Ecogenesis and primary soil formation on the East European Plain. A review

Numerous published studies have shown that soil formation, including primary pedogenesis, is closely connected functionally, energetically and operationally with ecogenesis as a key biogenic exploration mechanism of the Earth’s surface by living organisms. The ontogenetic stage of soil evolution, especially in the initial phases, is determined by geogenic conditions and the intensity and trends of biogenic-accumulative processes in the developing ecosystem. Primary soils are considered critical in the rapid development of the initial ancient biosphere, supporting multiple environmental possibilities for ecosystems in that stage of their formation. Currently, similar models of correlated soil formation and ecogenesis are actualised when new substrates appear suitable for biogenic-abiogenic interactions, which occur in both natural and anthropogenic landscapes. Biotic factors during primary pedogenesis have accumulative and transformative effects on the edaphic component complex. At this stage, the initial pedon is a key functional stage in the evolution of terrestrial ecosystems (biogeocenosis). When restoration of natural ecosystems occurs during the independent growth of exposed substrates, the natural regeneration mechanisms normally occur. These processes are based on the biogenic development of the substrate through the accumulation and transformation of organic matter.

The interdependence of hydrochemical and hydrodynamic processes in evaporite oil and gas basins

The article examines the reasons for the formation of vertical hydrochemical inversion within particular oil and gas basins and points out the role of waters of different genesis in the development of this phenomenon. The following processes of reverse hydrochemical zoning in the sedimentary cover are analyzed: thickening of heavy clay strata and the related squeezing of loosely bound waters, dehydration of clay minerals and catagenic fluid generation accompanying the transformation of organic matter into hydrocarbons of the petroleum series. The hydrochemical inversion at great depths is noted to occur and persist in the environment of the passive hydrodynamic regime; in closed water-drive systems, the demineralization of waters with depth causes the decrease in the hydrodynamic potential gradient, determining the migration pattern not only of water but also of hydrocarbons and, consequently, the location of oil and gas accumulation zones.

Structural and biochemical basis of a marine bacterial glycoside hydrolase family 2 β-glycosidase with broad substrate specificity

Uronic acids are commonly found in marine polysaccharides and increase structural complexity sanand intrinsic recalcitrance to enzymatic attack. The glycoside hydrolase family 2 (GH2) include proteins that target sugar conjugates with hexuronates and are involved in the catabolism and cycling of marine polysaccharides. Here, we reported a novel GH2, Aq GalA from a marine algae-associated Bacteroidetes with broad-substrate specificity. Biochemical analyses revealed that Aq GalA exhibits hydrolyzing activities against β-galacturonide, β-glucuronide, and β-galactopyranoside via retaining mechanisms. We solved the Aq GalA crystal structure in complex with galacturonic acid (GalA) and showed (via mutagenesis) that charge characteristics at uronate-binding subsites controlled substrate selectivity for uronide hydrolysis. Additionally, conformational flexibility of the Aq GalA active site pocket was proposed as a key component for broad substrate enzyme selectivity. Our Aq GalA structural and functional data augments the current understanding of substrate recognition of GH2 enzymes and provided key insights into the bacterial use of uronic acid containing polysaccharides. IMPORTANCE The decomposition of algal glycans driven by marine bacterial communities represents one of the largest heterotrophic transformation of organic matter fueling marine food webs and global carbon cycling. However, our knowledge of the carbohydrate cycling is limited due to structural complexity of marine polysaccharides and the complicated enzymatic machinery of marine microbes. To degrade algal glycan, marine bacteria such as members of Bacteroidetes produce a complex repertoire of carbohydrate-active enzymes (CAZymes) matching the structural specificity of the different carbohydrates. In this study, we investigated an extracellular GH2 β-glycosidase, Aq GalA from a marine Bacteroidetes to identify the key components responsible for glycuronides recognition and hydrolysis. The broad substrate specificity of Aq GalA against glycosides with diverse stereochemical substitutions indicates its potential in processing complex marine polysaccharides. Our findings promote a better understanding of microbially-driven mechanisms of marine carbohydrate cycling.

