Natural Water Research Articles

Freshwater jellyfish in northeastern Argentina: a risk to human health.

Although cnidarians are mostly marine organisms, the occurrence of freshwater jellyfish frequently arouses the interest of ecologists, due to their sudden and unusual appearances in natural and artificial water bodies around the world. This study describes a series of cases compatible with cnidarian envenomation that occurred coincidentally in time and space with the presence of Craspedacusta sowerbii Lankester, 1880 jellyfish in the province of Misiones (El Saltito stream) in January 2022. A year later, its presence was confirmed in another watercourse of this province (Cazador stream). Based on these findings, its possible toxicological consequences in humans were evaluated by characterizing the jellyfish extract using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and enzymatic/toxic activities. We revealed the presence of proteolytic enzymes and cytolytic toxin(s), which-by means of activating the inflammatory cascade-could explain the stinging skin lesions observed in the suspected cases described. In addition to recording for the first time the occurrence of this cnidarian in northeastern Argentina, this work provides, for the first time, a toxinological explanation for the clinical observations after contact with the most widespread freshwater jellyfish species in the world, giving support to health professionals in the diagnosis and management of such accidents/envenomation.

In-situ formation of La2O2CO3 uniformly immobilized on biomass-derived carbon aerogel for enhanced phosphate removal

In the face of the dual pressures of eutrophication and phosphorus shortages, it is of utmost importance to efficiently remove and recover phosphate from wastewater. In this study, waste-biomass-derived carbon aerogel (CA) was utilized as a dispersing carrier for lanthanum (La), resulting in the successful in-situ generation of an La2O2CO3 (La3.5-CA-450) phosphate adsorbent on the CA matrix. The results demonstrated that the introduction of CA as an adsorbent led to abundant carbon defects and pore structures, which significantly enhanced its performance. Moreover, through the coordinated pyrolysis of CA and La3+, CO32−, capable of exchanging with PO43−, was generated, thereby contributing to the exceptional phosphate adsorption capacity exhibited by the adsorbent. Specifically, La3.5-CA-450 displayed a high phosphate adsorption capacity of 155.8 mg P/g (272.4 mg P/g La), with the molar ratio of P to La being 1.22:1, indicating a high utilization efficiency for La. The adsorbent exhibited exceptional performances in terms of selectivity, renewability, efficient use in natural water environments, and robust application in a broad range of synthetic availability. This research adheres to the green concept “using waste to treat waste” while providing a novel approach for preparing efficient La-based phosphate adsorbents.

Polyaromatic hydrocarbons of small reservoirs of the Tomsk region

Relevance. The assessment of the state of natural waters includes the determination of a number of physico-chemical indicators, on the basis of which various indices and classifications are developed. However, they do not take into account a number of pollutants that have a significant impact on the state of the reservoir, for example, polyaromatic hydrocarbons. The article considers some aspects of determining priority pollutants, which include polyaromatic hydrocarbons, according to environmental hazard criteria: toxicity, carcinogenicity, prevalence, frequency of occurrence, source of origin (anthropogenic or natural). Hydrochemical parameters such as pH, dissolved oxygen content, biological oxygen consumption (BPK5), and ion content are taken into account to determine water quality. An attempt was made to assess the impact of polyaromatic hydrocarbons on the ecological state of water bodies and to take into account their contribution to changes in the values of the water pollution index. All these data prove the relevance of the study. Aim. To establish the composition of polyaromatic hydrocarbons in the surface waters of small reservoirs of the Tomsk region to assess anthropogenic load and to show the relationship with the indices of natural water quality. Methods. Extraction, liquid adsorption chromatography, high-performance liquid chromatography, capillary electrophoresis, amperometry, titrimetry. Results. Small lakes of the Tomsk region were studied for the content of 13 polyaromatic hydrocarbons. The authors have carried out the identification by high-performance liquid chromatography with fluorimetric detection. The total content of polyaromatic compounds in the studied surface water samples varies from 0.37 to 0.54 mcg/l. In the polyaromatic hydrocarbons mixture in aqueous samples, there is an increased content of light 2–3 nuclear polyarenes with better solubility (naphthalene, fluorene and phenanthrene), as well as benz[a]anthracene. The content of inorganic components represented by cations and anions does not exceed the maximum permissible concentrations. The water pollution index was calculated; all lakes are moderately polluted, closer to polluted. The paper demonstrates the dependence of the water pollution index coefficient on the content of high-molecular polyaromatic hydrocarbons and the ratio of high-molecular to low-molecular polyaromatic hydrocarbons. It is shown that the higher the value of the water pollution index coefficient, the higher the proportion of difficult-to-oxidize components in surface waters.

