Search Results (924)

Environmental pollution by polycyclic aromatic hydrocarbons (PAHs) is a serious environmental problem. One of the effective methods of cleaning the environment from these toxicants is the use of sorbents based on clay minerals. Special organo-mineral, bio-mineral and bio-organo-mineral complexes were obtained. Organo-mineral complexes (organoclays) were synthesized on the basis of Na-bentonite and anionic, amphoteric and nonionic surfactants. Bio-mineral and bio-organo-mineral complexes were produced by inoculating bentonite and organoclays with a consortium of bacteria. The adsorption characteristics of the complexes to benzopyrene and naphthalene were studied. Modification of bentonite with various types of surfactants leads to a significant increase in the percentage adsorption of both benzopyrene and naphthalene, with benzopyrene being more so. All bio-organo-mineral complexes adsorb more benzopyrene than pure bentonite and the bentonite + bacteria complex. In most cases, this pattern is also characteristic of naphthalene adsorption. Organoclay complexes with bacteria adsorb PAHs in greater quantities than organoclays, typically at the average concentrations of benzopyrene and naphthalene used (30–60 μg mL⁻¹) and when modified with individual surfactants. Based on the determination coefficients, the adsorption of benzopyrene and naphthalene by all studied sorbents is best described by the Langmuir equation. The maximum (limiting) adsorption of benzopyrene by all organo-mineral complexes (organoclays) exceeds the maximum adsorption of benzopyrene by bentonite. Modification of bentonite with surfactants may not change, decrease, or increase the maximum adsorption of naphthalene compared to the original bentonite, depending on the surfactant used. Colonization of the organoclay surface by bacteria, with rare exceptions, results in a decrease in the maximum adsorption values of benzopyrene and naphthalene compared to organoclay, or has no effect at all. Full article

Saimaluu-Tash I, located in a high-altitude glacial valley in Kyrgyzstan, preserves one of Central Asia’s largest and most culturally significant concentrations of rock engravings. Despite extensive archaeological research, the physical, mechanical, and chromatic properties of the sandstone substrates relevant for conservation assessment remain poorly characterized. This study integrates petrographic microscopy, scanning electron microscopy, colorimetry, and Vickers hardness testing with the digital documentation of twelve engraved blocks to evaluate weathering processes, engraving practices, and long-term preservation. The engravings are carved into arkosic sandstone with carbonate cement, characterized by a weathered surface enriched in clay minerals and covered by a dark surface coating (patina). Weathered surfaces exhibit significantly lower hardness (0.6 ± 0.2 GPa) than unweathered stone (2.8 ± 0.6 GPa), which facilitated the engraving of the petroglyphs by allowing tools to penetrate more deeply into the stone. Colorimetric analyses reveal a strong chromatic contrast between the surface patina and the lighter sandstone exposed by engraving (ΔE ≈ 22.7). This contrast would have enhanced the original visibility of the petroglyphs and highlights potential conservation issues associated with the progressive reformation of this surface layer. Iconographic analysis identifies recurrent themes related to hunting, herding, mobility, animal management, and symbolic spatial practices within a nomadic high-mountain landscape. Overall, the results demonstrate how an integrated material and interpretative approach contributes to understanding rock art production processes. They support preventive and sustainable conservation strategies for vulnerable engraving landscapes shaped by long-term interactions between geological processes and human activity. Full article

Arsenic represents a ubiquitous element in the environment, characterized by high mobility, complex chemical speciation and a strong sensitivity to redox conditions and biological activity, with microbial processes play a central role in its biogeochemical cycling. The present review provides a comprehensive and integrative synthesis of arsenic biogeochemical cycling across terrestrial, freshwater and marine environments, in which chemical speciation is explicitly treated as the central unifying concept controlling arsenic mobility, transformation and bioavailability, linking geological, chemical and biological processes across environmental compartments. Natural processes regulating arsenic distribution are examined from mineralogical sources and soil–water interactions to biologically mediated transformations in aquatic and marine biotic compartments, largely driven by microbial activity, highlighting the contrast between inorganic arsenic dominance in abiotic reservoirs and the prevalence of organoarsenicals in tissues of living organisms. The review further explores arsenic behaviour under natural environmental alterations and in extreme or unconventional ecosystems, where redox constraints, sulphide chemistry or intense fluid–sediment exchanges lead to deviations from the baseline speciation patterns. Against this framework, anthropogenic perturbations are discussed through several documented case studies, illustrating how industrial releases, the long-term effects of mining activities, agricultural practices and the use of synthetic arsenical compounds may change arsenic pathways primarily by altering geochemical and biological controls rather than through a generalized increase in total arsenic content. Overall, the topics covered provide an integrated framework for interpreting arsenic dynamics across environmental systems, emphasizing the complex biogeochemical processes governing arsenic cycling. Full article

