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This document describes the content, purpose, methods and uses of the nutrient concentration data set for the UC Santa Barbara North Campus Open Space (NCOS) Restoration Project. Nutrient concentrations have been taken as one way to assess the value of the newly established wetland and understand the impact that storms have on the system.

Nitrate, the form of nitrogen often associated with kelp growth, is typically low in summer during periods of high macroalgal growth. More ephemeral, regenerated forms of nitrogen, such as ammonium and urea, are much less studied as sources of nitrogen for kelps, despite the relatively high concentrations of regenerated nitrogen found in the Southern California Bight, where kelps are common. To assess how nitrogen uptake by kelps varies by species and nitrogen form in southern California, USA, we measured uptake rates of nitrate, ammonium, and urea by Macrocystis pyrifera and Eisenia arborea individuals from four regions characterized by differences in nitrogen availability-Orange County, San Pedro, eastern Santa Catalina Island, and western Santa Catalina Island-during the summers of 2021 and 2022. Seawater samples collected at each location showed that overall nitrogen availability was low, but ammonium and urea were often more abundant than nitrate. We also quantified the internal %nitrogen of each kelp blade collected, which was positively associated with ambient environmental nitrogen concentrations at the time of collection. We observed that both kelp species readily took up nitrate, ammonium, and urea, with M. pyrifera taking up nitrate and ammonium more efficiently than E. arborea. Urea uptake efficiency for both species increased as internal percent nitrogen decreased. Our results indicate that lesser-studied, more ephemeral forms of nitrogen can readily be taken up by these kelps, with possible upregulation of urea uptake as nitrogen availability declines.

Castellaniella species have been isolated from a variety of mixed-waste environments including the nitrate and multiple metal-contaminated subsurface at the Oak Ridge Reservation (ORR). Previous studies examining microbial community composition and nitrate removal at ORR during biostimulation efforts reported increased abundances of members of the Castellaniella genus concurrent with increased denitrification rates. Thus, we asked how genomic and abiotic factors control the Castellaniella biogeography at the site to understand how these factors may influence nitrate transformation in an anthropogenically impacted setting. We report the isolation and characterization of several Castellaniella strains from the ORR subsurface. Five of these isolates match at 100% identity (at the 16S rRNA gene V4 region) to two Castellaniella amplicon sequence variants (ASVs), ASV1 and ASV2, that have persisted in the ORR subsurface for at least 2 decades. However, ASV2 has consistently higher relative abundance in samples taken from the site and was also the dominant blooming denitrifier population during a prior biostimulation effort. We found that the ASV2 representative strain has greater resistance to mixed metal stress than the ASV1 representative strains. We attribute this resistance, in part, to the large number of unique heavy metal resistance genes identified on a genomic island in the ASV2 representative genome. Additionally, we suggest that the relatively lower fitness of ASV1 may be connected to the loss of the nitrous oxide reductase (nos) operon (and associated nitrous oxide reductase activity) due to the insertion at this genomic locus of a mobile genetic element carrying copper resistance genes. This study demonstrates the value of integrating genomic, environmental, and phenotypic data to characterize the biogeography of key microorganisms in contaminated sites.

As the most abundant element in the atmosphere, nitrogen is a vital nutrient for plant growth. Nitrate is the main form of nitrogen uptake by plants. Although nitrates are relatively low in toxicity, if they accumulate in vegetables can be converted to nitrite and nitrous acids in the human body. This study collected 83 tomato and 40 onion samples cultivated in Fars province; then nitrate concentration was determined by an HPLC, also cadmium (Cd) and lead (Pb) concentration by an atomic absorption instrument. The Cd and Pb in samples were below the detection limits (LOD) of the techniques used. However, the nitrate concentration in tomato and onion samples from Fars province varied from 0 to 154.40 mg/kg and 0 to 317.20 mg/kg, respectively. The mean chronic daily intake (CDI) for tomatoes in children, women and men was 0.1188, 0.0375, and 0.0366, and for onions, 0.1899, 0.0605, and 0.0447, respectively. On the other hand, the 95th percentile hazard index in the probabilistic method for nitrate for children, women, and men were 0.81, 0.26, and 0.21, respectively. Also, nitrate concentration in onion for children and tomatoes in both men and women was identified as the most considerable parameter in assessing the non-carcinogenic risk of nitrate. This study showed that the amount of nitrate in some samples of tomatoes and onions was not within the acceptable international standard limits. Therefore, monitoring the nitrate concentration in these high-consumption vegetables is crucial. [ABSTRACT FROM AUTHOR]