Uranium in groundwaters of North Kazakhstan

Relevance. The need to dentify the characteristics of the distribution of radioactive elements in the groundwater of Northern Kazakhstan. Aim. Generalization of available data on the geochemistry of groundwater and uranium and radon distribution in them using the example of the northern regions of the Republic of Kazakhstan. Methods. Generalization of long-term hydrogeochemical research and compilation of an electronic data bank on the territory of Northern Kazakhstan. A laboratory study of the chemical composition of groundwater was carried out at the Research Laboratory of Hydrogeochemistry of the School of Natural Resources Engineering of Tomsk Polytechnic University. Measurements of 222Rn contents in waters were carried out using the Alfarad Plus complex in the Laboratory of Hydrogeology of Sedimentary Basins of Siberia, Institute of Geology and Geography, Siberian Branch, Russian Academy of Sciences. Results. The groundwater of aquifers of different ages, distributed in the territory of Northern Kazakhstan (North Kazakhstan uranium province), was studied. Two geochemical sets of groundwater were identified. The first is characterized by the dominance of HCO3– and Mg2+ in the water composition, and the second by Cl– and Na+. A change in composition and an increase in the value of total mineralization from 0,1 to 49 g/dm3, in the direction from north to south, indicate the development of continental salinization. In natural waters of the first group, uranium content varies from 0.065 to 16000 μg/dm3 and radon activity from 4 to 3885 Bq/dm3. For sodium chloride waters of the second set, concentrations can reach 32500 μg/dm3, and radon activity is 6–59 Bq/dm3, since the emanating reservoir (granitoids) is located to the north – at a distance of 80–100 km. Naturally, granitoid massifs of the studied region are sources of uranium. Their drainage by the river network leads to its removal and concentration on geochemical barriers in the groundwater of the Neogene-Quaternary aquifer. This distribution of radioactive elements is associated with the high migration ability of uranium in solution in the form of uranyl ion in oxidizing geochemical conditions.

Assessment of catchment water resources allocation under climate change in Luwombwa sub-catchment, Zambia

The uncertainty in climate change and high water demand pose pressure on the natural water resources supply. Not only does this require better understanding but also a call for immediate interventions, mitigation and adaptive measures. This study evaluates catchment water resources in the Luwombwa sub-catchment in Zambia through statistical analysis in the downscaling of past, present and future climatic variables from the CMIP6 climatic model. These variables are then integrated into WEAP - a semi-distributed hydrological and water evaluation model - to perform water demand and allocation scenario modelling. Mult-site calibration and validation were conducted on five selected micro-catchments within Luwombwa sub-catchment. The model performance was assessed usng the R2, NSE and PBIAS as the objective functions. Satisfactory values of 92 % for R2, 82 % for NSE and 6.9 % for PBIAS were achieved. This allowed for scenario modelling on water demand and allocation among competing users. Three future scenarios (2022–2050) were developed from the historical to baseline (1988–2022) and included state of water resources availability under climate change, expansion of irrigation area and impact of dam construction in the sub-catchment. The study reveals a decrease of 20 % in sub-catchment's water availability resulting from 9.3 % (equivalent to 4oC) rise in maximum temperature and 4.5 % reduction in rainfall within the entire sub-catchment. This is especially under the persistence of SSP370 climate variability scenario projections downscaled from four GCM models by the year 2050. The study further revealed that the change point for anticipated future climate extremes is likely to occur between 2027 and 2030. The results are indicative of downward trends in streamflow under climate change and socioeconomic development leading to increase in water value and water scarcity. The insights from the study are critical to inform formulation of effective catchment water resources management strategies such as the development of management plans and adapation measures in the face of climate change and the needs for different stakeholders involvement.

