Search Results (45)

Rivers are a key pathway for the transport of plastics into the ocean. Studies of plastic pollution in Arctic rivers remain limited due to the inaccessibility of sampling sites and work in extreme weather conditions. This work presents the results of a three-year (2019–2021) survey of floating large microplastics (0.5–5 mm) and meso/macroplastics (>5 mm) in the Northern Dvina River, an actively navigated river that drains a densely populated region into the White Sea. Sampling was conducted during the ice-free periods (May–October) along a ∼3.5 km transect using a Neuston net, providing a multi-year dataset spanning three ice-free seasons. A critical methodological advancement was the calculation of plastic river–sea flux using the discharge of the sampled surface layer (upper 20 cm), which constitutes only ∼3% of the river’s total discharge, rather than the total discharge itself. Observed microplastic concentrations (average 0.003 items ${\mathrm{m}}^{-3}$) were low compared to many European rivers, and lower than those reported in the adjacent Barents and Kara Seas. Microplastic abundance was significantly lower during the high-water season than during the low-water season, which resulted in practically no seasonal variability in microplastic fluxes from the river to the White Sea (average 0.3 items ${\mathrm{s}}^{-1}$). A notable finding was that in some cases, meso/macroplastics outnumbered microplastics by item count, underscoring the river’s role as a significant source of larger plastic debris. A geospatial assessment of Arctic rivers’ pollution potential was performed, using socio-economic indicators such as near-delta population density and port activity. This study identified the Northern Dvina River as a major contributor of microplastics among the Arctic rivers. Full article

Hydrological memory reflects the persistence of hydrological processes and plays an important role in understanding basin regime dynamics under changing climatic conditions. This study investigates the temporal stability of hydrological memory in the ten largest European basins: Volga, Danube, Dnieper, Don, Northern Dvina, Pechora, Neva, Rhine, Vistula, and Elbe. The analysis used rolling cross-correlation (CCF) and auto-correlation (ACF) functions calculated with a 50-month moving window to assess temporal changes in hydrological dependence structures. Additionally, an Instability Index was applied to quantify the variability of hydrological memory over time. The results indicate that the strongest correlations occur mainly at lag 0 and ±1, suggesting a relatively short hydrological memory in most basins. The lowest Instability Index was observed in the Volga basin, whereas the highest values were recorded in the Danube and Rhine basins. Full article

The spatial localization of plant secondary cell wall polymers is a controversial issue. A relief of parallel-organized cellulose microfibrils was discovered, on the surface of which spherical nanoparticles were visualized. Spherical nanoparticles with a diameter of 20–50 nm were isolated using size exclusion chromatography from an aqueous extract of differentiating xylem of Norway spruce and visualized by SEM and AFM. The composition of isolated nanoparticles was determined by pyrolytic GC-MS, ¹H NMR spectroscopy, and nitrobenzene oxidation, followed by separation of the products by liquid chromatography. Lignin was detected in the isolated nanoparticles already at the stage of cell wall formation. The hypothesis about the intracellular synthesis of lignin was proposed based on the results obtained. Lignin in the form of a lignocarbohydrate complex is formed not in the cell wall, but inside the cell. The formation of lignin–carbohydrate complexes occurs in Golgi apparatus and vesicles, which discharged into the inner surface of the cell wall simultaneously with the deposition of cellulose microfibrils. A new model of the structure of secondary cell wall postulates the formation of cellulose microfibrils surrounded by lignin–carbohydrate spherical complexes having a carbohydrate shell and an aromatic core. Full article

A promising application of smart materials based on natural polymers is the potential to solve problems related to hemostasis in cases of severe bleeding caused by injury or surgery. This can be a life-threatening situation. Cellulose and its modified derivatives represent one of the most promising sources for creating effective hemostatic systems, as well as for various sensing applications related to disease detection, infection diagnosis, chronic condition monitoring, and blood analysis. The aim of this review was to identify key criteria for the efficiency of cellulose-based gels with hemostatic activity. Experimental studies aimed at evaluating new hemostatic devices were analyzed based on international sources using the PRISMA methodology. A total of 111 publications were identified. Following the identification and screening stages, 20 articles were selected for the final qualitative synthesis. The analyzed publications include experimental studies focused on the development and analysis of highly porous cellulose-based scaffolds in the form of aerogels and cryogels. The type and origin of cellulose, as well as the influence of additional components and synthesis conditions on gel formation, were investigated. Three major groups of key criteria that should be considered when developing new cellulose-based highly porous scaffolds with hemostatic functionality were identified: (I) physicochemical and mechanical properties (pore size distribution, compressive strength, and presence of functional groups); (II) in vitro tests (blood clotting index, red blood cell adhesion rate, hemolysis, cytocompatibility, and antibacterial activity); (III) in vivo hemostatic efficiency (hemostasis time and blood loss) in compliance with the 3Rs policy (replacement, reduction, refinement). The prospects for the development of highly porous cellulose-based scaffolds are not only focused on their hemostatic properties, but also on the development of smart platforms. Full article

