Excess Nitrate Research Articles

How Do Satellite Precipitation Products Affect Water Quality Simulations? A Comparative Analysis of Rainfall Datasets for River Flow and Riverine Nitrate Load in an Agricultural Watershed

Excessive nitrate loading from agricultural runoff leads to substantial environmental and economic harm, and although hydrological models are used to mitigate these effects, the influence of various satellite precipitation products (SPPs) on nitrate load simulations is often overlooked. This study addresses this research gap by evaluating the impacts of using different satellite precipitation products—ERA5, IMERG, and gridMET—on flow and nitrate load simulations with the Soil and Water Assessment Tool Plus (SWAT+), using the Tar-Pamlico watershed as a case study. Although agricultural activities are higher in the summer, this study found the lowest nitrate load during this season due to reduced runoff. In contrast, the nitrate load was higher in the winter because of increased runoff, highlighting the dominance of water flow in driving riverine nitrate load. This study found that although IMERG predicts the highest annual average flow (120 m3/s in Pamlico Sound), it unexpectedly results in the lowest annual average nitrate load (1750 metric tons/year). In contrast, gridMET estimates significantly higher annual average nitrate loads (3850 metric tons/year). This discrepancy underscores the crucial impact of rainfall datasets on nitrate transport predictions and highlights how the choice of dataset can significantly influence nitrate load simulations.

Partitioned granular sludge coupling with membrane-aerated biofilm reactor for efficient autotrophic nitrogen removal

The partial nitritation-anammox process based on a membrane-aerated biofilm reactor (MABR) faces several challenges, such as difficulty in suppressing nitrite-oxidizing bacteria (NOB), excessive effluent nitrate, and ineffective synergy between denitrification and anammox bacteria. Therefore, a novel partitioned granular sludge coupling with MABR (G-MABR) was constructed. The chemical oxygen demand (COD) and nitrogen removal efficiency were 88.8 ± 1.8 %–92.6 ± 1.2 % and 88.8 ± 1.5 %–93.6 ± 0.7 %, respectively. The COD was mainly lowered in the lower granular sludge-zone, while nitrogen was removed in the upper MABR-zone. NOB was significantly suppressed in the MABR-zone due to competition for substrate with denitrifying bacteria and anammox bacteria. This partitioned configuration reduced the C/N ratio in the MABR-zone, thus facilitating autotrophic nitrogen removal. Both partial nitrification and denitrification provided nitrite for anammox bacteria in granular sludge, whereas partial nitrification mainly supplied nitrite to the anammox bacteria in membrane biofilms.

Nitrate sources and transformation in surface water and groundwater in Huazhou District, Shaanxi, China: Integrated research using hydrochemistry, isotopes and MixSIAR model

Global water resources affected by excessive nitrate (NO3−) have caused a series of human health and ecological problems. Therefore, identification of NO3− sources and transformations is of pivotal significance in the strategic governance of widespread NO3− contaminant. In this investigation, a combination of statistical analysis, chemical indicators, isotopes, and MixSIAR model approaches was adopted to reveal the hydrochemical factors affecting NO3− concentrations and quantify the contribution of each source to NO3− concentrations in surface water and groundwater. The findings revealed that high groundwater NO3− concentration is concentrated in the southwestern region, peaking at 271 mg/L. NO3− concentration in the Wei River and Yuxian River exhibited an increase from upstream to downstream, but in the Shidi River and Luowen River, its concentration was highest in the upstream. Groundwater NO3− has noticeable correlation with Na+, Ca2+, Mg2+, Cl−, HCO3−, TDS, EC, and ORP. In surface water, NO3− level is significantly correlated with NH4+ and ORP. Major sources of NO3− in surface and groundwater comprise manure & sewage and soil nitrogen. Source contribution for surface water was calculated by MixSIAR model to obtain soil nitrogen (57.7%), manure & sewage (23.8%), chemical fertilizer (12%), and atmospheric deposition (6.4%). In groundwater, soil nitrogen and manure & sewage accounted for 19% and 63.8% of nitrate sources, respectively. Both surface water and groundwater exhibited strong oxidation, with nitrification the primary process. It is expected that this study will provide insights into the dynamics of NO3− and contribute to the development of effective strategies for mitigating NO3− contaminant, leading to sustainable management of water resources.

