Oxidation-reduction Potential Research Articles

Effect of Nitrification Inhibitors on Soil Nitrogen Dynamics and Microbial Community Structure in Aerated Paddy Field

The aim of this study was to clarify the effects of nitrification inhibitors on the dynamic changes in the nitrogen and microbial community in paddy soil under aerated irrigation by using the indica hybrid rice Zhongzheyou 8 as experimental material. A trial with three treatments was conducted in 2023： conventional flooding irrigation （CF）, micro-nano bubble water aeration irrigation （MB）, and micro-nano bubble water aeration irrigation combined with nitrification inhibitor （MBNI）. The effects of nitrification inhibitors on the contents of NH4+-N and NO3--N and the apparent nitrification rate of soil under aerated irrigation were analyzed, as well as the characteristics of bacterial community diversity and its correlation with soil chemical factors. The results showed that compared with those in the CF treatment, the MB and MBNI treatment significantly increased the dissolved oxygen concentration, oxidation-reduction potential, pH, and soil NH4+-N content. Compared with that under the MB treatment, the MBNI treatment increased soil pH, reduced NH4+-N content in a short time after nitrogen fertilizer application, and later increased NO3--N content. Compared with that in the CF treatment, the MB and MBNI treatments could increase the diversity and richness of soil bacteria, while the relative abundance of Proteobacteria and Nitrospirota significantly increased, and the relative abundance of Bacteroidota decreased. The MBNI treatment reduced the diversity and richness of bacteria compared with that in the MB treatment and significantly decreased the relative abundance of Nitrospirota. Correlation analysis showed that soil chemical properties were significantly correlated with bacterial community structure. In conclusion, the combined application of nitrification inhibitors under aerated irrigation can improve soil nitrogen supply capacity, increase soil inorganic nitrogen content, improve soil chemical properties, and affect microbial community diversity and richness to optimize microbial community structure.

Physicochemical and spectroscopic Research of Molecular Signal Transfer of Highly Diluted <em>Arnica Montana</em> extract

The presentation explores the transmission of molecular signals in ultra-highly diluted (UHD) solutions of Arnica Montana. The study utilizes various physicochemical methods including electrical conductivity, oxidation-reduction potential (ORP), pH measurements, and UV/VIS/NIR spectroscopy to investigate the effects of different potencies (D6, C30, and C200) of A. Montana compared to control solutions.

Testing MasterPeace Zeolite Z™ for Temperature, pH, and Oxidative Reduction Potential (O.R.P.) When Formulated with SOLergy™ Sea Plasma Salts™

Testing MasterPeace Zeolite Z™ for Temperature, pH, and Oxidative Reduction Potential (O.R.P.) When Formulated with SOLergy™ Sea Plasma Salts™

Evaluation of the bactericidal activity of plasma-activated NaCl solution (PAN) against foodborne pathogens: Inactivation mechanism and application to mackerel

The objective of this study was to assess the bactericidal effect of plasma-activated NaCl solution (PAN) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes and apply PAN as a brine salting solution for mackerel. To enhance the bactericidal effect of plasma-activated water (PAW), NaCl solutions (0, 3.5, 7, and 10 %) were treated with plasma for 20 and 40 min to generate PAN. Plasma-activated glycerol solution (PAG) was also included to evaluate the influence of water activity on plasma activation and its effect on microbial activity. Physicochemical analysis revealed that elevating the NaCl concentration of PAN led to a decrease in pH, an increase in oxidation–reduction potential, and higher levels of reactive species such as H2O2 and HOCl. PAN showed greater antibacterial activity compared to PAW and PAG, except for L. monocytogenes, where 40 min activation time and treatment time exceeding 20 min was required for significantly higher reduction to occur. PAN exhibited greater antibacterial activity at higher NaCl concentrations, which was attributed to increased ionic strength and reactive chlorine species. Additionally, we evaluated the microbial mechanisms of PAN by assessing cellular damage and alterations. The common observation across the three pathogens was that PAN resulted in increased cell membrane damage, reduced intermembrane enzyme activity, higher intracellular ROS levels, and changes in zeta potential values, while DNA damage was observed only in PAN-treated L. monocytogenes. Furthermore, when PAW and PAN were stored for up to four weeks, PAN showed higher efficacy compared to PAW. 10 % PAN was also effective against foodborne pathogens on mackerel, achieving log reductions of 3.62 for E. coli O157:H7, 4.62 for S. Typhimurium, and 3.18 for L. monocytogenes after a 20 min treatment without adversely affecting quality. Our results demonstrated the antibacterial activity and action mechanism of PAN, presenting its potential application in the seafood industry.

