Search Results (3,381)

The synergistic application of biochar and straw could improve soil properties and influence soil microbial community. However, its impacts on microbial community interactions and functions within various aggregate fractions remain unclear. We conducted a three-year field trial in black soil in northeastern China, under the restoration measures of biochar application (BR, 30 t ha⁻¹ once), straw return (SR, 5 t ha⁻¹ year⁻¹), and the combination of BR and SR (BS, BR at 30 t ha⁻¹ once and SR at 5 t ha⁻¹ year⁻¹). Utilizing high-throughput sequencing, we assessed the influence of different straw-returning methods on the structure and function of microbial communities in the mega-aggregates (ME, >2 mm), macroaggregates (MA, 0.25–2 mm), and microaggregates (MI, <0.25 mm). Relative to the control (CK), the BR, SR and BS treatments significantly decreased the bacterial Shannon index, mainly dependent on ME (p < 0.05). Conversely, compared with the CK and SR treatments, both BR and BS treatments notably reduced the fungal Shannon index, largely influenced by MI (p < 0.05). Moreover, the BS treatment significantly increased the relative abundance (RA) of Mortierellomycota (p < 0.05) compared to the CK, BR and SR treatments. Meanwhile, the SR and BS treatments substantially reduced the RA of Nitrospirae (p < 0.05) in comparison to the CK and BR treatments. Furthermore, compared with the CK, the BR and SR treatments enhanced microbial network connectivity, while the BS treatment diminished it, especially in ME and MI. Concurrently, the keystone of co-occurrence networks shifted from Phycisphaeraceae, Blastocatellaceae, and Glomeraceae in the CK treatment to uncultured_bacterium_c_JG37-AG-4 and DA111 in the BS treatment. Additionally, BR and SR exhibited synergistic effects on most microbial community functions (e.g., enhanced chitinolysis and carbon fixation but reduced nitrogen-cycling functions), but they also possessed distinct differential functions. In short, the combined application of biochar and straw adversely impacted soil microbial community diversity and stability, especially in ME and MI. Full article

Microbial metabolism is intricately governed by thermodynamic constraints that dictate energetic efficiency, growth dynamics, and metabolic pathway selection. Previous research has primarily examined these principles under carbon-limited conditions, demonstrating how microbes optimize their proteomic resources to balance metabolic efficiency and growth rates. This study extends this thermodynamic framework to explore microbial metabolism under various non-carbon nutrient limitations (e.g., nitrogen, phosphorus, sulfur). By integrating literature data from a range of species, it is shown that growth under anabolic nutrient limitations consistently yields more negative Gibbs free energy ($\Delta G$) values for the net catabolic reaction (NCR) per unit of biomass than carbon-limited scenarios. The findings suggest three potentially complementary hypotheses: (1) proteome allocation hypothesis: microbes favor faster enzymes to reduce the proteome fraction used for catabolism, thus freeing proteome resources for additional nutrient transporters; (2) coupled transport contribution hypothesis: the more negative $\Delta G$ of the NCR may in part stem from the increased reliance on ATP-coupled or energetically driven transport mechanisms for nutrient uptake under limitation; (3) bioenergetic efficiency hypothesis: microbes prefer pathways with a more negative $\Delta G$ to enhance the cellular energy status, such as membrane potentials or the ATP/ADP ratio, to support nutrient uptake under anabolic limitations. This integrative thermodynamic analysis broadens the understanding of microbial adaptation strategies and offers valuable insights for biotechnological applications in metabolic engineering and microbial process optimization. Full article

By alternately depositing hydrogen-free amorphous carbon (a-C) and hydrogenated amorphous carbon (a-C:H) nanolayers on HSLA-100 steel through arc-ion plating, multilayer diamond-like carbon (DLC) architectures were engineered, with the modulation period adjusted from 1 to 10 cycles. SEM and Raman spectroscopy served as the analytical tools for characterizing the microstructure. For assessing key functional behaviors, nanoindentation was used to test mechanical properties, dry-sliding tribometry and in-situ tribocorrosion tests targeted tribological and tribocorrosion performance, and polarization tests focused on corrosion resistance. Introducing C₂H₂ increased the sp³ fraction and hardness relative to pure a-C. The ten-period film (S5) yielded the highest H/E (0.0767) and H³/E² (0.171), reflecting the best hardness–toughness synergy. All coatings lowered the dry friction coefficient to 0.08–0.10 and cut wear by more than 1 order of magnitude versus the substrate; the ten-period film (S5) showed the minimum dry wear rate (1.39 × 10⁻⁷ mm³·N⁻¹·m⁻¹) and tribocorrosion wear rate (4.53 × 10⁻⁷ mm³·N⁻¹·m⁻¹) in 3.5 wt% NaCl. The superior performance is due to interlayer interfaces that dissipate stresses, arrest crack propagation, and block electrolyte ingress through defects. These findings indicate that the rational stacking of a-C/a-C:H significantly improves the tribological and tribocorrosion resistance of HSLA-100, providing a reliable protective approach for components used in marine services. Full article