Influence of Carbon Nanotube Support on Electrochemical Nitrate Reduction Catalyzed by a Cobalt Complex

Access to clean water is a pressing environmental and public health concern. Excess nitrate (NO3 -) from the overuse of fertilizer finds its way into our surface water and groundwater, which leads to adverse health effects such as cancer and causes significant damage to ecosystems.1-4 The electrochemical nitrate reduction reaction (NO3RR) has emerged as a promising water treatment approach to address this issue. The NO3RR involves the transformation of waste NO3 - into value-added nitrogen species, such as ammonia (NH3), via reduction. NH3 serves as a valuable chemical in various applications, including its use as a fertilizer, chemical precursor, fuel, and a potential hydrogen (H2) carrier for energy storage and transportation.5-7 Leveraging renewable energy, the NO3RR provides a sustainable approach to distributed NH3 production, which stands in stark contrast to the energy-intensive Haber-Bosch process.8-10 As a result, there is growing interest in designing catalysts for the selective reduction of NO3 - to NH3. However, this requires that we obtain a clear understanding of the role of each component in the catalyst structure.Molecular catalysts have unique advantages over other electrocatalytic materials due to their well-defined structures, which can be tailored through the choice of the metal center and ligands.11,12 Moreover, molecular catalysts can be immobilized on substrates to create heterogeneous electrocatalysts capable of achieving a high current density.13,14 In previous investigations, we showcased the efficacy of multi-walled carbon nanotubes (CNTs) as a catalyst support for electrochemical carbon dioxide reduction reactions.13,15 In heterogenized molecular catalysts, CNTs are generally believed to provide high surface area and electron conduction. However, our recent investigation reveals that CNTs can serve as catalysts themselves for the NO3RR,16 which expands our understanding of the diverse roles CNTs play in NO3 - reduction electrocatalysis.A major challenge in the field of electrocatalysis is the development of catalyst design strategies to control the reaction selectivity. We report on an underexplored approach to overcome this challenge by tuning the CNT support for a cobalt complex. With pristine CNTs as the support, the cobalt complex/CNT hybrid catalyst is selective for NO3 - reduction to NH3 with a maximum Faradaic efficiency of 70%. In contrast, the cobalt complex supported on oxidized CNTs (OCNTs) generates mostly H2 under the same conditions. On the basis of kinetic measurements which reveal that the rate-determining step of NO3 – reduction is limited by the first electron transfer without involving a proton, we propose that the oxygen functional groups on the OCNT support help deliver protons and steer the supported cobalt complexes from catalyzing NO3 - reduction to H2 evolution. The performance of both of these hybrid catalysts is compared with the controls of bare CNTs and OCNTs. Additional control experiments include tests conducted in the absence of NO3 -. These control experiments together with the rest of the experimental data provide strong evidence to support the notion that the product selectivity of the NO3RR catalyzed by cobalt complexes can be controlled via the CNT support. This study demonstrates the importance of tailoring the catalyst support to advance reactivity in catalysis for environmental remediation.

Electrochemical Hydrogenation of Refractory Organics in Wastewater

Wastewater treatment is an essential process for the sustainable development of a society. The handling and degrading of different refractory and toxic organic pollutants heavily relies on conventional biodegradation. Herein, we developed an electrochemical hydrogenation method to enhance the biodegradability of organic substrates, which subsequently improves their availability to other biological-driven processes, namely denitrification. The strategy presents an unprecedented "kill-two-birds-with-one-stone" strategy to simultaneously deal with excessive organic components and nitrate's presence in wastewater. The strategy was discovered by comparing the biodegradability of some organic compounds and their hydrogenation forms. It was found that the hydrogenation product was much more bioavailable. Motivated by this discovery, we synthesized a carbon-supported Ru electrode by electrodepositing Ru on activated carbon cloth (ACC), named Ru/ACC. After that, 4-chlorophenol was used to optimize the experimental conditions, and Ru/ACC electrodes successfully converted 99.9% of 4-chlorophenol with an overall yield reached 90.9%. After that, the Ru/ACC electrodes proved efficient in transferring various wastewater organic pollutants. Besides, the electrochemical hydrogenation effect on biochemical degradation and denitrification was studied. It is significant for the electrochemical hydrogenation method to be applied to wastewater treatment.

In-Line Thermal Desorption and Dielectric Barrier Discharge Ionization for Rapid Mass Spectrometry Detection of Explosives.