Optimization of the Disinfection Process in Potabilization Systems in Cuenca Alto Atoyac, Mexico

Access to drinking water in Cuenca Alto Atoyac (CAA), serving over 3.5 million people, is challenged by contamination and inadequate disinfection processes. This study investigates the use of oxidation–reduction potential (ORP) as a tool to optimize disinfection in CAA’s water systems. The research was conducted in three stages: an initial pilot phase with 10 sampled sources, expanding to 14 supply sources in the experimental phase, followed by analyses defining optimal chlorine dosing and contact times across two distinct hydrogeological zones. Principal component analysis (PCA) identified key factors, explaining 53.52% of water quality variability, while ORP measurements revealed significant differences in water quality among sources, with “Ameca” and “Pozo #2 Santa María Atlihuetzían” representing the extremes. Adjusted chlorine doses and contact times were tailored to local conditions, achieving target ranges and ensuring improved microbial control. In the final stage, significant correlations were established between ORP levels, chlorine doses, and total coliform concentration, supporting the effectiveness of ORP in guiding disinfection processes. Overall, chlorine doses of 0.3–1.5 mg/L with contact times around 15 min yielded ORP values (594–687 mV) optimal for CAA water safety.

EDNA metabarcoding reveals differences in fish diversity and community structure in Danjiang River

Fish diversity, an important indicator of aquatic ecosystem health, is declining due to water pollution, overfishing, climate change, and invasive species. Effective surveying and monitoring are required to protect fish diversity. Here, a high-sensitivity environmental DNA (eDNA) metabarcoding technique was used to investigate fish diversity in the Danjiang River, Shaanxi Province, China. In total, 59 species were identified in eight orders, 19 families, and 40 genera. Cypriniformes and Perciformes were the main groups in the survey area, while Cyprinidae accounted for 50.85% of the total fish species. Rhinogobius similis (19%), Hemibarbus umbrifer (11%), Gnathopogon herzensteini (10%), Triplophysa stewarti (8%), and Zacco platypus (7%) were the dominant species. Eight rare and two exotic fish species were identified. Combined with analysis of historical data, the richness of fish identified using eDNA metabarcoding was significantly higher than that of fish captured in ground cages. Temperature, pH, and oxidation-reduction potential are the main environmental factors that affect the spatial distribution of fish communities. These results suggest that eDNA metabarcoding could be a new tool with broad application prospects; however, local databases must be improved. This study provides theoretical data and a methodological reference for protecting and managing fish diversity in the Qinling Mountains.

Impact of Oxidative Stress on Sperm Quality in Oligozoospermia and Normozoospermia Males Without Obvious Causes of Infertility

Background: Male factors contribute to approximately 50% of infertile couples. However, obvious causes remain unknown in many cases. This observational study aimed to investigate the associations of clinical and lifestyle parameters with sperm parameters. Methods: This study enrolled 41 men in infertile couples without obvious causes for male infertility from July 2023 to April 2024. Semen samples were evaluated for sperm number, motility, DNA fragmentation, and oxidative stress (OS) marker oxidation–reduction potential (ORP). Blood samples were analyzed for biochemical parameters, including advanced glycation end products (AGEs), and systemic OS marker diacron-reactive oxygen metabolites (d-ROMs). Skin-accumulated AGE levels were identified with an autofluorescence method. Lifestyle factors were assessed with a lifestyle questionnaire. Results: Most of the participants were under 40 years old and non-obese with normal clinical parameters. Multiple regression analyses revealed that body mass index, serum d-ROMs, and semen ORP levels were independently associated with decreased sperm number. Additionally, serum zinc and semen ORP levels were associated with sperm motility. Furthermore, serum zinc and high-density lipoprotein cholesterol levels were associated with sperm progressive motility and DNA fragmentation, respectively. The rest of the clinical and lifestyle factors, including skin-accumulated and serum AGE levels, were not correlated with any sperm parameters. Furthermore, serum d-ROM and semen ORP levels were not correlated with each other or any of the clinical and lifestyle factors. Conclusions: Our present study indicates that both systemic and local OS may be independently involved in sperm abnormality in healthy men without obvious causes for male infertility.