Risk factors for the occurrence of schistosomiasis mansoni in a quilombola community in an endemic area in northeastern Brazil

Objective: To identify the risk factors related to Schistosomiasis mansoni in a quilombola community located in a highly endemic area in the Northeast of Brazil. Methods: This is an ecological epidemiological study conducted with 497 individuals, of both sexes aged over 4 years. Information on sociodemographic, economic, and environmental data from the quilombola community of Patioba was collected through a questionnaire, stored in an Excel database, and evaluated by descriptive statistics. Results: From the sample, 53.92% were women and 46.08% men, approximately 43.25% of the population had incomplete elementary education, 58.35% had a family income between 1 and 3 minimum wages, 49.89% disposed sewage in the street, 95.97% stated they had household garbage collection, 88.93% reported consuming well water, 65.19% reported having contact with natural waters, 26.15% had undergone diagnostic testing for schistosomiasis, and 15.69% had tested positive for the disease. During the visits, several snail breeding sites were observed. Conclusion: The absence of water supply and sewage treatment, the low socioeconomic status of the studied families, and the significant presence of the parasite's intermediate hosts in the streets of the settlement are strong indicators that this population is exposed to the risk of contracting the disease.

Adaptable Plasmonic Membrane Sensors for Fast and Reliable Detection of Trace Low-Micrometer Microplastics in Lake Water.

In freshwater environments, low-micrometer microplastics (LMMPs) have captured significant attention due to their prevalence and toxicity. Yet, rapid detection of LMMPs (1-10 μm) at the single-particle level within complex freshwater matrices remains a hurdle. We developed an adaptable plasmonic membrane sensor for fast detection of individual LMMPs in eutrophic lake waters. The plasmonic membrane sensor functions both as a membrane filter and as a sensor for LMMP collection and analysis. Among the four types of membrane sensors, polycarbonate track-etch (PCTE) membrane sensors exhibit superior imaging quality for LMMPs due to their flat and homogeneous surfaces. Besides the significantly improved imaging contrast and reduced background interferences, the Raman intensity of LMMPs is enhanced by 48% ± 25% on PCTE membrane sensors compared to unmodified membranes. The increased Raman intensities of a chemical probe with an increasing gold layer thickness and a decreasing membrane pore size suggest a surface-enhanced Raman scattering effect from the membrane sensors. The membrane sensors achieve a detection limit of 1 μg/L and an ultrafast scanning time of 0.01 s for individual LMMPs across natural eutrophic lake water. The developed membrane sensors offer an adaptable tool for the swift and reliable detection of individual LMMPs in complex environmental matrices.

Healing properties of natural mineral water of Tajikistan

Aim. To study the composition and medicinal properties of water from natural mineral springs in the Republic of Tajikistan.Materials and Methods. This study analyzed the climatic and geographical regions, as well as the water quality and chemical composition of four mineral springs: Khoja-Obi-Garm, Obi-Garm, Garm-Chashma, and Shoambary. The research also investigated the influence and effectiveness of these mineral waters in treating skin diseases.Results and Discussion. The Republic of Tajikistan has numerous mineral springs that are used for treating skin conditions and other health issues. Mineral waters in Tajikistan are classified into five types based on their chemical composition: bicarbonate, chloride, sulfate, nitrate, and mixed composition waters. In addition, there are waters with active ions and gaseous elements such as hydrogen sulfide, radon, nitrogen, and methane. Based on temperature, these waters are categorized as cold, warm, or hot/thermal waters. The springs at Khoja-Obi-Garm, Obi-Garm, Garm-Chashma, and Shoambary are hot thermal baths of the bicarbonate-chloride-sulfate-sodium type. In addition to the primary salts and gases, these waters contain biologically active trace elements, including aluminum, titanium, manganese, copper, silicon, molybdenum, strontium, barium, boron, fluorine, and others.Conclusion. Tajikistan holds a leading position in Central Asia regarding the abundance of mineral springs, and the mineral waters from these springs meet the requirements for therapeutic use. These waters contain a variety of chemical elements that exert significant biological effects, and, when used appropriately, can effectively treat many diseases.

