Search Results (2,172)

Land-use carbon emissions denote the release or sequestration of greenhouse gases (e.g., CO${}_2$, N${}_2$O) resulting from human land-use activities, with land-use changes exerting a major influence on land-use carbon emissions. Revealing the coupling mechanism between land-use changes and carbon emissions is of crucial theoretical significance for achieving “dual carbon” goals and mitigating global climate change. Based on the land-use change data of Jiangxi Province, this study explored the Spatial–temporal relationship between land-use carbon emissions and land-use changes in Jiangxi Province from 2000 to 2020 using a model of land-use dynamic degrees, a model of land-use transfer matrices, and the IPCC carbon emission accounting model. In this study, the factors influencing changes in land-use carbon emissions were comprehensively analyzed using an LMDI model and the Tapio decoupling model. The results indicated that: (1) Jiangxi Province’s land-use changes show a “two-increase, four-decrease” trend, with construction land and unused land experiencing the most significant shifts, while water, grassland, cropland, and forestland changes stayed near 1%. (2) Net land-use carbon emissions exhibit a rapid then gradual increase, with higher emissions in the north/south and lower levels in central regions. While overall land-use carbon emission intensity is declining, per capita emissions continue to rise. (3) Land-use carbon emission changes are primarily driven by emission intensity, land-use structure, efficiency, and economic level. In Jiangxi, economic growth mainly increases land-use carbon emissions, while land-use efficiency enhancement counters this trend. Jiangxi Province shows weak land-use carbon emission–economic growth decoupling, with land-use carbon emissions rising more slowly than economic growth. This study not only provides a typical case analysis and methodological framework for understanding the carbon emission effects of human–land relationships in rapidly urbanizing regions but also offers a specific scientific basis and policy insights for Jiangxi Province and other similar regions to formulate differentiated territorial spatial planning, promote ecological protection and restoration, and achieve green and low-carbon development pathways under the “dual carbon” goals. Full article

Constructed wetlands (CWs) are sustainable and cost-effective systems that utilise plant–microbe interactions and natural processes for wastewater treatment. Microbial communities play a pivotal role in pollutant removal by crucial processes like nitrogen transformations, phosphorus cycling, organic matter degradation and the breakdown of emerging contaminants. Dominant phyla, such as Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes, collectively orchestrate these biogeochemical functions. Advances in molecular tools, including high-throughput sequencing and metagenomics, have revealed the diversity and functional potential of wetland microbiomes, while environmental factors, i.e., temperature, pH and hydraulic retention time, strongly influence their performance. Phosphorus removal efficiency is often lower than nitrogen, and large land requirements and long start-up times restrict broader application. Microplastic accumulation, the spread of antibiotic resistance genes and greenhouse gas emissions (methane, nitrous oxide) present additional challenges. The possible persistence of pathogenic microbes further complicates system safety. Future research should integrate engineered substrates, biochar amendments, optimised plant–microbe interactions and hybrid CW designs to enhance treatment performance and resilience in the era of climate change. By acknowledging the potential and constraints, CWs can be further developed as next-generation, nature-based solutions for sustainable water management in the years to come. Full article