Thermal desorption (TD) of wipe-based samples was coupled with an in-line dielectric barrier discharge ionization (DBDI) source and rugged compact time-of-flight mass spectrometer (MS) for the detection of explosives, propellants, and postblast debris. The chromatography-free TD-DBDI-MS platform enabled rapid and sensitive detection of organic nitramine, nitrate ester, and nitroaromatic explosives as well as black powder and black powder substitute propellants. Parametric investigations characterized the response to TD temperature and optimized DBDI voltage, aerodynamically assisted entrainment, and fragmentation through in-source collision induced dissociation (isCID). Excess nitrate generated by the DBDI source yielded predominantly nitrate-adduct formation. Subnanogram sensitivities were demonstrated for all explosives investigated, except for nitroglycerin, specifically due to its volatility. Further, most analytes/explosives exhibited tens of picograms sensitivities. The platform also demonstrated the detection of propellant and military explosives from postblast debris. The TD-DBDI-MS system performed well without the need for aerodynamically assisted entrainment (and the associated rough pump), which along with requiring no additional gases (i.e., N2 or He) or solvents, aid in potential field deployment. The ease of TD-DBDI attachment and removal added trace solid or liquid residue detection to the rugged mass spectrometer, designed primarily for the analysis of volatile organic and inorganic compounds.

Effect of Nitrates supplementation on Muscle Hypertrophy and Athletic Performance: A Narrative Review

Background and Study Aim. The consumption of nitrate has been linked to various advantages, including aiding recovery by lessening fatigue, enhancing oxygen supply to muscles, and increasing the elimination of metabolic by-products during intense physical activity. Given the rising trend of utilizing dietary supplements for peak athletic performance, this literature review aims to explore the role and promise of nitrate supplementation in influencing muscle function and boosting physical prowess, while also shedding light on its potential perks and drawbacks. Material and Methods. Electronic databases including Web of Science (all databases), PubMed, Scopus, Google Scholar, Science Direct, were explored on June 11, 2022. The search terms were drawn from prior systematic reviews on nitrate supplementation and exercise and informed by a recent narrative review on Nitrates impact on athletic performance and muscle hypertrophy. Results. The findings of this review indicate that nitrate intake, owing to its ability to widen blood vessels, could potentially enhance blood flow and oxygen delivery to muscles during exercise. Consequently, this improved circulation might facilitate better nutrient and oxygen transportation to muscle tissue, thereby fostering muscle development through enhanced nutrient absorption and waste removal during physical exertion. However, it's crucial to note that excessive nitrate consumption might trigger adverse effects related to the formation of nitrosamines. Conclusion. In summary, investigations into the potential advantages of nitrate supplementation, whether through dietary sources or supplements, in augmenting athletic performance are promising. This is evident from the observed effects of increased muscle protein synthesis, reduced muscle soreness, and enhanced cognitive function under stressful conditions. Nonetheless, it's imperative to exercise caution against over-supplementation due to the potential risks of toxicity and associated side effects.

SlTrxh functions downstream of SlMYB86 and positively regulates nitrate stress tolerance via S-nitrosation in tomato seedling.

Nitric oxide (NO) is a redox-dependent signaling molecule that plays a crucial role in regulating a wide range of biological processes in plants. It functions by post-translationally modifying proteins, primarily through S-nitrosation. Thioredoxin (Trx), a small and ubiquitous protein with multifunctional properties, plays a pivotal role in the antioxidant defense system. However, the regulatory mechanism governing the response of tomato Trxh (SlTrxh) to excessive nitrate stress remains unknown. In this study, overexpression or silencing of SlTrxh in tomato led to increased or decreased nitrate stress tolerance, respectively. The overexpression of SlTrxh resulted in a reduction in levels of reactive oxygen species (ROS) and an increase in S-nitrosothiol (SNO) contents; conversely, silencing SlTrxh exhibited the opposite trend. The level of S-nitrosated SlTrxh was increased and decreased in SlTrxh overexpression and RNAi plants after nitrate treatment, respectively. SlTrxh was found to be susceptible to S-nitrosation both in vivo and in vitro, with Cysteine 54 potentially being the key site for S-nitrosation. Protein interaction assays revealed that SlTrxh physically interacts with SlGrx9, and this interaction is strengthened by S-nitrosation. Moreover, a combination of yeast one-hybrid (Y1H), electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR), and transient expression assays confirmed the direct binding of SlMYB86 to the SlTrxh promoter, thereby enhancing its expression. SlMYB86 is located in the nucleus and SlMYB86 overexpressed and knockout tomato lines showed enhanced and decreased nitrate stress tolerance, respectively. Our findings indicate that SlTrxh functions downstream of SlMYB86 and highlight the potential significance of S-nitrosation of SlTrxh in modulating its function under nitrate stress.