The aim of this study was to critically assess the usefulness of pollution indicators in monitoring riverside soils (fluvisols) for heavy metal content. A novel methodological approach was used, comparing areas located inside and outside flood embankments, which allowed for a precise determination of the impact of fluvial and anthropogenic processes on heavy metal accumulation. The experimental logic validated the usefulness of four indicators: the Individual Pollutant Index (PI), the Background Enrichment Factor (PIN), the Potential Ecological Risk (RI), and the Pollution Load Index (PLI). Comparative analysis revealed that soils within the embankment zone have higher metal concentrations, resulting from the continuous deposition of alluvial material, which often contains industrial and municipal pollutants. The vertical distribution of pollutants in fluvisols was shown to be closely related to sediment dynamics and soil properties (clay fraction, organic matter, redox conditions). Validation of the indicators revealed their varying sensitivity. The study revealed the limitations of the PLI, which, due to its summary nature, did not account for significant variability in contamination within the soil profile. Consequently, the PI, PIN, and RI indices were shown to be the most effective tools in assessing the actual degree of soil contamination by fluvisols in the middle Oder Valley. The study results emphasise the need for the selective selection of indicators in environmental monitoring. This comparative approach provides a reliable method for assessing the effectiveness of floodplain management strategies under exposure to chemical pressure. Full article

Humus substances are an important part of stable soil organic matter, which is also influenced by the soil tillage system, particularly indirectly through the mechanisms of stabilisation. This study evaluated relationships within the humus substances–cations–soil texture system and differences between invasive and non-invasive tillage systems in four soils. The influence of exchangeable cations (K⁺, Na⁺, Ca²⁺, Mg²⁺, Fe³⁺, Al³⁺) and particle size distribution (sand, silt, clay) on quantity (humic and fulvic acids) and quality (ratio of HA/FA, degree of humification, colour coefficients) of humus substances was studied. In reduced tillage, the humus substances interacted mainly with iron and aluminium. Higher humus substance contents were associated with higher K⁺; the influence of Ca²⁺ was greater in coarse-grain soils (Haplic Chernozem, Eutric Regosol); and Al³⁺ was positively correlated with humic acids and negatively with fulvic acids. The statistical associations indicate that in conventional tillage, humus substances interacted mainly with Ca²⁺. Higher humic acid contents indicate an association pattern with higher Na⁺ contents; the relationship of Ca²⁺ appears more pronounced in fine-grained soils (Mollic Fluvisol, Haplic Luvisol); and Al³⁺ was positively correlated with fulvic acids and negatively with humic acids. The soil tillage system influenced the humus substances indirectly by a combination of factors—cation composition and soil texture in different ways. In reduced tillage, clay and silt were statistically associated with iron and aluminium; in conventional tillage, there were two branches: clay with divalent cations and silt with trivalent cations. The soil tillage system can modify the impact of carbonates on humus substances and thus indirectly change the character of transformation processes in the soil. Depth is very important in evaluating the influence of the soil tillage system. Full article

