Search Results (1,069)

Groundwater quality assessment in urban and peri-urban environments is often constrained by incomplete monitoring records, irregular sampling frequencies, and heterogeneous environmental datasets. The primary objective of this study is to predict the Water Quality Index (WQI) in the Attica River Basin, Greece, using advanced machine learning (ML) techniques. A groundwater quality dataset comprising 958 observations from 80 monitoring stations was analyzed using six physicochemical parameters, namely electrical conductivity, ammonium, nitrate, nitrite, chloride, and sulphate. Three modeling approaches, namely TabNet (with Winsorization), SVM, and Gradient Boosting Machines (GBM), were implemented to estimate groundwater quality conditions. To address the challenge of missing data, Multiple Imputation by Chained Equations (MICE) with Predictive Mean Matching (PMM) was implemented and systematically compared against conventional imputation approaches, including smoothed averages, interpolation, and forward-fill methods. The novelty of this study lies in the integration of open-access groundwater chemistry data, advanced multivariate imputation (MICE-PMM), and attention-based deep learning (TabNet) for groundwater quality prediction in a Mediterranean peri-urban area under data-scarce conditions. Using a multi-year groundwater monitoring dataset, the results indicate that the integrated MICE-PMM and TabNet framework achieved the highest predictive performance, with R² = 0.91, NSE = 0.91, RMSE = 52.21, and MAE = 25.68. Feature importance and sensitivity analyses identified nitrate as the dominant driver of WQI variability, highlighting the strong influence of anthropogenic nutrient loading on groundwater quality. Overall, the proposed framework provides a transferable, data-driven approach for groundwater quality prediction, environmental monitoring, and groundwater resource management in urban and peri-urban aquifer systems characterized by incomplete environmental datasets. Full article

Background and Objectives: Oxidative stress is recognized as an important contributor to heart failure (HF) pathophysiology, but the relationships of individual oxidative and antioxidant biomarkers with symptomatic severity and systolic dysfunction remain insufficiently defined. This study examined circulating oxidative and nitrosative stress markers across New York Heart Association (NYHA) classes and left ventricular ejection fraction (LVEF) categories in HF and their associations with HF severity. Materials and Methods: In this case–control study, 85 patients with HF and 33 healthy controls were included. Malondialdehyde (MDA), nitrates and nitrites (NOx), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), sulfhydryl (SH) groups, and NT-proBNP were measured. Group differences were analyzed using the Kruskal–Wallis test with post hoc comparisons. Adjusted ordinal logistic regression models examined associations with NYHA class and LVEF category, and receiver operating characteristic (ROC) analysis evaluated discriminatory performance. Results: Compared with controls, all biomarkers differed significantly across NYHA classes and LVEF categories (all p < 0.001). In separate adjusted models, higher NOx, MDA, and NT-proBNP were associated with worse NYHA class and more impaired LVEF, whereas higher antioxidant marker levels were associated with lower odds of severe HF. In combined models, NOx remained independently associated with worse NYHA class (OR 1.07, 95% CI 1.04–1.11; p < 0.001), while MDA remained independently associated with more impaired LVEF (OR 1.02, 95% CI 1.00–1.03; p = 0.022). NT-proBNP showed the best discrimination for NYHA III/IV versus I/II (AUC 0.966), while among oxidative biomarkers NOx performed best for symptomatic severity (AUC 0.782) and MDA for LVEF ≤ 40% (AUC 0.751). Conclusions: HF is characterized by increased oxidative and nitrosative stress together with reduced antioxidant defense. NOx appears more closely related to symptomatic severity, whereas MDA appears more closely related to systolic dysfunction. However, NT-proBNP remained the strongest overall discriminator. NOx and MDA may provide complementary mechanistic information on redox imbalance across HF severity categories. Full article

A binder-free Co₃O₄ nanoneedle electrode grown directly on nickel foam (Co₃O₄@NF) was fabricated by hydrothermal synthesis followed by calcination and evaluated for electrocatalytic nitrate reduction to ammonium. The integrated three-dimensional architecture combines the catalytic activity of Co₃O₄ with the high conductivity and open porosity of nickel foam, thus exposing abundant active sites, shortening electron-transfer pathways, and facilitating mass transport. Among the electrodes prepared at different calcination temperatures, Co₃O₄@NF calcined at 400 °C delivered the best performance. Under the optimal conditions of −1.4 V vs. Ag/AgCl, pH 7, and an initial NO₃⁻-N concentration of 50 mg L⁻¹, the electrode achieved 83.4% nitrate removal within 480 min together with 98.7% ammonium selectivity. Electrochemical measurements revealed a markedly enlarged electrochemically active surface area and reduced charge-transfer resistance after Co₃O₄ loading. Mechanistic analyses via TBA quenching experiments and DFT calculations revealed that both the direct pathway and the hydrogen-assisted indirect pathway were operative, with the indirect pathway being dominant due to its lower free energy barrier while maintaining negligible nitrite accumulation. The electrode also showed good cycling stability and retained high ammonium selectivity in real water matrices. These results demonstrate that binder-free Co₃O₄ nanoneedles supported on nickel foam constitute a promising cathode architecture for coupling nitrate removal with ammonia recovery. Full article

