Search Results (1,411)

In this study, we sought to improve the productivity of Far Eastern catfish (Silurus asotus) and tropical eel (Anguilla bicolor), which are high-value fish species in the Republic of Korea, as well as that of associated crops by applying biofloc technology (BFT)-based aquaponics systems. The following three systems were used: the flow-through system (FTS), BFT, and BFT aquaponics system (BAPs). Caipira lettuce (Lactuca sativa) was utilized and hydroponics (HP) was implemented to compare crop productivity. After 42 days of treatment, the BAPs and BFT systems improved fish productivity, with weight gain rates of 134.47 ± 1.80% in BAPs-cat, 130.38 ± 0.95% in BFT, and 114.21 ± 6.62% in FTS for S. asotus, and 70.61 ± 3.26% in BAPs-eel, 62.37 ± 7.04% in BFT, and 47.83 ± 1.09% in FTS for A. bicolor. During the experiment, the total ammonia nitrogen and NO₂⁻-N concentrations were stable in all plots. In the case of NO₃⁻-N, BFT showed an increasing tendency while both BAPs showed a decrease compared with that of the BFT. BAPs-cat (total weight: 224.1 ± 6.37 g) and HP (220.3 ± 7.17 g) resulted in similar growth. However, in BAPs-eel was 187.7 ± 3.46 g due to root degradation. Water content analysis showed that BAPs-cat and BAPs-eel contained sufficient K, Ca, P, and S, which are important for crop growth. Overall, the effect of BAPs on fish growth was higher than that of FTS. This study reveals that integrating BFT with aquaponics improves productivity for high-value fish and associated crops while maintaining stable water quality. This method offers sustainable, efficient production, reduces environmental impact, and provides insights for future research in sustainable aquaculture practices. Full article

Flavonoids serve as crucial plant antioxidants in drought tolerance, yet their antioxidant regulatory mechanisms within mycorrhizal plants remain unclear. In this study, using a two-factor design, trifoliate orange (Poncirus trifoliata (L.) Raf.) seedlings in the four-to-five-leaf stage were either inoculated with Funneliformis mosseae or not, and subjected to well-watered (70–75% of field maximum water-holding capacity) or drought stress (50–55% field maximum water-holding capacity) conditions for 10 weeks. Plant growth performance, photosynthetic physiology, leaf flavonoid content and their antioxidant capacity, reactive oxygen species levels, and activities and gene expression of key flavonoid biosynthesis enzymes were analyzed. Although drought stress significantly reduced root colonization and soil hyphal length, inoculation with F. mosseae consistently enhanced the biomass of leaves, stems, and roots, as well as root surface area and diameter, irrespective of soil moisture. Despite drought suppressing photosynthesis in mycorrhizal plants, F. mosseae substantially improved photosynthetic capacity (measured via gas exchange) and optimized photochemical efficiency (assessed by chlorophyll fluorescence) while reducing non-photochemical quenching (heat dissipation). Inoculation with F. mosseae elevated the total flavonoid content in leaves by 46.67% (well-watered) and 14.04% (drought), accompanied by significantly enhanced activities of key synthases such as phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), 4-coumarate:coA ligase (4CL), and cinnamate 4-hydroxylase (C4H), with increases ranging from 16.90 to 117.42% under drought. Quantitative real-time PCR revealed that both mycorrhization and drought upregulated the expression of PtPAL1, PtCHI, and Pt4CL genes, with soil moisture critically modulating mycorrhizal regulatory effects. In vitro assays showed that flavonoid extracts scavenged radicals at rates of 30.07–41.60% in hydroxyl radical (•OH), 71.89–78.06% in superoxide radical anion (O₂^•−), and 49.97–74.75% in 2,2-diphenyl-1-picrylhydrazyl (DPPH). Mycorrhizal symbiosis enhanced the antioxidant capacity of flavonoids, resulting in higher scavenging rates of •OH (19.07%), O₂^•− (5.00%), and DPPH (31.81%) under drought. Inoculated plants displayed reduced hydrogen peroxide (19.77%), O₂^•− (23.90%), and malondialdehyde (17.36%) levels. This study concludes that mycorrhizae promote the level of total flavonoids in trifoliate orange by accelerating the flavonoid biosynthesis pathway, hence reducing oxidative damage under drought. Full article

