Search Results (198)

Growing freshwater fish in saline environments is being explored as a potential solution to the freshwater shortage. However, growing these organisms in suboptimal salinity conditions leads to chronic stress that can be challenging to manage. To address this goal, it is crucial to improve the health of fish through the use of dietary supplements. This study evaluated the effects of varying levels of arginine supplementation on the growth, health status, and expression of stress-related molecular markers in juveniles of Nile tilapia exposed to chronic salinity stress. The tilapia were fed four experimental diets supplemented with 0, 1, 2, and 3% of L-arginine (T0, T1, T2, and T3). After an acclimatization period, the tilapias were exposed to a salinity level of 20‰ for 57 days in a recirculating aquaculture system. Our findings revealed that overall performance parameters were significantly influenced by L-arginine supplementation, except for the condition factor, viscerosomatic index, and hepatosomatic index. Additionally, intermediate levels of L-arginine supplementation positively influenced various blood parameters, including hematological profiles (hemoglobin and leukocytes), blood chemistry (total protein, albumin, globulin, and triglycerides), and the frequency of certain nuclear abnormalities. Furthermore, L-arginine supplementation appeared to regulate the expression of molecular markers related to stress and the immune system. In conclusion, this study indicates that L-arginine supplementation can help alleviate the chronic stress caused by salinity in juvenile Nile tilapia. Full article

Background/Objectives: Opioid use disorder (OUD) remains a severe health problem globally, resulting in substantial social and economic challenges. While existing medications for managing OUD are proven to be effective, they also present certain challenges. A vaccine offers a promising therapeutic strategy to combat OUD and potentially reduce the risk of overdose death. The TT-6-AmHap heroin conjugate vaccine has effectively reduced heroin-induced pharmacological effects in behavioral assays as well as demonstrated the induction of high titer and high affinity antibody responses in mice and rats. In this GLP study conducted in rabbits, the potential local and systemic toxicity of the TT-6-AmHap heroin vaccine in combination with or without adjuvants ALF43 and Alhydrogel^® (ALFA) was investigated. Methods: Male and female New Zealand White rabbits were administered with vaccines or a saline control intramuscularly at two-week intervals over a 57-day study period. The presence, persistence or reversibility of any toxic effects of the vaccine was determined over a four-week recovery period. Results: Administration of TT-6-AmHap with or without the adjuvants induced high antibody-specific IgG in treatment groups compared to the controls. The study found no TT-6-AmHap-related effects on mortality, physical examinations, dermal Draize observations, body weights, body weight changes, food consumption, ophthalmology, clinical pathology (hematology, coagulation, clinical chemistry, and urinalysis), macroscopic pathology, or organ weights. Conclusions: Under the conditions of this study, these results demonstrate that the TT-6-AmHap vaccine with or without adjuvants was well tolerated, immunogenic, and the effects were not considered adverse in both male and female rabbits. Full article

This study focused on the carbonate system dynamics and air–sea CO₂ fluxes in the open-ocean waters of the Madeira–Tore Seamount Complex during August 2024. Surface water properties revealed pronounced latitudinal gradients in sea surface temperature (21.9–23.1 °C), salinity (36.2–36.7), and dissolved oxygen (228–251 µmol Kg⁻¹), influenced by mesoscale eddies and topographically driven upwelling. Despite oligotrophic conditions, distinct phytoplankton assemblages were observed, with coccolithophores dominating southern seamounts and open-ocean stations, and green algae and diatoms indicating episodic nutrient input. Surface total alkalinity (TA: 2236–2467 µmol Kg⁻¹), dissolved inorganic carbon (DIC: 2006–2183 µmol Kg⁻¹), and pCO₂ (467–515 µatm) showed spatial variability aligned with water mass characteristics and biological activity. All stations exhibited positive air–sea CO₂ fluxes (2.8–11.5 mmol m⁻² d⁻¹), indicating the region is a CO₂ source during summer. Calcite and aragonite saturation states were highest in stratified, warmer waters. Principal Component Analysis highlighted the role of physical mixing, carbonate chemistry, and biological uptake in structuring regional variability. Our findings emphasize and contribute to the complex interplay of physical and biogeochemical drivers in modulating carbon cycling and ecosystem structure across Atlantic seamounts. Full article