Wildfires are increasing in frequency and severity across Mediterranean ecosystems. However, the immediate soil biogeochemical responses that determine shortly post-fire resilience remain poorly understood. This study assessed how contrasting fire severity levels influence soil physicochemical, nutrient, and biochemical properties in ecologically relevant vegetation microsites—beneath Quercus ilex L. canopy, Stipa tenacissima L. tussock, and open interspaces—in a Mediterranean holm oak woodland in central Spain. Soils were sampled early after a wildfire and analyzed for organic matter, nutrient pools, water repellency, microbial respiration, nitrogen mineralization, and enzyme activities. Fire severity was the dominant driver of immediate post-fire soil responses. High-severity fire reduced soil organic matter, cation exchange capacity, total C and N, nitrate, microbial respiration, and all measured enzyme activities, with the most pronounced losses occurring beneath Q. ilex canopy. In contrast, ammonium, labile phosphorus, pH and soil water repellency increased under high severity, mainly in this microsite. Low-severity fire generally preserved biological functioning, with values comparable to unburned soils. Microsite identity modulated the magnitude of fire effects, with soils beneath Q. ilex cover microsite showing the greatest sensitivity, and open interspaces the least. The microsite × severity interaction detected for key nutrients and biochemical variables suggests that high-severity fire might destroy the microsite-specific fertility islands that constitute the functional core of Mediterranean woodland soils. These findings should be considered in management strategies prioritizing their monitoring and protection. Full article

Iron (Fe) is an essential micronutrient that constrains primary productivity across approximately 50% of the global ocean, thereby regulating ocean–atmosphere carbon exchange and climate. Atmospheric deposition dominates the external supply of Fe to the open ocean, directly impacting marine biogeochemical cycles. This review systematically synthesizes current knowledge on the sources of total and soluble aerosol Fe and on the key factors and mechanisms governing Fe solubility, including proton- and ligand-promoted dissolution, photoreduction, cloud processing, and their spatiotemporal variability. We critically evaluate the methodologies used to measure Fe solubility across studies, highlighting persistent uncertainties that arise from inconsistent extraction solutions, filter pore sizes, and leaching protocols. By identifying these challenges and integrating field observations, laboratory experiments, and model results, we aim to clarify the controls on atmospheric Fe solubility and provide a more robust assessment of its contribution to marine primary productivity and biogeochemistry. Full article

The Petaquilla gold mine in Panama was abruptly closed without restoring the site. The objective of this study is to assess mine soils from a geochemical perspective, identify potential contaminants, and conduct a human health risk assessment (HHRA). Soil samples were analysed to determine pH, EC, OM, texture, hydrocarbons (TPHs), enzymatic activity (DHA), and the following potentially toxic elements (PTEs): As, Ba, Cd, Cu, Hg, Sb, Pb and Zn. The Igeo, PLI and HHRA indexes were evaluated. The Igeo indicates that the processing zone has atypical values of Cu (1.47), indicating moderate pollution (1 < Igeo ≤ 2), Zn (3.80), indicating strong pollution (3 < Igeo ≤ 4), and Pb (7.62), indicating extreme pollution (Igeo > 5), with enrichment due to mining activity. The PLI map shows that the affected areas are surrounding the Molejon River (1.62) and the processing zone (1.21), which are slightly contaminated (1 ≤ PLI < 2), and one site in the processing zone with moderate to considerable contamination (PLI ≥ 3) at the warehouse (6.07). Regarding TPHs, the processing area in front of transformer (54,844.47 mg kg⁻¹) and the workshop entrance (2045.26 mg kg⁻¹) have values above industrial use (620 mg kg⁻¹) due to visible hydrocarbon spills. In terms of HHRA, the non-carcinogenic risk associated with exposure to PTEs exceeds the reference threshold for both children and adults under a residential exposure scenario, whereas the non-carcinogenic risk for TPHs remains below the acceptable limit. Regarding carcinogenic risk, exposure to Pb and As remains within acceptable limits for both receptors. With a view to restoring the mine’s soil, the processing area and the workshop entrance are the first areas that need to be addressed. Full article