A facile way to prepare Cu(OH)₂ inorganic nanofiltration membranes with neatly arranged multilayers has been developed based on the reaction of a sodium hydroxide solution and a copper ammonia solution at the liquid–liquid interfaces. The effects of the concentration, temperature, and time of the liquid–liquid reaction on membrane structure and pore sizes were studied by SEM, TEM, and X-ray diffraction. The growth mechanism of the membrane was discussed and the formation process model was proposed. It was found that the reaction temperature was a key factor in obtaining a Cu(OH)₂ monolayer, and this could be used to adjust the thickness and pore size of the monolayer. The as-prepared Cu(OH)₂ membranes exhibited excellent filtration performance with the pure water fluxes of 156.2 L·m⁻² h⁻¹ bar⁻¹ and retention rates of 100% for methylene blue (50 ppm) at a pressure of 0.1 MPa. This successfully opens up a new method of synthesizing multilayer nanoarrays’ Cu(OH)₂ structure for nanofiltration. Full article

Effective transport strategies are critical for the survival and welfare of juvenile Ictalurus punctatus, but the effects of pre-transport salt bath treatments remain uncertain. In this study, we systematically evaluated the effects of pre-transport salt bath acclimation at 0‰ (S1), 1‰ (S2), 5‰ (S3), and 9‰ (S4) salinity for 30 min on stress resilience and recovery in fingerlings during 12 h of simulated transport and 24 h of recovery. All fish survived, but total ammonia nitrogen (TAN) increased, and pH decreased in all groups, except S3, which showed significantly lower TAN and higher pH (p < 0.05). The S3 and S4 groups showed attenuated increases in serum cortisol and glucose, with S3 exhibiting the fastest return to baseline levels and stable serum sodium and potassium levels. Liver antioxidant enzyme activities in group S3 remained stable, with the lowest malondialdehyde (MDA) accumulation. Integrated biomarker response (IBR) and histological analyses demonstrated that S3 had the lowest systemic stress and tissue damage, whereas S1 and S4 displayed marked cellular disruption. These results indicate that a 5‰ salt bath applied prior to transport may improve water quality, mitigate stress responses, and preserve tissue integrity in juvenile channel catfish. Further studies are needed to confirm these findings in other species and under commercial transport conditions. Full article

In recent years, Ga-based liquid metals have emerged as a prominent research focus in catalysis, owing to their unique properties, including fluidity, low melting point, high thermal and electrical conductivity, and tunable surface characteristics. This review summarizes the synthesis strategies for Ga-based liquid metal catalysts, with a focus on recent advances in their applications across electrocatalysis, thermal catalysis, photocatalysis, and related fields. In electrocatalysis, these catalysts exhibit potential for reactions such as electrocatalytic CO₂ reduction, electrocatalytic ammonia synthesis, electrocatalytic hydrogen production, and the electrocatalytic oxidation of alcohols. As to thermal catalysis, these catalysts are employed in processes such as alkane dehydrogenation, selective hydrogenation, thermocatalytic CO₂ reduction, thermocatalytic ammonia synthesis, and thermocatalytic plastic degradation. In photocatalysis, they can be used in other photocatalytic reactions such as organic matter degradation and overall water splitting. Furthermore, Ga-based liquid metal catalysts also exhibit distinct advantages in catalytic reactions within battery systems and mechano-driven catalysis, offering innovative concepts and technical pathways for developing novel catalytic systems. Finally, this review discusses the current challenges and future prospects in Ga-based liquid metal catalysis. Full article

This study aims to select the most suitable submerged plants for the remediation and ecological rehabilitation of nutrient-enriched aquatic environments. The experiment selected Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii as research objects. An artificial outdoor pot experiment was conducted with six different levels of ammonia nitrogen: 2, 4, 6, 8, 12, and 16 mg/L. The present study measured the physiological and growth parameters of submerged macrophytes under varying ammonia nitrogen concentrations. The response characteristics of plants to ammonia nitrogen stress were analyzed, and the tolerance thresholds of different submerged macrophyte species to ammonia nitrogen were determined. This enabled us to screen for ammonia nitrogen-tolerant pioneer species suitable for water ecological restoration in eutrophic water bodies. The experiment spanned 28 days. The results showed that the maximum suitable concentration and maximum tolerance concentration of ammonia nitrogen for Vallisneria natans, Myriophyllum verticillatum, and Elodea nuttallii were 2, 4, and 4 mg/L and 4, 12, and 8 mg/L. Submerged plants can grow normally within their maximum ammonia nitrogen tolerance concentration. When the concentration exceeds the maximum tolerance level, the growth of submerged plants is severely stressed by ammonia nitrogen. Low ammonia nitrogen concentrations promote the growth of submerged macrophyte biomass and chlorophyll content as well as the accumulation of dry matter in plants, while high ammonia nitrogen concentrations damage the antioxidant enzyme system and inhibit the growth of submerged plants. The tolerance of the three submerged macrophytes to ammonia nitrogen is as follows: Myriophyllum verticillatum > Elodea nuttallii > Vallisneria natans. Therefore, Myriophyllum verticillatum should be chosen as the ammonia nitrogen-tolerant pioneer species in the ecological restoration of eutrophic water bodies. The research results can provide a theoretical basis for the application of aquatic macrophytes in the treatment of eutrophic water bodies and ecological restoration. Full article

