis and evaluation. In spite of the diversity of analytical methods applied, reasonable conformity in quantitative results was obtained for the associated minerals (quartz, calcite and dolomite). On the other hand, qualitative identification of the clay minerals showed considerably stronger divergencies, causing a stronger deviation of quantitative data; analysis of the Freydegg sample proved to have been particularly difficult. The evaluation methods of the different participants were examined to determine whether similar methods provided results that could be more easily compared. In addition, the authors calculated the clay mineral composition according to three different recognized methods, using the same diffractograms and same preparation and measuring conditions. In spite of this, different results were obtained. In the next phase of the programme, an inter-laboratory comparison of methods will be achieved under exactly defined conditions of preparation and analysis.

Investigation of various adsorbents for their ability to bind aflatoxin B1

The contamination of animal feed with mycotoxins represents a worldwide problem for the animal industry. The most applied method for protecting animals against aflatoxicosis is the utilization of clay minerals. In the course of a research project adsorption experiments were performed in buffer solutions in order to evaluate the ability to bind Aflatoxin B1 (AfB1) at various pH-values. In order to investigate the strength of binding, the chemisorption index was calculated. Isothermal analysis was used to determine the values for the maximum adsorption capacity. Adsorption experiments in simulated gastrointestinal fluid and real gastric juice were carried out. Furthermore binding capability of the materials regarding selected vitamins was examined. Special attention was paid to the formation of AfB2a during experimental conditions. Based on the obtainedin vitro results, highly promising sorbent materials were ranked for furtherin vivo studies. Some adsorbing bentonites were also analysed mineralogically, but the results did not indicate which smectite property influences the adsorption process for AfB1

Assessment of Factors Governing Biodegradability of PAHs in Three Soils Aged Under Field Conditions

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants of great environmental concern due to their toxic, mutagenic and carcinogenic properties. This study correlates soil characteristics (i.e. soil organic matter, particle- and pore-size distribution) with extractability and toxicity data (LUMIStox, Ostracod) to investigate factors that govern biodegradability of PAHs in three historically contaminated soils. Desorption of PAHs occurred most readily from soil TA1 (82%), followed by soil AS3.7 (69%) and soil WG2 (20%). This is in line with toxicity data, as the soil in which the greatest contaminant desorption (SFE) was observed exhibited the highest toxicity (TA1). Of the three soils, pronounced biodegradation of 2-4-ring, and slight biodegradation of 5-ring PAHs was observed only in AS3.7, while no decrease of PAHs was reported for soils WG2 and TA1 during the degradation experiment. Strong sorption reduced pollutant bioavailability in WG2 and hence hampered biodegradation. By contrast, pollutant sorption was weak in TA1 and microbial activity was most likely inhibited due to high toxicity in this soil. Based on our results we conclude that biodegradation of PAHs in soils is determined by a number of phenomena with complex interactions between them. Consideration of a single factor will be misleading and may result in false prediction of the biodegradation potential.

Polycyclic luvisols in Northern Italy: palaeopedological and clay mineralogical characteristics

Abstract Two long Pleistocene palaeosol sequences in the southwestern fringe of the Lago Maggiore region (Northern Italy) were studied by a wide range of pedological methods. Particular emphasis was placed on clay mineralogy in order to distinguish the weathering intensity of different palaeosols. The clay mineralogical analyses showed a gradual transformation from the top to the central part of the studied sequences. Whereas the uppermost horizons include chlorite as a sign of weak alteration processes, the underlying palaeosols are dominated by vermiculites and mixed layers. The lowermost parts of the palaeosol sequences show different conditions as they contain neoformed kaolinite. Paleosols and pedocomplexes were correlated by mean of their pedologicial characteristics. Six main pedogenetic units have been identified in both sequences, representing different stages of soil formation. Paleopedological and clay mineralogical results indicate at least four interglacial phases, two of them showing warmer and more humid conditions than today and two of them showing climatic conditions comparable with the present day climate.

Retention of inorganic pollutants in clayey base sealings of municipal landfills

Abstract The 10-year-old base sealing of a municipal waste deposit near Horn, located in the Austrian part of the Bohemian Massif, was examined by mineralogical and geochemical methods. The objective of this study was to measure its retention capability with respect to selected inorganic pollutants, especially heavy metals. The mineralogical results show a homogeneous composition of the base sealing, which consists of clay dominated by kaolinite. In the Bohemian Massif, this pattern is typical for products of weathered rocks, which were originally rich in feldspar. The hydraulic conductivity is very low ( k f ≈1×10 −11 m s −1 ). Geochemical analyses show that heavy metals like Pb, Cu, Zn and Cd are concentrated in the uppermost parts of the sealing. Only a few centimeters below, the concentrations of these elements are at the geochemical background level. Anionic contaminants, however, are found in greater depth due to an almost nonexistent adsorption on the clay. This is the reason why they were used as tracers for further research on diffusion processes (apparent diffusion coefficient of chloride D a,Cl =2.6×10 −10 m 2 s −1 ). Detailed studies of the behavior of Cu, Pb, Zn and Cd were performed using sorption tests (diffusion and batch tests) and sequential extraction methods. From the diffusion experiments, breakthrough times of some heavy metal ions were evaluated for the actual thickness of the sealing. There were Zn >200 years and Pb >700 years. These times can be considered as “worst case” examples which give good indications of the retention capability of the sealing. The results clearly demonstrate that even after a period of 10 years of contact with contaminated landfill leachates, the clayey liner had fulfilled the requirements of retaining heavy metals. Furthermore, the base sealing was far from reaching the limits of its retention capacity.