Unacclimated activated sludge improved nitrate reduction and N2 selectivity in iron filling/biochar systems

Iron (Fe)-based denitrification is a proven technology for removing nitrate from water, yet challenges such as limited pH preference range and low N2 selectivity (reduction of nitrate to N2) persist. Adding biochar (BC) can improve the pH preference range but not N2 selectivity. This study aimed to improve nitrate reduction and N2 selectivity in iron filling/biochar (Fe/BC) systems with a simplified approach by coupling unacclimated microbes (M) in the system. Factors such as initial pH, Fe/BC ratio, and Fe/BC dosage on nitrate removal efficiency and N2 selectivity were evaluated. Results show that the introduction of microbes significantly enhanced nitrate removal and N2 selectivity, achieving 100 % nitrate removal and 79 % N2 selectivity. The Fe/BC/M system exhibited efficient nitrate reduction at pH of 2–10. Moreover, the Fe/BC/M system demonstrated an improved electrochemical active surface area (ECSA), lower electron transfer resistance and lower corrosion potential, leading to enhanced nitrate reduction. The high i0 value in Fe/BC/M system means more Hads could be generated, thus improving the N2 selectivity. This study provides valuable insights into a novel approach for effective nitrate removal, offering a potential solution to the environmental challenges posed by excessive nitrate in wastewater, surface water and ground water.

Key biogeochemical processes and source apportionment of nitrate in the Bohai Sea based on nitrate stable isotopes

Excessive nitrate input is one of the primary factors causing nearshore eutrophication. This study applied the nitrate stable isotope techniques to analyse the biogeochemical processes and sources of nitrate in the Bohai Sea (BHS). The results showed that intensive NO3− assimilation probably occurred at surface in summer, while nitrification primarily occurred in the Yellow River diluted water. In autumn, regional assimilation and nitrification were still identified. For avoiding the interference from assimilation, the isotopic fractionations were further calculated as correction data for the quantitative analysis of nitrate sources. The river inputs were identified as the primary source of nitrate in the BHS in summer and autumn, accounting for >50 %, and the atmospheric deposition was the secondary source. This study provides quantitative data for evaluating the significance of river inputs to the nearshore nitrate, which will be beneficial to policy formulation on the BHS eutrophication control.

Research Advances of Groundwater Nitrate Pollution and Source Apportionment in China

Groundwater nitrate (NO3-) contamination in China has become a serious environmental problem, especially in agricultural production areas, which greatly affects the safety of drinking groundwater and requires urgent attention. In this study, the main sources of groundwater nitrate in China were reviewed, including atmospheric deposition, soil nitrogen, agricultural fertilization, and fecal sewage, among which fecal sewage and agricultural fertilization were the main reasons for the excessive groundwater nitrate. The application of hydrochemical analysis, multivariate statistical analysis, stable isotope tracer method, and microbial source tracking in the source apportionment of groundwater nitrate was summarized. All types of source apportionment methods had certain limitations. It is suggested that a variety of methods should be used to identify the source of groundwater nitrate, and the contribution rate of different pollution sources should be calculated using multivariate statistical analysis and isotope quantitative analysis models. The source apportionment of nitrate pollution has undergone a process from qualitative to quantitative research. At present, the SIAR and MixSIAR models based on δ15N-NO3-and δ18O-NO3- have been used widely to analyze the source of nitrate. However, due to the overlap of isotope characteristic values of different input end-members, the difference in δ15N-NO3-and δ18O-NO3- values under different spatial and temporal changes, and the influence of isotope fractionation in the process of nitrogen migration and transformation, the results calculated by the model remain uncertain. It is necessary to further optimize the analytical method of the model to obtain the source of nitrate pollution and its contribution rate more accurately to further aid in the scientific management of groundwater resources.

