Search Results (3,997)

Understanding trade-offs and synergies among ecosystem services (ESs) along environmental gradients is crucial for sustainable oasis management. This study investigated four key ESs—carbon storage (CS), habitat quality (HQ), water yield (WY), and soil conservation (SC)—in three typical oases along water–heat gradients in arid northwestern China. The InVEST model was used to quantify ESs in 1990, 2005, and 2022, and Pearson correlation, geographically weighted regression, K-means clustering, and random forest models were applied to analyze service relationships, ecosystem service bundles (ESBs), and driving factors. The results showed that CS and HQ maintained strong synergies, while the WY–SC relationship shifted from weak trade-offs under drier conditions to stronger synergies under more favorable water–heat conditions. Geographically weighted regression revealed spatial heterogeneity and directional asymmetry in ES relationships. Four ESB types were identified: ecologically fragile zones, ecological transition or buffer zones, agricultural production zones, and core ecological source zones. Driving-factor analysis indicated that vegetation-related services were mainly associated with land-cover structure and vegetation growth, whereas hydrological and erosion-related services were more closely linked to precipitation, potential evapotranspiration, temperature, and topography. These findings support differentiated oasis management through ecological restoration, development regulation, water-saving agriculture, and strict ecological protection. Full article

In the practical operation of air-source heat pump heating systems coupled with phase-change energy storage tanks, wide fluctuations in outdoor temperatures often cause issues such as excessive heating, frequent unit start–stops, and low operational efficiency. Traditional start–stop control strategies struggle to balance heating quality with system energy savings. To enhance the system’s energy efficiency across all operating conditions and improve the stability of indoor temperatures, this study introduces a straightforward and easy-to-implement return water temperature zone control strategy. Using physical reference points, a three-zone control approach for return water temperature was created, which integrates outdoor temperature feedback along with combined indoor temperature adjustments. The proposed strategy’s effectiveness was confirmed through comparative experiments that split the heating season into two parts: one employing traditional control and the other using the zone control method. The results show that, compared to empirical start–stop control, the segmented control strategy increased the system’s average coefficient of performance (COP) from 3.06 to 3.11, representing a 1.63% improvement; reduced indoor temperature deviation from 1.4 °C to 1.2 °C, a 14.2% decrease; and narrowed the amplitude of extreme temperature deviations from 7.9 °C to 3.9 °C, a 50.6% reduction. Total electricity consumption for the entire heating season was approximately 4191 kWh. These findings indicate that the proposed control strategy effectively improves system energy efficiency and indoor temperature stability while meeting heating demands. It significantly suppresses excessive heating during transitional seasons and enhances heating reliability under extreme low-temperature conditions. This study involves low retrofitting costs and balances both energy-saving and comfort objectives, providing a practical, engineering-ready solution for the intelligent control of air-source heat pump heating systems. Full article

Dry direct seeding (DDS) is a water-saving and high-efficiency rice cultivation system. However, drought stress during DDS severely constrains seedling establishment. This study used the conventional rice variety Zhonghua 11 (ZH11) and the drought-tolerant hybrid Hanyou 73 to investigate the effects of exogenous silicon (Si) on seed germination and seedling growth under drought stress, and to explore the underlying mechanisms of Si-enhanced drought tolerance. Drought stress was imposed using PEG-6000 simulation and pot experiments with different soil relative water contents (60%, 45%, 25%, and 10%). Si treatment significantly alleviated simulated drought inhibition of seed germination, increasing germination percentage and index, improving seedling growth in both varieties. Under simulated DDS conditions, Si significantly improved plant height, biomass, and root development, while maintaining higher net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, transpiration rate, and chlorophyll content. Meanwhile, Si reduced oxidative damage by promoting proline accumulation, enhancing peroxidase (POD) and catalase (CAT) activities in both leaves and roots, reducing malondialdehyde (MDA) accumulation, and upregulating the expression of key drought-responsive genes (SNAC1, DREB1A, SKIPa, P5CS2). Furthermore, Si upregulated the expression of genes involved in abscisic acid (ABA) (ABA1, ABA2, MHZ5, ABI3) and jasmonic acid (JA) (AOS2, AOS3, JAR1, JAR2, MYC2, COI1a) biosynthesis and signaling. Compared with the wild-type, the ABA signaling mutant abi3 and the JA signaling mutant myc2 exhibited significantly attenuated improvement of plant growth by Si treatment. Collectively, Si enhances antioxidant capacity and osmotic adjustment, maintains photosynthetic function, and is associated with the activation of ABA and JA signaling pathways, which together alleviate the inhibition of rice seedling establishment under DDS-associated drought stress. Our findings provide a theoretical basis for the application of Si fertilizer in DDS rice production. Full article

