Search Results (422)

This study analyzes climatological trends and variability of the main greenhouse gases (GHGs)—carbon dioxide (CO₂), methane (CH₄), and carbon monoxide (CO)—over Greece using Copernicus Atmosphere Monitoring Service (CAMS) data (EAC4 and EGG4) alongside global emission inventories and satellite-derived fluxes. A statistically significant positive long-term trend was identified for both CO₂ and CH₄. CO₂ concentrations have been increased by approximately 2 ppm/year, reaching over 415 ppm in 2020 compared to 380 ppm in 2003, following the global trends of ground-based measurements in the northern hemisphere. CH₄ showed a rapid increase since 2007, linked to anthropogenic activities, although natural sources also contribute. In contrast, CO exhibits a negative trend of about 0.6 ppb/year, with significant seasonal variability due to both anthropogenic sources and wildfires. Notably, CO concentrations increased during wildfire episodes in 2021 and 2023, with enhanced CO concentrations over 100 ± 20 ppb, well above typical summer values of 80 ± 10 ppb. Both CO₂ and CH₄ exhibit positive seasonal anomalies relative to the 2003–2013 reference period. Analysis of short- and mid-term variability reveals that CO₂ fluctuates within ±0.5%, with higher winter concentrations linked to anthropogenic emissions, while CH₄ variability reaches ±2%, reflecting diverse urban, industrial, and agricultural sources. CO exhibits the highest variability (±10–50%) due to its shorter atmospheric lifetime and sensitivity to local emissions and wildfire events. Sectoral comparisons with the Greek National Inventory Report indicate a general decline in GHG emissions in Greece, although sector-specific differences persist. Seasonal patterns show elevated fossil CO₂ emissions during colder months, CH₄ emissions peaking in agricultural seasons, and CO peaks during summer wildfires. In general, CAMS GHG emission trends fall well within the National Inventory Report of Greece. These findings emphasize the importance of combining long-term trends with short- and mid-term variability to capture both anthropogenic and natural influences on GHGs, providing a more comprehensive understanding of emission dynamics in Greece, when global warming and climate change remain an inherently challenging issue during the last decades. Full article

Background: Genome-scale metabolic models (GEMs) are foundational tools for systems biology, enabling quantitative interrogation of human metabolism across physiological and pathological states. However, many legacy reconstructions exhibit heterogeneous identifier usage, incomplete pathway integration, and limited thermodynamic refinement, constraining reproducibility, interoperability, and translational applicability. Methods: We present EHMN 2026, an update of the Edinburgh Human Metabolic Network. The reconstruction was refined through systematic identifier reconciliation using MetaNetX and ChEBI mappings, duplicate reaction consolidation, thermodynamic directionality assessment, and structured pathway annotation via Reactome. The final model was encoded in Systems Biology Markup Language (SBML) Level 3 Version 2 with the Flux Balance Constraints (FBC2) package, ensuring explicit gene–protein–reaction (GPR) representation and compatibility with modern constraint-based modelling toolchains. Results: EHMN 2026 comprises 11 compartments, 14,321 metabolites (species), and 22,642 reactions, supported by 3996 gene products. Of all reactions, 9638 (42.6%) contain GPR associations, linking metabolic transformations to 2887 unique Ensembl gene identifiers (ENSG). Pathway integration yielded 2194 unique Reactome identifiers, providing structured pathway-level organisation of metabolic functions. Thermodynamic refinement reduced infeasible energy-generating cycles and improved reaction directionality coherence while preserving global network connectivity. The reconstruction is fully SBML-compliant and portable across major modelling platforms. Compared with Recon3D and Human1, EHMN 2026 uniquely combines native Reactome reaction-level annotation, systematic MetaNetX identifier harmonisation, documented thermodynamic cycle elimination (37 cycles, 0 remaining), and an 11-compartment architecture supporting organelle-specific modelling—features designed for QSP and multi-layer integration applications. Conclusions: EHMN 2026 delivers a rigorously harmonised, thermodynamically refined, and pathway-annotated human metabolic reconstruction with enhanced annotation depth and standards-based interoperability. By combining genome-scale coverage with structured gene and pathway integration, the model establishes a robust computational backbone for reproducible metabolic analysis and provides a scalable foundation for future multi-layer systems pharmacology and integrative modelling frameworks. Full article