The Optimum Substrate Moisture Level to Enhance the Growth and Quality of Arugula (Eruca sativa)

Arugula (Eruca sativa Mill.) is a nutritious vegetable, commonly used in salads, known for its high glucosinolate content and various health benefits and flavors. However, arugulas may contain -excessive nitrate levels, potentially harmful to human health. We aimed to examine the effect of substrate moisture levels on the growth and quality of arugula under controlled irrigation conditions to investigate a proper irrigation practice for the quality production of arugula. The plants were cultivated using a sensor-based automated irrigation system to maintain the substrate volumetric water content (VWC) levels at 0.20, 0.30, 0.40, and 0.50 m3·m−3 over three weeks (vegetative stage). The treatment with VWC of 0.20 m3·m−3 resulted in reduced shoot growth, primarily attributed to drought-induced constraints on leaf expansion. Despite the initial reductions in stomatal conductance in arugulas subjected to lower VWC treatments, they eventually recovered and exhibited similar stomatal conductance levels across all VWC treatments 15 days after treatment, indicating acclimation to drought stress. The VWC treatment did not affect the nitrate and total glucosinolate contents of arugula, except for a decrease in glucoerucin content observed in the lowest VWC treatment. Maintaining a VWC level at 0.20 m3·m−3 could impair both the growth and quality of arugula due to severe drought conditions. Alternatively, maintaining the VWC at 0.30 m3·m−3 would ensure a high water use efficiency while securing the growth and quality of arugula.

Toxin production and transcriptomic response to nitrate concentrations in the toxic dinoflagellate Alexandrium tamarense

The bloom-forming dinoflagellate Alexandrium tamarense is one of the most important producers of paralytic shellfish poisoning toxins. Annually recurrent blooms of this dinoflagellate species is associated with the incremental nitrogen influx, especially excessive nitrate input. However, limited studies have been conducted on the toxin production and underlying molecular regulation mechanisms of A. tamarense under various nitrate (N) conditions. Therefore, toxin production and transcriptomic responses of this species were investigated. The toxin profile of A. tamarense was consistently dominated by the C2-toxins, and the cellular toxicity increased with N concentrations peaking at 9.23 ± 0.03 fmol/cell in the 883 μM N-added group. Under lower N conditions, expressions of two STX-core genes, sxtA and sxtG, were significantly down-regulated, suggesting that N regulated sxt expression and triggered responses related to toxin biosynthesis. Results of this study provided valuable insights into the ecophysiology of A. tamarense, enhancing our understanding of the occurrence of toxification events in natural environments.

‘Cropaganda’: Mythology of Corn Belt agriculture

Even as scholars have increasingly recognized the role of industrial agricultural practices in contributing to non-point source pollution, drinking water in the Corn Belt remains perilously contaminated with excess nitrates, which pose a significant risk to human health and the environment. A recent lawsuit filed by the city of Des Moines, Iowa against three upstream counties over chronic nitrate pollution sparked heated debate around the roles and responsibilities of agricultural production. Drawing on Barthes’ theory of mythology, this paper explores how three core myths influence agricultural management paradigms and practices that contribute to the water quality crisis in Iowa and shape how key stakeholders have responded (Barthes, R. 1972 [1957]. Mythologies. New York: Hill and Wang). This article relies on ethnographic data to explain agricultural nitrate pollution and the stalled progress on water quality improvement. Together these myths draw on post-enlightenment ideas of nature, security, and modernity to perpetuate productivist behavior, claim resources for conventional commodity agriculture, and impede widespread adoption of alternative agricultural practices. By identifying and interrogating each myth, I aim to reveal and complicate the inherent contradictions in its representation of reality to strip it of ideological function and, in doing so, cultivate opportunities to imagine and create an alternative system that benefits both people and the planet.

