Search Results (28)

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

Reliable surveillance of dissolved ²²²Rn in arid-region aquifers is challenged by very low natural activity and method-dependent biases, especially humidity sensitivity in electrostatic detectors and air–water partitioning during closed-loop aeration, which can obscure true concentrations needed for defensible drinking-water baselines under preventive frameworks. This study aimed to optimize and field-validate a low-background RAD7 Big-Bottle (RAD H₂O) closed-loop protocol tailored for arid conditions and apply it in a regional survey of groundwater used for potable supply in northeastern Saudi Arabia. Groundwater from wells across the region (shallow and deep completions) was collected and analyzed using isotope-resolved alpha spectroscopy (Po-218 and Po-214 windows) with strict chamber humidity control (≤7% RH), background checks, systematic blanks, duplicates, drift control (±10%), and uncertainty propagation. Air-phase chamber counts were mandatorily converted to water-phase activity using the CAPTURE parameterized by measured loop volumes, temperature, salinity, and humidity, and agreement was evaluated using regression diagnostics and Bland–Altman analysis. The optimized method achieved sub-Bq·L⁻¹ performance, with MDL improving from ~0.1645 Bq·L⁻¹ (30 min) to ~0.0233 Bq·L⁻¹ (1500 min) and ~0.0165 Bq·L⁻¹ (3000 min), and LOQ decreasing from ~0.50 to ~0.0707 and ~0.050 Bq·L⁻¹, respectively. Raw air-phase readings systematically overestimated dissolved radon by ~26% (slope ≈ 1.26), a bias removed by the validated air → water conversion. Surveyed ²²²Rn concentrations were uniformly low (0.03–3.20 Bq·L⁻¹), far below commonly used reference values (e.g., ~11.1 and ~100 Bq·L⁻¹), with no persistent spatial hotspots and broadly overlapping shallow/deep distributions, indicating variability dominated by local lithology and fracture-controlled flow rather than depth. A tiered monitoring scheme is recommended: short screening, routine baselining at ~900–1500 min total counting, and ~3000 min for ultralow verification, providing a transferable template for sustainable baseline programs in arid aquifers. Full article

Rhizosphere hypoxia, caused by soil compaction and waterlogging, is a major constraint on agricultural productivity. It severely impairs crop growth and yield by inhibiting root aerobic respiration, disrupting energy metabolism, and altering the rhizosphere microecology. Micro-nano bubbles (MNBs) show significant potential for alleviating rhizosphere hypoxia due to their unique physicochemical properties, including large specific surface area, high oxygen dissolution efficiency, prolonged retention time, and negative surface charge. This paper systematically reviews the key characteristics of MNBs, particularly their enhanced mass transfer capacity and system stability, and outlines mainstream preparation methods such as cavitation, electrolysis, and membrane dispersion. And the multiple alleviation mechanisms of MNBs—including continuous oxygen release, improvement of soil pore structure, and regulation of rhizosphere microbial communities—are clarified. The combination of MNBs aeration and subsurface drip irrigation can increase soil aeration by 5%. When applied in soilless cultivation and conventional irrigation systems, MNBs enhance crop yield and nutrient use efficiency. For example, tomato yield can be increased by 12–44%. Furthermore, the integration of MNBs with water–fertilizer integration technology enables the synchronized supply of oxygen and nutrients, thereby optimizing the rhizosphere environment efficiently. This paper sorts out the empirical effects of MNBs in soilless cultivation and conventional irrigation, and provides directions for solving problems such as “insufficient oxygen supply to deep roots” and “reactive oxygen species (ROS) stress in sensitive crops”. Despite these significant advantages, the industrialization of MNBs still needs to overcome challenges including high equipment costs and insufficient precision in parameter control, so as to promote large-scale agricultural application and provide an innovative strategy for the management of rhizosphere hypoxia. Full article