Continuous cropping and long-term excessively using nitrogen fertilizers in facilities vegetables has led to the imbalance of nitrogen conversion in soil and plants. A pot experiment was conducted to investigate the effects of biochar on soil and plant nitrogen transformation in cucumber under simulated different nitrogen contents in facility cultivation. Eight pot treatments: no nitrogen (N0), 100 kg·hm⁻² of nitrogen (N100), 150 kg·hm⁻² of nitrogen (N150), 200 kg·hm⁻² of nitrogen (N200), and which with the addition of 5% biochar named BN0, BN100, BN150, BN200. The results showed that BN100 (100 kg·hm⁻² N + 5% biochar) significantly increased the soil nitrogen transformation and the growth of cucumber. Specifically, the nitrate reductase, GOGAT activity, and the nitrate nitrogen absorption of cucumber roots were enhanced. It also elevated soil pH by 0.43 units and increased urease, neutral protease, nitrite reductase (NIR, and NR activities by 136.63%, 23.95%, 18.4%, and 12.1%, respectively. The relative abundance of nitrogen metabolism-related microorganisms such as Nitrospira and Sphingomonas were increased. The nitrification, nitrogen fixation, the contents of nitrate nitrogen and nitrite nitrogen in soil were increased. These changes collectively improved soil nitrogen transformation and ultimately promoted cucumber plant growth. This study reveals the potential role of biochar in regulating soil nitrogen transformation and facilitating plant growth. Full article

The exposome concept combines classic risk factors for cardiovascular disease with new, non-classical factors. One of the main non-classical factors is environmental pollution, including water pollution. This pollution is widespread worldwide. Based on government reports on water pollution in Poland and Uzbekistan and the available literature, the authors point to health problems affecting residents of both countries. The presented tabulation of cardiovascular disease incidence rates indicates an upward trend. It was found that the components of water pollution and the mechanisms by which this pollution affects the cardiovascular system are similar in both countries. These include heavy metals, arsenic, cadmium, lead, mercury, as well as nitrogen compounds from soil and microplastics. This article is an observational report and represents an important step towards understanding the relationship between water pollution and the cardiovascular system. Due to the lack of comprehensive knowledge, particularly regarding the impact of microplastics, nitrates, and nitrites found in water on the cardiovascular system, further research in this area is necessary. Full article

Plasma-assisted nitrogen fixation has emerged as a promising strategy for sustainable nitrate production. However, the coexistence of multiple interfaces and complex multi-step reaction pathways within the plasma-liquid system often leads to the formation of mixed nitrogen species, posing a significant challenge for achieving high product selectivity. In this study, a dual-cell reactor was introduced in liquid-phase plasma (LPP) system, enabling selective product distribution. Optical emission spectroscopy revealed pronounced signals corresponding to the second positive system (SPS) of N₂ and the first negative system (FNS) of N₂⁺, indicative of strong plasma excitation and ionization processes that facilitated the formation of reactive nitrogen oxide intermediates. These species were subsequently converted into aqueous NO₂⁻ and further oxidized into NO₃⁻ only in the reaction cell where reactive species are generated. The effects of key parameters, including electrode material, treatment time, solution pH, and discharge conditions, were comprehensively evaluated. As a result, the reaction cell achieved a nitrate selectivity of 98.9%, whereas the absorption cell achieved a nitrite selectivity of 100%. Findings from EPR and scavenger analyses collectively provide a detailed mechanistic understanding of LPP-driven nitrogen fixation and highlight the importance of controlling plasma parameters to achieve highly selective production of nitrogen compounds. Full article