Conventional high-temperature calcination for activating MFI zeolite membranes is energy-intensive and prone to inducing defects. Here, we demonstrate that a rapid ozonation treatment at 200 °C for only 1 h effectively decomposes organic templates while preserving membrane integrity. The resulting membrane exhibits H₂/CH₄ and H₂/N₂ ideal selectivities of 10.3 and 6.5, respectively, at room temperature, with C₃H₈ and SF₆ permeances below the detection limit. These results confirm a dense, defect-minimized architecture and good molecular sieving performance of the zeolite membrane. In contrast, extending ozonation to 48 h leads to defect formation and a marked reduction in selectivity. For H₂/CH₄ mixture separation, the membrane achieves a selectivity of 23.8 at 100 °C, which is highly competitive among reported MFI membranes. In isopropanol dehydration, it achieves a water flux of 2.3 kg·m⁻²·h⁻¹ and a separation factor of 3278 at 70 °C with a 10 wt% water feed, while maintaining >99.5 wt% water content in the permeate over a broad operating temperature range (30–70 °C). This work establishes rapid ozonation as a scalable, energy-efficient activation method for high-performance MFI zeolite membranes in both gas and liquid separations. Full article

This paper investigates the combustion dynamics of interacting lazy multi-component gas plumes (i.e., buoyancy-dominated gas releases with a low initial momentum flux), a configuration relevant to coal mining waste emissions. By coupling a three-dimensional large eddy simulation (mesh size of 10⁻² m; paralleling with 2048 processors) with detailed chemical kinetics (GRI-Mech 3.0), we analyzed the sensitivity of the flow structure and plume stabilization to the vent spacing of twin hydrogen-rich multi-component gas plumes (H₂-CO-CH₄-air). The results identified a distinct topological transition. While gas plumes from vents spaced at $\delta /D=5$ ($\delta$ and D are the spacing and width of gas vents, respectively) evolve independently, those at closely spaced sources ($\delta /D=5/4$) exhibit rapid coalescence driven by hydrodynamic shielding. This hydrodynamic merging results in a unified column with an effective hydraulic diameter of $D_{eff}\approx \sqrt{2}D$. This leads to a significant reduction in the surface-to-volume ratio available for ambient air entrainment, maintaining a coherent combustible-rich core to higher altitudes than isolated-source correlations would predict. However, despite this mass retention, the rapid vertical acceleration of buoyancy-dominated flows induces high strain rates, significantly disrupting the reaction zone structure. These findings establish that, for clustered emission sources, the dispersion hazard is governed by a coupling between hydrodynamic coalescence, which maintains reactant concentration, and finite-rate chemistry, restricting oxidation efficiency. This paper provides critical insights for designing gas capture infrastructure and assessing flammability limits in multi-vent systems. Full article

Plant-mediated CH₄ transport can enhance ecosystem CH₄ emission by transporting soil-produced CH₄. This pathway can exceed diffusion and ebullition as the dominant CH₄ emission route. However, limited studies have investigated the morphological and anatomical factors influencing CH₄ transport in plants. Through a series of manipulative experiments on the shoots and roots, this study examines the role of root and shoot structures in CH₄ transport and release in six widespread wetland species: Carex rostrata Stokes, Carex lasiocarpa Ehrh., Carex aquatilis Wahlenb., Iris pseudacorus L., Juncus effusus L., and Alocasia odora (Lodd.) Spach. CH₄ flux from all investigated species dropped significantly after clipping fine roots, while it did not change significantly after removing coarse roots. Shoot clipping and sealing significantly decreased CH₄ flux from the investigated Carex species, but not from the other species. Our results demonstrate the important role of fine roots in controlling CH₄ flux, whereas coarse roots play a minor role. Leaf blades are the major release site of CH₄ from Carex species, while micropores at the shoot base are the primary release site of CH₄ from the other species. Our study suggests that integrating plant-specific anatomical and morphological characteristics into global methane models is crucial to better predict and mitigate climate change impacts. Full article