Pyrochar has been identified as a favorable soil conditioner that can effectively ameliorate soil acidification. Hydrochar is considered a more affordable carbon material than pyrochar, but its effect on the process of soil acidification has yet to be investigated. An indoor incubation and a soil column experiment were conducted to study the effect of rice straw hydrochar application on nitrification and NO₃⁻-N leaching in acidic red soil. Compared to the control and pyrochar treatments, respectively, hydrochar addition mitigated the net nitrification rate by 3.75–48.75% and 57.92–78.19%, in the early stage of urea fertilization. This occurred mainly because a greater amount of dissolved organic carbon (DOC) was released from hydrochar than the other treatments, which stimulated microbial nitrogen immobilization. The abundances of ammonia-oxidizing archaea and ammonia-oxidizing bacteria were dramatically elevated by 25.62–153.19% and 12.38–22.39%, respectively, in the hydrochar treatments because of DOC-driven stimulation. The cumulative leaching loss of NO₃⁻-N in soils amended with hydrochar was markedly reduced by 43.78–59.91% and 61.70–72.82% compared with that in the control and pyrochar treatments, respectively, because hydrochar promoted the soil water holding capacity by 2.70–9.04% and reduced the residual NO₃⁻-N content. Hydrochar application can dramatically diminish total H⁺ production from soil nitrification and NO₃⁻-N leaching. Thus, it could be considered an economical soil amendment for ameliorating soil acidification. Full article

While significant progress has been made in controlling point source pollution, agricultural non-point source pollution (AGNPSP) has emerged as a major contributor to global water pollution, posing a severe threat to ecological quality. According to China’s Second National Pollution Source Census, AGNPSP constitutes a substantial proportion of water pollution, making its mitigation a critical challenge. Identifying AGNPSP risk zones is essential for targeted management and effective intervention. This study focuses on Yongchuan District, a representative hilly–mountainous area in the Yangtze River Basin. Applying the landscape ecology “source–sink” theory, we selected seven natural factors influencing AGNPSP and constructed a minimum cumulative resistance model using remote sensing post-processing data. An attempt was made to classify the “source” and “sink” landscapes, and ultimately conduct a risk assessment of AGNPSP in Yongchuan District, identifying the key areas for AGNPSP control. Key findings include: 1. Vegetation coverage is the most significant natural factor affecting AGNPSP. 2. Extremely high- and high-risk zones cover 90% of Yongchuan, primarily concentrated in the central and southern regions, indicating severe AGNPSP pressure that demands urgent management. 3. The levels of ammonia nitrogen and total phosphorus in the typical sections are related to the risk levels of the corresponding sections. Consequently, the risk level of AGNPSP directly correlates with the pollutant concentrations measured in the sections. This study provides a robust scientific basis for AGNPSP risk assessment and targeted control strategies, offering valuable insights for pollution management in Yongchuan and similar regions. Full article

Copper is an essential micronutrient for plants, but excessive levels can induce toxicity and impair physiological functions. This study evaluates the toxic effects of copper sulfate (CuSO₄) on the germination of common wheat (Triticum aestivum), with emphasis on the gas emission dynamics and oxidative stress biomarkers. Seeds were germinated in agar and exposed to CuSO₄ at concentrations of 1 µM, 100 µM, 1 mM, and 10 mM; distilled water served as the control. Ethylene and ammonia emissions were quantified using CO₂ laser photoacoustic spectroscopy, while electron paramagnetic resonance (EPR) spectroscopy was employed to detect free radicals and Cu²⁺ complexes. Exposure to Cu concentrations ≥ 1 mM significantly inhibited germination and biomass accumulation. Enhanced ethylene and ammonia emissions, particularly at 10 mM, indicated stress-related metabolic responses. The EPR spectra confirmed the presence of semiquinone radicals and Cu²⁺ complexes under higher Cu levels. These results demonstrate that photoacoustic and EPR techniques are effective tools for the early detection of metal-induced phytotoxicity and offer a non-invasive approach to environmental toxicity screening and plant stress assessment. Full article