Aiming at the defects of the low mass transfer efficiency and large floor space of the traditional ozone process, a cross-tube ozone catalytic oxidation pilot plant was designed and developed. By implementing lateral aeration and a modular series configuration, the gas–liquid mass transfer pathways were optimized, achieving a hydraulic retention time of 25 min and maintaining an ozone dosage of 43 mg/L, which significantly improved the ozone utilization efficiency. During the pilot operation in an industrial park in Suzhou, Anhui Province, the average COD removal efficiency of the device for the actual biochemical tail water (COD 82.5~29.7 mg/L) reached 35.47%, and the effluent concentration was stably lower than 50 mg/L, which meets the stricter discharge standard. The intermediate products in the system were also analyzed by liquid chromatography–mass spectrometry (LC-MS), and the key pollutants were selected for degradation path analysis. Compared to the original tower process in the park, the ozone dosage was reduced by 46%, the reaction residence time was reduced by 60%, and the cost of water treatment was reduced to 0.067 USD, which is both economical and applicable to engineering. This process provides an efficient and low-cost solution for the deep treatment of wastewater in industrial parks, and has a broad engineering application prospect. Full article

Hydroelectric power plants are widely used around the world, particularly in the countries of Central and South America. In Russia, there are more than 15 large hydroelectric power plants, which form the backbone of the country’s energy sector, providing about 20% of its energy needs. The construction and operation of these plants take a long time, and it is important to plan carefully and minimize environmental damage during their use. The most significant factors affecting the environmental condition of reservoirs is the low oxygen content and the impossibility of water self-purification due to low water turbulence in deep layers. Coastal erosion caused by large hydroelectric dams can lead to increased land and population destruction, as well as sedimentation in reservoirs. The objective of this review was to select a method that would enhance the quality of water in the reservoirs of hydroelectric power stations. The technical solution that has been proposed is the implementation of the aeration of the reservoir and the cleaning of the aquatorium from sediments, with the aim of compensating for the damage caused by the construction of the dam. Full article

Soil fertility is declining in low-input agriculture due to insufficient fertilizer application by small-scale farmers. On the other hand, concerns are rising regarding the environmental pollution of both air and water in high-input agriculture due to the excessive use of N fertilizers in short growing seasons for vegetable crops, which is directly linked to the health of human beings and environmental safety. This study aimed to determine genotypic differences in the Nitrogen Use Efficiency (NUE) levels of different leafy vegetable species (Arugula, Spinach, Cress, Parsley, and Dill) grown hydroponically under two different N rates, low N (0.3 mM) and high N (3.0 mM), and to identify the plant traits that are contributing to NUE. A nutrient solution experiment was conducted between March and April 2024 by using an aerated Deep-Water Culture (DWC) technique in a fully automated climate room with a completely randomized block design (CRBD) with three replications for five weeks. The results indicated that shoot growth, as well as root morphological and leaf physiological responses, was significantly (p < 0.001) affected by genotype, the N rate, and genotype–N rate interactions. Shoot growth in some vegetable species (Arugula, Spinach, and Cress) was significantly higher under a low N than a high N rate, illustrating that they have a great capability for NUE under low N stress conditions. Similar results were also recorded for the root growth of the N-efficient species under low N rates. The NUE levels of these species were closely associated with leaf physiological (leaf area, leaf chlorophyll index (SPAD), photosynthesis, and total leaf chlorophyll (a + b) and carotenoids) and root morphological (root length, root volume, and average root diameter) characteristics. These plant traits could be useful indicators for the selection and breeding of ‘N-efficient’ leafy vegetable species for sustainable low-input agriculture systems in the future. However, further investigation should be carried out at the field level to confirm their commercial production viability. Full article

Water quality deterioration is a major problem faced by reservoirs globally, owing to the inflow of pollution from industrial and municipal activities. Water-lifting aeration is an in situ water quality improvement technology that mixes and oxygenates deep water bodies in reservoirs to improve pollution control efficiency and water quality. While previous studies have mainly focused on the mixing process in the reservoir outside the water-lifting aerator (WLA), knowledge of the internal flow remains limited. In this study, a two-phase flow within a WLA system was numerically studied using the volume of fluid (VOF) method to comprehensively analyze the internal two-phase flow characteristics and the influence on the water-lifting and oxygenation performance of the system. The statistical analysis results showed that increasing the aeration chamber volume enhanced the bottom oxygenation performance by 27% because of the prolonged time of the deflector plate outlet outflow. Additionally, increasing the air release rate enhanced the water-lifting performance by 47%, which was induced by the shortened air piston release period. This study demonstrates the internal flow mechanism of the WLA and provides technical support for parameter optimization design, which has significant scientific research and engineering application value. Full article