The soil of abandoned rural residential land is often deficient in organic matter and low in nutrient content, which limits agricultural productivity. Organic carbon input (OCI) is recognized as an effective strategy to enhance soil quality, yet it remains unclear which active carbon and nitrogen fractions drive yield enhancement and how their cycles are coupled. A three-year field experiment included five treatments: an unfertilized control (CK) and four OCI levels applied at an equal total N rate of 270 kg N ha⁻¹: 0.51 t ha⁻¹ (T1), 0.77 t ha⁻¹ (T2), 1.02 t ha⁻¹ (T3), and 2.56 t ha⁻¹ (T4). Compared with CK, T1–T4 treatments significantly increased dissolved organic carbon (DOC) by 56.04–137.25%, readily oxidizable organic carbon (ROC) by 56.46–85.29%, particulate organic carbon (POC) by 35.26–50.17%, microbial biomass carbon (MBC) by 33.87–49.90%, acid-hydrolyzable ammonium nitrogen (AN) by 21.54–30.66%, acid-hydrolyzable amino sugar nitrogen (ASN) by 11.05–24.21%, acid-hydrolyzable amino acid nitrogen (AAN) by 23.56–31.92%, and rice yield by 44.50–69.56%. Overall, among T1–T4 treatments, T2 and T3 treatments performed best in improving soil fertility and rice yield in the current study. Structural equation modeling (SEM) analysis indicated that ROC significantly influenced total hydrolyzable nitrogen (THN), which in turn was the main direct determinant of rice yield. Collectively, these findings demonstrate that a medium OCI rate (0.77–1.02 t ha⁻¹ in the current study) at 270 kg N ha⁻¹ delivers the most balanced improvement in soil C-N cycling and yield formation, providing a sound theoretical and practical basis for optimizing organic fertilization strategies in abandoned rural residential land soil. Full article

This study investigates the transformation behavior of advanced high-strength dual-phase (DP) steel subjected to thermal cycling, aiming to support improved automotive steel-processing technologies in terms of properties, cost, and speed. The heat treatment applied consisted of 1–7 cycles through the intercritical region at a conventional heating rate. Results were compared with the conventional dual-phase steel treatment currently used in industry, as well as with variants that combine thermal cycling and fast heating, the latter offering potential for carbon-free methods. The goal is to gain a deeper understanding of the transformations that occur in the material and the potential benefits that may result. Characterization was performed using dilatometry, electron microscopy techniques, and Vickers hardness testing. Findings show the initial ferrite–martensite microstructure remained largely unchanged after cycling, though preferential austenite nucleation within ferrite and Mn segregation remained. The resulting microstructure consisted of ferrite, bainite, martensite, and retained austenite. Crystallographic orientation analysis revealed texture memory effects, with preferred orientations persisting after multiple cycles. Grain refinement occurred mainly in transformed zones, while ferrite showed slight growth with more cycles, correlating with a reduced bainite/martensite fraction. Hardness increased significantly after the first cycle but declined with subsequent cycles, reflecting a reduction in bainite/martensite fraction. It is found that when up to two cycles are used, the process can be beneficial for the steel properties; otherwise, other alternatives, such as fast heating, can be applied to optimize production. Full article

Lignocellulosic biomass—the non-edible fraction of plants composed of cellulose, hemicellulose, and lignin—is the most abundant renewable carbon resource and a key lever for shifting from fossil to bio-based production. Agro-industrial residues (straws, cobs, shells, bagasse, brewery spent grains, etc.) offer low-cost, widely available feedstocks but are difficult to process because their polymers form a tightly integrated, three-dimensional matrix. Within this matrix, lignin provides rigidity, hydrophobicity, and defense, yet its heterogeneity and recalcitrance impede saccharification and upgrading. Today, most technical lignin from pulping and emerging biorefineries is burned for energy, despite growing opportunities to valorize it directly as a macromolecule (e.g., adhesives, foams, carbon precursors, UV/antioxidant additives) or via depolymerization to low-molecular-weight aromatics for fuels and chemicals. Extraction route and severity strongly condition lignin structure linkages (coumaryl-, coniferyl-, and sinapyl-alcohol ratios), determining reactivity, solubility, and product selectivity. Advances in selective fractionation, reductive/oxidative catalysis, and hybrid chemo-biological routes are improving yields while limiting condensation. Remaining barriers include feedstock variability, solvent and catalyst recovery, hydrogen and energy intensity, and market adoption (e.g., low-emission adhesives). Elevating lignin from fuel to product within integrated biorefineries can unlock significant environmental and economic benefits. Full article