Alzheimer’s disease (AD) is a neurodegenerative condition in which amyloid-beta (Aβ) plaques trigger oxidative stress (OS) and neuroinflammation, causing memory loss. OS and neurodegeneration can also be caused by reactive astrocytes, thereby promoting AD via toxic metabolite accumulation in the astrocytic urea cycle. However, the effect of molecular hydrogen (H₂) on this cycle remains unknown. Therefore, we investigated whether H₂ treatment could reduce OS-induced neurodegeneration and memory loss. 5xFAD (n = 14) and wild-type (n = 15) mice were randomized into four groups and treated with either 3% hydrogen gas (H₂) or vehicle for 60 days. Cognitive behaviors were evaluated using the Morris water maze and Y-maze tests. In addition, we used biochemical assays to measure ammonia and hydrogen peroxide (H₂O₂) levels in the hippocampi of the mice and AβO-treated primary mouse astrocytes. Aβ, γ-aminobutyric acid (GABA), and the expression of inflammatory markers were evaluated using immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (qRT-PCR). We observed that H₂ treatment significantly prevented cognitive deficits, oxidative stress, the accumulation of toxic metabolites, and the increase in inflammatory markers in 5xFAD mice. These results suggest that H₂ therapy can mitigate toxic metabolites in the astrocytic urea cycle, thereby reducing neurodegeneration and memory loss in AD. Full article

This study examined a strategy for effective reject water treatment involving hydrodynamic cavitation (HC) combined with subsequent adsorption using natural zeolites. Two experiments were conducted: The first involved the selection of optimal pre-treatment conditions of HC for biodegradability and to reduce the ammonium nitrogen and phosphate content. Three inlet pressures of 3, 5, and 7 bar and two types of cavitation inducers, i.e., multiple- and single-hole orifice plates, were evaluated. Adsorption experiments were conducted in batch mode using natural zeolite, and three doses of zeolite (50, 100, and 200 g/L) and six contact times (4–24 h) were examined. In the HC experiments, the application of 3 bar pressure, a single-hole cavitation inducer, and a cavitation time of 30 min resulted in the removal of ammonia nitrogen and phosphates amounting to 26.5 and 23%, respectively. In this case, 3.6-fold enhancement in the biodegradability index was also found. In the second experiment, the use of zeolite led to a decrease in the remaining content of both ammonia nitrogen and phosphates, improving the chemical oxygen demand-to-total nitrogen ratio. The highest removal efficacy was found for the highest zeolite dose of 200 g/L and the longest cavitation time of 24 h. Under these conditions, the ammonia nitrogen and phosphate removal rates were 70 and 94%, respectively. Full article

In recent years, passive acoustic monitoring (PAM) technology has significantly contributed to advancements in aquaculture techniques, system iterations, and increased production yields within intelligent feeding systems for Penaeus vannamei. However, current PAM-based intelligent feeding systems do not incorporate environmental factors into the decision process, limiting the improvement of monitoring accuracy in complex environments such as ponds. To establish a connection between environmental factors and the feeding acoustics of P. vannamei, this study utilized PAM technology combined with video analysis to investigate the effects of three key environmental factors—temperature, ammonia nitrogen, and nitrite nitrogen—on the feeding behavioral characteristics of shrimp, with a specific focus on acoustic signals “clicks”. The results demonstrated a significant correlation between the number of clicks and feed consumption in shrimp across different treatments, establishing this stable relationship as a reliable indicator for assessing shrimp feeding status. When water temperature increased from 20 °C to 32 °C, shrimp feed consumption showed an elevation from 0.46 g to 0.95 g per 30 min, with the average number of clicks increasing from 388 to 2947.58 and sound pressure levels rising accordingly. Conversely, ammonia nitrogen at 12 mg/L reduced feed consumption by 0.15 g and decreased click counts by 911.75 pulses compared to controls, while nitrite nitrogen at 40 mg/L similarly suppressed feed consumption by 0.15 g and the average number of clicks by 304.75. A rise in water temperature stimulated shrimp behaviors such as feeding, swimming, and foraging, while elevated concentrations of ammonia nitrogen and nitrite nitrogen significantly inhibited shrimp activity. Redundancy analysis revealed that temperature was the most prominent factor among the three environmental factors influencing shrimp feeding. This study is the first to quantify the specific effects of common environmental factors on the acoustic feeding signals and feeding behavior of P. vannamei using PAM technology. It confirms the feasibility of using PAM technology to assess shrimp feeding conditions under diverse environmental conditions and the necessity of integrating environmental monitoring modules into future feeding systems. This study provides behavioral evidence for the development of precise feeding technologies and the upgrade of intelligent feeding systems for P. vannamei. Full article