Methanogens dominate methanotrophs and act as a methane source in aquaculture pond sediments

Aquaculture pond sediments act as hotspots for methane (CH4) emissions; however, knowledge gaps on the regulation of microorganisms hinder our further understanding of methane dynamics in aquaculture pond sediment. Using field sampling and molecular analysis, we examined CH4 fluxes, the methanogenic community composition, and their interaction with methanotrophs to comprehensively understand the methane cycling in sediments of aquaculture ponds in northern China. Compared with a fishing pond without feed inputs, the abundances of methanogens mcrA and methanotrophs pmoA genes increased significantly in aquaculture ponds sediments. The dominant methanogens were Methanothrix, Methanoregula, and Methanolinea, and the α-diversity indices of methanogens demonstrated higher levels in 0–5 cm surface sediment. The methanotrophs were dominated by Methylocystis, Methylocaldum, and Methylobacter, and the α-diversity indices of methanotrophs showed no significant difference. The total organic carbon (TOC) contents and oxidation reduction potential (ORP) were the key factors driving methanogenic and methanotrophic communities on methane cycle in aquaculture sediment. The inter-domain ecological network (IDEN) analysis revealed that total number of network nodes, links, connectances, and links per species in the aquaculture sediments presented relatively higher levels, whereas the IDEN modules were fewer. The methanogens dominated in the networks and the interaction of methanogens and methanotrophs was more competitive and complex in aquaculture sediments. These findings highlight the marked methane production in aquaculture sediment, primarily due to the abundance, diversity, and competitive advantage of methanogens over methanotrophic communities.

Impact of gradient zero-valent iron pollution from steel works on soil microaggregate geochemical processes and dissipative structures

Abstract: Zero-valent iron (ZVI) contamination from steel works poses significant threats to soil quality and ecosystem health, particularly affecting soil microaggregates, which are fundamental to soil structure and function. In this study, we systematically investigated the impact of gradient ZVI pollution on the organic geochemical environment of soil microaggregates around steel works located in the core water source area of the Middle Route of the South-to-North Water Diversion Project in China. Advanced analytical techniques, including X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray fluorescence spectroscopy (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), were employed to comprehensively characterize the geochemical processes, mineralogy, and organic matter environment of soil microaggregates. The findings revealed that soils near the steel works were acidified and strongly oxidized, with heavy metal contents, particularly Fe, significantly decreasing with increasing distance from the steel works (Fe content decreased from 27,516.2 mg/kg to 23,492.6 mg/kg). The pH of soils near the steel works was lower, while oxidation-reduction potential (ORP) and electrical conductivity were higher. XPS analysis indicated a higher content of reactive oxygen species (ROS) near the steel works and significantly lower soil organic matter content. The iron valence distribution showed spatial differences, with higher Fe2⁺ content on the surface of soil microaggregates near the steel works and Fe³⁺ dominating in areas farther away. These results suggest an evolutionary sequence of ZVI from Fe (0) oxidation to Fe(II) and then to Fe(III). The formation of dissipative structures in soil microaggregates due to ZVI contamination significantly affects soil physicochemical properties and the organic environment. This study provides valuable insights into the multifaceted impacts of industrial activities on soil ecosystems and offers a scientific basis for soil conservation and remediation strategies.