In this work, we describe a simple strategy for the preparation of a low-cost electrode material based on polypyrrole (PPy) film grown on an insulating cellulosic paper substrate via in-situ oxidative polymerisation technique and functionalised by silver nanoparticles (AgNPs) uniformly dispersed on its surface. The properties of the obtained AgNPs-PPy composites were characterised using X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis. The electrocatalytic activity of the prepared electrode was investigated for the electroreduction of nitrate using cyclic voltammetry in 0.1 M KOH solution. Results demonstrated that the incorporation of AgNPs into the PPy matrix improves significantly the catalytic behaviour of this film. The effect on the electrode response of the amount of the incorporated AgNPs was also investigated. This paper highlights a simple procedure for the making of low-cost paper electrodes for the efficient reduction of nitrates. [ABSTRACT FROM AUTHOR]

The current study was conducted to assess the concentration of nitrate (NO3) and fluoride (F), and associated health risks in the four tehsils of district Khyber i.e. Jamrud, Bara, Landi Kotal, and Mula Gori. A total of 61 samples from various groundwater sources were collected and analysed. Groundwater results showed that the mean values of F were 0.86, 0.83, 0.67, and 2.9 mg/l, and that of NO3 15.8, 8.38, 9.76, 4.22 mg/l in Bara, Jamrud, Landi Kotal, and Mula Gori, respectively. Furthermore, health risk assessment was carried out for different age groups i.e. adult male/female (66 years), teens male/female (16 years), and children (6 years). The results revealed that HI values of F through groundwater consuption was > 1 in 39.3% and 16.4% of the samples for children and other age groups (teen and adults), respectively. Similarly, HI values of NO3 for children, adults, and teens were higher than the threshold value in 62.3%, 34.4%, and 39.3% of the samples, respectively. The principal component analysis (PCA)revealed that the predominant source of F enrichment in groundwater was geogenic. However, for the NO3 proportion in the region, the potential causes were agricultural activities. Results revealed that the region requires immediate attention, and remedial measures must be implemented to protect residents from the adverse effects of NO3 and F in the district of Khyber. [ABSTRACT FROM AUTHOR]

The nanofiltration (NF) membrane has not been extensively competent for rejection of monovalent ions (such as Cl− and NO3−), and the strategy for enhancing monovalent ion rejection and permeation flux still faces a significant challenge. Herein, based on our previous polyethersulfone (PES)‐type NF membrane (NF‐0), two novel NF membranes were fabricated with additional incorporations of 2,2′‐benzidinedisulfonic acid (BDSA) and forward osmotic extraction solution‐functioned nanoparticles (MNPs) to remove nitrate from the aqueous solution. The fabricated NF‐BDSA membrane with introduction of BDSA in ultrathin layer displays a significant nitrate rejection of 92.2% and an acceptable permeation flux of 21 L m−1 h−1 at 0.6 MPa. As anticipated, the obtained NF‐MNPs1.0 membrane with additional incorporation of MNPs (1.0 wt% addition) in the substrate layer of NF‐BDSA membrane achieves further improvements in nitrate rejection (95%) and water permeability (32.3 L m−1 h−1); encouragingly, this membrane exhibits comparable monovalent ion rejection and permeation flux to reverse osmosis membrane under relatively low pressure. Compared with those of NF‐0 membrane, the permeation flux and nitrate rejection of NF‐MNPs1.0 membrane increase by 111.1% and 6.1%, respectively. Moreover, the superior performances of endurance, antifouling and chlorine resistance of NF‐MNPs1.0 membrane demonstrate its expectable perspective of potential engineering applications. [ABSTRACT FROM AUTHOR]