Ammonium nitrogen pollution presents a significant challenge in wastewater treatment. Traditional activated sludge processes often suffer from limitations such as low efficiency and high energy consumption when treating high-ammonium nitrogen wastewater. This study utilized previously screened high-efficiency heterotrophic nitrification aerobic denitrification (HN-AD) bacterial strains (Pseudomonas alcaliphila and Paracoccus versutus) synergistically with microalgae to construct an immobilized bacteria algae symbiotic system (IBAS). The nitrogen removal performance and microbial community response of the system were investigated under different nitrogen sources, carbon to nitrogen (C/N) ratios, and light intensities. Results demonstrated that the system achieved a removal rate of over 95% for nitrite and nitrate. Under conditions of C/N = 15 and high light intensity (335.36 μmol/(m² · s)), the removal rates of NH₄⁺-N, TN, and COD exceeded 90% without nitrite accumulation. Microbial community analysis revealed that high C/N conditions significantly enriched HN-AD functional bacteria (such as Acinetobacter) in the Pseudomonadota phylum and Gammaproteobacteria class. High light intensity promoted the proliferation of microalgae (Chlorella and Halochlorella), enhanced algal bacterial interaction, and improved system stability. This study elucidated the nitrogen removal mechanism of the IBAS under multi-factor regulation, providing a theoretical foundation and demonstrating application potential for low-carbon and high-efficiency wastewater treatment technologies. Full article

Introduction: Spontaneous and recurrent epileptic seizures cause neuroinflammation, whereas the chronic administration of antiepileptic drugs may lead to hepatotoxicity and nephrotoxicity. Investigating natural compounds such as naringenin, which exhibits antioxidant, anti-inflammatory, and neuroprotective properties, could mitigate these toxic effects. However, whether naringenin delays seizure onset through anti-inflammatory mechanisms remains unclear. Objective: We evaluated the anticonvulsant effect of subchronic naringenin administration and its impact on inflammatory biomarkers in rats. Methods: Thirty-two male Wistar rats were divided into four groups (n = 8 each): vehicle (10% DMSO), naringenin (50 mg/kg), naringenin (100 mg/kg), and diazepam (4 mg/kg). Treatments were administered once daily for ten days through the intraperitoneal route. On day 11, status epilepticus (SE) was induced via the lithium-pilocarpine model. One hour after SE onset, cardiac blood was collected, and the serum was analyzed via ELISA to quantify the following inflammatory markers: superoxide dismutase (SOD), C-reactive protein (CRP), carbonyl protein, and nitrite/nitrate. Results: We found that 100 mg/kg naringenin increased the latency to SE and the first generalized seizure and shortened the duration of generalized seizures. Fifty percent of the rats in the 100 mg/kg naringenin group did not develop SE. The group treated with 100 mg/kg naringenin demonstrated reduced levels of CRP, protein carbonyls, and nitrates; conversely, the inhibition of SOD activity increased. Conclusions: Naringenin exerted anticonvulsant activity associated with a reduction in oxidative stress and inflammatory plasma biomarkers, suggesting its potential utility in the future development of alternative treatments to reduce epilepsy symptoms. Full article

This study investigates the dielectric behavior and NO_x storage properties of Pt/Ba–Al₂O₃ NO_x storage materials using microwave cavity perturbation, operando DRIFTS, and impedance spectroscopy with respect to their applicability in a radio-frequency-based NO_x dosimeter-type sensor. Dielectric losses (ε″) are identified as the most sensitive indicator of NO_x storage, exhibiting a clear linear correlation with both the accumulated NO_x dose and the utilization of Ba storage sites. Approximately 35% of the available Ba sites participate in nitrite and nitrate formation, and the absolute dielectric loss response increases proportionally with the Ba content of the NOx storage catalyst. In contrast, the permittivity (ε′) shows only minor changes, which are mainly influenced by temperature. Temperature-dependent experiments reveal stable NO_x storage with negligible desorption up to 350 °C, whereas pronounced desorption processes at 400 °C significantly limit the linear dosimeter behavior. Operando DRIFTS measurements on Pt/Ba–Al₂O₃ functional films confirm temperature-dependent formation of nitrites and nitrates, with nitrates dominating the NO_x storage at elevated temperatures. Capacitance measurements show a slight increase during NO_x storage, indicating a moderate increase in permittivity. Overall, Pt/Ba–Al₂O₃ NO_x storage materials exhibit a robust, quantitatively interpretable dielectric response that is well suited for radio-frequency-based, dosimeter-type NO_x sensing. Full article

