Russian Journal of General Chemistry

Mathematical models have been proposed to relate median lethal concentrations of metal cations with respect to daphnia and nematodes to their physicochemical characteristics (descriptors). The most informative descriptors quantitatively related to the toxicity of metal cations for Daphnia magna and Caenorhabditis elegans have been found to be the negative logarithm of the first hydrolysis constant, negative logarithm of the solubility product of the corresponding sulfides, and stability constant of the metal complex with ethylenediamine. The linear regression equations for the median lethal concentrations of metal ions for Daphnia magna and Caenorhabditis elegans can be used as predictive correlations due to their significant predictive ability.

A new method for graphene preparation by self-propagating high-temperature synthesis process was proposed. The effect of the resulting material on various microorganisms and the process of graphene nanoparticles conjugation with microbial cells were discussed.

Coal mining waste rock dumps contain a lot of rare and precious microelements and are a single complex mechanism of the chemical and biochemical transformations of substances, and the key role in such transformations belongs to sulfuric acid formed as a result of the vital functions of thionic bacteria Th. Ferrooxidans. The aim of the present work was to develop an environmentally friendly biotechnology for processing coal mining waste rock dumps of the Luhansk Region as man-made metal deposits. The spectral analysis of the waste rocks of the Luhansk Region revealed high concentrations of precious, rare-earth, and trace elements. A high prevalence of gallium and germanium clarkes was found, and their actual concentration in the waste was close to the minimum industrial concentration. The results of chemical analysis of the waste rock for Al₂O₃ showed that its concentration was close to that in poor bauxites, a traditional raw material for alumina. A method and technology of the biochemical leaching of aluminum, gallium, and germanium, which make use of the natural processes of sulfuric acid formation in waste rock were proposed, and their efficiency was experimentally confirmed. The proposed biochemical technology for the processing of coal mining waste rocks can serve as the basic method for diminishing their environmental impact and rational use of natural resources.

The results of an experimental study of chemical and thermal modification of galvanic sludge which is the basis of composite sorption materials intended for wastewater treatment were presented. It was shown that the sorption material based on ferritized galvanic sludge possesses magnetic properties, which allows its extraction from water by magnetic separation. The specific surface area, particle size distribution, and bulk density of the sorption material were determined. Bioassay testing was performed to assess the material toxicity.

—The article focuses on the changes in the hydrochemical regime of the Kiliya delta of the Danube River, which have occurred during many years of research. It is established that after damming of the Danube River, supersaturation of the river water with dissolved oxygen is observed in the upper and middle river course, which results from an increase in the photosynthetic activity of the algae, a reduction in the content of suspended solids, and pollution of the water with inorganic nitrogen and phosphorus compounds. It is shown that since the 1970s the water mineralization level has increased by approximately 30%. The concentration of Na⁺, K⁺, SO₄^2–, and Cl^– ions has increased. Cases of saltwater penetration into the waters of the Prorva, the Gneushev, and the Bystryi branches have been observed. In modern conditions, the concentrations of nitrate ions and inorganic phosphorus remain high, whereas the concentration of ammonium nitrogen, on the contrary, has decreased almost thrice. It is found that there is an increase in the concentration of dissolved organic substances, especially in spring and summer, which is due to the intensification of bioproduction processes. Among dissolved organic substances in the water of the Kiliya delta of the Danube River, the dominating position is occupied by humic substances, the relative content of which reaches 54.8–85.6%.

V.I. Vernadsky (1863‒1945) formulated three biogeochemical principles. These principles were set forth, e.g., in his monograph ‟The Chemical Structure of the Biosphere of the Earth and Its Environment” (the first biogeochemical principle was given in Paragraph 95 of that his monograph, the second biogeochemical principle, in Paragraph 198, and the third biogeochemical principle, in Paragraph 208). In addition to those fundamental principles, the author attempted formulating an additional, fourth (4th) principle, consistent with Vernadsky’s ideas on the important role of organisms in modification of the chemical parameters of the biosphere. The new principle highlights additional aspects of the vital role of living organisms in conditioning the geochemical environment. The fourth principle emphasizes a regulatory role of organisms in abiogenic migration of chemical elements in the biosphere.

Biological experiments with non-medical application antibiotics lucensomycin, tetramycins A and B, aureofungins A and B, and antimycin A were carried out. It was revealed that these antibiotics exhibit growth-promoting activities and may be considered as eco-friendly biopreparations. Prospects of their application for increasing the agricultural crop yields were shown.

—In a pond, the trophic press of fish suppresses the development of large-size filter-feeders (Daphnia longispina and Simocephalus vetulus). Large-size cladoceran species are replaced by smaller species. The Micro-cystis aeruginosa blooms and the trophic press of fish are accompanied by a loss of the species diversity of filter-ing zooplankton and by a drop in its biomass to minimal levels. Flow-through experimental ecosystems separate zooplankton-consuming fish, thereby causing abrupt increases in zooplankton abundance and biomass. Water flow in the experimental ecosystem destroys cyanobacterial colonies and increases the proportion of their fractions with a size making them edible. This favors increases in zooplankton abundance, size, and fertility.

Four innovations added to the V.I. Vernadsky’s concepts on the biosphere in recent author’s publications were summarized. These innovations are as follows: (a) a new typology of the matter in the biosphere; (b) modernization of the concept of the biogenic migration of chemical elements; (c) a new, fourth, biogeochemical principle; and (d) a more detailed presentation of the concept of a substantial influence of organisms on physical and chemical parameters of the biosphere: namely, the development of a new theory of the multifunctional role of the biota in water self-purification in the hydrosphere.

Past and present data on the concentration and speciation of metals (Al, Fe, Cu, Zn, Pb, Cr, Cd, Mo, Ni) in the Kiliya Danube delta have been generalized, and variations in their concentrations have been compared. It has been shown that the highest pollution of the Danube lower reach has occurred from the second half of 1980s to the first half of 1990s due to intensive anthropogenic impact on the river delta ecosystem. Subsequently, decrease of the metal concentration was observed as a result of industrial crisis in the late 1990s–early 2000s. The major part of metals is transferred by water flow in the form of suspended solids, which is related to their relatively high content in water of the Kiliya part of the Danube delta. The results of studying dissolved metal species, in particular the ratio of the labile fraction that is potentially toxic to hydrobionts and complexes with dissolved organic matter, have been discussed. Data on the distribution of metals among complexes with dissolved organic substances of different chemical natures and molecular weights are given. Humic substances have been shown to contribute most to the complexation. Compounds with molecular weights of 1 to 5 and less than 1 kDa constitute the major part of anionic metal complexes with humic substances.