Given the mounting pressure on agricultural water resources in China, which poses a threat to agricultural production safety, this study focuses on Hunan Province and analyzes five major crops over the period 2012–2022. Using a water footprint (WF) accounting method, it quantifies grey water from non-point source pollution and optimizes planting structures under 5%, 10%, and 15% water-saving scenarios. The results indicate that crop water footprints per unit mass follow the descending order: oilseeds, leaf tobacco, rice, fruits, and vegetables. Regarding water footprint components, green water footprint accounts for the largest proportion, playing a dominant role in crop water use, followed by grey water footprint. Blue water footprint and irrigation losses contribute the least. After optimization, under the 5% and 10% water-saving scenarios, the cultivated areas for rice, oilseeds, and leaf tobacco decreased compared to 2021, while those for vegetables and fruits increased. Under the 15% water-saving scenario, all crop planting areas were reduced relative to 2021. The optimized crop planting structure enhanced water use efficiency by 0.35%, 0.58% and 0.77%, respectively, under water-saving scenarios of 5%, 10% and 15%. These results provide a scientific basis for sustainable agricultural water management in Hunan Province. Full article

Deep excavation dewatering is an energy-intensive groundwater control process in underground engineering, especially under strong recharge and heterogeneous hydrogeological conditions. Conventional dewatering designs often rely on conservative pumping schemes to ensure the required drawdown, which may generate redundant groundwater extraction, unnecessary electricity consumption, additional carbon emissions, and excessive drawdown-induced settlement. To address this problem, this study develops a coupled improved genetic algorithm and MODFLOW optimization model, termed IGA-M, for dewatering well-group operation under engineering safety constraints. The purpose of the proposed model is not to reduce pumping arbitrarily, but to identify and eliminate redundant pumping while satisfying prescribed requirements for target water levels, settlement control, and hydraulic-gradient safety. Through the FloPy interface, the Improved Genetic Algorithm is dynamically linked with MODFLOW to establish a closed-loop simulation-optimization framework. In each optimization iteration, candidate well operation schemes are automatically transferred to MODFLOW, and the simulated hydraulic heads and settlement responses are returned to evaluate the objective function and safety constraints. In this framework, groundwater extraction, electricity consumption, carbon emissions, and land subsidence are treated as physically linked performance indicators of the optimized dewatering scheme. Validation using an idealized case shows that, under the same safety requirements, the IGA-M model reduces redundant hydraulic loading compared with the traditional uniformly distributed pumping method. By removing redundant pumping beyond the safety requirement, the optimized scheme reduced groundwater extraction by 62.7%, which was accompanied by a 44.9% decrease in both carbon emissions and comprehensive costs, as well as a 57.7% reduction in settlement at observation points. In a practical high-permeability deep excavation adjacent to the Yellow River, the model achieved well-group flow regulation under strong recharge conditions. Compared with the traditional scheme, it eliminated approximately 661,000 m³ of redundant groundwater extraction, corresponding to a 17.7% decrease, and consequently saved 26,800 kWh of electricity and reduced CO₂ emissions by nearly 16,000 kg during the dewatering period. These results demonstrate that the proposed IGA-M framework can transform MODFLOW from a post-design verification tool into an active optimization engine for dewatering design. It provides a physically based decision-support method for reducing redundant pumping and improving energy efficiency while maintaining engineering safety. Full article

Seasonal thermal stratification in deep reservoirs easily causes bottom hypoxia and a sharp decrease in oxidation–reduction potential (ORP), leading to the pulsed release of internal phosphorus from sediments. Under climate warming, this has become a hot issue for sustainable reservoir eutrophication control. Taking the Quanmin Reservoir in Southwest China as the research object, this study combined high-resolution profile monitoring and a Box–Behnken response surface experiment to construct a semi-empirical model coupling redox threshold effect and Arrhenius kinetics. Results showed that during thermal stratification, the water body below 18 m formed a significant redox gradient, resulting in a 21-fold vertical difference in phosphorus concentration. The response surface experiment confirmed that ORP dominates phosphorus release, and the temperature (T) effect is strictly redox-dependent: warming only promotes phosphorus release under anaerobic conditions (−50 mV), with a 26% increase in release amount when temperature rises from 10 °C to 30 °C, while temperature has a negligible effect under aerobic conditions (+30 mV). Model fitting yielded an ORP critical threshold of −17.2 ± 4.8 mV and a normalized steepness of 0.033 mV⁻¹, indicating joint control by diffusion and reaction. Based on these results, a synergistic regulatory mechanism of redox threshold and temperature was proposed, providing a quantitative basis for reservoir eutrophication management under climate warming. Maintaining ORP above −17 mV through bottom aeration can effectively block internal phosphorus release from the redox threshold perspective, though practical in situ application is constrained by aeration-induced water mixing and microbial variations, and such precise redox control may save energy, supporting the sustainability of reservoir ecosystems and long-term water quality security. Full article