Nitrogen (N) fertilization is essential to maximize crop production. However, around half of the applied N is lost to the environment, causing water and air pollution and contributing to climate change. Understanding the natural genetic and metabolic basis underlying plants N use efficiency is of great interest to attain an agriculture with less N demand and thus more sustainable. The study of ammonium (NH4+) nutrition is of particular interest, because it mitigates N losses due to nitrate (NO3–) leaching or denitrification. In this work, we studied Brachypodium distachyon , the model plant for C3 grasses, grown with NH4+ or NO3– supply. We performed gene expression analysis in the root of the B. distachyon reference accession Bd21 and examined the phenotypic variation across 52 natural accessions through analyzing plant growth and a panel of 22 metabolic traits in leaf and root. We found that the adjustment of primary metabolism to NH4+ nutrition is essential for the natural variation of NH4+ tolerance, notably involving NH4+ assimilation and phosphoenolpyruvate carboxylase (PEPC) activity. Additionally, genome-wide association studies (GWAS) indicated several loci associated with B. distachyon growth and metabolic adaptation to NH4+ nutrition. We found that the GDH2 gene was associated with the induction of root glutamate dehydrogenase activity under NH4+ nutrition and that two genes encoding malic enzyme were associated with leaf PEPC activity. Altogether, our work underlines the value of natural variation and the key role of primary metabolism to improve NH4+ tolerance. [ABSTRACT FROM AUTHOR]

Introduction: The wound healing in diabetes is hindered and prolonged due to long-term inflammation, oxidative stress damage, and angiogenesis disorders induced by high glucose status. The management of such difficult-to-treat wounds continues to pose a significant challenge in clinical treatment. Dietary nitrate, commonly found in greens such as beets and spinach, acts as a nutritional supplement and is metabolized in the body through the salivary nitrate-nitrite-NO pathway. This pathway plays a crucial role in various physiological functions, including enhancing blood flow and attenuating inflammation. Methods: In this study, we established a diabetic rat wound model. Forty-eight rats were randomly divided into six groups (n = 8): the Con group, the Con + Nitrate group, the STZ group, the STZ + NaCl group, the STZ + rhEGF group, and the STZ + Nitrate group. Skin wound healing was assessed on the day of surgery and on postoperative days 3, 7, 10, and 14. Specimens were taken on days 7 and 14 post-surgery for relevant tests. Results: We found that dietary nitrate could accelerate skin wound healing by promoting angiogenesis and increasing blood perfusion. Significantly, dietary nitrate also regulated glucose and lipid metabolism and exhibited anti-inflammatory and antioxidant properties. Discussion: These findings provide a novel theoretical basis for managing wounds in diabetic individuals, indicating the broad potential of dietary nitrate in future clinical applications. [ABSTRACT FROM AUTHOR]