Efficient Capture of Phosphate From Aqueous Media Using Bimetallic La‐Zr‐MOF

ABSTRACTDeposition of excessive phosphate in natural water column caused several issues, like the eutrophication and destruction of aquatic ecosystems. Adsorption has been an effective and convenient method for phosphate elimination. Herein, a novel bimetallic metal–organic framework adsorbent, namely, La‐Zr‐MOF, was prepared, and the morphology, crystallite, characteristic functional groups, specific surface area, and composite material surfaces were analyzed using XRD, FT‐IR, SEM‐EDS, and BET. The adsorption performance of the adsorbent was systematically evaluated by batch adsorption experiments, and the adsorption thermodynamic and kinetic properties were analyzed. The results reveal that La‐Zr‐MOF exhibits a high selectivity and sorption performance for phosphate, and the adsorption of La‐Zr‐MOF follows the Langmuir and pseudo–second‐order models; the phosphate removal procedure is a chemisorption accompanied by an endothermic reaction, and the maximum capacity was 127.7 mg g−1. Combined with batch adsorption experiments, kinetic and thermodynamic studies and various characterization analyses together revealed the phosphate removal mechanism, mainly ligand exchange and electrostatic interactions.

New challenges regarding the environmental and sanitary condition of Ukrainian water bodies

Today Ukraine is faced with new challenges that have a significant impact on natural water bodies and aquaculture. As a result of hostilities, there is an additional pressure on aquatic ecosystems. Unfortunately, large territories with important fishery complexes of Ukraine are either occupied, located in the war zone, or mined. Currently it is impossible to carry out comprehensive monitoring investigations into the actual environmental condition of inland water bodies of Ukraine. Therefore, in order to establish a true picture of the state of the water fund of Ukraine, an analytical review of publications was performed. Unfortunately, after the large-scale hostilities on the territory of Ukraine, a significant number of water bodies changed their status according to saprobic indicators. The situation is difficult with the reservoirs of the Dnipro River Cascade, which accumulate all pollutants released into the water from the catchment area. The destruction of the Kakhovka Hydroelectric Power Station led to a massive killing of all biota, including fish. The reservoirs are mostly polluted by biogenic, organic and surface-active substances, oil products, phenols, pesticides, and heavy metals. Even in the pre-war period, the problem of water pollution required immediate decisions, and with the beginning of the full-scale war, it became one of the most urgent tasks for Ukraine. Today, Ukraine’s water bodies suffer from pollution by pyrogens, fuel, and lubricants after rocket attacks and even from the total destruction of fish farms, water reservoirs, i.e., the Kakhovka Reservoir. Therefore, monitoring of the environmental condition of inland water bodies of Ukraine will provide an opportunity to assess their real condition and, in the future, to select the complex of methods aimed for their restoration.

Dual‐functional UiO‐66/g‐C3N4 composites for photocatalytic pesticide removal and in situ adsorption of phosphate byproducts in water

AbstractBACKGROUNDWith the increasing global demand for food, a significant amount of organophosphorus pesticides is applied to farmland, leading to pollution as they are discharged into natural water bodies with agricultural runoff. This study employed a coupling approach, utilizing a 6:4 mass ratio of zirconium‐based metal–organic framework UiO‐66 and g‐C3N4 through a grinding and annealing method to construct a Z‐type heterojunction composite material named UG 6:4.RESULTSThis material is employed for photocatalytic removal of the representative organophosphorus pesticide, dichlorvos (DDVP), from water and simultaneous in situ adsorption of its inorganic phosphorus byproducts. Results demonstrate that for initial DDVP concentrations below 5 mg L−1 (calculated as total phosphorus), both the mineralization rate under ultraviolet light irradiation with a wavelength of 365 nm and a power of 125 W and the adsorption rate of phosphorus were 100% when the pH was 6 and the UG 6:4 dosage was 0.2 g L−1. The sheet‐like g‐C3N4 tightly envelops the surface of UiO‐66, forming a Z‐scheme heterojunction. This structure imparts UG 6:4 with enhanced light absorption, faster generation and separation of photogenerated electron–hole pairs compared to individual UiO‐66 or g‐C3N4, and the establishment of an internal electric field suppresses the recombination of photogenerated charge carriers.CONCLUSIONConsequently, UG 6:4 exhibits outstanding photocatalytic pesticide removal capabilities. Furthermore, UG 6:4 demonstrates specific adsorption of inorganic phosphorus through electrostatic attraction and ligand exchange. This study indicates that UG 6:4 is a promising dual‐functional photocatalytic adsorbent with excellent application prospects. © 2024 Society of Chemical Industry (SCI).