CLAY-MINERAL TRANSFORMATIONS AND HEAVY-METAL RELEASE IN PADDY SOILS FORMED ON SERPENTINITES IN EASTERN TAIWAN

Serpentinites, which contain high concentrations of Cr and Ni, weather easily into layer silicates and are therefore a possible source of metal contamination in soils. In the present study three soil profiles formed on serpentinites in a paddy field in eastern Taiwan were investigated to understand pedogenic clay-mineral transformations and to determine the relationship between the mineralogical characteristics and labile Cr and Ni in the soil. To this end, physicochemical analyses, micromorphology, X-ray diffraction, and Fourier transform infrared spectroscopy were employed. Serpentine and chlorite were the dominant minerals in the soil parent material, with smaller amounts of pyroxene, amphibole, and talc. Progressive weathering and the release of cations from the parent material resulted in the pedogenic formation of smectite, vermiculite, and interstratified chlorite-vermiculite, demonstrated by their presence in all Ap and AC horizons but their absence from the C horizons. Serpentine, pyroxene, amphibole, and talc are proposed to be transformed to low-charge smectite, while chlorite transformed to vermiculite through an interstratified chlorite-vermiculite phase. The surface soils were enriched in oxalate-extractable Fe relative to the subsoils, which was probably generated by the artificial flooding and draining of the paddy soils. The artificial flooding, which typically releases Fe, may also drive the observed partial hydroxyl interlayering of smectite and incomplete interlayer OH sheets of chlorite. Labile Cr and Ni (extracted with 0.1 N HCl) ranging from 4.7 to 26.8 mg kg−1 and from 56 to 365 mg kg−1, respectively, increased significantly toward the surface soil, consistent with weathering. The heavy metals released may pose a threat to the environment as well as to human health by entering the food chain.

Adsorption of mycotoxins

In vitro binding studies with different mycotoxins are often made to test various adsorbents for their ability to detoxify these toxins in animal feed. In this study different clays were investigated for their ability to bind aflatoxin B1, zearalenone, ochratoxin A and deoxynivalenol in two different buffer systems (pH 3 and pH 6.5). In addition chemical/physical properties like cation exchange capacity and the concentration of exchangeable Ca2+, Na+, Mg2+ and K+ ions in the adsorbents were determined to establish if there is a connection between these parameters and the capacity to bind mycotoxins. Most of the tested clays showed high adsorption rates for aflatoxin B1 in both buffer systems. Adsorption rates for ochratoxin A and zearalenone of the tested clays were in the range of 0–100%. None of the tested adsorbents had the ability to bind deoxynivalenol. In this study no correlation between the cation exchange capacity of the clays or the concentration of exchangeable Ca2+, Na+, Mg2+ and K+ ions and the ability to adsorb mycotoxins could be investigated.

Layer-charge heterogeneity in smectites of I-S phases in pelitic sediments from the Molasse Basin, Austria

The purpose of this study was to characterize more fully the surface charge characteristics of the end-member smectite in illite-smectite (I-S) mixed-layer phases found previously in pelitic sediments of the Molasse Basin in Austria. The smectite end member was shown to have an unusually high interlayer charge (0.58). Based on earlier work on pure smectites, it was hypothesized that this high charge represents the mean of a mixture of a higher- and lower-charged smectite component intermixed with illite. To test this hypothesis, the magnitude of the interlayer charge of the smectites was evaluated using 2 different methods: alkylammonium ion orientation and K-fixation by wetting and drying.Using 2 I-S samples of different I-S ratios, saturated with alkyammonium ions of chain lengths nc = 5–18, X-ray diffraction patterns (XRD) could be interpreted as representing a 3-component system, consisting of randomly interlayered high- and low-charged smectite and illite.K-fixation, carried out by K-treatment and followed by 100 wetting and drying (WD) cycles, confirmed the presence of a high-charged smectite component admixed with low-charged smectite, both interlayered with illite. The wetting and drying of the K-treated samples led to interlayer collapse of the high-charged smectite component and to the production of illite layers stable against exchange with 0.1 N SrCl2. The 2 smectites occur in the ratio of about 1:1 and consist of 1 phase with an interlayer charge of about 0.76 and another phase with a normal charge of about 0.40. During diagenesis, the 2 kinds of smectite are altering simultaneously to the same end-member illite along 2 different reaction paths.

Frost Susceptibility of Unbound Bases: An Improved Mineralogical Assessment

ABSTRACT The Mineral Criterion is an important part of the evaluation process of frost susceptibility concerning base materials for road construction in Austria. Dependent on grain size distribution, it defines mineralogical limiting values for the fraction < 0,02 mm. On the one hand the Mineral Criterion has proved successful, but on the other hand it turned out to be too strict. In order to improve this criterion, 15 different base materials have been examined. The results of reliable mineralogical analyses have been correlated with frost heave tests and moderate mineralogical influences could be verified. Finally, a procedure to improve the existing limiting values of the current MineralCriterion and an alternative way to assess frost susceptibility mineralogically have been introduced.