Bio-irrigation Promotes Reactive Phosphorus Recycling in an Oxidized Sedimentary Environment

Bio-irrigation by burrowing macrofauna regulates benthic functioning via direct and indirect effects on sediment properties, microbial activities, oxygen dynamics, and organic matter and nutrient turnover. The effects of macrofauna bio-irrigation on benthic nitrogen cycling have been thoroughly investigated, whereas those on phosphorus (P) are comparatively understudied. This is surprising as such effects contribute to sediment oxidation and have a large potential to regulate P mobility and increase P retention. Dissolved oxygen (O2) and inorganic phosphorus (DIP) fluxes, pore water chemistry (DIPpw, Fe[II]pw, Mn[II]pw, pHpw, and oxidation–reduction potential (ORPpw)), and solid-phase Fe(III) pools were measured in reconstructed sediments without or with surface (the amphipod Corophium volutator) and deep (the polychaete Alitta succinea) burrowing macrofauna. Sediments and burrowing macrofauna were collected from the Goro Lagoon (Po River Delta, Italy) in April 2022. Measurements were carried out after a 2-week preincubation to allow sediment conditioning by bioturbators (e.g., burrow construction, bio-irrigation, burrow wall oxidation, steady chemical gradients within sediments and between pore and bottom waters). ORPpw analysis suggested that bio-irrigated sediments were less reduced, and Fe solid-phase analysis suggested a tendency towards an increase in the Fe(III) pool in deep bio-irrigated sediments. Both bioturbators stimulated O2 fluxes and DIP recycling (by a factor of ~ 2), and halved DIPpw, Fe(II)pw, and Mn(II)pw concentrations. The amphipod contributed to DIP fluxes via direct excretion, whereas polychaete excretion was negligible. Polychaetes contributed to DIP fluxes by ventilation of deep burrows within DIP-rich pore water. Bio-irrigation by both burrowers simultaneously promoted higher DIP recycling and sediment oxidation, ensuring the mobilization of a limiting nutrient and preventing the accumulation of reduced chemical species in the surface sediment.

Nuclear Magnetic Resonance (NMR) and Density Functional Theory (DFT) Study of Water Clusters of Hydrogen-Rich Water (HRW)

The present study investigated the 1H Nuclear Magnetic Resonance (NMR) spectra of hydrogen-rich water (HRW) produced using the EVObooster device. The analyzed HRW has pH = 7.1 ± 0.11, oxidation–reduction potential (ORP) of (−450 ± 11) mV, and a dissolved hydrogen concentration of 1.2 ppm. The control sample was tap water filtered by patented technology. A 600 NMR spectrometer was used to measure NMR spectra. Isotropic 1H nuclear magnetic shielding constants of the most stable clusters (H2O)n with n from 3 to 28 have been calculated by employing the gauge-including-atomic-orbital (GIAO) method at the MPW1PW91/6-311+G(2d,p) density function level of theory (DFT). The HRW chemical shift is downfield (higher chemical shifts) due to increased hydrogen bonding. More extensive formations were formed in HRW than in control filtered tap water. The exchange of protons between water molecules is rapid in HRW, and the 1H NMR spectra are in fast exchange mode. Therefore, we averaged the calculated chemical shifts of the investigated water clusters. As the size of the clusters increases, the number of hydrogen bonds increases, which leads to an increase in the chemical shift. The dependence is an exponential saturation that occurs at about N = 10. The modeled clusters in HRW are structurally stabilized, suggesting well-ordered hydrogen bonds. In the article, different processes are described for the transport of water molecules and clusters. These processes are with aquaporins, fusion pores, gap-junction channels, and WAT FOUR model. The exponential trend of saturation shows the dynamics of water molecules in clusters. In our research, the chemical shift of 4.257 ppm indicates stable water clusters of 4–5 water molecules. The pentagonal rings in dodecahedron cage H3O+(H2O)20 allow for an optimal arrangement of hydrogen bonds that minimizes the potential energy.

Design, perspectives, and challenges of modification strategies for alkali metal anodes

Abstract. The alkali metal anode has emerged as a focal point of research due to its extremely low oxidation-reduction potential and high theoretical specific capacity. However, challenges such as unstable solid electrolyte interphase (SEI), infinite volume expansion, and uncontrollable dendrite growth result in low coulombic efficiency and irreversible losses during the deposition and stripping processes. To address these issues, various effective strategies have been proposed to protect the alkali metal anode and achieve dendrite-free growth. In this review, we summarize recent advancements in enhancement strategies for alkali metal anodes, including the construction of three-dimensional current collectors and interface engineering. Specifically, we delve into the development of carbon-based current collectors with various dimensions and structures and the application of interface engineering techniques to tackle the challenges of unstable SEI, volume changes, and dendrite growth. Furthermore, we explore advanced characterization techniques that provide deeper insights into the reaction mechanisms and behavior of these enhancement strategies. Finally, we discuss the current limitations and future research directions in protecting alkali metal anodes, aiming to provide valuable insights into the study of dendrite growth and the development of effective protection strategies for alkali metal anodes.