As a major energy producer and consumer, China has witnessed rapid growth in carbon emissions, which are closely linked to changes in regional climate and the environment. Water, energy, and food (W-E-F) are the three most critical components of human production and daily life, and achieving the coordinated development of these three resources and connecting them with climate change through the carbon emissions generated during their utilization processes has become a key issue for realizing regional ecological sustainable development. This study constructs a dynamic two-stage network slack-based measure-data envelopment analysis (SBM-DEA) model, which integrates the water–energy–food (W-E-F) system with the climate change process to evaluate China’s comprehensive ecological efficiency from 2011 to 2022, and adopts the Dagum Gini coefficient decomposition, kernel density estimation, hierarchical clustering, and geographical detector model to analyze provincial panel data, thereby assessing efficiency patterns, regional differences, and driving mechanisms. The novelty and contributions of this study can be summarized in three aspects. First, it establishes a unified framework that incorporates the W-E-F nexus and climate change into a dynamic network SBM-DEA model, enabling a more systematic assessment of ecological efficiency. Second, it uncovers that interregional overlap effects and policy-driven factors are the dominant sources of spatial and temporal disparities in ecological efficiency. Third, it further quantifies the interactive effects among key driving factors using Geodetector, thus offering practical insights for regional coordination and policy design. The results show that China’s national ecological efficiency is at a medium level. Southern China has consistently maintained a leading position, while provinces in northwest and southwest China have remained relatively backward; the efficiency of the water–energy–food integration stage is relatively high, whereas the efficiency of the climate change stage is medium and exhibits significant temporal fluctuations. Interregional differences are the main source of efficiency gaps; ecological quality, environmental protection efforts, and population size are identified as the primary driving factors, and their interaction effects have intensified spatial heterogeneity. In addition, sub-indicator analysis reveals that the efficiency related to total wastewater, air pollutant emissions, and agricultural pollution shows good synergy, while the efficiency associated with sudden environmental change events is highly volatile and has weak correlations with other undesirable outputs. These findings deepen the understanding of the water–energy–food-climate system and provide policy implications for strengthening ecological governance and regional coordination. Full article

The electromagnetic induction (EMI) and frequency domain reflectometry (FDR) sensors, which measure the soil apparent electrical conductivity (ECa) in situ, have emerged as efficient and rapid tools for the indirect assessment of soil salinity, conventionally determined by the electrical conductivity of the saturated soil paste extract (ECe). However, the limitations of applying a single soil sensor and the ECa dependence on multiple soil properties, such as soil moisture and texture, can hinder the interpretation of ECe, whereas selecting the most appropriate set of sensors is challenging. To address these issues, this study explored the prediction ability of a noninvasive EM38-MK2 (EMI) and a capacitance dielectric WET-2 probe (FDR) in assessing topsoil salinity and texture within 0–30 cm depth across diverse soil and land-use conditions in Laconia, Greece. To this aim, multiple linear regression models of laboratory-estimated ECe and soil texture were constructed by the in situ measurements of EM38-MK2 and WET-2, and their performances were individually evaluated using statistical metrics. As was shown, in heterogeneous soils with sufficient wetness and high salinity levels, both sensors produced models with high adjusted coefficients of determination (adj. R² > 0.82) and low root mean square error (RMSE) and mean absolute error (MAE), indicating strong model fit and reliable estimations of topsoil salinity. For the EM38-MK2, model accuracy improved when clay was included in the regression, while for the WET-2, the soil pore water electrical conductivity (ECp) was the most accurate predictor. The drying soil surface was the greatest constraint to both sensors’ predictive performances, whereas in non-saline soils, the silt and sand were moderately assessed by the EM38-MK2 readings (0.49 < adj. R² < 0.51). The results revealed that a complementary use of the contemporary EM38-MK2 and the low-cost WET-2 could provide an enhanced interpretation of the soil properties in the topsoil without the need for additional data acquisition, although more dense soil measurements are recommended. Full article

This study develops a novel analytical solution for three-dimensional axisymmetric consolidation of unsaturated soils incorporating radial–vertical composite seepage mechanisms and anisotropic permeability characteristics. A groundbreaking dual orthogonal expansion framework is established, utilizing innovative Bessel–trigonometric function coupling to solve the inherently complex spatiotemporal coupled partial differential equations in cylindrical coordinate systems. The mathematical approach synergistically combines modal expansion theory with Laplace transform methodology, achieving simultaneous spatial expansion of gas–liquid two-phase pressure fields through orthogonal function series, thereby transforming the three-dimensional problem into solvable ordinary differential equations. Rigorous validation demonstrates exceptional accuracy with coefficient of determination R² exceeding 0.999 and relative errors below 2% compared to numerical simulations, confirming theoretical correctness and practical applicability. The analytical solutions reveal four critical findings with quantitative engineering implications: (1) dual-directional drainage achieves 28% higher pressure dissipation efficiency than unidirectional drainage, providing design optimization criteria for vertical drainage systems; (2) normalized matric suction variation exhibits characteristic three-stage evolution featuring rapid decline, plateau stabilization, and slow recovery phases, while water phase follows bidirectional inverted S-curve patterns, enabling accurate consolidation behavior prediction under varying saturation conditions; (3) gas-water permeability ratio k_a/k_w spanning 0.1 to 1000 produces two orders of magnitude time compression effect from 10⁻² s to 10⁻⁴ s, offering parametric design methods for construction sequence control; (4) initial pressure gradient parameters λ_a and λ_w demonstrate opposite regulatory mechanisms, where increasing λ_a retards consolidation while λ_w promotes the process, providing differentiated treatment strategies for various geological conditions. The unified framework accommodates both uniform and gradient initial pore pressure distributions, delivering theoretical support for refined embankment engineering design and construction control. Full article