Land-use change contributes significantly to climate change mitigation through biophysical changes (albedo, α) and biogeochemical (greenhouse gases, GHG) emissions (here refers to methane, CH₄, and nitrous oxide, N₂O). While the impact of grassland–cropland conversion on global warming potential (GWP) is well-documented globally, research remains scarce in the saline-alkaline agropastoral transition zone (APTZ) of the western Songnen Plain, Northeast China, an ecotone uniquely characterized by soil-crusting and seasonal inundation. We conducted in situ bi-weekly measurements of N₂O and CH₄ fluxes (June–September) to acquire growing season ${\mathrm{GWP}}_{{\mathrm{N}}_2\mathrm{O}}$ and ${\mathrm{GWP}}_{{\mathrm{C}\mathrm{H}}_4}$, alongside α. The study compared an undisturbed fenced meadow (FMD) with three adjacent land-use types, clipped meadow (CMD), saline-alkaline meadow (SAL), and paddy rice field (PDY), converted from FMD from 2018 to 2022. Annual α-induced GWP (GWPΔα) was positive across all converted sites (CMD, SAL, and PDY), indicating a warming effect due to lower α compared to FMD. The PDY exhibited the highest CH₄ emission (5.04 kg CO₂ m⁻² yr⁻¹), exceeding other land uses by three orders of magnitude (p < 0.05). Conversely, N₂O emissions remained consistently minimal and stable across all sites. When integrating the net ecosystem exchange of CO₂ (NEE), the PDY functioned as a net warming source. In contrast, the warming effects of α and non-CO₂ GHGs were effectively offset by the NEE in other land uses. Machine learning identified soil water content (SWC) as the dominant predictor of α across all land uses in growing season. However, a mechanistic divergence was observed, i.e., α in low saline-alkali ecosystems (FMD, CMD and PDY) was shaped by coupled biotic and soil moisture controls, whereas in the degraded SAL ecosystem, α is almost exclusively abiotic-driven. These findings demonstrate that land-use conversion in the Songnen Plain governs complex land-surface feedbacks through distinct pathways. This study provides a quantitative framework for integrating biophysical and biogeochemical impacts to optimize land management for climate resilience in saline-alkaline agropastoral ecotones. Full article

In this study, the growth of high-quality graphite single crystals from a molten metal flux at atmospheric pressure was optimized. The crystals were precipitated from a saturated iron–carbon solution by slowly cooling (4 °C/h) from a maximum temperature to reduce the carbon solubility. The graphite flakes were >25 square millimeters in area and >10 microns thick, with individual crystal grains as large as 1.2 mm². The crystals were (0002) oriented, as determined by X-ray diffraction. The high structural quality of the graphite crystals was verified by Raman spectroscopy. For graphite with the natural distribution of carbon isotopes, the G-peak at 1580 cm⁻¹ was narrow (~12 cm⁻¹) and the defect peak (D-peak) was absent. To demonstrate the process versatility, graphite crystals enriched in the ¹³C isotope were grown at 5 degrees of enrichment. The Raman G-peak linearly shifted from 1580 cm⁻¹ to 1520 cm⁻¹ for graphite crystals enriched from 1 to 99% ¹³C. The etch pit densities from defect-sensitive etching ranged from 0 to 1.6 × 10⁸ per cm². The process was refined by examining the grain size and quality as functions of the carbon concentration in the starting sources, the carrier gas composition, and maximum temperature. The simplicity of this process suggests it can be scaled to produce very large graphite crystals that would be suitable for a wide range of technologies. Full article