Ornamental Plant Growth in Different Culture Conditions and Fluoride and Chloride Removals with Constructed Wetlands

Natural water resources often contain fluorides and chlorides due to wastewater discharge; however, excessive exposure to fluorides can pose health risks to humans. Elevated chloride levels can negatively affect aquatic fauna and disrupt the reproductive rates of plants. This study assessed constructed wetlands (CWs) featuring monocultures (including Canna hybrid, Alpinia purpurata, and Hedychium coronarium) and polycultures (combinations of species from the monoculture systems) of ornamental plants (OPs) to evaluate their efficiency in removing fluorides and chlorides. The results revealed that the ornamental plants flourished in the CW conditions without sustaining any physical damage. C. hybrid demonstrated the longest roots and the highest volume, as well as greater height compared to other species. However, this did not affect the ion removal efficiency. In polyculture systems, 42.2 ± 8.8% of fluoride was removed, a result that was not significantly different (p > 0.05) from the removal rates observed in monocultures of C. hybrid (42.5 ± 7.5%), H. coronarium (36.8 ± 7.0%), or A. purpurata (30.7 ± 7.9%). For chloride, a similar pattern emerged, with 32.4 ± 4.8% removed in constructed wetlands (CWs) using a polyculture of ornamental plants, a figure that was also not significantly different (p > 0.05) from the removal percentages in monocultures of C. hybrid (29.1 ± 5.3%), H. coronarium (28.1 ± 5.0%), or A. purpurata (32.0 ± 5.7%). Our results indicate that CWs with polyculture species contribute to pollutant removal at levels comparable to those found in monoculture systems. However, polyculture systems offer enhanced aesthetic appeal and biodiversity, incorporating various ornamental flowering plants. The use of this eco-technology for removing fluoride and chloride pollutants helps prevent river contamination and associated health issues.

Effects of mercury and magnetic fields on the activity of proteinases and glycosidases in the intestine of common carp Cyprinus carpio.

Aquatic ecosystems are increasingly affected by anthropogenic pollution, including heavy metals like mercury, which accumulate in organisms and cause harmful effects. At the same time, human activities such as industrial operations and the use of electric power lines also alter the magnetic background in natural water bodies. However, the interaction between mercury exposure and magnetic fields remains poorly understood. This study aimed to investigate the combined effects of mercury and magnetic fields on the digestive enzyme activity of common carp (Cyprinus carpio), focusing on the relevance of magnetic fields due to their increasing presence in industrialized environments. Two groups of fish were fed diets with low (0.02mg/kg) or high (0.27mg/kg) mercury content for 6months and exposed to extremely low-frequency magnetic fields or hypomagnetic conditions. Results showed significant differences in mercury accumulation between groups, with higher levels in carps fed with high-mercury content diets. These fish also exhibited increased body length and weight compared to those on a low-mercury diet. The amylolytic activity (total activity of enzymes hydrolyzing starch: α-amylase, glucoamylase, and maltase) and proteolytic activity (total activity of serine proteinases) in the fish intestine were assessed. Magnetic exposure had contrasting effects on enzyme activity, depending on mercury levels in the diet. Fish fed the low-mercury diet exhibited decreased amylolytic activity following magnetic field exposure, while fish on the high-mercury diet showed increased activity. Proteolytic activity followed a similar pattern, with opposite effects observed between the two dietary groups. These findings suggest that mercury accumulation alters the biological response to magnetic fields, possibly through compensatory biochemical mechanisms. Understanding the interactions between toxic substances and magnetic fields is critical for improving environmental risk assessments.

LIFs-Based Fluorescent Analysis of Silver Ions in Water Using AIEgen-Embedded PVA Hydrogel.

The detection and quantification analysis of silver ions is important to protect human health and improve the level of wastewater treatment. In this work, a polyvinyl alcohol (PVA) hydrogel-based sensing material based on an aggregation-induced emission strategy was developed and combined with a portable laser-induced fluorescence spectroscopy (LIFs) device for the direct detection and quantification of silver ions in water. Considering the requirements of environmental water analysis regarding portability, reliability, and convenience, this fluorescence turn-on strategy was optimized accordingly to ensure the accuracy and stability of the analysis in complex natural water environmental. This sensing method showed operational excellence and good sensitivity (down to 1 ppb) and may provide a stable and convenient strategy for the on-site, real-time analysis of environmental water samples.