High-frequency immersed plasma discharge represents an efficient method for the generation of reactive oxygen and nitrogen species (RONS) in liquid media, leading to complex redox and oxidative processes in biologically relevant systems. Although plasma-generated reactive species in liquids have been widely investigated, it remains insufficiently understood how working-gas-dependent plasma chemistry translates into oxidative outcomes in iron-containing model systems, where plasma-derived species may interact with transition-metal redox cycling. The novelty of this study lies in the combined assessment of gas-dependent RONS accumulation, deoxyribose oxidative degradation, and plasma-induced changes in Fe(II) availability using a high-frequency immersed plasma discharge. Herein, we examined whether treatment with high-frequency immersed discharge influences the redox state of iron in a working gas-dependent manner, thereby affecting oxidative degradation in the deoxyribose model. Plasma treatment was performed under air and argon working gas conditions, and oxidative degradation was evaluated using the thiobarbituric acid reactive substances (TBA-RS) assay. In parallel, the concentrations of long-lived reactive species, including hydrogen peroxide, nitrites, and nitrates, were determined spectrophotometrically. The results demonstrated a treatment-time-dependent increase in oxidative degradation and reactive species accumulation, with more pronounced oxidative effects observed under argon plasma conditions. In the presence of ferrous ions, plasma treatment resulted in a gas-dependent effect, characterized by a synergistic enhancement of oxidative degradation under argon and a biphasic effect under air. Most notably, in Fe(II)-containing samples, 10 min of argon plasma treatment increased TBA-RS formation to approximately 2.7-fold of the Fe(II) control, whereas air plasma produced a biphasic response, with an initial decrease followed by an approximately 40% increase at the longest exposure time. Additional experiments suggest that plasma may influence the redox state and availability of ferrous ions, thereby affecting their participation in Fenton-type reactions and radical-mediated processes. The findings suggest that the overall oxidative outcome in plasma-treated systems is governed not only by the concentration of plasma-generated reactive species but also by plasma-induced modifications of transition metal redox chemistry. These preliminary results on the combined roles of plasma-generated reactive species and transition-metal chemistry contribute to understanding plasma–liquid interactions in such systems. Full article

To address the issues of high water exchange rates and significant negative environmental impacts associated with eel aquaculture, this study explored the use of yellow clay as a carrier for nitrifying bacterial communities. By pre-enhancing the nitrification capacity of the yellow clay, we aimed to improve the control of inorganic nitrogen in the aquaculture water. Three experimental groups were established: NF-YCA (nitrifying-functional yellow clay-added eel aquaculture system); NN-YCA (non-nitrifying yellow clay-added eel aquaculture system); and YC-F (yellow clay-free eel aquaculture system, blank control). The NF-YCA group had zero water exchange, while the YC-F and NN-YCA groups underwent water exchange equivalent to 28.36 times the system volume. Nitrification was most pronounced in the NF-YCA group, where both mean and peak concentrations of total ammonia nitrogen and nitrite nitrogen were lower than in the YC-F and NN-YCA groups, whereas nitrate nitrogen concentrations in the NF-YCA group were significantly higher than in the other two groups. No significant differences were observed in the survival rate and specific growth rate of elvers among the three systems during the experiment. High-throughput sequencing results revealed that Pseudomonadota and Bacteroidota were the most dominant phyla across all systems. However, the bacterial community structure in NF-YCA was more abundant and stable, and nitrification-related genera, such as Nitrosomonas, were detected in high abundance in this system. The preliminary results demonstrate that the eel aquaculture system with enhanced yellow clay nitrification function, can effectively maintain water quality without water exchange, highlighting its potential for practical application. Full article

Wildfires severely disrupt soil nitrogen (N) cycling, yet the mechanisms driving this disruption in fragile karst forest ecosystems remain poorly understood. We investigated how wildfires affect soil N transformation dynamics and the microclimatic drivers of these dynamics in a karst forest. Using an in situ paired burned versus unburned plot design, we evaluated post-fire soil physicochemical properties, N fractions, and N-acquiring enzyme activities in the 0–10 cm soil layer. Wildfires significantly deteriorated the soil microenvironment, increasing mean soil temperature by 9.93% and bulk density by 36.66%, while sharply reducing soil water content, porosity, and saturated hydraulic conductivity. Consequently, the fires severely depleted total and organic soil N pools. Furthermore, N-acquiring enzymes (urease, protease, nitrate reductase, and nitrite reductase) initially declined in activity before gradually recovering. Notably, partial least squares structural equation modeling (PLS-SEM) revealed a fundamental shift in the drivers of nitrogen transformation. In unburned soil, abiotic climatic factors regulated N dynamics. After wildfire, enzyme-mediated biological processes controlled N dynamics, and these processes were constrained by altered soil physics. Restoring soil physical structure and stimulating enzymatic mineralization are therefore critical, rate-limiting steps for the recovery of soil N reservoirs in fire-prone karst landscapes. Full article