In permanently submerged coastal wetlands, interactions between biogeochemical processes and microbial communities strongly influence greenhouse gas (GHG) fluxes. To improve our understanding of how redox-driven processes shape GHG dynamics in these ecosystems, we investigated the relationships among iron (Fe) pools, microbial dynamics, and the potential GHG production in subaqueous soils from an interdunal wetland in San Vitale Park (Italy), permanently submerged and affected by seasonal oscillations of the saline water table. Two subaqueous soil columns (WAS-2 and WAS-4), collected from similar settings, were analyzed. Surface layers of WAS-4 showed higher salinity and carbonate content, whereas WAS-2 was characterized by overall higher Fe concentrations. Distinct vertical distributions of organic matter and sulfur (S) were shown along depth. Laboratory incubations revealed that nitrous oxide (N₂O) production was up to ten times higher in WAS-2 than in WAS-4, with peaks in the top 13–14 cm, consistent with more active nitrification-denitrification in surface layers. Methane (CH₄) and carbon dioxide (CO₂) fluxes decreased with depth, reflecting reduced availability of labile carbon. Methanomicrobiales dominated CH₄-producing layers, indicating hydrogenotrophic methanogenesis, while amoA-carrying Nitrosomonadales and Thaumarchaeota, occurred in shallow, organic-rich layers where ammonia supported nitrification and denitrification. Denitrifiers mainly belonged to α- and β-Proteobacteria, consistent with their direct contribution to N₂O peaks. Spearman’s correlations showed N₂O positively correlated to sulfur and labile carbon (C), supporting denitrification under moderately reducing conditions. CH₄ and CO₂ positively correlated with organic C (Corg), total nitrogen (TN), and reactive Fe forms, reflecting redox-mediated microbial respiration and methanogenesis. Trace elements (B, Cr, Cu, Ni) acted as micronutrients or inhibitors depending on concentration. Canonical correspondence analysis indicated depth-structured links among gas fluxes, soil chemistry (Corg, TN, S/C, CaCO₃, P), and microbial distributions: surface layers, rich in labile C and nutrients, supported active bacteria and archaea involved in decomposition, nitrification, and denitrification, whereas deeper layers hosted oligotrophic archaea adapted to inorganic substrates. Overall, Fe pools appeared to be associated with soil processes relevant to GHG dynamics, although the extent of their regulatory role remains uncertain due to potential alterations of redox-sensitive Fe fractions during sample handling. These results contribute to broader efforts to predict GHG emissions in submerged wetland soils by linking redox stratification, inorganic chemistry, and microbial functional groups. Full article

Coastal wetlands represent significant sources of greenhouse gases (GHGs) and serve as crucial ecological interfaces between terrestrial and marine environments, substantially contributing to global biogeochemical cycles. However, GHG emission fluxes are strongly influenced by complex anthropogenic activities, yet their underlying microbial mechanisms remain poorly understood. This study investigated seven representative human-impacted sites within the Yellow River Delta. Employing a combined approach of in vitro microcosm cultivation, molecular biology, and multivariate statistical analysis, we investigated the integrated mechanisms controlling nitrous oxide (N₂O) and methane (CH₄) fluxes, with consideration of soil depth, environmental factors, microbial communities, and functional microbes. The results indicated that significant differences in GHG fluxes among different anthropogenic activities and soil depths (p < 0.05). Surface soil N₂O fluxes were positive within sewage irrigation areas (20.98–35.08 mg N₂O-N m⁻² h⁻¹) and tourism development areas (12.52–23.87 mg N₂O-N m⁻² h⁻¹), while mariculture areas displayed negative fluxes. CH₄ fluxes were positive exclusively in natural areas (surface soil: 25.02–55.54 mg CH₄-C m⁻² h⁻¹; deep soil: 8.38–356.68 mg CH₄-C m⁻² h⁻¹), while other areas predominantly showed negative values (surface soil: −130.98–44.32 mg CH₄-C m⁻² h⁻¹; deep soil: −106.16–65.24 mg CH₄-C m⁻² h⁻¹). Furthermore, a structural equations model highlighted the pivotal role of key functional microbes in soil carbon–nitrogen cycling (e.g., nirK, nosZII, and SRB) involved in soil carbon–nitrogen cycling in negatively regulating N₂O and CH₄ fluxes. The study also revealed distinct microbial responses across diverse habitats, underscoring the significant role of Proteobacteria in wetland soil. This research enhances our understanding of GHG dynamics in coastal wetlands and provides scientific evidence and potential regulatory pathways for enhancing soil biological mitigation functions and achieving carbon neutrality and sustainability within wetland ecosystems. Full article