Selenium plays a crucial role in estuarine biogeochemistry, balancing essential nutrient functions with potential environmental toxicity. This study examines the seasonal distribution of dissolved Se species, including volatiles, in the Adour estuary in relation to anthropogenic influences. To characterize major Se inputs from upstream watersheds to downstream tributaries, water samples were collected at low tide during three different seasons in upstream freshwaters, industrial/urban effluents and downstream estuarine waters. A tidal-cycle sampling campaign was conducted under low discharge conditions to assess Se dynamics during downstream estuarine mixing. Total dissolved Se (TDSe) concentrations ranged from 71 (pristine river) to 656 ng L⁻¹ (industrial/urban-impacted tributaries). TDSe correlated strongly with nitrate (r = 0.84) in upstream waters, indicating significant agricultural and livestock contributions at the watershed scale. Selenate was the dominant species, followed by Se(-II+0) fraction and selenite. Volatile Se compound concentrations varied from 51 to 2757 pg L⁻¹. Seasonal changes suggest that Se speciation is mainly controlled by watershed inputs derived from land use (agricultural and livestock practices) rather than downstream estuarine inputs. This speciation study further indicates that Se reactivity/bio-availability in estuarine systems can be largely influenced by anthropogenic activities, although further characterization of the aqueous reduced Se fraction is still needed. Full article

We hypothesized that the application of digestate (D) to winter oilseed rapeseed would have the same effect on seed production as nitrogen fertilizer (N_f). It impacts yield by altering the mass of readily available N in the vegetative and reproductive periods of plant growth. This allows for a good yield forecast. This hypothesis was assessed in field experiments with rapeseed carried out in 2015/2016, 2016/2017, and 2017/2018. The experiment included three N fertilization systems (FSs): AN, based on ammonium nitrate (AN); D, with digestate-based N; DAN, using ²/₃ of digestate + ¹/₃ of AN—and five N_f doses: 0, 80, 120, 160, and 240 kg N ha⁻¹. The net seed yield increase due to N application was 1.44 t ha⁻¹ in the AN system, 1.53 t ha⁻¹ in D, and 1.77 t ha⁻¹ in DAN. The optimal N rates were 160, 250, and 224 kg N ha⁻¹. The N economy of winter oilseed rapeseed was assessed in two periods: vegetative—before anthesis (from the rosette stage to the beginning of anthesis, BBCH 30–BBCH 60) and reproductive (from the beginning of anthesis to full maturity, BBCH 60–BBCH 89). The mass of available N at the beginning of anthesis increased by 54.3% (151 kg N ha⁻¹ to 233 N ha⁻¹) and doubled (151 kg N ha⁻¹ to 302 kg N ha⁻¹) compared to its value at the rosette stage, taking into account the mass of N in the rapeseed canopy and its total mass in the soil/rapeseed continuum. No differences in NUE were found for the tested N carriers. The net increase in N available resources resulting from the application of N fertilizer was 55.1, 104.9, 102.8, and 93.0 kg N ha⁻¹ for respective plots fertilized with 60, 120, 180, and 240 kg N ha⁻¹. Three N indices were measured at the beginning of rapeseed anthesis—N in crop biomass (NAF, r = 0.87 ***), N balance (Nb60, r = 0.87 ***), and N released from soil resources (Ngain60, r = 0.79 ***)—and showed potential for seed yield (SEY) prediction. The linear dependence of SEY on these indicators indicates that the potential of the rapeseed canopy to effectively accumulate N during the vegetative growth was too low. This limitation was fully confirmed by analogous N management indicators, but developed for rapeseed during the seed-filling period. The key indicator of SEY at harvest was the N mass in rapeseed biomass (NAH, r = 0.95 ***). N from digestate acted as a slow-release fertilizer, giving it an advantage over ammonium nitrate. In summary, digestate is an optimal N carrier under conditions of average rapeseed yield. Full article

Solidago gigantea Aiton is an invasive plant species rich in bioactive secondary metabolites. The aim of this study was to characterize the phytochemical profile of an ethanolic S. gigantea extract and to evaluate its antibacterial and chemoprotective potential using in vitro models. Chemical analysis revealed a high content of phenolic compounds, dominated by chlorogenic acid, along with other phenolic acids and flavonoids, including rutin and quercitrin. The extract also contained saponins and a diverse lipophilic fraction composed of long-chain hydrocarbons, alcohols, fatty acids, phytosterols, and triterpenoids. The extract exhibited strong antibacterial activity against Gram-positive bacteria, including methicillin-resistant Staphylococcus strains, while Gram-negative bacteria and yeasts were less susceptible. In cancer cell models, the extract showed selective antiproliferative and cytotoxic effects, particularly in colorectal and breast cancer cell lines, including doxorubicin-resistant phenotypes, with minimal effects on normal fibroblasts. The extract also showed antioxidant and cytoprotective properties, reflected by a reduction in intracellular reactive oxygen species under both basal and oxidative stress conditions. Increased accumulation of rhodamine 123 in resistant cancer cells suggested a potential inhibition of P-glycoprotein-mediated efflux. Overall, the results indicate that S. gigantea extract exhibits multi-target biological activity associated with its polyphenolic composition, supporting its potential application in chemoprevention, adjuvant cancer therapy, and the control of Gram-positive bacterial infections. Full article

