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Iron overload consequences for submerged plants stoichiometry, homeostasis and performance
AbstractAccelerated lakes eutrophication is one of the greatest challenges nowadays. To counteract its negative effects, large-scale restoration treatments are carried out worldwide. However, research in this field is mainly focused on the process effectiveness and there is a scarcity of studies concerning the impact of restoration treatments on water organisms and ecosystem homeostatsis. Our microcosm study presents the effects of a phosphorus coagulant (iron [III] chloride) on functional traits changes, oxidative stress and macro- and microelement stoichiometry disturbances in macrophyte Myriophyllum spicatum, a model species inhabiting eutrophic waters. Application of the coagulant to experimental vessels influenced the physicochemical and optical parameters of water and led to significant changes in biogeochemistry. Stoichiometric alterations were reflected by disturbances in the relative contents of macro- (C, N, P, Ca, Mg) and microelements (Fe, Zn, Cu, Co) and induced luxury consumption of available ions. Physicochemical and stoichiometric changes mutually exerted negative influence on M. spicatum functional traits. The parameters of oxidative stress remained at low levels, comparable to the untreated control whereas stoichiometric analysis revealed the activation of mechanisms responsible for minimizing low light stress. The ability of M. spicatum to maintain homeostasis of Cu and Co under simulated chemical water restoration was closely related to high concentrations of Fe and Zn ions, which simultaneously were not subjected to homeostasis control. Thus, chemical lake restoration treatments based on phosphorus coagulants are not as environmentally safe as previously considered and may have far-reaching consequences for the biogeochemical cycle and food web functioning.
Biopolymer Paperboard Impregnation Based on Chitosan and Nanocellulose with Addition of Caffeine and Gallic Acid
In this study, the preparation and detailed characterization of a chitosan (CHT) impregnation system modified with cellulose nanofibrils (CNFs) and enriched with bioactive compounds—caffeine (CAF) and gallic acid (GA)—applied to the surface of unbleached paperboard were described. Their mechanical properties (tensile strength, elongation at break, and bursting strength), structural features, and surface barrier parameters (water absorption) were evaluated. The antibacterial activity of the formulations comprising 1% chitosan (1% CHT), 1% chitosan with 1% caffeine (1% CHT/1% CAF), and 1% chitosan with 1% gallic acid (1% CHT/1% GA)—applied to enhance the functionality of the coated paperboard—was additionally assessed. The incorporation of cellulose nanofibrils into the coating matrix markedly improved the mechanical performance of the paperboard, particularly in terms of puncture resistance and elongation at break, while all modified coatings retained high burst strength. Impregnations containing gallic acid or caffeine showed similar mechanical characteristics but improved flexibility without compromising structural integrity. Chitosan solutions containing gallic acid and solutions containing caffeine exhibited activity against the tested Gram-positive (S. aureus, L. monocytogenes) and Gram-negative (E. coli, P. aeruginosa) bacterial strains. Antibacterial analysis showed moderate activity against Gram-positive strains and strong inhibition of Gram-negative bacteria, with the 1% CHT/1% GA impregnation giving the largest zone of growth inhibition around the sample—19 mm in the agar diffusion test—indicating the strongest suppression of E. coli. It was found that incorporation of nanocellulose into the chitosan matrix significantly reduces water uptake by treated paperboard surface, which is critical in the context of food packaging. The best result—Cobb60 value of 32.85 g/m2—was achieved for the 1% CHT/1% CNF formulation, corresponding to an 87% reduction in water absorption compared to the uncoated control. The results obtained in this study indicate a promising potential for the use of these impregnation systems in sustainable packaging applications.