European peatlands have been extensively drained for agriculture, resulting in substantial carbon losses and widespread soil degradation. Peatland restoration is therefore a global priority, with rewetting recognised as a key strategy for mitigating greenhouse gas emissions and climate change. This review synthesizes current knowledge on soil transformations following the rewetting of agriculturally drained peatlands in Europe. We describe major degradation processes induced by drainage, including land subsidence, organic matter oxidation, and microbial community shifts from anaerobic to aerobic conditions. We then examine key rewetting approaches—ditch blocking, controlled flooding, and paludiculture—and their intended restoration outcomes. Rewetting fundamentally alters soil physical, chemical, and biological properties by raising and stabilizing water tables, restoring anoxic conditions, and modifying nutrient cycling and microbial processes. Findings indicate long-term stabilization of organic carbon in peat soils under anaerobic conditions, but also reveal trade-offs between reduced CO₂ emissions and increased CH₄ and N₂O fluxes. Vegetation–soil interactions strongly influence recovery trajectories, and paludiculture offers potential to align agricultural land use with climate mitigation objectives. Finally, we evaluate current research methodologies and identify major knowledge gaps, including limited long-term data and insufficient integration of hydrological, chemical, and biological processes. We highlight priorities for future research to support evidence-based rewetting strategies that deliver climate benefits while maintaining ecological and economic sustainability in European peatlands. Full article

Replacing conventional chemical binders with natural polymers in geotechnically treated soil allows for the creation of more sustainable materials with both valuable ecological and mechanical properties. Xanthan gum and sodium alginate are natural polymers with excellent binding properties and water retention, which can help reduce carbon emissions. However, there is a lack of research on how to achieve optimal performance through the rational formulation of different biopolymers. This study investigates the use of these two natural biopolymers as binders (xanthan gum and sodium alginate) in slope-protection habitats treated with soil optimised using response surface methodology (RSM) within Design-Expert analysis software. The effects of xanthan gum concentration, sodium alginate concentration, and time, as well as their interactions on the properties of treated soil, ryegrass growth, and soil greenhouse gas emissions were evaluated, resulting in an optimized substrate formulation that balances good geotechnical properties with low environmental impact. Pot cultivation trials indicated that cohesion (c) and internal friction angle (φ) increased linearly with rising xanthan gum and sodium alginate concentrations, while the number of ryegrass plants (N_p) and root area ratio (RAR) decreased linearly with increasing binder concentration. Both CO₂ and CH₄ fluxes increased with rising binder concentrations. An analysis of variance (ANOVA) revealed that xanthan gum concentration had a stronger promoting effect on c and φ and a stronger inhibiting effect on N_p and RAR than sodium alginate. In contrast, sodium alginate concentration exhibited a stronger inhibitory effect on CO₂ and CH₄ fluxes. Through comprehensive optimization of geotechnical properties, vegetation growth, and greenhouse gas emissions, the optimal formulation was determined to be 0.885% for xanthan gum and 0.791% for alginate. The optimized composition resulted in increases of 38.6% and 19.1% for c and φ, respectively, while N_p and RAR increased by 7.7% and 15.0%, respectively. CO₂ and CH₄ fluxes decreased by 61.6% and 65.2%, respectively. This study contributes to advancing the sustainability of geotechnical treatments to favour vegetation regrowth. However, these materials will need to be further tested under field conditions to verify their effectiveness and duration. Full article

Agriculture is a major global source of methane (CH₄), and accurate emission estimates are essential for refining national greenhouse gas inventories and supporting climate-resilient policies. This study develops a high-resolution estimation framework for CH₄ emissions from Korean rice paddies by integrating multi-source datasets, including Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices, European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis Version 5 (ERA5)-Land meteorological variables, and Harmonized World Soil Database (HWSD) soil properties. Using CH₄ flux observations from four global rice ecosystems (Italy, Japan, South Korea, and USA), we constructed parallel daily and hourly machine learning models using an automated machine learning (AutoML) framework to compare their performance and process-level interpretability. The daily model demonstrated high predictive accuracy with correlation coefficients (CC) of 0.897 in 5-fold cross-validation and 0.819 in Leave-One-Year-Out (LOYO) cross-validation. Shapley Additive Explanations (SHAP) analysis revealed that while soil temperature is the dominant predictor for daily emissions (explaining ~50% of the variance), variable importance shifts significantly at finer resolutions. The hourly model exhibited a more complex multivariate structure. In this high-resolution context, although Normalized Difference Vegetation Index (NDVI) remains constant diurnally, its importance strengthens as a critical regulator of emission sensitivity, interacting with hourly meteorological fluctuations to capture short-term dynamics. The resulting 500 m daily gridded maps provide a robust foundation for national inventory refinement and spatially targeted mitigation planning. Our findings suggest that while the daily model offers optimal computational efficiency for long-term monitoring, the hourly model is superior for mechanistic understanding and detecting episodic emission events. This multi-resolution framework establishes an empirical basis for selecting appropriate temporal scales in operational greenhouse gas monitoring systems. Full article