Addressing the pressing demand for biogas and landfill-gas upgrading within the global energy transition, this work strategically combines thermodynamic and kinetic separation principles to identify, from a cooperative-separation perspective, the effective pore-size range that governs carbon molecular sieve (CMS) performance. Thirty anthracite-derived CMS samples with distinct pore structures were synthesized and employed as a statistical set to link pore architecture with dynamic adsorption performance. The results clarify the effective pore-size range and mechanism for enhanced CMS selectivity: CH₄ uptake depends exclusively on ultramicropores (<10 Å), with a negligible contribution from mesopores (>20 Å), whereas CO₂ uptake is less sensitive to pore-size distribution. CO₂/CH₄ separation performance improves linearly with the volume fraction of mesopores >20 Å, defining a 20–60 Å mesopore window as optimal for cooperative CMS. Mechanistic studies show that a high mesopore fraction significantly slows CH₄ adsorption while maintaining a fast CO₂ uptake, thereby amplifying their intrinsic adsorption-rate difference. This work breaks from the conventional purely thermodynamic or kinetic sieving paradigm and offers new design criteria for CMS tailored to on-site biogas and landfill-gas purification. Full article

Understanding how organic amendments affect microbial carbon use efficiency (CUE) and necromass C (MNC) is crucial for understanding soil organic C (SOC) formation and accrual in paddy fields, but the underlying mechanisms remain largely unclear. In this study, the microbial CUE, MNC, and microbial community composition, as well as SOC fractions and chemical composition, were measured under long-term organic amendments: rice straw (RS), green manure (GM), and pig manure (PM) in paddy soils. Four treatments were included: (1) chemical fertilizers (CF); (2) CF plus RS (CF + RS); (2) CF plus GM (CF + GM); and (4) CF plus PM (CF + PM). The CUE, MNC, and microbial community were determined by ¹⁸O-H₂O incubation, amino sugars levels, and phospholipid fatty acids (PLFAs) content, respectively. Results showed that SOC, particulate organic C (POC), and mineral-associated organic C (MAOC) concentrations were significantly increased by organic amendments compared with chemical fertilization alone. The O-alkyl C decreased, but aromatic C increased with long-term organic amendments, suggesting enhanced SOC hydrophobicity. GM and PM inputs significantly enhanced microbial CUE, but straw return did not affect microbial CUE compared to CF. Microbial growth and C uptake increased by 25.2–42.4% and 19.8–30.0% under organic amendments relative with CF. Microbial respiration was increased by RS and GM amendments. Turnover time was more rapid in CF + RS and CF + GM than in CF and CF + PM. Compared to CF, organic amendments increased the MNC concentration due to the increase in microbial biomass. In addition, CF + RS and CF + GM enhanced the MNC contribution to SOC, but PM had no effect, suggesting that PM contributed more organic C from non-microbial sources. The SOC, POC, and MAOC increased with microbial CUE and MNC, indicating that microbial traits play a crucial role in SOC accrual. Higher microbial CUE and biomass explained the increased MNC accumulation under organic amendments. Our study highlights the crucial role of microbe-mediated processes in SOC accrual under long-term organic amendments in paddy soils. Our findings show that organic amendments are an effective management practice for accumulating more SOC in paddy soils. Full article

The accurate characterisation of soil spatial variability is essential for the development of site-specific and sustainable agricultural practices. This study proposes an integrated methodology for effective soil mapping in Mediterranean environments. A preliminary agronomic context assessment (climate and pedology) was followed by electromagnetic induction (EMI) surveying at 14, 7 and 3 kHz. EMI data were processed by ordinary kriging to model spatial structure; the 14 kHz conductivity map—resulting from the frequency most sensitive to topsoil characteristics—was adopted to guide subsequent analysis. Sentinel-2 imagery acquired under bare-soil conditions was screened using the Bare Soil Index (BSI) to confirm vegetation absence, then processed to derive the Clay Index (CI). Guided by the 14 kHz kriged surface, twelve sampling points were selected with ESAP to capture both homogeneous zones and areas of maximum variability. Soil was sampled at 30 cm and analysed for texture, pH, electrical conductivity (EC_e) and carbon fractions. CI correlated strongly with apparent electrical conductivity (EC_a) (R² = 0.76; r = 0.87) and showed significant relationships with clay (R² = 0.69; r = 0.83). The proposed approach provides a robust and scalable alternative to conventional soil mapping, turning routine proximal and satellite data into decision-ready layers for site-specific management. Full article