Enhanced photocatalytic performance of magnetically reclaimable N-doped g-C3N4/Fe3O4 nanocomposites for efficient tetracycline degradation

The growing environmental challenge posed by the persistence of tetracycline (TC) antibiotics in natural waters is of increasing concern. To address this, there is an imperative need for advanced methods to mitigate TC residues. Herein, we demonstrate the preparation of nitrogen-doped graphitic carbon nitride integrated with magnetic Fe3O4 (N-g-CN/Fe3O4) composites, showcasing narrow band gaps optimized for TC degradation. These advanced materials, conceived through a thermal poly-condensation approach, utilize citric acid and melamine as precursors for nitrogen and g-CN, respectively. These composites exhibit a face-centered cubic architecture, with particle dimensions between 8 to 12 nm and encompassing both meso and microporous structure. The results of the Brunauer–Emmett–Teller analysis indicated specific surface areas of 6.73 m²/g for g-CN, 69.80 m²/g for N-g-CN, 62.55 m²/g for Fe3O4, and 148.32 m²/g for N-g-CN/Fe3O4. These values demonstrate an increase in surface area upon the incorporation of heteroatom of nitrogen and Fe3O4, into the g-CN matrix, thus influence the photocatalytic performance. Under solar light exposure, the synthesized photocatalysts demonstrated photocatalytic activity with a degradation efficiency of 94.16 % within 120 min. Specifically, the N-g-CN/Fe3O4 (22.5 %) composites exhibited remarkable photocatalytic efficiency due to the narrow band gap energy between N-g-CN and Fe3O4, enhanced light absorption in the visible range, and effective charge carrier separation and transportation to the pollutants. N-g-CN/Fe3O4 (22.5 %) composites demonstrated good recyclability (five cycles), magnetic sustainability, and stability for the degradation of TC and emerging pollutants from wastewater using photocatalysts. Similarly, FGCN composites exhibited good recyclability (five cycles), magnetic retrievability, and stability for degrading organic and emerging pollutants from wastewater through photocatalysis. This efficiency can be attributed to the harmonious combination of nitrogen doping, refined surface area, and the natural heterojunction between N-g-CN and Fe3O4.

Nanoplastics Distribution during Ice Formation: Insights into Natural Surface Water Freezing Conditions.

The migration characteristics of nanoplastics (NPs) in the natural freezing process are complex and have attracted increasing attention in simulating natural freezing in recent years. However, simulated freezing conditions often fall short of replicating natural freezing processes, and studies on the vertical distribution of NPs remain inadequate. This study established a more realistic simulation of the natural freezing process in surface water by controlling both the air temperature (T1) and the water temperature (T2). Additionally, we introduced a new parameter, the local distribution coefficient (Kiw1), to compare with the effective distribution coefficient (Kiw2). The values of Kiw1 and Kiw2 for PS-500 nm were 0.18 and 0.21, respectively, at T1 = -20 °C and T2 = 1 °C. The results revealed the NPs concentration differed in ice, near-ice liquid, and far-ice liquid. Both properties of NPs and environmental factors could regulate the vertical distribution of NPs. The findings underscored the importance of freezing temperature regulated by T1 and T2, elucidating the roles of various influencing factors on the vertical distribution characteristics of NPs and unraveling the mechanisms of NPs distribution in the ice-water system. This study can provide valuable insights for understanding the migration of NPs in surface water in cold regions.

MoS2/porous carbon nanofiber heterostructures for efficient evaporation-driven generators.

Evaporation power generators (EPGs) based on natural water evaporation can directly convert heat energy from the surrounding environment into electrical energy. However, EPGs are difficult to commercialize due to the low charge generation and transport efficiency of single material systems, resulting in unsatisfactory open-circuit voltages and short-circuit currents. Here, we step by step prepared MoS2/porous carbon nanofiber (PCNF) heterogeneous systems by electrospinning and hydrothermal methods. Electron microscope measurements proven the uniform coating of high-crystalline quality MoS2 nanosheets on PCNF fabrics, and the uneven concave-convex surface increased the specific surface area. MoS2 covered PCNF fabrics retained good hydrophilicity, which was suitable for absorbing water and keeping the surface wet during long-term evaporation. Moreover, layered MoS2 with rich surface charge improved the charge transfer of the MoS2/PCNF fabrics. As a result, the open-circuit voltage and short-circuit current of the EPGs prepared with MoS2/PCNF fabrics were improved to 0.25 V and 75 μA, respectively, compared with those based on PCNF fabrics, which demonstrated that the MoS2 coatings improved the interaction area with water and the charge transfer effect of the EPGs. This heterogeneous combination strategy provides ideas for the preparation of high-performance EPG materials.&#xD.