Biogenic elements and organic matter production in the ecosystem of Lake Arey, Transbaikal region, Russia

Maintaining an ecological balance of Lake Arey is crucial in terms of nature conservation. Lake Arey is located in Eastern Siberia and is a central object of a designated conservation area of regional significance. The lake is used for recreation (organized and unorganized tourism, sport fishing, mud collection for balneological purposes) not only by residents but also by holidaymakers from other regions. In terms of mineralization level, Lake Arey is a freshwater body. Significant factors affecting the aquatic ecosystem are temperature, TDS, pH and dissolved oxygen, depth, and turbidity. High contents of ammonium ions are observed in the ecosystem. The concentration of dissolved inorganic phosphorus is 23.6% of total phosphorus. The ratio of PO (permanganate oxidizing ability of organic matter) to COD (chemical oxygen demand) indicates active processes of production, mineralization, and transformation of organic matter in the water body. Carotenoids prevail in planktonic pigments. The chlorophyll a amount is insignificant. The chlorophyll b content increases from July to September. Currently, Lake Arey belongs to the α-mesotrophic type of water body. However, increased anthropogenic load and high-water years can promote eutrophication processes.

Elemental and Molecular Composition of Humic Acids Isolated from Soils of Tallgrass Temperate Rainforests (Chernevaya taiga) by 1H-13C HECTCOR NMR Spectroscopy

The soils of Chernevaya taiga (tallgrass fir-aspen hemiboreal rainforest) have high fertility in comparison with oligotrophic analogs formed in boreal taiga. We have studied humic acids isolated from the soils of Chernevaya and oligotrophic taiga in the Novosibirsk, Tomsk, Kemerovo and the Altai regions of Russia and for the first time the structural and molecular composition of humic acids was determined using 13C CP/MAS and 1H-13C HETCOR NMR spectroscopy. According to data obtained in this study, up to 48% of aromatic compounds accumulate in the soils of Chernevaya taiga, which is higher than in the oligotrophic taiga and comparable with this rate of steppe Chernozems. In the course of active processes of transformation of organic matter, a significant number of aromatic fragments accumulates in the middle horizons of soil profiles. Using 13C CP/MAS spectroscopy, it was possible to identify the main structural fragments (aliphatic and aromatic) that formed in humic acids of the Chernevaya taiga. The HETCOR experiment made it possible to accurately determine the boundaries of chemical shifts of the main groups of structural fragments of humic acids. Our results demonstrate that the stabilization of organic compounds occurs in the soil of the Chernevaya taiga, which leads to the resistance of organic matter to biodegradation that is not typical for benchmark soils of boreal environments.

The Theory of Naphthidogenesis: A Quantitative Model of the Catagenetic Evolution of Aquatic Organic Matter

—This study discusses the evolution of the composition of dispersed organic matter from the Bazhenov Formation (West Siberian petroleum basin) and the products of its catagenetic transformation on the basis of the balance and kinetic approaches to modeling of the catagenetic transformation of organic matter and its individual components, primarily kerogen. The results show that the variations in the elemental composition of kerogen and the extent of generation of both hydrocarbons and nonhydrocarbons can be quantitatively described using a simplified kinetic model. Preliminary estimates of the model parameters are given for the averaged Bazhenov-type kerogen. It is shown that numerical modeling of the catagenetic transformation of dispersed organic matter confirms the validity of the recognition of the main phase (zone) of oil generation and the main phase (zone) of gas generation.

Geochemical Characteristics of Alluvial Aquifer in the Varaždin Region

The variation in the major groundwater chemistry can be controlled by dissolution and precipitation of minerals, oxidation-reduction reactions, sorption and exchange reactions, and transformation of organic matter, but it can also occur as a result of anthropogenic influence. The alluvial aquifer represents the main source of potable water for public water supply of the town Varaždin and the surrounding settlements. Sampling campaigns were carried out from June 2017 until June 2019 to collect groundwater samples from nine observation wells. Major cations and anions, dissolved organic carbon and nutrients were analyzed in the Hydrochemical Laboratory of Croatian Geological survey. The sampled waters belong to the CaMg-HCO3 hydrochemical type, except the water from observation well P-4039 that belongs to NaCa-HCO3 hydrochemical type. It was identified that groundwater chemistry is mainly controlled by hydrogeological environment (natural mechanism), but anthropogenic influence is not negligible. The results of this research have significant implications on sustainable coexistence between agricultural production and water supply.