Drought stress is most alarming and destructive among the abiotic stresses that increased in intensity in recent years affecting global food and nutritional security. The main resource limiting global agricultural productivity is water. The previous two decades have seen a surprising amount of study reports on genetically modifying plants to increase their ability to withstand drought, but actual progress has lagged behind expectations. Applying bioirrigation techniques in drought-prone areas might be a workable alternative strategy. It does apply to the usage of living things or biological creatures, such as potential microorganisms that can move soil moisture from a zone with enough water to plants that are drought-stressed through the modification of agricultural microclimate using agronomic strategies. Potential microorganisms include Gram+ and Gram− bacterial consortiums, as well as plant-growth-promoting rhizobacteria (PGPR). In addition to PGPR, the utilization of soil macro-fauna in agriculture, such as earthworms, lugworms, termites, etc., can be utilized and explored in the near future towards bioirrigation. Earthworms and other macro-fauna are abundant in soil, digging deep burrows in the sediment and providing aeration to the plants. PGPR evolved with plant roots to enhance plant resilience under biotic and abiotic stresses. Benthic microorganisms, which include bacteria and microalgae, for instance, have a 70–80% higher water-holding capacity. Through research findings, these benthic microorganisms can be successfully identified and used in agriculture, and they may prove to be a cutting-edge method to increase plant-water-use efficiency. Similarly, plant roots of legume plants act as bioindicators under drought-stress conditions. These new developments make a significant contribution to addressing the problems of food security that come with changing climate. This review article offers information on bioirrigation techniques, their potential, estimating techniques, etc. Overall, this article goes into detail about how bioirrigation techniques aid crop plants in overcoming drought stress. Future research should focus on creating the most appropriate and effective microbes, dealing with the problem of delivery systems, and evaluating potential organisms in the field for microbial formulations to improve plant performance under drought stress and significantly lower yield losses in drought-affected areas. Full article

Developing degradable bio-plastics has been considered feasible to lessen marine plastic pollution. However, unanimity is still elusive regarding the actual degradability of bio-plastics such as polylactide (PLA) and poly(hydroxybutyrate) (PHB). Thus, herein, we studied the degradability of fabrics made from PLA/PHB blends in marine seawater. The dry-mass percentage of the PLA/PHB fabrics decreased progressively from 100% to 85~90% after eight weeks of immersion. Two environmental aging parameters (UV irradiation and aerating) were also confirmed to accelerate the abiotic hydrolysis of the incubated fabrics. The variation in the molecular structure of the PLA/PHB polymers after the degradation process was investigated by electrospray ionization mass spectrometry (ESI-MS). However, the hydrolysis degradability of bulky PLA/PHB blends, which were used to produce such PLA/PHB fabrics, was negligible under identical conditions. There was no mass loss in these solid PLA/PHB plastics except for a decrease in their tensile strength. Finally, a deep learning artificial neural network model was proposed to model and predict the nonlinear abiotic hydrolysis behavior of PLA/PHB fabrics. The degradability of PLA/PHB fabrics in marine water under the synergistic destructive effects of seawater, UV, and dissolved oxygen provides a pathway for more sustainable textile fibers and apparel products. Full article

