Glacial and postglacial sedimentary infill in Slovakian High Tatra Mts. lakes: Acoustic survey and lithological data.

The data presented in this paper are related to the research article "Sub-bottom and bathymetry sonar inspection of postglacial lacustrine infill of the alpine lakes (Tatra Mts., Slovakia)" (Dhavamani et al., 2022). An implementation of acoustic sonar protocols provided data for the interpretation of glacigene, glaciolacustrine, postglacial, mass-movement deposits, and geodynamic factors influencing the sedimentation in seven alpine and sub-alpine Tatra Mountains lakes. The field data document the survey track lines of the sonars and allow to identify the location of the geomorphologic phenomena described in (Dhavamani et al., 2022). The laboratory data obtained by micro-CT document the lithology of glaciolacustrine and postglacial lake infill and support the interpretation of sub-bottom sonar record.

Determination of water content in raw perlites: Combination of NIR spectroscopy and thermoanalytical methods.

A new approach to determination of water content in raw perlites, an industrially important material, and obsidian was proposed, utilizing diffuse reflectance spectroscopy in the near-IR region. The phase composition of the perlite of the perlite samples was over 94% rhyolitic volcanic glass, with only small admixture of other components. The observed volatile species contents detected from both thermogravimetric analysis (TG) and the loss of ignition method (LOI) varied from 3 to 7%. The samples with the highest content of volatiles released over the temperature interval 30-250 °C (based on thermogravimetric analysis) displayed sharp signals in the 1H MAS NMR spectra, with chemical shifts of 4.6-4.7 ppm attributed to water molecules of high mobility. Using IR spectra taken in the near-infrared region, the water content of perlites was evaluated using the combination mode (ν + δ)H2O near 5240 cm-1. The band area depended on the H2O content, with the highest value found for the sample which displayed the highest mass loss in the thermoanalytical experiments. The samples showed variations in properties depending on the location in the deposit they were taken from. The relationship between water content determined gravimetrically and calculated band areas showed a correlation coefficient of 0.78 and 0.74 for TG and LOI respectively. The correlation was significantly improved by adding internal standards, hexadecyltrimethylammonium bromide salt (HDTMA) or layered hydrosilicate talc, to the perlite samples, and then normalizing the spectra of the mixtures to selected bands of those standards (R2 = 0.89 and 0.88 respectively for TG methods). A better correlation between infrared and TG/LOI results was obtained for HDTMA-Br than for talc. The proposed method using standards could be a reliable way of estimating water content in raw perlites in processing plants.

Evaluation of aluminium mobilization from its soil mineral pools by simultaneous effect of Aspergillus strains' acidic and chelating exometabolites.

This contribution investigates aluminium mobilization from main aluminium pools in soils, phyllosilicates and oxyhydroxides, by acidic and chelating exometabolites of common soil fungi Aspergillus niger and A. clavatus. Their exometabolites' acidity as well as their ability to extract aluminium from solid mineral phases differed significantly during incubation. While both strains are able to mobilize aluminium from boehmite and aluminium oxide mixture to some extent, A. clavatus struggles to mobilize any aluminium from gibbsite. Furthermore, passive and active fungal uptake of aluminium enhances its mobilization from boehmite, especially in later growth phase, with strong linear correlation between aluminium bioaccumulated fraction and increasing culture medium pH. We also provide data on concentrations of oxalate, citrate and gluconate which are synthesized by A. niger and contribute to aluminium mobilization. Compared to boehmite-free treatment, fungus reduces oxalate production significantly in boehmite presence to restrict aluminium extraction efficiency. However, in presence of high phyllosilicates' dosages, aluminium is released to an extent that acetate and citrate is overproduced by fungus. Our results also highlight fungal capability to significantly enhance iron and silicon mobility as these elements are extracted from mineral lattice of phyllosilicates by fungal exometabolites alongside aluminium.

Structural incorporation of As5+ into hematite.

Hematite (α-Fe2O3) is one of the most common iron oxides and a sink for the toxic metalloid arsenic. Arsenic can be immobilized by adsorption to the hematite surface; however, the incorporation of As in hematite was never seriously considered. In our study we present evidence that, besides adsorption, the incorporation of As into the hematite crystals can be of great relevance for As immobilization. With the coupling of nanoresolution techniques and X-ray absorption spectroscopy the presence of As (up to 1.9 wt %) within the hematite crystals could be demonstrated. The incorporated As(5+) displays a short-range order similar to angelellite-like clusters, epitaxially intergrown with hematite. Angelellite (Fe4As2O11), a triclinic iron arsenate with structural relations to hematite, can epitaxially intergrow along the (210) plane with the (0001) plane of hematite. This structural composite of hematite and angelellite-like clusters represents a new immobilization mechanism and potentially long-lasting storage facility for As(5+) by iron oxides.