Effect of Antisolvent Used to Regenerate Cellulose Treated with Ionic Liquid on Its Properties
The solvolysis reaction with ionic liquids is one of the most frequently used methods for producing nanometer-sized cellulose. In this study, the nanocellulose was obtained by reacting microcrystalline cellulose with 1-ethyl-3-methylimidazolium acetate (EmimOAc). The aim of this research was to determine the influence of various antisolvents used in the regeneration of cellulose after treatment with ionic liquid on its properties. The following antisolvents were used in this research: acetone, acetonitrile, water, ethanol and a mixture of acetone and water in a 1:1 v/v ratio. The nanocellulose was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM) and elemental analysis (EA). The results show that the antisolvent used to regenerate cellulose after the solvolysis reaction with EmimOAc affects its properties. Water, ethanol and a mixture of acetone and water successfully removed the used ionic liquid from the cellulose structure, while acetone and acetonitrile were unable to completely remove EmimOAc from the cellulosic material. The results of the XRD analysis indicate that there is a correlation between the ionic liquid content in the regenerated cellulose and its degree of crystallinity. Among the tested solvents, water leads to the effective removal of EmimOAc from the cellulose structure, which is additionally characterized by the smallest particle size and non-formation of agglomerates.
Fruit Vinegars as Natural and Bioactive Chitosan Solvents in the Production of Chitosan-Based Films
Natural fruit vinegars, derived from various fruits, enhance culinary experience and offer potential health benefits due to their bioactive compounds. In this study, fruit vinegars (apple, blackcurrant, and cherry) were used as natural solvents for producing chitosan films, introducing an environmentally friendly approach. Fruit vinegars and chitosan-based solutions were examined for their antioxidant and antimicrobial properties. In turn, the obtained chitosan films were characterized by their antimicrobial, mechanical, and structural properties. Both fruit vinegars and film-forming chitosan solutions showed antioxidant activity, and chitosan–cherry vinegar solutions exhibited the highest antiradical and ferrous ion-chelating effect. All solvents and chitosan-based solutions were characterized by antimicrobial properties, especially against Pseudomonas aeruginosa (inhibition zone > 28 mm). Antimicrobial activity was also preserved in the case of chitosan-based film, especially when produced with cherry vinegar, which showed activity against the broadest spectrum of bacteria. The largest zone of inhibition for all samples was observed for P. aeruginosa in the range of 19 mm from the inhibition zone to >28 mm, depending on the type of vinegar used as a solvent. The conducted tests showed that the type of vinegar used also affects the mechanical parameters of the films obtained, such as elongation at break, for which values were recorded from 3.97 to 4.93 MPa, or tensile strength, for which the values were recorded from 48.48 to 70.58 MPa. The results obtained demonstrate that natural fruit vinegars, serving as chitosan solvents, can be an alternative to traditionally used acidic solvents, yielding films with favorable properties.
Kombucha as a Solvent for Chitosan Coatings: A New Strategy to Extend Shelf Life of Red Peppers
Plastic pollution and environmental degradation necessitate the development of natural, biodegradable food preservation materials. This study examined chitosan-based film-forming solutions using kombucha derived from black tea, lemon balm, and chamomile as natural solvents rich in bioactive compounds. Lemon balm kombucha solutions were used to create chitosan films and coat red peppers. The study assessed the mechanical properties of the films and the effects of chitosan coating on peppers, including texture, ascorbic acid content, sensory attributes, and antioxidant activity. Microbiological tests showed that a chitosan–lemon balm kombucha solution acted against Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica. Lemon balm kombucha had high total phenolic (381.67 µg GAeq/mL) and flavonoid (21.05 µg Qeq/mL) contents. The chitosan film exhibited a tensile strength of 11.08 MPa and an elongation at break of 53.45%. The water vapor transmission rate of the obtained chitosan film was 131.84 g/m2·24 h. Coated peppers showed a 32% increase in skin strength and retained 11% more ascorbic acid after 15 days. Sensory evaluation revealed no significant differences from controls. These results highlight lemon balm kombucha as a promising natural solvent for chitosan coatings, which have the potential to extend red pepper shelf life and to support food preservation.