Soil salinization severely limits global agricultural sustainability, particularly across the saline–alkaline landscapes of the Qinghai–Tibet Plateau. We examined how potassium fulvate (PF) modulates oat (Avena sativa L.) performance, soil chemistry, and rhizospheric microbiota in the saline–alkaline soils of the Qaidam Basin. PF markedly boosted shoot and root biomass, with the greatest response observed at 150 kg hm⁻². At the same time, it enhanced soil fertility by increasing organic matter, nitrate-N, ammonium-N, and available potassium, and improved ionic balance by lowering Na⁺ concentrations and the sodium adsorption ratio (SAR), while increasing Ca²⁺ levels and soil moisture content. Under the high-dose treatment (F2), endogenous fungal contributions declined sharply, exogenous replacements increased, and fungal α-diversity fell; multivariate ordinations confirmed that PF reshaped both bacterial and fungal communities, with fungi exhibiting the stronger response. We integrated three machine learning algorithms—least absolute shrinkage and selection operator (LASSO), Random Forest (RF), and eXtreme Gradient Boosting (XGBoost)—to minimize the bias inherent in any single method. We identified microbial β-diversity, organic matter, and Na⁺ and Ca²⁺ concentrations as the most robust predictors of the Soil Salinization and Alkalization Index (SSAI). Structural equation modeling further showed that PF mitigates salinity chiefly by improving soil physicochemical properties (path coefficient = −0.77; p < 0.001), with microbial assemblages acting as key intermediaries. These findings provide compelling theoretical and empirical support for deploying PF to rehabilitate saline–alkaline soils in alpine environments and offer practical guidance for sustainable land management in the Qaidam Basin. Full article

In this article, we examine water chemistry and carbonate precipitation in the alkaline waterbody Lake Van in Turkey, analyzing the possible role of microbial communities in stromatolite formation. Lake Van represents a unique environment characterized by high salinity and pH and extensive microbial communities, as revealed by SEM observation. Microbial activity, including that of cyanobacteria, can influence carbonate precipitation processes, leading to the formation of authigenic carbonates through physicochemical or metabolic mechanisms such as photosynthesis or sulfate reduction. In these environments, which are often dominated by cyanobacteria, carbonate precipitation can be influenced by biologically induced processes. This study presents new data on the hydrochemistry of lake water, focusing on the behavior of rare-earth elements (REEs) in this water and the carbon and oxygen isotopic compositions of carbonate microbial mats. The oxygen isotope data suggest that inorganic carbonate precipitation is the dominant process, but a biological influence on inorganic precipitation cannot be ruled out. For a deeper understanding of the role of biological processes in Lake Van, further studies on microbialites are needed. Full article

The current paper examines the sustainable possibility for recycling unused or expired Metoprolol (MET), a benzodiazepine derivative, as an effective corrosion inhibitor for carbon steel in saline solutions. Repurposing expired medicinal drugs aligns with green chemistry concepts and supports circular economy initiatives by reducing pharmaceutical waste and averting the production of new synthetic inhibitors. The technical benefit of recycling expired MET drugs pertains to the elimination of costs associated with organic inhibitor manufacturing and the decrease in disposal expenses for the expired medication. A combination of electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy) and quantum chemical calculations was employed to evaluate the inhibitory mechanism and efficacy of MET. At a concentration of 10⁻³ M, MET reduced the corrosion current density from 19.38 to 5.97 μA cm⁻², achieving a maximum IE of 69.1%. Adsorption Gibbs free energy, determined using different adsorption isotherms, revealed that interactions between metal atoms and MET adsorbed molecules have a chemical character with a ∆G^o_ads value of −50.7 kJ·mol⁻¹. Furthermore, quantum chemistry calculations indicate that the investigated drug, owing to its molecular structure (E_HOMO = −9.12 eV, E_LUMO = 0.21 eV, µ = 3.95 D), possesses the capacity to establish an adsorption layer on the metal surface, thereby impeding the diffusion of molecules and ions involved in the overall corrosion process. The results obtained using the different techniques were in good agreement and highlighted the effectiveness of MET in the corrosion inhibition of carbon steel. Full article

Seawater desalination is considered the first option to meet the domestic and industrial requirements of freshwater in desert areas, such as the Atacama Desert (Chile). However, its environmental implications remain poorly characterized. This study evaluated the effects of brine discharge from a desalination plant located in Caldera Bay, where fishing and tourism coexist. Sampling was conducted at increasing distances from the outfall to assess physicochemical parameters, sediment metal content, and nutrient concentrations. The results revealed a clear spatial gradient: salinity decreased from 57.75 to 34.87 PSU and nitrate from 10.49 to 4.05 µM. The sediment samples near the outfall showed elevated concentrations of Al, Fe, and Cr(VI). These findings suggest that brine discharge alters water chemistry and sediment quality. This study highlights the need for long-term environmental monitoring and regulatory frameworks to ensure sustainable desalination in sensitive coastal systems. Full article