The Influence of Fluoride Ions on the Forms of Lanthanide Migration in Natural and Polluted Waters of the Lovozero Massif (The Kola Peninsula)

A comprehensive study (monitoring, thermodynamic modeling) of natural and anthropogenically polluted waters of the Lovozero Massif has been carried out. A thermodynamic study of the weathering of the Lovozero Massif within the “water-rock-atmosphere” system at a temperature of 5 °C showed that the elements contained in the rocks of the studied massif influence the formation of the chemical composition of natural waters. It has been established that an increase in the degree of “water-rock” interaction leads to an increase in the concentrations of F−, Cl−, SO42−, and HCO3− in the solution. This affects the mobility of lanthanum, cerium, and other elements due to the formation of complex compounds with them. The relatively high content of fluorine, phosphorus, and HCO3− (weak and medium acids) in the solution promotes the dissolution of silicates while Si, Al, and P are released into the solution. Monitoring of water from a flooded mine in which there is an increase in the degree of interaction of water with rock showed higher pH values for the concentrations of Na, HCO3−, F−, P, Al, Si, V, U, La, and Ce. The conclusions are relevant in the context of the use of groundwater for drinking water supply purposes. The obtained information is useful to evaluate the health of the population of the region under study.

Natural Self-Purification of Creek Ecosystems: The Role of Foam Formation in Pollutant Absorption and Microbial Decomposition

<p style="text-align:justify;text-indent:36.0pt;"><span style="font-family:"Times New Roman","serif";font-size:12.0pt;line-height:115%;" lang="EN">This study investigates the natural self-purification ability of a creek through the process of froth formation. The research focuses on the creek's capacity to clean itself by capturing and removing pollutants naturally. The problem addressed is the accumulation of organic and inorganic contaminants in the water, which poses a threat to the aquatic ecosystem. The proposed solution explores how naturally formed froth can act as an effective mechanism for trapping and eliminating a wide range of pollutants. The froth formation is driven by biological processes, including the decomposition of organic matter by fungi, bacteria, Archaea, Algae, Virsus, Protozoa and animal parasites. These processes release biological surfactants and biogas microbubbles, which, combined with dissolved air and pollutants, lead to the creation of froth enriched with contaminants. The findings confirm that the creek has a natural ability to purify itself, as the froth effectively absorbs and collects dissolved pollutants. This process reduces the organic load in the water, thereby improving water quality. The study demonstrates that froth formation is a vital subprocess in the self-purification of river ecosystems, particularly through microbial decomposition of organic material. This natural mechanism supports water treatment by enhancing the removal of contaminants. The research validates the hypothesis that the creek's froth formation plays a significant role in its self-cleaning process, offering insights into the potential for natural water purification methods.</span></p>

A Reaction-Based Approach to Colorimetric Detection of Organic Analytes in Water Using a Chlorine-Containing Carbocyanine Dye and Hypochlorite

Water quality control employs techniques mostly targeting individual analytes; group detection is also practiced, but the choice of group methods is limited, which supports interest in developing such methods. We have examined the interaction of hypochlorite with a chlorine-containing heptamethine carbocyanine dye in the presence of 30 organic and inorganic model analytes that were found to induce diverse color changes in the system. The main supposed mechanisms are retardation of the dye oxidation with hypochlorite (presumably by scavenging chlorine radicals) and substitution of chlorine atom in the dye by the most nucleophilic analytes (amines, amino acids, proteins, DNA, phenol). The grass-green substitution product is more contrastingly visible against the dark-purple hypochlorite oxidation product of the dye than against the original emerald-green dye. The indicator reaction is monitored photographically for 10–40 min and the images are processed using principal component analysis (PCA) or linear discriminant analysis (LDA), allowing for data convolution for the complex color transitions. Nitrogen compounds are discriminated from the others, and more reactive analytes (tryptophan, cysteine, bovine serum albumin, and DNA) are detected in the presence of less reactive ones in natural water. The system is promising for the development of group assays for dissolved organic matter and the discrimination of water samples.