To meet the demand for superabsorbent, long-acting water-retentive, and recyclable hydrogel materials in landscaping applications, a series of AG-PAA/DA composite hydrogels were prepared using agarose (AG) and polyacrylic acid (PAA) as the network backbone, incorporating different mass fractions (2–30%) of dopamine (DA) via free radical polymerization initiated by ultraviolet light. The effects of DA content on the chemical structure, morphology, thermal stability, mechanical properties, water retention behavior, swelling kinetics, and cyclic water absorption–desorption performance were systematically investigated. The results show that DA is successfully integrated into the AG-PAA network through hydrogen bonding, electrostatic interactions, and covalent crosslinking, forming an amorphous homogeneous system. Thermal stability increases with DA content (residual mass at 800 °C rises from 77% to 88%). Mechanical properties exhibit a trend of increasing stress but decreasing strain, with optimal toughness (~670 kJ/m³) achieved at 10 wt% DA. Water retention performance is environment-dependent: in pure water, water retention increases with higher DA content, whereas in soil the opposite trend is observed. The kinetics of swelling conform to the pseudo-second-order model. The hydrogel with 10 wt% DA exhibits an equilibrium water absorption of 50 g/g in 0.9% saline solution and 1060 g/g in deionized water, and after 20 swelling–deswelling cycles the capacity retention fluctuates by less than 5%, demonstrating excellent cyclic stability. Considering all properties, AG-PAA/DA-10 is identified as the optimal formulation. This hydrogel combines high water absorption capacity, good environmental adaptability, and recyclability, showing great promise for water-saving irrigation in landscaping. Full article

Improving the irrigation water effective utilization coefficient (IWEUC, η) is important for improving agricultural water management and reducing pressure on agricultural water resources. However, in humid agricultural regions, the main factors associated with observed IWEUC improvement remain uncertain. They could be either interannual climate variability or structural improvements in irrigation engineering and management. Using measurement data from 202 representative irrigation districts in Hunan Province, China, from 2014 to 2022, this study combined the head–tail measurement method, comparative trend analysis, and correlation analysis to distinguish climate-related variability from structural change. Province-wide η increased from 0.4884 to 0.5502, and differences among large, medium-sized, and small districts narrowed over time. Structural differences also remained evident. Pumped systems generally showed higher efficiency and faster improvement than gravity-fed systems, and medium-sized gravity-fed districts remained the main low-efficiency category. No stable significant relationships were found between η and hydrometeorological indicators, whereas water-saving investment showed a positive association with η, with the strongest positive association observed in medium-sized gravity-fed districts. These results suggest that IWEUC improvement in humid agricultural regions is more closely associated with structural modernization related to engineering investment and management improvement than with annual hydrometeorological variability. Full article