The first survey of legacy and emerging per- and polyfluoroalkyl substances (PFAS) in Hulun Lake, China: Occurrence, sources, and environmental impacts

Many per- and poly-fluoroalkyl substances (PFAS) studies in environmental media have been conducted in heavily industrialized and densely populated areas. However, there has been limited research on legacy and emerging PFAS contamination in cold and arid regions. In the present study, we investigated the concentrations of 30 PFAS compounds in the surface water and sediment of Hulun Lake and its inflowing rivers. The main components in water were short chain perfluoroalkyl carboxylic acids (PFCAs) in both Hulun Lake (33.57 %) and its inflowing rivers (30.47 %). However, long chain perfluoroalkane sulfonates (PFSAs) and long chain PFCAs accounted for more than half of the total PFAS content in sediment. Total PFAS concentrations (∑30PFAS) ranged from 3.67 to 8.84 ng/L in water, and 0.97–1.73 μg/kg in sediment. Significant spatial differences were apparent between Hulun Lake and its inflowing rivers in both water and sediment samples. Source apportionment revealed that wastewater, aqueous film forming foams, textiles and paper-based food packaging, and paper products and cosmetics were the primary sources of PFAS. The partitioning coefficients of PFCAs were dependent on the carbon chain length. Temperature, conductivity, pH, salinity, chemical oxygen demand, total phosphorus (TP), total nitrogen (TN), As, and oxidation-reduction potential were the main influencing factors in water. Heavy metals (Co, Pb, Cu, Ni, Hg, Cd, and As), TP, salinity, and pH were positively correlated with the PFAS concentration in sediment. Furthermore, Hailar River contributed the majority (99.74 %, ∼15.05 kg/year) of the PFAS mass flux. This is the first study showing PFAS contamination in Hulun Lake and the results suggest that long term monitoring is needed for the effective control of PFAS pollution in this typical cold and arid region of China.

Relationship Between Aquatic Factors and Sulfide and Ferrous Iron in Black Bloom in Lakes: A Case Study of a Eutrophic Lake in Eastern China

Black bloom is a very serious water pollution phenomenon in eutrophic lakes, with Fe(II) and S(−II) being the key limiting factors for this problem. In this paper, three different machine learning methods, namely, Random Forest (RF), Gaussian Mixture Model (GMM), and Bayesian Network (BN), were used to explore the complex interactions among Fe(II), S(−II), and other aquatic factors in the estuary of Chaohu Lake to better characterize and monitor water degradation by black bloom. The results of RF showed that total nitrogen (TN), ammonia, total phosphorous (TP), suspended sediment concentration (SSC), and oxidation–reduction potential (ORP), which were chosen from 11 factors, had the most important relationships with Fe(II) and S(−II). The 69 sampling sites were divided in three groups identified as worst, worse, and bad according to the observed values of seven factors using the GMM. Then, the BN model was applied to three observation groups. The results showed that the structures of the interaction networks were different between the groups. S(−II) controlled only SSC production in the bad and worse group sites, while SSC was determined by both S(−II) and Fe(II) in the worst group. Ammonia and TN exhibited the most direct importance for S(−II) and Fe(II) production in all observation groups. According to the indications from the BNs, potential management strategies for different water pollution conditions were developed. Finally, the threshold values of Fe(II), S(−II), TP, ammonia, TN, SSC, and ORP, which were 0.80 mg/L, 0.04 mg/L, 0.45 mg/L, 3.44 mg/L, 4.15 mg/L, 55 mg/L, and 135 mv, respectively, were determined on the basis of the BN models. These values will be helpful to develop accurate strategies of oxygenation to quickly eliminate black bloom in the lake.