Detecting and quantifying disinfection by-products (DBPs), especially brominated species (Br-DBPs), is analytically challenging, often necessitating multiple techniques and specific standards for each target. This complexity hinders comprehensive assessment. To overcome these limitations, we present a powerful, integrated approach combining liquid chromatography with inductively coupled plasma mass spectrometry (LC-ICP-MS) and high-resolution mass spectrometry (LC-HRMS). This method enables rapid, non-targeted group screening of Br-DBPs: LC-ICP-MS selectively identifies bromine-containing compounds, while LC-HRMS provides tentative structural identification. Crucially, this synergistic combination allows for the quantification of any Br-DBP without requiring individual reference standards. This study successfully demonstrates the application of this combined LC-ICP-MS and LC-HRMS strategy for the non-targeted detection, identification, and subsequent quantification of Br-DBPs in real drinking water samples, offering a significant advancement for DBP monitoring and risk assessment. Full article

Rhododendron tomentosum is a widespread evergreen shrub used in folk medicine due to the high biological activity of its secondary metabolites, including lignans, that has not been sufficiently studied, and overcoming this problem requires advanced analytical techniques. This study proposes a two-stage analytical strategy for non-targeted screening and identification of lignans in plant extracts that involves the detection of specific lignan-related structures by 2D NMR and the establishment of corresponding fragment ions for further mass spectrometry analysis (HPLC-ESI-MS/MS). The polyphenolic fraction of R. tomentosum stem extract was the object of the study. Eight secoisolariciresinol-type lignans (xylosides, glucosides, and rhamnoside), including one previously unknown compound (5-methoxysecoisolariciresinol 9-xyloside), were identified for the first time. The structures of the five compounds were additionally confirmed by preparative HPLC isolation and NMR studies. All of the obtained compounds had antioxidant activity (FRAP and DPPH) similar to that of ascorbic acid. The proposed analytical strategy can be considered an efficient tool for rapid and reliable group screening and identification of lignan derivatives in plant extracts. Its application in the study of R. tomentosum extracts has revealed a number of lignan glycosides that may contribute to the medicinal properties of the plant. Full article

Birds, fish, and marine mammals consumed by indigenous people are included in Arctic biomonitoring. However, there are still many gaps in the data on the microbiota associated with these animals. In the current study, we used high-throughput 16S rRNA gene sequencing to explore the bacterial diversity and composition in the intestines of willow ptarmigans, greater white-fronted geese, and taiga bean geese, which are widely consumed by indigenous people in the Arctic. For the first time, meta-taxonomic data have been obtained on the lungs of wild resident and migratory birds of the Russian North. The potentially pathogenic bacterial genera Helicobacter and Olsenella were found in the intestinal microbiomes of three bird species and in the lungs of willow ptarmigan. Bacteria of the genus Staphylococcus were individually identified in the intestines of willow ptarmigan, Campylobacter sp. in the intestines of taiga bean goose, and Sutterella sp. in the intestines of greater white-fronted goose as potential pathogens. The primary findings will be used to propose a next-generation sequencing scheme for monitoring both chemical and biological contaminants in the Arctic in line with One Health approach. Full article

ABS plastic is an inexpensive material with attractive physical and chemical properties. Unfortunately, it is susceptible to degradation under UV radiation, so it limits the use of this material outdoors. In this paper, we demonstrate a low-cost approach to reduce the photodegradation of ABS plastic by using additives of kraft lignin and dioxane lignin as UV absorbers. Lignin is an abundant plant polymer, which is a waste product of the pulp and paper industry. Non-regular structure of lignin hampers its use in industry. However, there is possible use of lignin as an addition to enhance the properties of resulting materials. In this study, we obtained composites of ABS and lignin with the hot extrusion method. Adding up to 15% of lignin to ABS plastic does not have a significant negative impact on tensile properties. We irradiated the resulting composites with UV and studied the UV effects on their mechanical properties and chemical structure. Oxidative degradation was characterized by FTIR and 2D NMR methods. The results showed that small lignin additions reduced the photodegradation of ABS. The previously undescribed product of the degradation of the obtained composites was detected with the use of the set of 2D NMR spectra of the composites. We proposed a scheme for the formation of this photodegradation product based on the obtained data. Full article