Ag nanofilm enhanced S-type Ag@AgCl/tubular g-C3N4/Ti photoanode visible light response photocatalytic fuel cell

In this study, based on Ag@AgCl/tubular g-C3N4 (Ag@AgCl/TCN) composite, Ag nanoparticles were deposited on its surface to form Ag nanofilm enhanced composite through photoreduction of excessive silver nitrate solution to obtain Ag nanofilm Ag@AgCl/TCN photocatalyst. Finally, Ag nanofilm Ag@AgCl/TCN/Ti photoanode was successfully prepared by silica-sol drop-coating method, and assembled with Cu2O/Cu cathode to construct a photocatalytic fuel cell (PFC). Ag nanofilm can not only enhance the light absorption and utilization of Ag@AgCl/TCN/Ti, but also extend its light response wavelength to visible light, and be used as an electron transfer medium to reduce internal resistance. The photocurrent density and the photoconversion efficiency of the Ag nanofilm/Ag@AgCl/TCN/Ti are 8.01 mA·cm−2 and 1.24%, respectively, which are 2.49 and 2.54 times those of the Ag@AgCl/TCN/Ti photoanode, respectively. The first-order kinetic constant and the maximum power density of the Ag nanofilm-coated Ag@AgCl/TCN/Ti-Cu2O/Cu PFC system are 0.064 min−1 and 46.37 μW·cm−2, respectively, which are 1.39 and 1.94 times those of the Ag@AgCl/TCN-Cu2O/Cu PFC system, respectively. In addition, it degraded more than 95% of rhodamine B, 72.68% of tetracycline and 54.25% of bisphenol A within 60 min. The excellent performance of Ag nanofilm/Ag@AgCl/TCN/Ti-Cu2O/Cu is due to the strengthening of Ag nanofilm and the formation of S-type heterojunctions between AgCl and TCN. Free radicals (•Cl, h+, •OH, •O2-) and non-radicals (1O2) are involved in the degradation reaction of RhB degradation. It is worth noting that 6% Ag nanofilm/Ag@AgCl/TCN/Ti-Cu2O/Cu has a positive effect on the production of •O2-, and its output is approximately 1.89 times that of the Ag@AgCl/TCN/Ti-Cu2O/Cu. A series of material characterization experiments have been completed and possible mechanisms of operation have been proposed. This study provides a new scheme for the design and preparation of high-efficiency photoanode of PFC.

Piped-slow-release calcium nitrate dosing: A new approach to in-situ sediment odor control in rural areas

Calcium nitrate addition is economically viable and highly efficient for the in-situ treatment of contaminated sediment and enhancement of surface water quality, particularly in rural areas. However, conventional nitrate addition technologies have disadvantages such as excessive nitrate release, sharp ammonium increase, and weakened sulfide oxidation efficiency owing to rapid nitrate injection into the sediment. To resolve these defects, we propose a piped-slow-release (PSR) calcium nitrate dosing method and investigate its treatment efficiency and underlying mechanisms. The results illustrated that PSR dosing had a longer half-life (t1/2 = 5.08 days) and a lower maximum apparent nitrate escape rate of 1.28 % than conventional nitrate injection and other dosing methods. In addition, the PSR managed the inorganic nitrogen release into the overlying water, and after the treatment, the nitrate, ammonium, and nitrite concentrations of 0 mg/L, 8.60 mg/L, and 0 mg/L on day 28 were close to those of the control group (0 mg/L, 8.76 mg/L, and 0 mg/L, respectively). Moreover, the PSR method maintained a moderate nitrate concentration of approximately 3000 mg/L in sediment interstitial water by its controlled-release design, thus greatly enhancing the sulfide oxidation efficiency by relieving the inhibitory effects of high nitrate concentrations, with 83.0 % sulfide being eradicated within 5 days. Sulfide-ferrous nitrate reduction (denitrification and dissimilatory nitrate reduction to ammonium) genera (e.g., Sulfurimonas, Thiobacillus, and Thioalkalispira) were successively enhanced and dominated the microbial community, and the related functional genes displayed high relative abundances. These results imply that the PSR dosing method for calcium nitrate, characterized by flexible operation, high efficiency, low cost, and controllable processes, is appropriate for remediating black-odorous sediment in rural areas.

