Russian Journal of General Chemistry最新文献

The literature review is devoted to the analysis of factors regulating the utilization of D-xylose and L-arabinose, structural components of various plant biomass wastes, by soil microscopic fungi. The data on transport, initial stages of catabolism of these pentoses in the context of microorganism adaptation to starvation conditions, osmotic and oxidative stresses are systematized. The possibilities of using soil microscopic fungi for complex utilization of plant wastes associated with the production of renewable energy sources, sugar substitutes, and organic acids are discussed.

The hydrochemical characteristics of Lake Pleshcheyevo and the Trubezh river were studied. It is noted that already at a distance of 1.5 km from the river mouth, a water mass is formed, the composition of which, according to the studied components, is little different from the main water mass of the lake. Pollution of the Trubezh river by biogenic elements occurs at the site “vil. Krasnoe ‒ estuary” due to non-sewage runoff from the territory of Pereslavl-Zalessky and untreated sewage from enterprises located on the riverbanks within the city limits. According to the studied indicators, the lake can be assessed as eutrophic.

In the present work, we solved the problem of converting low-density polyethylene waste into a powder state as the first stage of involving plastic in the biogeochemical processes of its natural degradation. Acceleration of the fragmentation of polyethylene waste was ensured by adding 2D graphene structures (few-layer graphenes, FLGs), obtained by carbonization of precursors represented by natural materials (glucose, starch, cellulose, lignin, cedar bark, and Sosnowski’s hogweed biomass), to the polymer matrix. It was shown that polyethylene modification with few-layer graphenes leads to a sharp drop in elasticity of the resulting composites compared to the original polyethylene. At the same time, the strength of the composite under deformations acceptable for disposable polymer products remains at the level of the original polymer, which provides the necessary service life of products made from the proposed composites. The FLGs obtained by carbonization of lignin and cedar bark were suggested as optimal modifiers for obtaining polyethylene-based composites such that products thereof can be involved in microbial recycling.

The study presents data on the concentration of polycyclic aromatic hydrocarbons (PAHs) in bottom sediments of Lake Baikal’s coastal zone, specifically in the Selenga shallow waters, during 2018–2023. Using high-performance liquid chromatography (HPLC) with fluorometric detection, the content of 16 priority PAHs was measured, ranging from 12.3 to 218.8 ng/g, with an average of 74.9 ng/g (n = 88). Higher PAH concentrations were observed near river discharges, particularly in the Ust-Kharauz stream. The bottom sediments in the Selenga landfill were classified as having a “low” level of PAH contamination (Σ PAH < 100 ng/g). Divergence coefficient analysis of PAH profiles allowed the sampling stations to be grouped into two groups: Cluster No. 1 (southwestern part of the Selenga WDS) and Cluster No. 2 (northeastern part). The mixed origin of PAHs (pyrogenic and petrogenic) in bottom sediments was determined using molecular ratios analysis, which revealed an increasing proportion of pyrogenic sources and anthropogenic influence from the northeast to the southwest of the Selenga shallow waters.

A brief literature review is presented on the priority of the (most significant) heavy metals (mercury, lead, cadmium, arsenic) polluting water bodies, soils, and atmospheric air. Examples of the toxic effects of these metals on human health are provided.

This study assesses the pollution of the Terek River, one of the main water sources in Kabardino-Balkaria, which flows through the North Caucasus republics. The Terek’s waters, entering the territory of Kabardino-Balkaria from the Republic of North Ossetia-Alania, are combined with the waters of the Malka River, which receives inflow from more than ten rivers, before continuing towards the Caspian Sea. Between 2021 and 2023, ongoing studies focused on the concentration of soluble compounds of heavy metals (Cr, Ni, Mo, Pb, Zn, Mn) and nitrogen forms (NO₂^‒, NO₃^‒, and NH₄⁺) in the Terek River basin. To measure the concentrations, methods including atomic-absorption spectroscopy, potentiometric techniques, and spectrophotometry were employed. The actual water discharge was determined to calculate the amount of pollutants carried by the Terek River from Kabardino-Balkaria between 2021 and 2023. Based on the average water discharge over the three-year period, the transport of toxic substances (Cr, Ni, Mo, Pb, Zn, Mn, NO₂^‒, NO₃^‒, and NH₄⁺) from Kabardino-Balkaria was calculated. The results are presented in tabular form.

This study aims to substantiate regional maximum permissible concentrations (MPC) of metals in the water of Lake Imandra. Primary hydrochemical monitoring data from 1991 to 2018 were used for the calculations. The regional MPCs of six metals – total iron, copper, manganese, zinc, nickel, and aluminum – were determined. Three calculation methods were applied: the S.A. Patin method, the D.G. Zamolodchikov method, and the method developed by E.V. Venitsianov and co-authors. The S.A. Patin method uses two parameters: the average concentration (C_avg) of the chemical element during the study period and its standard deviation (σ). The D.G. Zamolodchikov method relied on the upper and lower quartiles (UQ and LQ) of the distribution. The E.V. Venitsianov method employed three parameters: sample size, the upper quartile of the distribution, and the standard deviation for a quantile of approximately 0.75. The principle of sanitary maximalism was used to identify the optimal method for calculating regional MPCs. The E.V. Venitsianov method was found to be the most suitable. A strong correlation was observed between the natural logarithms of regional MPCs and the natural clarkes of metals in the Earth’s crust.

With a view to considering the boron industry on the waters of the Rudnaya river, the hydrochemical data of samples of river and drainage waters of tailing dumps selected seasonally were analyzed; their temperature, pH value and mineralization were determined. The use of the method of physico-chemical modeling in the Selector program made it possible to make mixing models of the studied waters on the geochemical barrier “natural surface—technogenic waters”, to determine the forms of migration of the main elements of ores and the main flotation reagent (H₂SO₄): Ca, B and S. The article presents the results of a seasonal assessment of the negative impact of the boron industry on the chemical composition of the waters of the Rudnaya River and shows the excess of MPC_fish and MPC_gen for Ca, P, Mn, Zn, B and S.

Arachidonic acid and its derivatives are a very promising alternative to the use of environmentally hazardous chemical plant protection products. It is widely used as a growth stimulant and anti-stress resistance for agricultural plants. In this work, the possibility of using beet pulp, a by-product of the sugar beet industry, as an accessible and environmentally friendly substrate for obtaining practically important arachidonic acid during solid-phase cultivation of the Mortierella alpina VKPM F-1280 fungus was studied. It was shown that on a glycerol-containing media with beet pulp as the main polyunsaturated acid in the composition of others, essential arachidonic acid is formed (82% of the total acids). At the same time, the lipid content in the aerial mycelium does not exceed 10% (of absolute dry substance). The addition of oat flakes (30–60 g/L) into the media with beet pulp increases the lipid content in the aerial mycelium to 18% (of absolute dry substance).

The work is devoted to the study of preferential solvation of dimethyl sulfoxide in binary solvents by IR spectroscopy. The absorption frequencies of stretching vibrations of S=O group of dimethyl sulfoxide in mixtures of carbon tetrachloride with acetone, acetonitrile and nitromethane at different ratios of components were determined. Shifts of absorption frequencies of stretching vibrations of the S=O group of dimethyl sulfoxide (Δν_{pref. solv}) in binary solvents as a measure of preferential solvation were calculated. Solvation shells (x*) in binary solvents for the S=O group of dimethyl sulfoxide have been determined using absorption frequencies. The role of the second component of the binary mixture on the effects of preferential solvation and changes in solvation shell composition (x*) was discussed.