Stream bryophytes (mosses and liverworts) are widely recognized as important macroinvertebrate habitats, but their overall role in the stream ecosystem, particularly in nutrient cycling, remains understudied. Hubbard Brook Experimental Forest in New Hampshire, USA, contains some of the most extensively researched streams in the world, yet few studies mention their bryophytes. Perhaps this is because early estimates place bryophyte coverage in these streams at an insignificant 2%. However, data from 2019 show that contemporary coverage ranges from 4 to 40% among streams. To investigate how stream bryophyte cover may be changing over time and influencing stream nutrient stocks, we conducted field surveys, measured the mass of organic and inorganic bryophyte contents, and quantified nutrient uptake with bottle incubations of bryophyte mats. This study marks a novel attempt to map stream bryophyte coverage with estimates of C, P, and N stocks and fluxes. From our 2022 field surveys, we found that median bryophyte coverage varied across streams in the same catchment (0–41.4%) and shifted from just 3 y prior. We estimate that these bryophyte mats stored between 14 and 414 g of organic matter per m2 of stream in the form of live biomass and captured particulates. Within 12 h of light incubation, 35 out of 36 bryophyte clump samples sorbed peak historical water-column concentrations of PO43–, as measured in the Hubbard Brook stream chemistry record. In Bear Brook, our scaled estimate of bryophyte mat NO3– uptake (2.3 g N/y) constitutes a substantial portion of previously estimated whole-stream NO3– uptake (12 g N/y). Cumulatively, our data demonstrate that bryophytes and their associated mineral substrates and biota—known as the bryosphere—are crucial in facilitating headwater stream nutrient cycling. These bryospheres may contribute significantly to interannual variability in stream nutrient concentrations within nutrient-poor streams, especially in climate-sensitive regions. [ABSTRACT FROM AUTHOR]

Nitrogen mainly exists as nitrate in aqueous environments. In karst areas, nitrate pollution caused by anthropogenic activities severely endangers aqueous systems. In order to identify nitrate sources, nitrate in the cave water of Mahuang Cave was comprehensively analysed using hydrochemistry, δ15N-δ18O isotopes and stable isotope analysis in R. The results indicate that the nitrate content in the cave water presented insignificant seasonal variations but significant spatial variations. Compared with the variation of δ15N-NO3−, the seasonal variation of δ18O-NO3− was positive (2.68‰) in the dry season and negative (−0.52‰) in the wet season. The variation of NO3− and Cl− and the isotopes of NO3− (δ15N, δ18O) suggest multiple sources of NO3− in the water. The average contribution of different nitrate sources in the karst cave water was assessed by the SIAR model: chemical fertilisers (46.29%) > soil nitrogen (30.57%) > manure & sewage (14.14%) > atmospheric precipitation (9.14%) in the dry season and chemical fertilisers (61.86%) > soil nitrogen (20.29%) > manure & sewage (12.43%) > atmospheric precipitation(5.57%) in the wet season. The contribution in dry and wet seasons was dominated by chemical fertilisers and soil nitrogen. [ABSTRACT FROM AUTHOR]

Background: Nitrate (NO3−) has been suggested as a prebiotic for oral health. Evidence indicates dietary nitrate and nitrate supplements can increase the proportion of bacterial genera associated with positive oral health whilst reducing bacteria implicated in oral disease(s). In contrast, chlorhexidine-containing mouthwashes, which are commonly used to treat oral infections, promote dysbiosis of the natural microflora and may induce antimicrobial resistance. Methods: A systematic review of the literature was undertaken, surrounding the effects of nitrate on the oral microbiota. Results: Overall, n = 12 in vivo and in vitro studies found acute and chronic nitrate exposure increased (representatives of) health-associated Neisseria and Rothia (67% and 58% of studies, respectively) whilst reducing periodontal disease-associated Prevotella (33%). Additionally, caries-associated Veillonella and Streptococcus decreased (25% for both genera). Nitrate also altered oral microbiome metabolism, causing an increase in pH levels (n = 5), which is beneficial to limit caries development. Secondary findings highlighted the benefits of nitrate for systemic health (n = 5). Conclusions: More clinical trials are required to confirm the impact of nitrate on oral communities. However, these findings support the hypothesis that nitrate could be used as an oral health prebiotic. Future studies should investigate whether chlorhexidine-containing mouthwashes could be replaced or complemented by a nitrate-rich diet or nitrate supplementation. [ABSTRACT FROM AUTHOR]