In‐Situ Characterization Technologies for Electrocatalytic Reduction nitrate to Ammonia on Copper‐Based Catalysts

AbstractThe excess nitrate (NO3−) in water mainly comes from agricultural fertilization and industrial wastewater, which breaks the nitrogen balance and poses a serious threat to the environment and human health. Driven by renewable energy, the electrocatalytic NO3− reduction to ammonia (NH3) (ENO3RA) is an environmentally friendly and sustainable technology. Due to its special structure, copper (Cu) is currently one of the best catalysts for ENO3RA, but the reaction mechanism and the structure–activity relationships of catalysts are still not clear enough. In‐situ characterization is a powerful tool to gain insight into the reaction process. This review introduces several types of in‐situ techniques such as in‐situ XAS, in‐situ FTIR and in‐situ DEMS, summarizes five pathways for converting *NO as the key intermediate to NH3 during ENO3RA on Cu‐based catalysts. The research progress of Cu‐based electrocatalysts in recent years is sorted out from the aspects of composition and structure, and the catalytic mechanisms are discussed with the help of in‐situ characterization technologies. This review would be of help to provide reference characterization methods for exploring the mechanism and the design of electrocatalysts for ENO3RA.

Hydrophobic barrier-free laminated paper-based analytical device (LPAD) using a diameter-based measurement for determination of iodide in pharmaceutical products

This work presents, for the first time, an exploitation of an argentometric Mohr's method for iodide detection using diameter-based measurement on laminated paper-based analytical device (LPAD). Our LPAD is simplified fabricated with no required hydrophobic barrier for patterning a detection flow channel. In the absence of a flow channel, the liquid is imbibed radially into the filter paper outward from the small center inlet hole. This imbibition leads to the measurement of diameter after the formation of the precipitation product. For LPAD, a rectangular piece of Whatman filter paper is cut and positioned between a top laminating sheet, which has a hole punched for inlet, and a bottom laminating sheet. The central inlet hole enables access to the liquid on the paper. For iodide analysis, silver nitrate is dispensed first, followed by the iodide standard/sample. This process leads to the formation of pale-yellow silver iodide solids on the paper. The chromate indicator solution is subsequently loaded to the paper. The color of the chromate solution imparts a tint to the circular band of silver iodide solids, resulting in an intense yellow color. When the silver iodide precipitates are stained, the chromate solution typically serves as an indicator, chemically reacting to an excess silver nitrate solution moistened on paper. This reaction generates an outer reddish-brown ring of silver chromate. The distinct color contrast between the intense yellow (tinted silver iodide) and reddish-brown (silver chromate) allows for clear observation of the measurement boundary, facilitating diameter-based measurements of the circular band of silver iodide. We demonstrate the applicability in analysis of pharmaceutical KI tablets. The quantitative results obtained from diameter-based measurement LPAD show good agreement with those obtained from the potentiometric method. Our hydrophobic barrier-free LPAD is rapid, cost-effective, low liquid consumption and applicable for onsite analysis.

Tomato SlNTRB improved excess nitrate stress tolerance by alleviating the oxidative damage in transgenic tobacco

Tomato SlNTRB improved excess nitrate stress tolerance by alleviating the oxidative damage in transgenic tobacco

Enhanced biosorptive incarceration of nitrate from aqueous solutions using novel green adsorbent: Performance optimization and mechanistic enlightenment

Excess nitrate contamination was lucratively addressed using the novel adsorbents prepared from waste seed pods of the Guilandina bonduc (L.) plant. Adsorbents BFP and EBFP (amino-grafted) were synthesized following a green pathway of thermo-chemical transformation. Adsorbents were successfully implemented for nitrate adhesion from natural and wastewater. The morphology of the adsorbents was studied using SEM-EDS, TGA, XRD, FTIR-ATR, and BET, including zeta potential and point of zero charges. The batch mode nitrate removal study was carried out using a colorimeter. The optimum efficiency in nitrate trapping was found to be 173.8 mg/g (EBFP) and 78.74 mg/g (BFP). The adsorption efficiency of the sorbents was further optimized using the RSM-CCD and found to be suitable. The batch sorption study was also supported by the column study with a breakthrough curve at 90% (EBFP) and 60% (BFP) for the regeneration study. The optimum value for EBFP was attained at an initial nitrate concentration of 110 mg/L, pH∼8, and a dosage of 12 g/L at room temperature within 75 minutes of contact. The Freundlich isotherm model and pseudo-second-order kinetics fit satisfactorily with the sorption trends followed by other isotherm and kinetic models. The influence of various competing ions e.g., PO43−, Cl−, HCO3−, SO42−etc., on nitrate adsorption study was investigated. The physicochemical sorption of nitrate was confirmed, and a plausible mechanism has been suggested accordingly. The field sample experiment, including the start-up opportunities with this work, has been highlighted. EBFP could be an excellent sorbent of choice at present that is ready for commercialization.