Global climate change and soil salinization pose challenges to licorice cultivation. Evaluating seed vigor based on the dynamic changes in radicle morphology is crucial for screening and cultivating licorice varieties that are tolerant to low temperatures and salts. Traditional manual measurement of licorice radicle characteristics suffers from issues such as high cost, long time consumption, and large errors. The YOLOv11 instance segmentation model in the field of deep learning offers advantages including a simple architecture, strong lightweight properties, and a unified detection-segmentation framework. Therefore, this study selected the YOLOv11 model to build a deep learning framework and used the continuous time-series crop growth vitality monitoring system to collect full-time-series images of 18 groups of licorice seeds germinating under different temperature and salt stress conditions. The YOLOv11-seg model was improved by adding a Spatial Strip Attention mechanism (SSA) to enhance the spatial correlation of radicle features, replacing ordinary convolutions with a Multi-scale Edge Detail Enhancement Module (MEEM) to optimize multi-scale feature extraction capabilities, and embedding a Normalized Weighted Distance (NWD) loss function to strengthen the segmentation ability for tiny targets. The YOLOv11-LicoSeg model was constructed for segmenting and extracting licorice radicle features and calculating root length. The experimental results showed that the mAP50 of the model’s detection reached 97.4%, mAP50–95 reached 81.7%, the mAP50 of the segmentation mask reached 97.0%, and mAP50–95 reached 78.2%. Compared with the unimproved YOLOv11-seg, the mAP50 of detection increased by 0.7%, mAP50–95 increased by 1.3%, the mAP50 of segmentation increased by 0.7%, and mAP50–95 increased by 0.8%. The linear regression coefficient between manual measurement and machine-vision measurement was 0.94218, and the goodness of fit R² was 0.94408. Using this model and the monitoring system, the morphological evolution of the licorice radicle contour characteristics over the germination time was obtained. The study indicated that the growth of licorice radicles was optimal under salt stress of 1200 µs/cm and 1800 µs/cm. YOLOv11-LicoSeg accurately segmented licorice radicles and calculated radicle length, with the performance to segment 100 licorice radicle images within 7 s. After deployment, it significantly reduced the labor cost and time consumption for acquiring licorice radicle phenotypes. In conclusion, YOLOv11-LicoSeg provides a rapid and accurate method for variety screening in licorice breeding and cultivation. Full article

Understanding the dynamics of root zone soil water content is crucial for precision irrigation scheduling in protected strawberry cultivation. The HYDRUS-3D model is capable of simulating three-dimensional water flow and root water uptake. Although the model has been tested in various settings, its validation under realistic greenhouse cultivation rack systems with direct soil moisture measurements remains limited. In this study, a HYDRUS-3D model was developed to simulate root zone soil water dynamics in a greenhouse U-shaped strawberry cultivation system under both irrigated and non-irrigated conditions, with and without plastic mulch. In the first year, the model’s accuracy was evaluated using a newly developed line-scale dielectric soil moisture sensor. The simulated volumetric soil water content showed good agreement with sensor measurements across all scenarios (R² ≥ 0.8302, RMSE ≤ 0.0309, NSE ≥ 0.5979). In the following two years, we utilized the established model to schedule irrigation and investigated its water-saving effects. Model-scheduled irrigation reduced water use by 8.45–13.36% compared with conventional irrigation scheduling. No significant differences were observed in most morphological, physiological, fruit quality, or yield indicators (p > 0.05). However, occasional improvements were detected in chlorophyll content, root activity, ascorbic acid and total soluble solids. These findings demonstrate that HYDRUS-3D effectively simulates root zone water content dynamics throughout the strawberry growth cycle and serves as a practical tool for precision soil water management in greenhouse cultivation rack systems. Full article

Water pumping systems play a critical role in various industries, including water supply, cooling, heating, and HVAC systems (Heating, Ventilation, and Air Conditioning systems), by ensuring efficient fluid transfer. In the control of pumps, Proportional–Integral–Derivative (PID) algorithms are widely employed for frequency adjustment in Variable Frequency Drives (VFDs). However, the performance of this conventional controller in nonlinear and time-variant systems, as well as its impact on energy consumption, needs further improvement. To overcome these shortcomings, this paper proposes a Modified Particle Swarm Optimization (MPSO)-based PID controller. The novelty of the proposed approach lies in the integration of a linearly decreasing inertia weight strategy with a composite objective function (Minf), which simultaneously considers multiple performance criteria, including overshoot, rise time, settling time, and the integral of absolute error. The proposed controller is experimentally compared with controllers developed using two different objective functions and conventional PSO. The results indicate that the proposed controller not only exhibits superior performance in terms of time response parameters (such as settling time, overshoot, and steady-state error) but also provides significant advantages in terms of energy savings. Full article