Compared with those of berries, the stems and leaves of the genus Vaccinium are important and underestimated sources of polyphenols with high antioxidant activity. In the course of this work, aqueous methanol extracts of the aerial parts of common bilberry (Vaccinium myrtillus L.) and bog bilberry (Vaccinium uliginosum L.) were studied to analyze the component compositions of their biologically active polyphenolic compounds. The aqueous methanol fractions of the stems and leaves of the studied samples contained 8.7 and 4.6% extractives, respectively, and were comparable in total polyphenol content, but presented significant differences in antioxidant activity. The identification of polyphenolic compounds was carried out via the following two-stage analytical procedure: (1) non-targeted screening of dominant structures via the 2D NMR method and (2) analysis of HPLC-HRMS data via the scanning of precursor ions for a specific ion. A total of 56 phenolic compounds were identified, including the glycosides quercetin, proanthocyanidins, and catechins, as well as various conjugates of caffeic and p-coumaric acids, including iridoids. Some of the latter, such as caffeoyl and p-coumaroyl hydroxydihydromonotropein, as well as a number of lignan glycosides, were described for the first time in V. uliginósum and V. myrtillus. Full article

Bromhexine and ambroxol are among the mucolytic drugs most widely used to treat acute and chronic respiratory diseases. Entering the municipal wastewater and undergoing transformations during disinfection with active chlorine, these compounds can produce nitrogen- and bromine-containing disinfection by-products (DBPs) that are dangerous for aquatic ecosystems. In the present study, primary and deep degradation products of ambroxol and bromhexine obtained in model aquatic chlorination experiments were studied via the combination of high-performance liquid and gas chromatography with high-resolution mass spectrometry. It was shown that at the initial stages, the reactions of cyclization, hydroxylation, chlorination, electrophilic ipso-substitution of bromine atoms with chlorine, and oxidative N-dealkylation occur. Along with known metabolites, a number of novel primary DBPs were tentatively identified based on their elemental compositions and tandem mass spectra. Deep degradation of bromhexine and ambroxol gives twenty-four identified volatile and semi-volatile compounds of six classes, among which trihalomethanes account for more than 50%. The specific class of bromhexine- and ambroxol-related DBPs are bromine-containing haloanilines. Seven of them, including methoxy derivatives, were first discovered in the present study. One more novel class of DBPs associated with bromhexine and ambroxol is represented by halogenated indazoles formed through dealkylation of the primary transformation products containing pyrazoline or tetrahydropyrimidine cycle in their structure. Full article

In this work, electrospun polylactide fibers with new photostabilizing additives, 4-methyl-2,6-diisobornylphenol (DIBP) and N-isocamphylaniline (NICA), have been tested under the influence of UV-C radiation (254 nm). The changes in the polymers’ chemical structure under UV-C radiation were revealed through the increase in absorption in the 3600–3100 cm⁻¹ region in regard to the FTIR spectra. In the samples that were irradiated for 1 h, the stabilizing effect of the photoprotectors became most noticeable as the difference in the content of the hydroxyl groups in stabilized and the pure PLA reached a maximum. The TG–DSC method revealed that the most sensitive indicator of the irradiation effect was the glass transition temperature (T_g), which persisted after 2 h of irradiation when using photostabilizers and their combinations. The PLA/DIBP(1) and PLA/NICA(1) samples showed the best results in protecting PLA from UV-C radiation based on the T_g values; although, the mixture of DIBP and NICA was not as effective. The chemical structure of the photostabilized PLA samples was studied using NMR, GPC, and Py–GC/MS analysis. The electrospun polylactide fibers were mechanically tested and the effects of the electrospun samples on cell viability were studied. Full article

Lignans constitute a large group of phenolic plant secondary metabolites possessing high bioactivity. Their accurate determination in plant extracts with a complex chemical composition is challenging and requires advanced separation techniques. In the present study, a new approach to the determination of lignans in coniferous knotwood extracts as the promising industrial-scale source of such compounds based on comprehensive two-dimensional liquid chromatography separation and UV spectrophotometric detection is proposed. First and second-dimension column screening showed that the best results can be obtained using a combination of non-polar and polar hydroxy group embedded octadecyl stationary phases with moderate (~40%) “orthogonality”. The optimization of LC × LC separation conditions allowed for the development of a new method for the quantification of the five lignans (secoisolariciresinol, matairesinol, pinoresinol, 7-hydroxymatairesinol, and nortrachelogenin) in knotwood extracts with limits of quantification in the range of 0.27–0.95 mg L⁻¹ and a linear concentration range covering at least two orders of magnitude. Testing the developed method on coniferous (larch, fir, spruce, and pine) knotwood extracts demonstrated the high selectivity of the analysis and the advantages of LC × LC in the separation and accurate quantification of the compounds co-eluting in one-dimensional HPLC. Full article