Borehole sealing materials have drawn significant research attention for their applications in mine disaster prevention, efficient utilization of coalbed methane resources and green mine construction. However, it is still an enormous challenge to simultaneously achieve sealing materials with lower material consumption, lower expense, and lower labor intensity for high-performance long-term borehole sealing. Meanwhile, drilling cuttings (DC) possess large production amounts, low granularity, a large workload for cleaning out the alley, high labor intensity, and high transportation cost. Herein, a composite with universal applicability to DC has been developed, which can be combined with different DC to produce a low-cost sealing material with adjustable strength, fulfilling the sealing requirements of various boreholes. The properties of the sealing material can be adjusted as required by regulating the water/cement ratio and DC content to meet the sealing requirements of different boreholes. Consequently, the DC-derived materials, featuring adjustable strengths and lower usage, can reduce cement usage, material costs, and labor intensity dramatically, displaying great promise in high-performance borehole sealing, coalbed methane extraction and utilization, timely mining waste reutilization, gas disaster prevention, and green mine construction. Full article

The insufficient availability of safe water has emerged as a prevalent issue severely impacting public health in developing nations. Moreover, studies reporting the efficacy of treatment plants (TPs)—specifically Phragmites karka and Typha latifolia—in removing toxic elements in aquaculture wastewater are scanty. Therefore, this study is aimed at investigating the effects of hydraulic retention time (HRT), seasonal variations, and TPs on the removal efficiency of pollutants from a vertical subsurface flow constructed wetland (VSSF-CW) in Nigeria. The experiments spanned three seasons (November–December–January—NDJ; March–April–May—MAM; and July–August–September—JAS) of the year, with samples collected from the CW at 7 day intervals for analysis. The aquaculture wastewater was analyzed in the laboratory to determine its chemical and toxic compositions before and after the introduction of treatment plants. Three-way ANOVA was used to analyze the main and interactive effects between HRT, seasons, and TPs on the physicochemical properties of the CW’s effluents. The removal efficiency was determined to evaluate the performance of the constructed wetland in comparison to the treatment plants. Results showed that these constructed wetlands effectively removed contaminants, with significant differences (p < 0.05) mostly observed in the effects of treatment plant types and seasons on the chemical and heavy metal concentrations. This was further confirmed by the main effects of HRT, seasons, and treatment plant choice, which significantly (p < 0.05) influenced treatment efficiency. Removal efficiencies increased with longer HRTs, reaching peak removal efficiencies of approximately 69, 67, and 61% for Na, K, and Ca, respectively. The BOD and COD reached 85 and 90% removal efficiency, while removal efficiency of 100% was achieved for most heavy metals at 21 day retention time. In summary, the study found that TPs (Phragmites karka and Typha latifolia), HRT, and seasonal variation are important for treating integrated poultry and aquaculture wastewater in a VSSF CWs. Full article

The use of reclaimed water is crucial to prevent pollution from wastewater discharges and mitigate the water deficit faced by irrigation districts or other non-potable water users. Therefore, the zero-discharge strategy represents a significant challenge for coastal cities affected by marine pollution from effluents. In regions such as the Mediterranean arc, agricultural areas located near these cities are increasingly exposed to reduced water allocations or rising irrigation demands due to the impacts of climate change. To address this dual challenge, a circular system is proposed through the implementation of hybrid treatment technologies that enable zero wastewater discharge into the sea. This approach would contribute up to 30 hm³ of reclaimed water annually for irrigation, covering approximately 27,000 hectares of cropland in the province of Alicante. The proposed system integrates advanced techniques, such as reverse osmosis, to ensure irrigation water quality, while also considering partial blending strategies to optimize resource use. Additionally, constructed wetlands are incorporated to regulate and treat the reject streams produced by these processes, minimizing their environmental impact. This combined strategy enhances water reuse efficiency, strengthens agricultural resilience, and provides a sustainable model for managing water resources in coastal Mediterranean regions. Full article