This is the first hydroponic study that evaluated the role of the heterotic plant characters of crossbreeding progenies and accessions which were used as rootstock for watermelon (scion) to improve the nitrogen (N) efficiency of this crop by grafting. The target of the research was to evaluate if grafting could enhance the nitrogen efficiency of watermelon through examining the responses of heterotic plant characters of crossbreeding rootstocks in the shoot development at the agronomical stage, root developments at the morphological stage, and leaf growth at various physiological stages. A hydroponic experiment was conducted by using an aerated deep-water culture (DWC) system in a well-equipped growth chamber of Erciyes University’s Plant Physiology Laboratory located at Kayseri, Türkiye. A watermelon cultivar Crimson Tide (CT) was grafted onto watermelon cultivars of Calhoun Gray (CG), Charleston Gray (Cha. G), and accessions of PI 296341 and PI 271769, the crossbreed progenies of Calhoun Gray × PI 296341, Calhoun Gray × PI 271769, and Charleston Gray × PI 296341. Plants were grown in 8 L plastic containers filled continuously with aired stock nutrient solution under two nitrogen (N) doses (low dose N: 0.3 mM unit N, and high dose N: 3.0 mM unit N) in a completely randomized block design (RBD) which was replicated three times, for six weeks. The grafted plants usually showed a higher crop growth performance than the self-grafted control plants, illustrating that nitrogen efficiency was significantly enhanced with respect to rootstocks of crossbreed progenies under a low N dose and high N dose. The N efficiency of grafted watermelon (CT) was improved by the high manifestation of heterosis in some root morphological characters (vigor root development and active root mechanism) of some of the crossbreeding rootstocks (Calhoun Gray × PI 271769) particularly in low-N conditions. Additionally, some of the crossbreeding rootstocks (Charleston Gray × PI 296341) exhibited high heterosis, which led to improving the N efficiency of grafted watermelon (CT) by inducing leaf physiological responses under high N supply. This clearly indicated that heterosis plays a crucial role in exploiting the genetic diversity in the N efficiency of watermelon. Therefore, these heterotic plant traits may be vital for the selection and breeding of nitrogen-efficient rootstocks for both small-scale and large-scale commercial farming in the nearby future. Full article

The three-phase flow in a aeration tank driven by an inverted umbrella aerator is relatively complex, including the processes of the hydraulic jump, air entrainment, and sludge particle sedimentation. A three-phase flow test bench for an inverted umbrella aerator is established for studying its influence on aeration performance. The experiment mainly studies the changed law of aeration performance under different immersion depths or sludge concentrations and measures the flow rate and sludge concentrations in the aeration tank in different working conditions. The results are as follows. (1) The total oxygen transfer coefficient, standard oxygenation capacity, and standard power efficiency increase with the increase in rotational speed. The total oxygen transfer coefficient and standard-charge oxygen capacity first increase and then decrease with the decrease in immersion depth, reaching a maximum at −20 mm immersion depth. The standard dynamic efficiency has a similar trend and reaches a maximum at −8 mm immersion depth. (2) In the aeration tank, the flow velocity near the impeller is faster and has greater turbulence. The shallow water is more profoundly affected by the impeller compared with the deeper water. (3) The shallow-water sludge varies greatly, and the deep-water sludge is distributed uniformly when the inverted umbrella aerator works stably. Full article

The entire water cycle is contaminated with largely undetected micropollutants, thus jeopardizing wastewater treatment. Currently, monitoring methods that are used by wastewater treatment plants (WWTP) are not able to detect these micropollutants, causing negative effects on aquatic ecosystems and human health. In our case study, we took collective samples around different treatment stages (aeration tank, membrane bioreactor, ozonation) of a WWTP and analyzed them via Deep-UV laser-induced Raman and fluorescence spectroscopy (LIRFS) in combination with a CNN-based AI support. This process allowed us to perform the spectra recognition of selected micropollutants and thus analyze their reliability. The results indicated that the combination of sensitive fluorescence measurements with very specific Raman measurements, supplemented with an artificial intelligence, lead to a high information gain for utilizing it as a monitoring purpose. Laser-induced Raman spectroscopy reaches detections limits of alert pharmaceuticals (carbamazepine, naproxen, tryptophan) in the range of a few µg/L; naproxen is detectable down to 1 × 10⁻⁴ mg/g. Furthermore, the monitoring of nitrate after biological treatment using Raman measurements and AI support showed a reliable assignment rate of over 95%. Applying the fluorescence technique seems to be a promising method in observing DOC changes in wastewater, leading to a correlation coefficient of R² = 0.74 for all samples throughout the purification processes. The results also showed the influence of different extraction points in a cleaning stage; therefore, it would not be sensible to investigate them separately. Nevertheless, the interpretation suffers when many substances interact with one another and influence their optical behavior. In conclusion, the results that are presented in our paper elucidate the use of LIRFS in combination with AI support for online monitoring. Full article