Ensuring the safety of sustainably managed medicinal plants is closely linked to the quality of plant raw materials, including the presence of heavy metals within safe limits. Sustainable management in the context of herbal raw materials therefore entails responsible management of herbal plant resources, integrating environmental protection with ensuring long-term economic profitability. The aim of this study was to analyze selected biochemical parameters and to determine metal concentrations in soils and leaves of Plantago lanceolata L. collected from natural habitats at increasing distances from traffic routes. The content of Zn, Cu, Ni, and Pb was determined in the soils and leaves of Plantago lanceolata L. Assessing the content of these elements in plant raw materials allows for: the prevention of harmful substances in final products, adaptation of raw materials to applicable safety standards (avoiding toxicity), and protection of consumer health. This promotes sustainable development by building a safe supply chain. The leaves of Plantago lanceolata L. were also tested for biochemical enzymatic (catalase (CAT) and superoxide dismutase (SOD)) and non-enzymatic (chlorophyll a and b (Chl a and b), carotenoids (Car), ascorbic acid (AAC)), and mechanisms regulating the activity of reactive oxygen species (ROS) were determined in the leaves of Plantago lanceolata L. Based on the results of leaf pH, relative water content (RWC), ascorbic acid content, and total chlorophyll content, the air pollution tolerance index (APTI) was calculated. The distance from the road has a significant impact on the concentration of the heavy metals analyzed. The soils were found to be free of Zn, Cu, Pb, and Ni contamination. However, analysis of Plantago lanceolata L. leaves revealed exceedances of acceptable lead limits for herbal plants. The content of pigments, the ratio of Chl a/b, and Chl (a + b)/Car in the leaves of Plantago lanceolata L. was significantly dependent on the distance from the road. The activity of CAT and SOD in the leaves of Plantago lanceolata L. growing closest to the road was significantly higher compared to the others. APTI values suggest that Plantago lanceolata L. exhibits sensitivity to pollution, independent of its distance from the emission source. Full article

Hydrochar has emerged as a promising carbonaceous amendment to enhance soil quality, yet its short-term effects on soil carbon (C) and nitrogen (N) dynamics and microbial functioning remain poorly understood. Here, a 77-day greenhouse pot experiment was conducted using a Cambisol cultivated with sunflower (Helianthus annuus L.) under two irrigation regimes simulating well-irrigated (WI) and water-deficit (WD) scenarios. Two doses of chicken-manure-derived hydrochar (3.25 and 6.5 t ha⁻¹, corresponding to 2.35 and 4.69 g kg⁻¹ of dry soil, respectively) and mineral fertilizer (MF) treatments providing equivalent N inputs were evaluated. Hydrochar promoted microbial growth and enhanced enzymatic and respiratory activities despite its low apparent C and nutrient input. After 77 days under WI, the addition of 6.5 t ha⁻¹ hydrochar enhanced the activity of phenol oxidase (POA) and acid phosphomonesterase (AcPA). Concomitantly, the availability of soluble C and N increased, whereas total organic C (TOC) and N decreased relative to the initial values. These responses may suggest enhanced mineralization potentially related to early-stage priming processes. The increase in POA relative to β-glucosidase is in line with a functional shift from a predominant degradation of labile compounds towards an increased oxidation of more complex structures. This interpretation is supported by solid-state ¹³C NMR data, revealing a higher degradation index of the soil organic matter. Under WD, the overall effects of hydrochar were attenuated or suppressed, particularly those related to C and N dynamics, emphasizing the interactive influence of moisture and amendment dose. Overall, our results show that hydrochar can modulate short-term soil biochemical processes, partly through enhanced microbial responses. Full article