Sulfite and kraft pulping are two principal methods of industrial delignification of wood. In recent decades, those have been considered as possibilities to pretreat recalcitrant wood lignocellulosics for the enzymatic hydrolysis of polysaccharides and the subsequent fermentation of obtained sugars to valuable bioproducts. Current work compares chemistry and technological features of two different cooking processes in the preparation of polysaccharide substrates for deep saccharification with P. verruculosum glycosyl hydrolases. Bleached kraft and sulfite pulps were subjected to hydrolysis with enzyme mixture of high xylanase, cellobiohydrolase, and β-glucosidase activities at a dosage of 10 FPU/g of dry pulp and fiber concentration of 2.5, 5, and 10%. HPLC was used to analyze soluble sugars after hydrolysis and additional acid inversion of oligomers to monosaccharides. Kraft pulp demonstrated higher pulp conversion after 48 h (74–99%), which mostly resulted from deep xylan hydrolysis. Sulfite-pulp hydrolysates, obtained in similar conditions due to higher hexose concentration (more than 50 g/L), had higher fermentability for industrial strains producing alcohols, microbial protein, or organic acids. Along with saccharification, enzymatic modification of non-hydrolyzed residues occurred, which led to decreased degree of polymerization and composition changes in two industrial pulps. As a result, crystallinity of kraft pulp increased by 1.3%, which opens possibilities for obtaining new types of cellulosic products in the pulp and paper industry. The high adaptability and controllability of enzymatic and fermentation processes creates prospects for the modernization of existing factories. Full article

The accumulation of trace metals in the shells of bivalves allows quantitative assessments of environmental pollution and helps to reconstruct paleo aquatic environments. However, the understanding on how marine and freshwater mollusks control the level of trace elements in their shells remains very limited. Here, we compared the trace element composition of marine and freshwater bivalves from boreal and subarctic habitats, using examples of widely distributed species of marine (Mytilus edulis, M. trossulus) and freshwater (Anodonta anatina, Unio sp., Beringiana beringiana) mussels. Sizable differences in several trace element concentrations were detected between different species, depending on their environmental niches. A multiparametric statistical treatment of the shell’s elemental composition allowed to distinguish the impact of external factors (water and sediment chemical composition) from active metabolic (biological) control. In particular, the obtained results demonstrated that Ba:Ca and Pb:Ca ratios in mussels’ shells are closely related to the primary productivity of aquatic ecosystems. The Mn:Ca ratio allowed to constrain the environmental conditions of mussels’ species depending on the trophic state of inhabited waterbody. Overall, the marine mussels exhibited stronger biological control of trace element accumulation, whereas trace element pattern in shells of freshwater mussels was chiefly controlled by environmental factors. The obtained results might help to use the trace element composition of bivalves in distinguishing marine and freshwater habitats of mollusks in paleo environments. Full article

The carbon (C) cycle in inland waters, including carbon concentrations in and carbon dioxide (CO₂) emissions from water surfaces, are at the forefront of biogeochemical studies, especially in regions strongly impacted by ongoing climate change. Towards a better understanding of C storage, transport and emission in Central Asian mountain regions, an area of knowledge that has been extremely poorly studied until now, here, we carried out systematic measurements of dissolved C and CO₂ emissions in rivers and lakes located along a macrotransect of various natural landscapes in the Sayan–Altai mountain region, from the high mountains of the Western Sayan in the northwest of Tyva to the arid (dry) steppes and semideserts in the intermountain basins in the southeast of Tyva on the border with Mongolia. New data on major hydrochemical parameters and CO₂ fluxes (fCO₂) gathered by floating chambers and dissolved organic and inorganic carbon (DOC and DIC, respectively) concentrations collected over the four main hydrological seasons allowed us to assess the current C biogeochemical status of these water bodies in order to judge possible future changes under climate warming. We further tested the impact of permafrost, river watershed size, lake area and climate parameters as well as ‘internal’ biogeochemical drivers (pH, mineralization, organic matter quality and bacterial population) on CO₂ concentration and emissions in lakes and rivers of this region and compared them with available data from other subarctic and mountain settings. We found strong environmental control of the CO₂ pattern in the studied water bodies, with thermokarst lakes being drastically different from other lakes. In freshwater lakes, pCO₂ negatively correlated with O₂, whereas the water temperature exerted a positive impact on pCO₂ in large rivers. Overall, the large complexity of counteracting external and internal drivers of CO₂ exchange between the water surfaces and the atmosphere (CO₂-rich underground DIC influx and lateral soil and subsurface water; CO₂ production in the water column due to dissolved and particulate OC biodegradation; CO₂ uptake by aquatic biota) precluded establishing simple causalities between a single environmental parameter and the fCO₂ of rivers and lakes. The season-averaged CO₂ emission flux from the rivers of Tyva measured in this study was comparable, with some uncertainty, to the C uptake fluxes from terrestrial ecosystems of the region, which were assessed in other works. Full article