There has been significant interest in deploying unmanned aerial vehicles (UAVs) for their ability to perform precise and rapid remote mapping and inspection of critical environmental assets for structural health monitoring. This case study investigates the use of UAV-based LiDAR and photogrammetry at Melbourne Water’s Western Treatment Plant (WTP) to routinely monitor high-density polyethylene floating covers on anaerobic lagoons. The proposed approach integrates LiDAR and photogrammetry data to enhance the accuracy and efficiency of generating digital elevation models (DEMs) and orthomosaics by leveraging the strengths of both methods. Specifically, the photogrammetric images were orthorectified onto LiDAR-derived DEMs as the projection plane to construct the corresponding orthomosaic. This method captures precise elevation points directly from LiDAR, forming a robust foundation dataset for DEM construction. This streamlines the workflow without compromising detail, as it eliminates the need for time-intensive photogrammetry processes, such as dense cloud and depth map generation. This integration accelerates dataset production by up to four times compared to photogrammetry alone, while achieving centimetre-level accuracy. The LiDAR-derived DEM achieved higher elevation accuracy with a root mean square error (RMSE) of 56.1 mm, while the photogrammetry-derived DEM achieved higher in-plane accuracy with an RMSE of up to 35.4 mm. An analysis of cover deformation revealed that the floating cover had elevated rapidly within the first two years post-installation before showing lateral displacement around the sixth year, which was also evident from a significant increase in wrinkling. This approach delivers valuable insights into cover condition that, in turn, clarifies scum accumulation and movement, thereby enhancing structural integrity management and supporting environmental sustainability at WTP by safeguarding methane-rich biogas for renewable-energy generation and controlling odours. The findings support the ongoing collaborative industry research between Monash University and Melbourne Water, aimed at achieving comprehensive structural and prognostic health assessments of these high-value assets. Full article

Against the background of global warming, the carbon emission of cities accounts for more than 70%, and its carbon sink increase and emission reduction have become the research focus. The water bodies and green spaces in the urban blue–green space have a synergistic carbon sequestration effect, but current research pays less attention to the small and medium scales. Therefore, taking the waterfront green space on both sides of Qinhuai New River in Nanjing as the research object, this paper explores the impact of the synergy between water and greenery on the carbon sequestration efficiency of green space. The study first estimates the carbon sequestration efficiency of green spaces by integrating measured Leaf Area Index (LAI) data with the mean carbon sequestration rate per unit leaf area for typical tree and shrub species. It then constructs a set of water–green spatial relationship indicators and applies a random forest regression model to identify the key factors influencing carbon sequestration efficiency. Finally, multiple scenario models are developed to simulate the effects of green spaces on CO₂ reduction, thereby validating the roles of the identified influencing factors. The study found that waterfront green spaces tended to exhibit slightly higher carbon sequestration efficiency compared with non-waterfront green spaces. The proportion of 10 m forest land area and the proportion of 10–20 m forest land area had a higher impact on the carbon sequestration capacity of waterfront green space; that is, the closer the distance between the green space and the water, the better the carbon sequestration capacity. In order to improve the carbon sequestration efficiency of the waterfront area, the green space should be arranged along the water bank as much as possible, the depth of the green space should be increased, the proportion of the forest land area should be increased, the arbor and shrub should be planted evenly, and ribbon planting should be avoided. The study confirmed the synergistic effect of water and greenery in carbon sequestration benefits, providing data support and theoretical reference for the optimization and renewal of urban waterfront green space, and contributing to the realization of urban waterfront green space planning, design, and renewal with the goal of a high carbon sink. Full article