Understanding stoichiometric adjustments in a freshwater plant: Responses to sediment and water nutrient dynamics across lake trophic gradients
AbstractDespite ongoing efforts to reduce nutrient inputs, eutrophication continues to disrupt biogeochemical cycles and destabilize freshwater food webs. In this study, we examine the stoichiometric responses of the freshwater plant Myriophyllum spicatum under varied environmental conditions across lakes of differing trophic status. Specimens were collected from lakes with a wide natural range of macro‐ (C, N, P) and micronutrient (Fe, Cu, Zn) concentration in both water and sediments. We applied the ecological stoichiometry framework and analyzed the relationship between nutrient availability (water and sediments) and the elemental composition of M. spicatum's organs (leaves, stems, and roots). The C : N : P ratios in organs were not affected by eutrophication. Instead, all macro‐ and micronutrient concentrations differed between plant organs. N concentration was highest in leaves and roots, indicating uptake from both sources. Furthermore, sediments significantly influenced the plant organs' C, P, and Zn concentration, while nutrients in the water column showed no correlation. Leaves demonstrated flexibility in C and Zn concentrations, negatively correlating with sediment levels of these elements. The concentration of micronutrients was highest in the roots. Our results indicate distinct nutrient allocation strategies for different plant organs: leaves are rich in N to support photosynthesis, stems store C and P, aiding growth and reproduction, and roots accumulate micronutrients Fe, Zn, and Cu. It highlights sediments as a critical nutrient source for M. spicatum, shaping its elemental composition. The relationship between organisms' biochemistry, trophic interactions, and their transformation into dead organic matter is crucial for understanding environmental stress impacts on aquatic ecosystems.
Valorization of Forest Biomass Through Pyrolysis: A Study on the Energy Potential of Wood Tars
Forest biomass is a renewable source of environmentally friendly material—wood. However, wood processing generates large amounts of by-products, including branches. These byproducts are often used as firewood; however, they can be used much more effectively. In this study, the pyrolysis of two woods, namely birch and pine, was proposed. The liquid products of pyrolysis were studied by FTIR spectroscopy, and the heating value of these products was evaluated. In order to find the optimal pyrolysis temperature from the point of view of the calorific value of the product, the process was carried out at four temperatures: 450, 500, 550, and 600 °C. The liquid product yielded three fractions, from which two were analyzed, namely the dense tar fraction and light liquid fraction. FTIR analysis results clearly demonstrated that samples from different fractions differ from one another, yet the results within the same fraction are remarkably similar. The tar fraction was characterized with a higher gross calorific value between 42 to 50 MJ/kg, while the liquid fraction gross calorific value was between 29 and 39 MJ/kg; in general, pine wood yielded products with higher calorific values. The pyrolysis of small wood industry by-products is an interesting method of utilization, yielding not only a liquid product with good calorific properties, but also a solid product, namely biochar, which may be used in carbon storage or used as a soil amendment.
Characteristics of Chitosan Films with the Bioactive Substances—Caffeine and Propolis
Chitosan is a natural and biodegradable polymer with promising potential for biomedical applications. This study concerns the production of chitosan-based materials for future use in the medical industry. Bioactive substances—caffeine and ethanolic propolis extract (EEP)—were incorporated into a chitosan matrix to increase the bioactivity of the obtained films and improve their mechanical properties. Acetic and citric acids were used as solvents in the production of the chitosan-based films. The obtained materials were characterized in terms of their antibacterial and antifungal activities, as well as their mechanical properties, including tensile strength and elongation at break. Moreover, the chemical structures and surface morphologies of the films were assessed. The results showed that the solution consisting of chitosan, citric acid, caffeine, and EEP exhibited an excellent antiradical effect. The activity of this solution (99.13%) was comparable to that of the standard antioxidant Trolox (92.82%). In addition, the film obtained from this solution showed good antibacterial activity, mainly against Escherichia coli and Enterococcus faecalis. The results also revealed that the films produced with citric acid exhibited higher activity levels against pathogenic bacteria than the films obtained with acetic acid. The antimicrobial effect of the chitosan-based films could be further enhanced by adding bioactive additives such as caffeine and propolis extract. The mechanical tests showed that the solvents and additives used affected the mechanical properties of the films obtained. The film produced from chitosan and acetic acid was characterized by the highest tensile strength value (46.95 MPa) while the chitosan-based film with citric acid showed the lowest value (2.28 MPa). The addition of caffeine and propolis to the film based on chitosan with acetic acid decreased its tensile strength while in the case of the chitosan-based film with citric acid, an increase in strength was observed. The obtained results suggested that chitosan films with natural bioactive substances can be a promising alternative to the traditional materials used in the medical industry, for example, as including biodegradable wound dressings or probiotic encapsulation materials.