Background: This paper develops a novel, interdisciplinary framework for optimizing high-speed rail (HSR) freight logistics hubs in the Ottawa–Quebec City corridor, addressing critical gaps in geospatial mismatches, static optimization limitations, and narrow sustainability scopes found in the existing literature. Methods: The research methodology integrates a hybrid graph neural network-reinforcement learning (GNN-RL) architecture that encodes 412 nodes into a dynamic graph with adaptive edge weights, fractal accessibility (α = 1.78) derived from fractional calculus (α = 0.75) to model non-linear urban growth patterns, and a multi-criteria sustainability evaluation framework embedding shadow pricing for externalities. Methodologically, the framework is validated through global sensitivity analysis and comparative testing against classical optimization models using real-world geospatial, operational, and economic datasets from the corridor. Results: Key findings demonstrate the framework’s superiority. Empirical results show an obvious reduction in emissions and lower logistics costs compared to classical models, with Pareto-optimal hubs identified. These hubs achieve the most GDP coverage of the corridor, reconciling economic efficiency with environmental resilience and social equity. Conclusions: This research establishes a replicable methodology for mid-latitude freight corridors, advancing low-carbon logistics through the integration of GNN-RL optimization, fractal spatial analysis, and sustainability assessment—bridging economic viability, environmental decarbonization, and social equity in HSR freight network design. Full article

Hybrid Renewable Energy Systems (HRESs) are a practical solution for providing reliable, low-carbon electricity to off-grid and remote communities. This review examines the role of energy storage within HRESs by systematically comparing electrochemical, mechanical, thermal, and hydrogen-based technologies in terms of technical performance, lifecycle cost, operational constraints, and environmental impact. We synthesize findings from implemented off-grid projects across multiple countries to evaluate real-world performance metrics, including renewable fraction, expected energy not supplied (EENS), lifecycle cost, and operation & maintenance burdens. Special attention is given to the emerging role of hydrogen as a long-term and cross-sector energy carrier, addressing its technical, regulatory, and financial barriers to widespread deployment. In addition, the paper reviews real-world implementations of off-grid HRES in various countries, summarizing practical outcomes and lessons for system design and policy. The discussion also includes recent advances in metaheuristic optimization algorithms, which have improved planning efficiency, system reliability, and cost-effectiveness. By combining technological, operational, and policy perspectives, this review identifies current challenges and future directions for developing sustainable, resilient, and economically viable HRES that can accelerate equitable electrification in remote areas. Finally, the review outlines key limitations and future directions, calling for more systematic quantitative studies, long-term field validation of emerging technologies, and the development of intelligent, Artificial Intelligence (AI)-driven energy management systems within broader socio-techno-economic frameworks. Overall, this work offers concise insights to guide researchers and policymakers in advancing the practical deployment of sustainable and resilient HRES. Full article

Soil heavy metal pollution is becoming increasingly severe, while traditional remediation methods are inefficient and lack long-term stability. This study innovatively combines electrokinetic remediation (EK), microbial-induced calcium carbonate precipitation (MICP), and biochar for synergistic stabilization of contaminated soil. It evaluates the combined technology by comparing it with individual EK and MICP treatments through chemical speciation analysis and the Toxicity Characteristic Leaching Procedure (TCLP). The concentration of 1 mol/L urea–CaCl₂ was identified as optimal for microbial activity, achieving a microbial cell density (OD₆₀₀) of 1.0, a urease activity of 12 U/g, and a soil pH maintained within the range of 7.8–8.2. Corn stover biochar significantly enhanced urease activity—being 49.4% higher than that in the coconut shell biochar group and 25% higher than that in the bamboo biochar group—and increased the microbial survival rate by 25.4%. Group D1, which adopted the sequence of “EK treatment first, followed by biochar-synergized MICP treatment,” exhibited the best performance. It achieved stabilization efficiency of 51.90%, 73.40%, and 36.26% for bioavailable Cu, Cd, and Pb, respectively—all higher than those of individual EK and MICP treatments. Additionally, the residual fractions of heavy metals increased significantly, the leaching concentration of Cd in the anode region was below 1 mg/L, and energy consumption was 12.16% lower than that of the EK group. Microstructural analysis confirmed that the combined method promoted the formation of stable calcite, thereby improving soil aggregation and alleviating soil compaction. These findings collectively validate the proposed technology as a highly effective and sustainable strategy for stabilizing heavy metal-contaminated soil. Full article