Comprehensive effects of biochar-assisted nitrogen and phosphorus bioremediation on hydrocarbon removal and microecological improvement in petroleum-contaminated soil

Biochar is widely used in agricultural soils, but its effects with nitrogen and phosphorus amendments on petroleum-contaminated soil are unclear. This study investigated biochar-assisted biostimulation in a microcosm experiment, focusing on hydrocarbon degradation, nitrogen cycling, and soil properties. Compared to the biostimulation alone (BS), biochar combined biostimulation (BSC) significantly enhanced the abundances of petroleum hydrocarbon degraders including Lysobacter and Brevundimonas, which led to a 17% increase in total petroleum hydrocarbon (TPH) degradation, with 9% and 39% enhancements in saturated hydrocarbon degradation and aromatic hydrocarbon fraction degradation, respectively. Biochar also promoted ammonia and nitrous oxide oxidation by upregulating AOA, AOB, norB, and nosZ genes, while controlling nitrogen loss by downregulating nirK. Soil moisture, oxidation–reduction potential (ORP), dehydrogenase activity (SDHA), and microbial proliferation were significantly enhanced. Structural equation models (SEM) indicated synergistic interactions between nitrogen cycling and hydrocarbon degradation. Biochar enhances hydrocarbon degradation and nitrogen cycling, offering a promising soil remediation approach.

The impact of temperature on the growth of Pseudomonas aeruginosa in mineral waters originated from different wells: A predictive approach

This study aimed to evaluate the behavior of Pseudomonas aeruginosa (PSA) in natural mineral water sourced from three different extraction wells and stored at various temperatures (10, 12, 20, 23, and 30 °C) to calculate the kinetic growth parameters of this microorganism through predictive modeling. The physicochemical characterization of waters was also evaluated at the time of collection, and included the analysis of 40 different minerals, and quality parameters such as pH, conductivity, oxidation-reduction potential (ORP), total dissolved solids (TDS), salinity (PSU), and temperature (T). PSA survived in raw mineral water incubated at 12, 20, 23, and 30 °C; however, no growth was observed at 10 °C. Growth curves started with an initial population of ~ 2.5–3 log CFU/mL, and final PSA populations ranged from 3.5 to 4.9 log CFU/mL. The maximum specific growth rate (μmax) at 30 °C varied among the wells, with Well P-07 showing the highest growth rate (0.2 h−1), followed by Well P-08 (0.195 h−1) and well P-01 (0.133 h−1). At 12 °C, well P-01 exhibited the highest growth rate (μmax = 0.22 h−1), indicating a influence of mineral composition in the growth of PSA. The lag time (λ) also varied, with minimum values of 2.4 ± 0.1 h at 30 °C and maximum values of 41.6 ± 0.2 h at 12 °C. From these primary estimated parameters, it was possible to obtain five robust secondary models to describe the influence of temperature on the maximum growth rates and lag phase of PSA in the well. The estimated PSA growth parameters at 20 and 23 °C were subjected to a hierarchical cluster analysis and correlation plots to verify the influence of the physicochemical composition of the waters on the PSA behavior at each well's specific annual average temperature. This analysis confirmed a positive relationship (p < 0.05) between the presence of minerals (Ca, Fe, Sr, Mn, Na) and ions (SO4−3, Cl−) and the PSA lag phase time. These results underscore the need for tailored water quality management strategies that consider chemical composition and temperature to address specific microbial contamination risks.

Fluid-rock reaction path modeling of uranium mobility in granite-related mineralization: A case study from the Variscan South Armorican Domain

The mobilization of uranium in granite-related systems presents a complex interplay of chemical and hydrodynamic factors. This is particularly obvious within syn-orogenic detachment zones where per descensum surface-derived fluids interact with per ascensum deeply sourced hydrothermal fluids. In this study, we employ a thermo-hydro-chemical (TH-C) modeling approach to explore the multifaceted processes that govern uranium transport and deposition in such environments. Our findings indicate that uranium mobility is not solely determined by the oxidizing nature of the percolating surface-derived fluids. Actually, the oxidation-reduction potential of these fluids varies as they flow in the crust, ultimately adjusting towards more neutral or mildly reducing conditions conducive to uranium dissolution and precipitation. Even in the presence of magnetite, which enhances the reductive potential of the fluids, uranium continues to dissolve, albeit in much smaller quantities, with U(IV) being the predominant species in the aqueous phase. The study highlights the crucial roles of temperature, pH, and fluid/rock interaction ratios in influencing uranium leaching efficacy. High fluid/rock ratios enhance uranium extraction from source rocks. A fluid/rock ratio around 1 is optimal, maximizing the dissolution of uranium-bearing minerals in the source rock and promoting the precipitation of uranium minerals in different locations along the fluid pathway due to changes in fluid chemistry. The TH-C modeling has the potential to be applied to a variety of other uranium deposits, developed below 300°C.