Enhancing Sustainability and Antifungal Properties of Biodegradable Composites: Caffeine-Treated Wood as a Filler for Polylactide
This study investigates the suitability of using caffeine-treated and untreated black cherry (Prunus serotina Ehrh.) wood as a polylactide filler. Composites containing 10%, 20%, and 30% filler were investigated in terms of increasing the nucleating ability of polylactide, as well as enhancing its resistance to microorganisms. Differential scanning calorimetry studies showed that the addition of caffeine-treated wood significantly altered the crystallization behavior of the polymer matrix, increasing its crystallization temperature and degree of crystallinity. Polarized light microscopic observations revealed that only the caffeine-treated wood induced the formation of transcrystalline structures in the polylactide. Incorporation of the modified filler into the matrix was also responsible for changes in the thermal stability and decreased hydrophilicity of the material. Most importantly, the use of black cherry wood treated with caffeine imparted antifungal properties to the polylactide-based composite, effectively reducing growth of Fusarium oxysporum, Fusarium culmorum, Alternaria alternata, and Trichoderma viride. For the first time, it was reported that treatment of wood with a caffeine compound of natural origin alters the supermolecular structure, nucleating abilities, and imparts antifungal properties of polylactide/wood composites, providing promising insights into the structure-properties relationship of such composites.
Chitosan-Based Films with Essential Oil Components for Food Packaging
Chitosan-based films show great potential in terms of application in food preservation and are also promising carriers of biologically active ingredients. This paper presents the potential use of chitosan-based films with the addition of essential oil components, e.g., carvacrol, eugenol, and isoeugenol, intended for food packaging. The characteristics of the obtained films were determined, including antibacterial, mechanical, barrier, and structural parameters. In addition, the antibacterial and antioxidant effects of the essential oil components were assessed. Eugenol (44.41%) and isoeugenol (43.56%) showed high antiradical activities, similar to the activity of Trolox (44.33%), which is used as a standard antioxidant. In turn, carvacrol was characterized by the strongest effect against the examined strains of bacteria, both Gram-positive and Gram-negative. The chitosan film with carvacrol showed the most valuable antibacterial and mechanical properties (tensile strength and elongation at break). The antibacterial activities of the chitosan–carvacrol films were higher than that of the carvacrol solution. The inhibition zones of the chitosan–carvacrol films were in the range 29–41 mm (except for Enterococcus faecalis, with an inhibition zone of 15 mm) compared to the inhibition zones of the carvacrol solution (28 mm). The results showed that chitosan is an effective carrier of fragrance compounds, mainly carvacrol. However, all the tested chitosan-based films with the addition of fragrance compounds showed appropriate parameters (biological, mechanical, and barrier), which makes them an ecological alternative to plastics intended for food packaging.