The water level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR) represents a distinctive ecotone with inverted hydrological regimes, where elevation gradients play a critical role in determining the spatial distribution and stability of soil organic carbon (SOC). The objective of this study was to test whether soil particle size mediates the effects of hydrological fluctuations on SOC dynamics across elevation gradients. In this study, soils from three elevation zones (155–165 m, 165–175 m, and non-flooded zones) were collected, and bulk soil and particle-size fractions (sand, silt, and clay) were incubated for 60 days to assess SOC mineralization. The results indicated that the SOC stock in the main stream was greater at middle elevations (3.94 ± 0.26 kg·m⁻²) than at high elevations (3.20 ± 0.18 kg·m⁻²), whereas the SOC stock in the tributary was greater at high elevations (3.39 ± 0.18 kg·m⁻²). Random forest and linear regression analyses revealed that total nitrogen (TN) and sand contents were the primary factors controlling SOC. Despite its lower SOC content, the sand fraction presented significantly higher turnover rates (102.14 ± 36.13 μg CO₂-C·g⁻¹C·h⁻¹) than the finer fractions, indicating lower carbon stability. These findings suggest that hydrological fluctuations regulate SOC by altering the soil particle-size composition across elevation gradients. Full article

Soil organic carbon (SOC) and its active fractions—labile organic carbon (Lab-C), dissolved organic carbon (DOC), and microbial biomass carbon (MBC)—govern soil carbon stability and climate feedback mechanisms. To investigate the distribution patterns and regulatory mechanisms of SOC and those active fractions along elevational gradients in the riparian zone of the Three Gorges Reservoir Area (subjected to intense waterlogging stress), soil sampling and analysis were conducted across four zones of the Longtanping: below 160 m, 160–170 m, 170–180 m, and above 180 m in early September 2021. Results indicated that as elevation increases, the content of SOC and active components exhibited a unimodal distribution pattern showing initial increases followed by decreases; moreover, this pattern can be attributed to the pH-riven changes in bacterial abundance under varying inundation stress conditions. The peak values occurred at elevations of 160–170 m, with the overall distribution pattern being as follows: 160–170 m > 170–180 m > above 180 m > below 160 m. Correlation analysis revealed significant positive correlations among SOC, DOC, MBC, Lab-C, pH, TN, and bacterial abundance (p < 0.05). Lab-C demonstrated the strongest explanatory power for SOC variations, serving as a sensitive indicator of SOC turnover and persistence dynamics. This study provides critical insights into the carbon cycling mechanism and regional carbon sink assessment in reservoir riparian ecosystems. Full article

Accurate quantification of carbon dioxide (CO₂) sources and sinks is becoming a key aspect in recent carbon flux research; yet our understanding of satellite performance on regional scales remains insufficient. In this work, the column-averaged dry-air mole fraction of CO₂ retrieved from OCO-2 v11.1r and GOSAT v03.05 was evaluated against CarbonTracker (CT) using data from March 2022 to August 2023. Also, the satellite data were validated against those from the Total Carbon Column Observing Network (TCCON) for March 2022 to February 2024. Comparison with CT revealed that both satellites had a general negative bias over land and the best performance in spring. In Southern Hemisphere land regions, the satellites captured monthly variability reliably, with OCO-2 obtaining the most accurate monthly concentrations. In Northern Hemisphere land regions, CT demonstrated the best performance, although both satellites accurately quantified monthly variations in some regions. In tropical land regions, none of the satellites showed superior performance. OCO-2 data showed bias features in sub-regional areas such as East and South Asia. For ocean regions, the bias was the largest in spring. Phase offset, slight underestimation of concentrations, and seasonal biases were found over several ocean regions in OCO-2 time series, whereas GOSAT was unable to provide reasonable results. When comparing TCCON with OCO-2 and GOSAT data, we found systematic errors of −0.12 and −0.56 ppm and root mean square errors of 1.08 and 1.70 ppm, respectively, mainly contributed by topographic variation and aerosol load. The errors were the smallest in spring and larger in summer and winter. Both CT- and TCCON-based analyses indicated that current satellite products may have better performance in desert surfaces. Clouds, aerosols, and surface pressure still challenged OCO-2 retrieval, while the bias-correction process can be emphasized for GOSAT. Full article