Groundwater is the main source of water for both domestic and agricultural use in arid regions. This study assessed the hydrogeochemical characteristics and suitability of groundwater for drinking and irrigation in Kenya’s Ewaso Ng’iro–Lagh Dera Basin. A total of 129 borehole groundwater samples were collected and analyzed for pH, electrical conductivity (EC), total hardness, and major ions. The groundwater was found to be mostly neutral to slightly alkaline and ranged from marginal to brackish in salinity. The dominant water type is Na-HCO₃, with the ionic order Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and HCO₃⁻ > Cl⁻ > SO₄²⁻ > NO₃⁻. Mineral saturation indices indicate that the water is undersaturated with gypsum and anhydrite but is saturated with calcite, dolomite, and aragonite. Groundwater chemistry is primarily influenced by ion exchange, the mixing of fresh and paleo-saline water, and rock weathering processes. The water quality index (WQI) reveals that 80.5% of groundwater is suitable for drinking. The rest have high levels of sodium, EC, and bicarbonate. Thus, they are not suitable. The irrigation water quality index (IWQI) places most samples in the moderate-to-severe restriction category due to high salinity and sodicity. These findings highlight the importance of properly treating groundwater before use. Full article

The Atacama Desert, an unexplored habitat, offers intriguing potential for natural product chemistry due to the unique adaptations of microorganisms to aridity, extreme salinity, and high UV radiation. Over several years, soil samples were collected from various locations across the desert, leading to the isolation of diverse microorganisms. This paper presents the isolation and structural characterisation of two new 10-membered lactones, curvulalide B and C (3 and 4). These compounds are epimers of each other and are produced by one of the fungi isolated from the samples collected, using LC–MS and 1D and 2D NMR techniques. The compounds were tested against the ESKAPE pathogens, bovine mastitis pathogens, and Cryptococcus neoformans but were inactive against them. Full article

The biologic response following the insertion of dental implants is a widely studied process. Recent research has highlighted the importance of implant surface topography and chemistry as highly influential factors in consolidating the dental implant with the surrounding biological environment. The hydrophilicity, or wettability, of dental implants plays a pivotal role in these interactions and successful osseointegration. A more well-established factor that can also influence the development of the tissue–implant interface is exposure to tobacco smoke. While the negative impact of smoking on the biological response of the tissue is clear, there has been no research evaluating the impact that tobacco smoke can have directly on the surface chemistry of dental implants. The present study aimed to explore the effect of smoking on implant surface chemistry and wettability in vitro. Five different implant disks (Ti-Mach, Ti-SLA, Ti-Alloy, Zirc-1 and Zirc-2) were subjected to contamination with tobacco smoke using a portable smoke infuser with dome enclosure. Occasional smoking (5×/day 10 min each for 3 days) and heavy smoking (20×/day for 10 min each for 10 days) were simulated. The wettability of the implant disks was evaluated via the contact angle technique using artificial blood and albumin, as well as saline as a control. It was determined that the contamination of implant surfaces due to smoking produces changes in the surface chemistry and wettability. Changes in the surface hydrophilicity differed based on the implant material. Within the constraints of this investigation, tobacco smoke improved the hydrophilicity of titanium surfaces but worsened that of ceramic surfaces when utilizing the testing solutions. Different implant surfaces exhibit different wetting behavior following contamination with nicotine smoke. This might have an impact on the treatment of peri-implantitis in smokers due to changes in implant surface hydrophilicity, which can affect the re-osseointegration process. Full article

