REGULARITIES OF THE MICROELEMENT COMPOSITION FORMATION OF SOILS UNDER THE MOUNTAIN-MEADOW VEGETATION OF THE GREATER CAUCASUS

Report. The purpose of the work is to identify the features of the formation of the microelement composition of soils under the mountain meadow vegetation of the Greater Caucasus based on the analysis of literary materials and the results of our own field research. Methods. The study of the microelement composition of soils under subalpine and alpine vegetation was carried out on the territory of the Teberdinsky State Biosphere Reserve. Traditional methods of soil-geochemical studies were used with the laying of soil sections, the selection of soil samples and their analysis for the content of four trace elements (Zn, Cu, Pb and Cd). Determination of trace elements was carried out by voltammetric and atomic absorption methods. The humus content was determined by the Tyurin method with wet salting, the pH of the water extract was determined potentiometrically. Statistical processing of the obtained data was performed in the Statistica 10 program. The microelement composition of soil-forming rocks was compared with the clarks of chemical elements in the upper part of the continental crust; the microelement composition of mountain-meadow soils was compared with the clarks of the soils of the world. The radial distribution of trace elements in the soil profile was analyzed. The qualitative trace element composition of soils was characterized as a sequence of decreasing the content of trace elements in the humus horizon. Results. It is established that the microelement composition of soils under the mountain-meadow vegetation of the Western Caucasus is formed under specific conditions that affect the course of soil processes. High solar insolation, low temperatures, intensive humidification throughout the year affects the features of the processes of humification, the formation of clay minerals in the soil and other products of intra-soil weathering. The predominance of acid hydrolysis processes leads to the predominant accumulation of aluminosilicates, Fe hydroxides, chelated organomineral complexes in the soil profile, which play a leading role in the binding of trace elements. The microelement composition of mountain-meadow soils under subalpine vegetation is formed with more intensive processes of humus formation and oglinivaniya. These soils are characterized by a more pronounced biogenic accumulation of Cu and Zn in the humus horizon, the illuvial nature of the Cd distribution is more pronounced. The microelement composicomposition of mountain-meadow soils under alpine and rock-scree vegetation is formed against the background of relatively weakened processes of humus formation, humus accumulation and oglinivaniya. This affects the lower intensity of biogenic accumulation of trace elements, their leaching into the lower part of the profile. Conclusions. The main regularities of the formation of the microelement composition of mountain-meadow soils are determined by the special conditions in which these soils develop. The fixation of trace elements in mountain-meadow soils occurs mainly on aluminosilicates, Fe, Mn hydroxides and chelated organomineral complexes, which largely form the silty fraction. The movement of silty particles along the soil profile leads to the redistribution of trace elements associated with them. The granulometric composition, which is an indicator of the content of the silty fraction and its distribution along the soil profile, is of great importance when characterizing the microelement composition of mountain meadow soils. The established regularities of the formation of the microelement composition of mountain-meadow soils allow us to determine the main directions of economic activity that will contribute to the preservation of their ecological state. This is, first of all, the rational use of pasture resources of mountain meadows with the introduction of a system of alternating mowing, changing the main pastures with spare ones during the year for their restoration. An important component should be monitoring changes in the trace element composition of mountain meadow soils, which will allow timely response to changes and make adjustments to the structure of the use of these soils.

Advances in Nanoscale Study of Organomineral Complexes of Termite Mounds and Associated Soils: A Systematic Review

Termite mounds are replete with natural nanoparticles, and they vary in physicochemical, geochemical, mineralogical, and biological properties from the adjoining soils. Although termite mounds have wide ecological and environmental roles including soil formation, faunal and vegetation growth and diversity, organic matter decomposition, geochemical exploration, water survey, treatment of underground contamination, thermoregulation, gas exchange, and global climate change, their nanoscale structures made by the associated organomineral complexes are still poorly understood because of technical limitations. In this review, we highlight the ecological and environmental significance of termite mounds and the documented techniques that have been successfully used to study nanostructure of termite mounds, namely, midinfrared spectroscopy (MIRS), photogrammetry and cross-sectional image analysis, a combination of transmission electron microscopy (TEM) and pyrolysis field ionization mass spectrometry (Py-FIMS), scanning transmission X-ray microscopy (STXM) using synchrotron radiation in conjunction with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) for further appraisals. There is a need to continually develop and integrate nanotechnology with the routine classical soil analysis methods to improve our understanding of the functional mechanisms of nanostructure of termite mounds that are responsible for specific properties. In view of the numerous roles termite mounds play in the environments, agriculture, and engineering, there is no better time to channel much research into understanding how they function at nanoscale.

The Production of Fluorine-Containing Composite Materials Based on Polydieneurethane and Montmorillonite

The effect of organomineral complexes of 1,1,3-trihydroperfluoropropanol-1 (modifier) with layered aluminosilicate montmorillonite (LAM) as filler on the structure and properties of fluorine-containing polydieneurethane (FPU) was investigated. The modifier and the LAM were introduced into the FPU at the stage of its production. Using a combination of methods – X-ray diffraction analysis (DRON-3), electron microscopy (Versa 3D DualBeam, USA), and Fourier IR spectroscopy (Nicolet-6700, USA) – we studied features of the layer separation of LAM in the elastomer matrix as a function of the modifier concentration. It was shown that FPU specimens filled with LAM containing 5.0% polyfluorinated alcohol disintegrate better and possess a higher resistance to thermooxidative ageing.

Sorption and photodegradation of tylosin and sulfamethazine by humic acid-coated goethite

Humic acid and mineral oxides are simultaneously present in soils and can form organomineral complexes.

Adsorption of Phenanthrene and Bisphenol A on Organo-Nano Iron Oxide Complexes

Organo-mineral complexes are important in regulating the transport and retention of hydrophobic organic contaminants in soils/sediments. Humic acid will be fractionated during adsorption on mineral. This study examined the sorption of model compounds with different properties (tannin acid, gallic acid, fumaric acid sodium and sodium oleate) on nanoiron oxide minerals and determined the sorption of phenanthrene and Bisphenol A on these organooxide complexes. The results showed that the sorption of model compounds on nanoFe2O3 followed the order of O > T > G> F. The higher adsorption of O and T was likely attributed to their higher molecule weight. The sorption of PHE and BPA on organomineral complexes was controlled by hydrophobic interactions. HOCs will adsorb preferentially on hydrophobic aliphatic compositions of organic matter.