Offshore reservoirs in the high water-cut stage present significant development challenges, including declining production, complex remaining oil distribution, and the inadequacy of conventional evaluation methods to capture intricate flow dynamics. To overcome these limitations, this study introduces a novel approach based on flow diagnostics for performance evaluation and potential adjustment. The method integrates key metrics such as time-of-flight (TOF) and the dynamic Lorenz coefficient, supported by reservoir engineering principles and numerical simulation, to construct a multi-parameter evaluation system. This system, which also incorporates injection–production communication volume and inter-well fluid allocation factors, precisely quantifies and visualizes waterflood displacement processes and sweep efficiency. Applied to the QHD32 oilfield, this framework was used to establish specific thresholds for operational adjustments. These include criteria for infill drilling (waterflooded ratio < 45%, remaining oil thickness > 6 m, TOF > 200 days), conformance control (TOF < 50 days, dynamic Lorenz coefficient > 0.5), and artificial lift optimization (remaining oil thickness ratio > 2/3, TOF > 200 days). Field validation confirmed the efficacy of this approach: an additional cumulative oil production of 165,600 m³ was achieved from infill drilling in the C29 well group, while displacement adjustments in the B03 well group increased oil production by 2.2–3.8 tons/day, demonstrating a significant enhancement in waterflooding performance. This research provides a theoretical foundation and a technical pathway for the refined development of offshore heavy oil reservoirs at the ultra-high water-cut stage, offering a robust framework for the sustainable management of analogous reservoirs worldwide. Full article

Soil erosion is an increasingly severe problem and a global focus. As one of the countries facing relatively serious soil erosion, China encounters significant ecological challenges. This study focuses on the carbon sink benefits of comprehensive soil and water conservation management in the red soil erosion area of southern China, conducting an in-depth analysis using the Ziyang small watershed in Shangyou County, Jiangxi Province, as a typical case. Research methods involved constructing an integrated monitoring approach combining basic data, measured data, and remote sensing data. Changes in soil and vegetation carbon storage in the Ziyang small watershed across different years were determined by establishing a baseline scenario and applying inverse distance spatial interpolation, quadrat calculation, feature extraction, and screening. The results indicate that from 2002 to 2023, after 21 years of continuous implementation of various soil and water conservation measures under comprehensive watershed management, the carbon storage of the Ziyang small watershed increased significantly, yielding a net carbon sink of 54,537.28 tC. Tending and Management of Coniferous and Broad-leaved Mixed Forest, Low-efficiency Forest Improvement, and Thinning and Tending contributed substantially to the carbon sink, accounting for 72.72% collectively. Furthermore, the carbon sink capacity of the small watershed exhibited spatial variation influenced by management measures: areas with high carbon density were primarily concentrated within zones of Tending and Management of Coniferous and Broad-leaved Mixed Forest, while areas with low carbon density were mainly found within zones of Bamboo Forest Tending and Reclamation. The increase in watershed carbon storage was attributed to contributions from both vegetation and soil carbon pools. Comprehensive management of soil erosion demonstrates a significant carbon accumulation effect. The annual growth rate of vegetation carbon storage was higher than that of soil carbon storage, yet the proportion of soil carbon storage increased yearly. This study provides a theoretical basis and data foundation for the comprehensive management of soil and water conservation in small watersheds in the southern red soil erosion region of China and can offer technical and methodological support for other soil and water conservation carbon sink projects in this area. Full article