The environmentally friendly concept in terms of water quality represents a condition for developing hydropower plants all around the world. Since 2017, hydropower has represented more than 70% of all renewable energy production and it is essential for the integration of the other renewable sources of energy and for regulation of the grid. To maintain the “green” label concerning the dissolved oxygen level (6 mg DO/L), the energy suppliers should respond to environmental concerns about the operation of hydropower plants. In the context of sustainable development, the ecological degradation of rivers is unacceptable due to the implementation of a hydropower plant on the watercourse. For deep reservoirs or tropical regions, the oxygen level in the water downstream of the hydropower plants may be low and affect the aquatic life for many kilometers downstream. This paper presents a new aeration system for discharged water from hydropower plants that provides water aeration with minimum energy consumption. The influence of the aeration process on the turbine operation and efficiency is analyzed. Experimental measurements are carried out on site on a small Francis turbine. The influence of the aeration process on the turbine mechanical performances (vibration level and relative displacement) and hydraulic performances (turbine efficiency, power output, and pressure fluctuation) is analyzed. The results showed that the impact of the aeration device implementation and operation over the energetic characteristics of the turbine is in the efficiency measurements accuracy range. The aeration through this device did not influence the turbine operation (vibration, level, or pressure fluctuations). Full article

Zooplankton is a good indicator of water quality state. Analysing the species composition and abundance, it is possible to assess the condition of the water body and predict the direction of changes. The aim of the study was to analyse the zooplankton in a shallow urban lake, in which restoration was limited to one method, i.e., wind-aeration. The results were compared with the earlier data obtained during sustainable restoration (three methods: wind-aeration, phosphorus inactivation, biomanipulation) and before the restoration period. The zooplankton was sampled monthly in 2015 and 2016 in the deepest place of the lake from the surface to the bottom. The trophic state was determined based on rotifer trophic state index for lakes (TSI_ROT). Although the species composition of zooplankton communities varied very little among the restoration periods (Keratella cochlearis f. tecta mainly dominated), significant changes in the abundance of zooplankton were found in the analysed lake. The maximum of total abundance was noted in 2015, almost 5500 ind. L⁻¹, and in the next year its decrease was almost 3-fold, to ca. 1800 ind. L⁻¹. Based on TSI_ROT, the water was still eutrophic. Leaving only one method of restoration (namely, oxygenation of the bottom waters) proved insufficient to support the development of crucial organisms as cladocerans. The changes in the abundance could have resulted more from seasonal changes than from the effects of aeration. A reduction in species number and maintaining a high proportion of rotifers typical for a high trophic state indicated a return of the ecosystem to its pre-restoration state. High variability in the rotifer abundance indicated a continuous imbalance of the ecosystem. Previous restoration treatments using several methods simultaneously showed better effectiveness. The change of strategy of restoration before obtaining a stable improvement of water quality destroyed previously achieved effects. Full article

Hydroponic production typically uses conventional fertilizers, but information is lacking on the use of organic hydroponic fertilizers. Development of microbial communities and biofilm that can reduce dissolved oxygen availability is a difficulty with organic hydroponics. One potential solution is the use of hydrogen peroxide (H₂O₂) which can reduce microbial populations and decompose to form oxygen. However, information is lacking on the impact of hydrogen peroxide on hydroponic crop performance. The aim of this study was to determine the effects of H₂O₂ concentrations in deep water culture hydroponics by assessing how it affects plant size and yield in lettuce (Lactuca sativa L.) “Rouxai”. In this experiment, three H₂O₂ treatments, namely the application of 0, 37.5 or 75 mg/L H₂O₂ to 4 L aerated hydroponic containers with either conventional or organic fertilizer, were compared. The containers had either fish-based organic fertilizer (4-4-1, N-P₂O₅-K₂O) or inorganic mineral based conventional nutrient solution (21-5-20, N-P₂O₅-K₂O), both applied at 150 mg/L N. Three replicates of each H₂O₂ treatment–fertilizer combination were prepared resulting in a total of eighteen mini hydroponic containers each with one head of lettuce. There were two growth cycles: fall 2018 and spring 2019. When added to conventional fertilizers, both 37.5 mg/L and 75 mg/L of H₂O₂ led to stunted growth or death of lettuce plants. However, when 37.5 mg/L of H₂O₂ was applied to organic fertilizers, the lettuce yield nearly matched that of the conventionally fertilized control, demonstrating that the application of H₂O₂ has the potential to make organic hydroponic fertilization a more viable method in the future. Full article