The aeration and dredging stimulate the reduction of pollution and carbon emissions in a sediment microcosm study

Sediment dredging and aeration are used as important technical measures to remediate internal loading of sediment in polluted rivers. However, previous studies have overlooked the impact of dredging and aeration on Greenhouse gases (GHGs) emission. We established three aeration rate(six different aeration intervals), one dredging treatment to investigate the effect of aeration and dredging on pollutant removals and CO2, CH4 and N2O emissions. The results indicated the pollutants and GHGs at 2.4, 3.4, 4.4 L min−1 aeration rates reached collaborative emission reduction after more than 3 h or within 1.5 h. Meanwhile, the GHGs fluxes after aeration decreased with the increasing aeration rate, with the mean CO2, CH4 and N2O fluxes of 69.74, 0.16, 7.53 mg m−2 h−1 and 33.64, 0.09, 4.17 mg m−2 h−1 before and after aeration, respectively. With respect to dredging, the pollutants and N2O reached synergic effects between reduction of pollution and carbon emissions after 1 h dredging. Specifically, the CO2 and CH4 emissions after dredging was lower than those of before dredging, but the N2O emissions was higher than those of before dredging. In addition, our analysis revealed that the dissolved oxygen (DO), oxidation-reduction potential (ORP), available potassium (AK) and ammoniacal nitrogen (NH4+-N) in the sediment influenced GHGs fluxes at the water-air interface in the aeration. Our study indicated moderate aeration and dredging can achieve the synergistic effect in reducing pollution and carbon emissions.

Exploring Spatial Dynamics of Water Quality in a Tropical Lake Affected by Aquaculture

Lake Maninjau, like many surface water bodies worldwide, faces significant water pollution challenges due to extensive aquaculture activities, making it an ideal site to study the impact of fish farming on water quality, which has contributed to eutrophication and declining water quality. This study investigates the physicochemical parameters and pollution levels in the lake, aiming to provide insights into its environmental health. In August 2022, a comprehensive sampling campaign was undertaken at nine stations within the upper layers of open water and littoral zones of Lake Maninjau. In situ measurements, including temperature, dissolved oxygen, and pH, were conducted, accompanied by water sample collection for laboratory analysis of trace elements and heavy metals. Our study revealed notable variability in water parameters across different sites, with surface water layers exhibiting the greatest differences. While certain parameters such as temperature and conductivity remain relatively stable, pH levels show a decreasing trend with increasing water depth. Dissolved oxygen levels vary widely, while oxidation–reduction potential indicates water pollution, particularly in littoral zones. Potassium dominance within cations likely suggests anthropogenic influences, notably from aquaculture activities, that may also contribute to nutrient enrichment and heavy metal pollution. Elevated levels of total nitrogen and ammonia underscore the lake’s moderate pollution levels, with heavy metals such as mercury exceeding permissible limits, posing risks to aquatic life and human health.

Green Pathway of Urea Synthesis Through Plasma–Ice Interaction: Optimization and Mechanistic Insights With N2 + CO2 and NH3 + CO2 Gas Mixtures

ABSTRACTThis study presents a green approach for urea synthesis using plasma–ice interaction with N₂ + CO₂ and NH₃ + CO₂ gas mixtures. Plasma characterization via electrical and optical emission spectroscopy revealed that urea formation involves complex reactions driven by high‐energy species, producing reactive nitrogen and carbon intermediates. Plasma‐treated ice exhibited increased pH, electrical conductivity (EC), and reduced oxidation–reduction potential (ORP). Optimization of parameters, especially treatment time, significantly influenced urea formation. The NH₃ + CO₂ plasma produced a higher urea concentration (7.7 mg L−1) compared to the N₂ + CO₂ plasma (0.55 mg L−1) due to ammonia's greater reactivity. This method offers a sustainable, energy‐efficient alternative to traditional urea synthesis processes.