Agriculture and animal feeding operations are responsible for 87% of ammonia emissions in the UK. Controlling NH₃ concentrations below 20 ppm is crucial to preserve workers’ and livestock’s well-being. Therefore, ammonia control systems are required for maintaining adequate air quality in livestock facilities. This study assessed the ammonia reduction efficiency of a novel air pollution abatement (APA) system used in a pig farm building. The monitoring duration was 11 weeks. The results were compared with the baseline from a previous pig cycle during the same time of year in 2023. A ventilation-controlled room was monitored during a two-phase campaign, and the actual ammonia concentrations were measured at different locations within the site and at the inlet/outlet of the APA system. A 98% ammonia reduction was achieved at the APA outlet through NH₃ absorption in tap water. Ion chromatography analyses of farm water samples revealed NH₃ concentrations of up to 530 ppm within 83 days of APA operation. Further scanning electron microscopy and energy-dispersive X-ray inspections revealed the presence of salts and organic/inorganic matter in the solid residues. This research can contribute to meeting current ammonia regulations (NECRs), also by reusing the process water as a potential nitrogen fertiliser in agriculture. Full article

The development of efficient and sustainable water recycling systems is essential for long-term human missions and the establishment of space habitats on the Moon, Mars, and beyond. Humidity condensate (HC) is a low-strength wastewater that is currently recycled on the International Space Station (ISS). The main contaminants in HC are primarily low-molecular-weight organics and ammonia. This has caused operational issues due to microbial growth in the Water Process Assembly (WPA) storage tank as well as failure of downstream systems. In addition, treatment of this wastewater primarily uses adsorptive and exchange media, which must be continually resupplied and represent a significant life-cycle cost. This study demonstrates the integration of a membrane-aerated biological reactor (MABR) for pretreatment and storage of HC, followed by brackish water reverse osmosis (BWRO). Two system configurations were tested: (1) periodic MABR fluid was sent to batch RO operating at 90% water recovery with the RO concentrate sent to a separate waste tank; and (2) periodic MABR fluid was sent to batch RO operating at 90% recovery with the RO concentrate returned to the MABR (accumulating salinity in the MABR). With an external recycle tank (configuration 2), the system produced 2160 L (i.e., 1080 crew-days) of near potable water (dissolved organic carbon (DOC) < 10 mg/L, total nitrogen (TN) < 12 mg/L, total dissolved solids (TDS) < 30 mg/L) with a single membrane (weight of 260 g). When the MABR was used as the RO recycle tank (configuration 1), 1100 L of permeate could be produced on a single membrane; RO permeate quality was slightly better but generally similar to the first configuration even though no brine was wasted during the run. The results suggest that this hybrid system has the potential to significantly enhance the self-sufficiency of space habitats, supporting sustainable extraterrestrial human habitation, as well as reducing current operational problems on the ISS. These systems may also apply to extreme locations such as remote/isolated terrestrial locations, especially in arid and semi-arid regions. Full article

Nitrifying bacteria, including ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), are players in the nitrogen cycle but pose serious health risks when colonizing drinking water distribution networks (DWDNs). While the global impact of these bacteria is increasingly recognized, a significant research gap remains concerning their effects in tropical regions, particularly in developing countries. This study aims to bridge that gap by systematically reviewing the existing literature on nitrifying bacteria in DWDNs, their behavior in biofilms, and associated public health risks, particularly in systems reliant on surface water sources in tropical climates. Using the PRISMA guidelines for systematic reviews, 51 relevant studies were selected based on content validity and relevance to the research objective. The findings highlight the critical role of nitrifying bacteria in the formation of nitrogenous disinfection by-products (N-DBPs) and highlight specific challenges faced by developing countries, including insufficient monitoring and low public awareness regarding safe water storage practices. Additionally, this review identifies key surrogate indicators, such as ammonia, nitrite, and nitrate concentrations, that influence the formation of DBPs. Although health risks from nitrifying bacteria are reported in comparable studies, there is a lack of epidemiological data from tropical regions. This underscores the urgent need for localized research, systematic monitoring, and targeted interventions to mitigate the risks associated with nitrifying bacteria in DWDNs. Addressing these challenges is essential for enhancing water safety and supporting sustainable water management in tropical developing countries. Full article