Lakes are important sources of greenhouse gases (GHGs), but diurnal flux dynamics across different aquatic vegetation habitats are not well quantified, leading to uncertainties in ecosystem-scale budgets. Here, we used high-frequency monitoring (static chamber coupled with Picarro G2301) to examine diurnal CO₂ and CH₄ fluxes at the water–air interface in three habitats—submerged macrophytes (SM), emergent macrophytes (EM), and non-vegetated control (BC)—in the shallow lake (Changshu Emergency Water Source Lake). During the study period, the lake was a consistent net CO₂ sink (mean flux: −17.53 ± 1.64 μmol·m⁻²·d⁻¹) but a net CH₄ source (mean flux: 5.86 ± 1.70 μmol·m⁻²·d⁻¹). Pronounced diel variability was observed: CO₂ uptake was strongly enhanced during the day, whereas CH₄ emissions peaked at night. Vegetation type exerted a strong control on flux magnitudes, with the SM habitat showing the highest CO₂ uptake and the EM habitat the lowest CH₄ emissions. Generalized linear models (GLMs) revealed that the regulatory effects of key environmental drivers (e.g., temperature, dissolved oxygen, turbidity) on gas fluxes varied significantly by habitat type and diurnal cycle, exhibiting distinct patterns of differentiation. Our findings highlight that accurate assessment of GHG fluxes from shallow lakes—and thus reliable carbon budgeting—must explicitly account for both diurnal cycles and the distinct regulatory roles of aquatic vegetation types. Full article

Numerous studies have confirmed that macrophytes contribute to improving water quality; however, it remains uncertain whether they can enhance lake carbon sequestration. We conducted a mesocosm experiment to compare six macrophyte species categorized into three life form groups: submerged, floating-leaved and emergent. The results showed that the concentrations of total phosphorus and total organic carbon in water were significantly lower in the submerged macrophyte group than in the other groups (p < 0.05). The sediment total phosphorus and sediment total carbon in the emergent macrophyte group were lower than those in the other groups. Plant tissue phosphorus in the submerged macrophyte group was significantly higher, while plant tissue carbon was significantly lower than in the other macrophyte groups (p < 0.05). Although the emergent macrophyte group released the highest CH₄ flux, it absorbed the most CO₂, resulting in a significantly lower CO₂-equivalent flux. Submerged macrophytes had a higher specific leaf area but a lower leaf area index and specific root length; floating-leaved macrophytes recorded a higher root mass ratio, total biomass, and relative growth ratio; meanwhile, emergent macrophytes had a lower root mass ratio. It is therefore recommended to configure macrophyte communities differentially based on specific restoration objectives. Full article

Climate change intensifies temperature extremes and drought frequency. However, the interactive effects of warming and drought on soil carbon fluxes remain poorly understood, particularly during extreme temperature events and across plant species. We conducted a factorial experiment examining warming (+3 and +5 °C) and drought effects on soil CO₂ emissions and CH₄ uptake in one-year-old Quercus variabilis Blume and Quercus acutissima Carruth seedlings during three successive warming periods (period 1, 2–12 July; period 2, 19–30 July; and period 3, 7–18 August 2024). In both species, warming initially increased CO₂ emissions by 23%–26% and subsequently reduced them by 26%–37% during period 2 (coinciding with the rainy season), highlighting critical temperature-moisture interactions. Drought reduced CO₂ emissions by 12%–36%. CO₂ emissions were positively correlated with soil moisture (r = 0.45–0.56). In Q. variabilis, warming initially reduced CH₄ uptake at +5 °C; however, during period 3, uptake increased by 44.5% and 24.8% under +3 and +5 °C treatments, respectively, while the drought treatment reduced CH₄ uptake by 11.7%. Contrarily, Q. acutissima showed no warming or drought treatment effects. These findings demonstrate that soil carbon flux responses to extreme climate conditions exhibit nonlinearity and are affected by soil moisture and species type. Full article