The coupling of partial root-zone drying (PRD) with nitrogen forms exerts an interactive “water-promoted fertilization” effect, which enhances rice (Oryza sativa L.) growth and development, improves water use efficiency (WUE), mediates the expression of aquaporins (AQPs), and alters root water conductivity. In this study, gene cloning and CRISPR-Cas9 technologies were employed to construct overexpression and knockout vectors of the OsPIP2;1 gene, which were then transformed into rice (cv. Meixiangzhan 2). Three water treatments were set: normal irrigation (CK); partial root-zone drying (PRD); and 10% PEG-simulated water stress (PEG), combined with a nitrogen form ratio of ammonium nitrogen (NH₄⁺) to nitrate nitrogen (NO₃⁻) at 50:50 (A50/N50) for the coupled treatment of rice seedlings. The results showed that under the coupled treatment of PRD and the aforementioned nitrogen form, the expression level of the OsPIP2;1 gene in roots was upregulated by 0.62-fold on the seventh day, while its expression level in leaves was downregulated by 1.84-fold. Overexpression of OsPIP2;1 enabled Meixiangzhan 2 to maintain a higher abscisic acid (ABA) level under different water conditions, which helped rice reduce water potential and enhance water absorption. Compared with the CK treatment, overexpression of OsPIP2;1 increased the superoxide dismutase (SOD) activity of rice under PRD by 26.98%, effectively alleviating tissue damage caused by excessive accumulation of O₂⁻. The physiological and biochemical characteristics of OsPIP2;1-overexpressing rice showed correlations under PRD and A50/N50 nitrogen form conditions, with WUE exhibiting a significant positive correlation with transpiration rate, chlorophyll content, nitrogen content, and Rubisco enzyme activity. Overexpression of OsPIP2;1 could promote root growth and increase the total biomass of rice plants. The application of the OsPIP2;1 gene in rice genetic engineering modification holds great potential for improving important agricultural traits of crops. This study provides new insights into the mechanism by which the AQP family regulates water use in rice and has certain significance for exploring the role of AQP genes in rice growth and development as well as in response to water stress. Full article

Anthropogenic barriers fragment Portuguese rivers, threatening endemic freshwater fish communities. This study compiled national inventories and peer-reviewed research (2002–2024) to quantify fishway implementation, evolution and typology, while evaluating fish performance from published research. One hundred fishways built between 1950 and 2024 were recorded, half of which were constructed after the implementation of the Water Framework Directive in Portugal (29 Dec 2005), tripling the annual construction rate. Fishways were found to be associated mainly with weirs (46%) and small hydropower plants (44%), with typology being dominated by the pool-type design (67%), nature-like facilities (18%), fish locks and combined systems (6% each), fish lifts (2%) and a single eel pass. Forty scientific contributions addressed fishway effectiveness; three-quarters dealt with pool-type facilities, while 12.5% and 10% focused on nature-like fishways and lifts, respectively. Experimental and field studies highlighted species-specific hydraulic preferences, the benefits of vertical slot and multislot configurations, and the potential of retrofitting fishways with macro-rugosities (i.e., fixed structural elements placed on the bottom) to improve non-salmonid fish passage. However, low attraction efficiency, limited multi-season monitoring and risks of aiding invasive species remain a concern. Research needs are proposed, including the refinement of species-specific hydrodynamic criteria, and the development of standardized efficiency metrics and of selective passage solutions, to advance fishway performance under Mediterranean hydrological constraints. Full article

The paper explores the application of heat pipes in thermal management for efficient heat dissipation, particularly in electrical equipment with high heat loads. Heat pipes are devices that transfer heat with high efficiency through the phase transition of the working medium (e.g., water, alcohol, ammonia) between the evaporator and the condenser, while they have no moving parts and are distinguished by their simplicity of construction. Different types of heat pipes—gravity, capillary, and closed loop (thermosiphon loop)—are suitable according to specific applications and requirements for the working position, temperature range, and condensate return transport. An example of an effective application is the removal of heat from the internal winding of a static energy converter transformer, where the use of a gravity heat pipe has enabled effective cooling even through epoxy insulation and kept the winding temperature below 80 °C. Other applications include the cooling of mounting plates, power transistors, and airtight cooling of electrical enclosures with the ability to dissipate lost thermal power in the order of 102 to 103 W. A significant advantage of heat pipes is also the ability to dust-tightly seal equipment and prevent the build-up of dirt, thereby increasing the reliability of the electronics. In the field of environmental technology, systems have been designed to reduce the radiant power of fireplace inserts by up to 40%, or to divert their heat output of up to about 3 kW into hot water storage tanks, thus optimising the use of the heat produced and preventing overheating of the living space. The use of nanoparticles in the working substances (e.g., Al₂O₃ in water) makes it possible to intensify the boiling process and thus increase the heat transfer intensity by up to 30% compared to pure water. The results of the presented research confirm the versatility and high efficiency of the use of heat pipes for modern cooling requirements in electronics and environmental engineering. Full article