Water Resource Carrying Capacity (WRCC) is a crucial measure for assessing the balance between regional water availability, socioeconomic development, and ecological needs, especially in arid and semi-arid regions. This study evaluates the spatiotemporal evolution of WRCC across 14 prefecture-level units in Gansu Province, China, from 2000 to 2023. A multi-dimensional evaluation system comprising 29 indicators across water resources, ecological environment, economy, society, and coordination subsystems was established. The Entropy Weight Method was applied to determine indicator weights and calculate a comprehensive index (CI) to quantify carrying pressure. A Random Forest model identified dominant influencing factors, and an autoregressive integrated moving average model projected trends from 2024 to 2028. The results show the provincial mean CI increased from 0.49 to 0.91, indicating intensifying pressure and a shift toward mild overload. Spatially, pressure exhibits a stable west–east gradient, with the highest levels persistently in western prefectures like Jiuquan, Jinchang, and Baiyin. In contrast, Gannan and Longnan in the south maintain lower pressure but show high interannual variability, indicating ecological sensitivity. The Random Forest model demonstrated strong performance, with training R² values exceeding 0.88 across all regions and mean absolute error mostly below 0.10. Projections suggest continued high pressure from 2024 to 2028 in the west, while central and southern regions show stable or slightly decreasing trends. These findings provide a quantitative basis for establishing differentiated, zoned water resource management and sustainable demand-side regulation strategies in water-limited regions. Full article

Combining oxygen-enriched combustion CO₂ capture technology and CO₂ hydrogenation with methanol technology, a new power–chemicals cogeneration (PCC) design is proposed for thermal power stations with CO₂ capture and utilization under the power-to-liquid concept. For material integration, CO₂ from an oxygen-enriched thermal power station and H₂ from water electrolysis using renewable power serve as raw materials for the methanol production process. O₂ from water electrolysis using renewable power is supplied to the oxygen-enriched thermal power station; thus, electricity can be saved and investment in an air separation unit can be beneficial. For energy integration, power for gas compression and heat for methanol rectification in the methanol production process are supplied by an oxygen-enriched thermal power station. The energy released from the methanol production process is fully recovered for extra power generation. Energy analysis results show that a high CO₂ capture and utilization ratio, which is defined as the ratio of the captured and utilized CO₂ to the total CO₂ generation, of 78.1% could be achieved. By integrating the system in a 600 MW thermal power station, the net power generation and methanol production of the proposed design reaches 473.1 MW and 56.1 kg/s, respectively. Economic analysis results show that the power cost is estimated to be 62.8 $/MWh, which has great market competitiveness compared to the conventional thermal power station with CO₂ capture. Due to the saved material expense and power and heat expense, the methanol cost is reduced from 1.33 $/kg to 1.20 $/kg. The H₂ expense by water electrolysis using renewable power has a decisive influence on the methanol cost. Full article

Food loss and waste (FLW) represent a significant source of resource inefficiency in water-scarce economies. This study quantifies the water footprint (WF) of FLW in Saudi Arabia using product-level blue, green, and grey WF coefficients from the Water Footprint Network database. Our analysis covers 3.997 million tons of FLW across 19 commodities grouped into cereals, fruits, vegetables, and meat. Results indicate that FLW is associated with a total blue and green WF of 7.3 billion m³, of which 2.1 billion m³ is blue water directly associated with managed water resources. The blue WF is equivalent to approximately 20% of agricultural water withdrawals and 62% of domestic water demand. Despite constituting only 13% of total FLW by mass, meat products account for 53% of the total water footprint, driven by their exceptionally high water intensity (7474 m³/ton). The consumption stage dominates water losses, contributing 56% of the total blue and green WF. Based on alternative water supply cost benchmarks, the blue WF embedded in FLW corresponds to an indicative production-cost equivalent ranging from 1.03 to 6.5 billion SAR. A 25% reduction in FLW could save over 500 million m³ of blue water annually. These findings demonstrate that FLW reduction represents an important supporting strategy for water resource management and provides a quantitative basis for prioritizing intervention across food groups and supply-chain stages. Full article

Indoor swimming pools are energy- and water-intensive facilities. Advanced technologies enable water recovery and eliminate heat consumption by recirculating water used for filter backwashing. The aim of this article is to assess the water and energy savings resulting from the use of backwash water from swimming pool filters through the implementation of a modern technological system. The results of the analyses allow for an assessment of the benefits depending on the assumptions adopted in the national regulations regarding swimming pools in two neighboring countries: Poland and the Czech Republic. The temperature of the water supply to the swimming pool system has a significant impact on heat consumption, as a 7 °C difference between water temperatures in Poland and the Czech Republic causes a 50% increase in heat consumption. The high efficiency of the recycling systems allows for water savings of up to 30 m³ per day. In the case of pools with a water temperature of 26 °C, the energy savings range from 645 to 967 GJ per year, depending on the fresh water temperature. Implementing the system has enormous benefits in the decarbonization process, reducing CO₂ emissions by 80%. Full article