The Bundelkhand granite (BG) constitutes the bulk of the granitoid complex in the Bundelkhand Craton and preserves imprints of its evolution from the magmatic to a protracted hydrothermal stage as deduced from the petrography. In order to reconstruct such a path of evolution in this study, thermobarometric calculations were attempted on the mineral chemistry of the major (hornblende, plagioclase, biotite) and minor (epidote, apatite) magmatic phases. They yielded magmatic temperatures and pressures (in excess of 700 °C and ~5 kbar), although not consistently, and indicate mid-crustal conditions at the onset of crystallization. Temperatures in the hydrothermal regime within the BG are better constrained by the chemistry of the chlorite and epidote minerals (340 to 160 °C) that conform with the ranges of homogenization temperatures of aqueous–biphase inclusions in matrix quartz in the BG and subordinate quartz veins. These reconstructions indicate that fluid within the BG evolved down to lower temperatures and towards the deposition of quartz and, more importantly, bears a striking similarity to the temperature–salinity characteristics of fluid in the giant quartz reef system. Scanty mixed aqueous–carbonic inclusions in the BG are indicative of the CO₂-poor nature of the BG magma and the exsolution of CO₂ at lower pressure (~2.6 kbar). The dominant mechanism of fluid evolution in the BG appears to be the incursion of meteoric fluid, which caused fluid dilution. Laser Raman microspectrometry reveals many types of solid phases in aqueous–carbonic inclusions in the BG domain. The occurrence of unusual, effervescent-type inclusions, though infrequent, bears a striking similarity to that reported in the giant quartz reef domain. Thus, the highlight of the present work is the convincing fluid inclusion evidence that genetically links the BG with the giant quartz reef system, although many cited discrepancies arise from the radiometric dates. We visualize the episodic release of silica-transporting fluid to the major fracture system (now occupied by the giant reef) from the BG, thus making the fluid in the two domains virtually indistinguishable. Full article

Wetland lakes are crucial ecosystems that serve as vital ecosystems that harbor rich biodiversity and provide essential ecological services, particularly in regulating regional water resources, purifying water quality, and maintaining ecological equilibrium. This study aims to conduct an in-depth investigation into the hydrochemical characteristics and their controlling factors during the dry season of the Hengshui Lake wetland system. By collecting water samples from the lake and shallow groundwater, and using water chemistry diagrams, ion ratios, mineral saturation indices, and multivariate statistical methods, the study systematically analyzes the hydrochemical characteristics of Hengshui Lake Wetland and its controlling factors. The results show: there is significant stratified differentiation in the water chemical composition: the lake water is weakly alkaline and fresh, while the shallow groundwater is highly mineralized and saline. Both are dominated by Na⁺, Mg²⁺, SO₄²⁻, and Cl⁻. Significant differences exist in water chemistry types between the lake and shallow groundwater. The lake water exhibits homogenized characteristics with a dominant SO₄·Cl·HCO₃-Na·Mg type, whereas shallow groundwater displays five distinct hydrochemical facies indicative of multi-source recharge processes. Evaporation–rock interaction mechanisms dominate the system, as evidenced by a Gibbs diagram analysis showing evaporation crystallization as the primary control. Ion ratio calculations demonstrate synergistic effects between silicate weathering and evaporite dissolution, while mineral saturation indices confirm cooperative processes involving calcite/dolomite oversaturation and ongoing gypsum dissolution. Cation exchange indexes combined with chloro-alkaline indices reveal unidirectional recharge from lake water to shallow groundwater accompanied by active cationic exchange adsorption. Although the wetland predominantly maintains natural hydrological conditions, elevated γ(NO₃⁻)/γ(Na⁺) ratios in nearshore zones suggest initial agricultural contamination infiltration. This study shows that, as a typical example of a closed wetland, the hydrochemistry evolution of Hengshui Lake during the dry season is primarily dominated by the coupled effects of evaporation and rock–water interaction, with silicate weathering and evaporation rock dissolution as secondary factors, and human activity having a weak influence. The findings provide new insights into the understanding of the hydrochemical evolution process and its controlling factors in closed lakes, offering valuable data support and theoretical basis for the ecological restoration and sustainable management of closed lakes. Full article

The Bushy Park Pb-Zn deposit, hosted in unmetamorphosed carbonates of Neoarchean age, displays similarities to Phanerozoic Mississippi Valley-type (MVT) and Irish-type deposits. Mineralization is dated, by radiogenic methods, to Paleoproterozoic time. As such, Bushy Park is one of the oldest mineral deposits of this type in the world. Synsedimentary silicification and dolomitization preserve sedimentary fabrics, including microbial laminates, stromatolites, and oolites. Dolomitization likely was by evaporated seawater, as in Phanerozoic analogs. Structural control on mineralization, particularly solution collapse breccias, is similar to many Phanerozoic MVT and Irish-type deposits. Fluid inclusion data indicate three fluid endmembers involved in mineralization: a high-temperature, moderate-to-high salinity fluid; a low-temperature, moderate-to-high salinity fluid; and a moderate-to-low temperature, low salinity fluid. Saline fluids may have been sourced by evolved, evaporated seawater, and dilute fluids by meteoric and/or normal seawater. The fluids repeatedly mixed during ore and gangue mineral formation. Compositional zoning in gangue dolomite cement indicates that mineralizing fluid chemistry fluctuated over time. Petroleum inclusions and solid bitumen indicate that petroleum (oil) was an important fluid component at Bushy Park. Petroleum may have played a critical role in sulfur availability, addressing the issue of limited oceanic sulfate prior to and during the Great Oxidation Event. Full article