Growing concern over synthetic nitrite in processed meat has increased interest in natural curing alternatives for clean-label meat products. This research aimed to evaluate the potential of fermented radish and beetroot powders as natural sources of nitrite and bioactive compounds for preserving and improving the quality attributes of beef burgers during refrigerated storage. Burgers were formulated with different levels (3% and 6%) of fermented radish (R3 and R6) and beetroot (B3 and B6) and compared with negative (no additive) and positive (sodium nitrite) controls during 14 days of refrigerated storage, with physicochemical, color, oxidative, microbial, and sensory properties evaluated throughout storage. At day 7, radish and beetroot treatments improved color attributes, reduced lipid oxidation, and controlled microbial growth compared with the negative control. Among the natural treatments, R3 showed the best overall performance, with marked phenolic enrichment, high sensory scores, improved color properties, reduced lipid oxidation, enhanced DPPH radical scavenging activity, and more controlled microbial growth. Radish and beetroot treatments showed performance close to that of the positive control across most evaluated parameters, while showing higher cooking yield, higher phenolic content, greater DPPH radical scavenging activity, better consumer sensory acceptance, and lower diameter shrinkage than the positive control. Overall, the results support the potential of radish and beetroot fermented powders, especially R3, as promising clean-label alternatives for enhancing the quality and storage stability of raw beef burgers. Full article

Understanding how external nitrogen sources regulate nitrogen fate in river water is critical for improving nitrogen removal and reducing greenhouse-gas risk. Here, short-term microcosm incubations were conducted using source water as the background matrix and seven representative source inputs. By integrating hydrochemical analyses, bacterial community profiling, metagenomics, RT-qPCR, and process-rate measurements, we evaluated source-dependent shifts in nitrogen-cycling pathways. Manure-related inputs generated the highest organic and nitrogen loading, suppressed nitrification, enhanced nrfA (cytochrome c nitrite reductase) abundance and transcription, and promoted DNRA, indicating a shift toward nitrogen retention via ammonium regeneration. In contrast, sewage-related inputs maintained relatively high NO₃⁻ availability, elevated nirS (cytochrome cd1 nitrite reductase) and nosZ (nitrous oxide reductase) expression, and enhanced denitrification, but also increased N₂O production. Metagenomic, transcriptional, and rate-based evidence consistently identified 12 h as a critical window for source-dependent pathway redistribution, highlighting the importance of short-term monitoring for detecting rapid nitrogen-cycle responses following pollution inputs. These findings support source-oriented nitrogen management that considers both nitrogen loading and hydrochemical controls on nitrate fate. Full article

Aquaculture in ponds supplied by streams or rivers requires careful evaluation of key physicochemical parameters and potential pollution threats, particularly metals and microplastics. To address these challenges, this research aims to monitor daily climatic and physicochemical parameters and quantify potentially toxic metals and microplastics in the water of 19 fishponds in the SCDP Nucet, Romania, over one winter season (i.e., December 2024 to February 2025). During this season, unique hydrochemical conditions arise, such as lower temperatures, reduced light, and decreased activity, which can affect the ecological balance and fish health. Accordingly, a total of 4650 samples were collected and analyzed in terms of physicochemical parameters (i.e., alkalinity, bicarbonate, calcium ions, magnesium ions, Ca²⁺/Mg²⁺ ratio, organic matter, nitrates, nitrites, phosphates, ammonium, total hardness, resistivity, dissolved oxygen, conductivity, salinity, turbidity, free and total chlorine), metals, and microplastics. Statistical analysis revealed the influence of winter weather on water quality, highlighting links between air and water temperatures and physicochemical parameters. Furthermore, water analyses revealed notable levels of microplastics, including fibers and fragments of various colors, shapes, and sizes. Polypropylene, polyethene, and nylon were the most prevalent. While appreciable quantities of blue, green, black, and yellow fibers were found in size ranges (0.09–0.3 mm), irregular yellow fragments or translucent particles were found in sizes less than 0.5 mm. Metal (i.e., Cr, Fe, Ni, Co, Cu, Zn, Cd, and Pb) concentrations do not exceed the standard values set by national and European regulations. However, it is worth noting that microplastics can amplify or mitigate metal toxicity. The results emphasize the importance of integrated monitoring of physicochemical parameters and emerging pollutants during the cold season, thereby improving understanding of the chemical processes governing water quality in fishponds, providing scientific support for future environmental risk assessment, and promoting innovative, adaptive technologies. Full article