The high adaptive potential of Abies alba Mill. seedlings – biochemical and physiological studies of succession along the environmental gradient of a Cambrian quarry
Abstract Abies alba Mill. (silver fir) needs specific soil and humidity conditions and seedlings are vulnerable to climatic extremes. Surprisingly, successful seedling establishment has been observed in disturbed habitats like active quarries. We compared 2-year old fir seedlings in three habitats—natural fir forest, disturbed forest, and exposed quarry—to explore the biochemical features that help them endure the first stages of succession in harsh environments. We assessed a range of parameters including reactive oxygen species (ROS) levels, antioxidant activity (2,2-diphenyl-1-picrylhydrazyl reduction), foliar pigments (chlorophylls and carotenoids), C and N contents, nonstructural carbohydrates, phenolics, and cell wall components analyzed via Fourier Transform Infrared (FTIR) spectroscopy, as well as ectomycorrhizal colonization and diversity. The analysis indicated that the fir seedlings were in unexpectedly good physiological condition despite the environmental constraints. Continuous exposure to harsh conditions (stony soils poor in C and N, extreme insolation, potential drought/flooding stress, etc.) was only slightly associated with ROS and antioxidant levels, roots of seedlings were fully mycorrhized, and their roots did not express signals of severe oxidative stress. Only a few seedling features clearly followed the environmental gradient; C (%), ectomycorrhizal fungal richness in roots, and total antioxidant content in stems decreased in harsh environments. Despite the lower chlorophyll levels, seedlings from the quarry had no decrease in C or N foliar levels. These firs did not have impaired N- or C-compound levels. Quarry seedlings had the highest nonstructural carbohydrates in needles and roots, protective foliar shifts (more carotenoids), and stronger stems (more structural carbohydrates, especially lignin). These findings demonstrate strong acclimatization capacity of A. alba seedlings and suggest the existence of stabilizing physiological mechanisms supporting survival in disturbed environments.
Phosphorus–Nitrogen Interaction in Fire Retardants and Its Impact on the Chemistry of Treated Wood
This work focuses on the changes in the chemical composition of wood caused by impregnation with fire retardants such as guanidine carbonate (GC), urea (U), diammonium phosphate (DAP) and their mixtures. The treated wood was tested using the oxygen index (LOI), Py–GC/MS analysis and FTIR Spectroscopy. The wood was vacuum treated at a pressure of 0.8 MPa for 20 min and then subjected to thermal degradation using the LOI. This way, degraded and nondegraded layers were obtained and ground (0.2 mm). All treatment variants achieved the class of non-flammable materials based on LOI tests; the exception was the 5% urea solution, defined as a flame-retardant material. Using the analytical methods, it was found that cellulose and hemicelluloses undergo the fastest thermal degradation. This study found that the variant protected with a 5% mixture of GC and DAP before and after the degradation process had the best fire-retardant properties regarding cellulose content in the wood. The highest content of anhydrosugars characterised the same variants, the amount of which indicates a slowdown in the degradation process and, consequently, a reduction in the release of levoglucosan during combustion, suggesting potential applications in fire safety.
Chitosan Films with Caffeine and Propolis as Promising and Ecofriendly Packaging Materials
This study addresses challenges faced by the packaging industry in finding suitable natural and biodegradable materials that can replace plastics while preserving the superior quality and freshness of the items contained within. Chitosan, a biodegradable natural polymer, shows great potential as a matrix for ecofriendly and biodegradable composite materials. In the present study, bioactive substances such as caffeine (CAF) and propolis extract (EP) were used for the enhancement of the bioactivity of chitosan-based films. Two acidic solvents, acetic acid and citric acid, were used to produce chitosan films. The study examined the antioxidant capabilities of the solutions used for film formation; similarly, the characteristics of the resultant films were also examined, encompassing antimicrobial, barrier, and mechanical characteristics. The findings suggested that the use of additives exhibiting antioxidant activity, such as CAF and EP in the chitosan matrix can be an effective method to counteract oxidative stress in food packaging. The study also showed that films produced with citric acid exhibit antimicrobial activity against many strains of bacteria, including foodborne pathogens. In addition, the antimicrobial activity of chitosan/citric acid film can be increased by adding CAF and EP. The results confirmed that both the additives and the acids used affect the mechanical and barrier features of the obtained chitosan-based films. This study suggests that chitosan films supplemented with natural bioactive substances have the potential to serve as viable replacements for traditional plastics in the packaging sector.