Despite the global imperative to enhance carbon sequestration in agricultural landscapes, saline–alkali soils present distinctive soil–microbe constraints that limit our understanding of optimal management strategies. This study addresses critical knowledge gaps regarding the mechanistic relationships between bacterial community structure and carbon stabilization processes in saline–alkali soil. A three-year field experiment was conducted in the Yellow River Delta, China, with two N levels (N1, 270 kg N ha⁻¹; N2, 210 kg N ha⁻¹) and three C treatments (S0, 0 kg C ha⁻¹; S1, 5000 kg C ha⁻¹; S2, 10,000 kg C ha⁻¹). SOC sequestration by straw incorporation increased by 16.34–22.86% and 8.18–11.91%, with no significant difference between the S1 and S2 treatments, because the specific C mineralization rate (SCMR) of the S2 treatment was 13.80–41.61% higher than the S1 treatment. The reduced nitrogen application (N2) enhanced SOC sequestration efficiency by 3.40–12.97% compared with conventional rates, particularly when combined with half straw incorporation. Furthermore, compared with the N1S1 treatment, the N2S1 treatment induced qualitative transformations in carbon chemistry, increasing aromatic carbon compounds (28.79%) while reducing carboxylic fractions (10.06%), resulting in enhanced structural stability of sequestered carbon. Bacterial community analysis revealed distinctive shifts in bacterial composition under different treatments. Half straw incorporation (S1) increased the abundance of oligotrophic strategists (Verrucomicrobiae and Acidimicrobiia) while decreasing copiotrophic bacteria (Bacteroidia), indicating a transition from r-strategy to k-strategy microbial communities that fundamentally altered carbon cycling. Half straw incorporation and reduced N application were beneficial to stabilize SOC composition, reduce mineralization rates, optimize bacterial survival strategy, and thus achieve SOC sequestration. Full article

Nitrate is the most prevalent inorganic pollutant in aquatic environments, posing a significant threat to human health and the ecological environment, especially in lakes and groundwater, which are located in the high agricultural activity intensity areas. In order to reveal the sources of nitrogen pollution in lakes and groundwater, this study of the transformation mechanism of nitrogen in the interaction zone between lakes and groundwater has become an important foundation for pollution prevention and control. The coupling effect between the biogeochemical processes of nitrate and iron has been pointed out to be widely present in various water environments in recent years. However, the impact of iron minerals on nitrate reduction in the lake–groundwater interaction zone of a high-salinity environment still remains uncertain. Based on the sediment and water chemistry characteristics of the Chagan Lake–groundwater interaction zone in northeastern China (groundwater TDS: 420~530 mg/L, Na⁺: 180~200 mg/L, and Cl⁻: 15~20 mg/L and lake water TDS: 470~500 mg/L, Na⁺: 210~240 mg/L, and Cl⁻: 71.40~87.09 mg/L), this study simulated relative oxidizing open system conditions and relative reducing closed conditions to investigate hematite and siderite effects on nitrate reduction and microbial behavior. The results indicated that both hematite and siderite promoted nitrate reduction in the closed system, whereas only siderite promoted nitrate reduction in the open system. Microbial community analysis indicated that iron minerals significantly promoted functional bacterial proliferation and restructured community composition by serving as electron donors/acceptors. In closed systems, hematite addition preferentially enriched Geobacter (denitrification, +15% abundance) and Burkholderiales (DNRA, +12% abundance), while in open systems, siderite addition fostered a distinct iron-carbon coupled metabolic network through Sphingomonas enrichment (+48% abundance), which secretes organic acids to enhance iron dissolution. These microbial shifts accelerated Fe(II)/Fe(III) cycling rates by 37% and achieved efficient nitrogen removal via combined denitrification and DNRA pathways. Notably, the open system with siderite amendment demonstrated the highest nitrate removal efficiency (80.6%). This study reveals that iron minerals play a critical role in regulating microbial metabolic pathways within salinized lake–groundwater interfaces, thereby influencing nitrogen biogeochemical cycling through microbially mediated iron redox processes. Full article