The objective of this systematic review and dose‒response meta-analysis was to assess the associations between the dietary consumption of nitrate and nitrite and the risk of gastric and esophageal cancer. MEDLINE, Scopus, Embase, Web of Science, Proquest, and Google Scholar were searched until April 1, 2024. Articles were selected by two independent researchers on the basis of the inclusion and exclusion criteria. Data regarding the study design, type of exposure and outcomes, intervals of intake of nitrate or nitrite in each layer, OR/RR/HR of the relationship for each layer of intake, total sample size, and number of cases of gastric or esophageal cancer were extracted. The certainty of the evidence was rated via the GRADE method. The pooled odds ratios, risk ratios, and dose‒response analyses were calculated via Stata version 17.0. The best-fit dose‒response model was assessed by the P value for linearity and nonlinearity. Study heterogeneity was assessed via the I2 and Q tests. We found 2124 nonredundant studies, 234 of which were potentially relevant. Eighteen articles met the inclusion criteria and were included in the review. The results of the meta-analysis revealed a significant positive association between nitrite intake and gastric cancer in both case‒control studies (OR = 1.29, 95 % CI = 1.09–1.52, P value = 0.001, I2 = 1.91 %) and cohort studies (RR = 1.17, 95 % CI = 1.00–1.37, P value = 0.04, I2 = 0.00 %). In addition, case‒control studies revealed a nonsignificant inverse association between nitrate intake and gastric cancer incidence (OR = 0.71, 95 % CI = 0.50–1.01, P value = 0.06, I2 = 74.89 %), and cohort studies (RR = 0.89, 95 % CI = 0.73–1.09, P value = 0.27, I2 = 0.00 %). Case‒control studies also revealed no significant correlation between nitrite intake and esophageal cancer incidence (OR = 1.48, 95 % CI = 0.91 to 2.42, P value = 0.12, I2 = 0.001 %). Nitrites correlated linearly with gastric cancer (linearity P value = 0.001). The most appropriate fit models for the relationship between nitrate and gastric cancer were both piecewise linear and natural polynomial regression (quadratic) models (P values = 0.003 and 0.005, respectively). There was no significant publication bias. According to this meta-analysis, high consumption of nitrites was associated with an increased risk of gastric cancer in case‒control and cohort studies with a linear regression model, and dietary nitrate intake was not associated with the risk of gastric cancer in either case‒control or cohort studies. These findings are inconclusive and require confirmation in future prospective studies with robust methodologies and adjustments for potential confounders. • High consumption of nitrites was associated with an increased risk of gastric cancer, but still require confirmation in future studies with robust methodology. • High nitrite intake was significantly associated with an increased risk of gastric cancer,but still require confirmation in studies with robust methodology. • No significant association was found between dietary nitrate intake and gastric cancer risk. • Nitrite intake showed a linear relationship with gastric cancer risk, However further investigation is still needed. • This research has significant implications for public health policymakers. [ABSTRACT FROM AUTHOR]

Background: The oral microbiome‐dependent nitrate (NO3−)–nitrite (NO2−)–nitric oxide (NO) pathway may help regulate blood pressure. NO2−‐producing bacteria in subgingival plaque are reduced in relative abundance in patients with untreated periodontitis compared with periodontally healthy patients. In periodontitis patients, the NO2−‐producing bacteria increase several months after periodontal treatment. The early effects of periodontal treatment on NO2−‐producing bacteria and the NO3−–NO2−–NO pathway remain unknown. The aim of this study was to determine how periodontal treatment affects the oral NO2−‐producing microbiome and salivary NO3− and NO2− levels over time. Methods: The subgingival microbiota of 38 periodontitis patients was analysed before (baseline [BL]) and 1, 7 and 90 days after periodontal treatment. Changes in NO2−‐producing bacteria and periodontitis‐associated bacteria were determined by 16s rRNA Illumina sequencing. Saliva samples were collected at all‐time points to determine NO3− and NO2− levels using gas‐phase chemiluminescence. Results: A significant increase was observed in the relative abundance of NO2−‐producing species between BL and all subsequent timepoints (all p < 0.001). Periodontitis‐associated species decreased at all timepoints, relative to BL (all p < 0.02). NO2−‐producing species negatively correlated with periodontitis‐associated species at all timepoints, with this relationship strongest 90 days post‐treatment (ρ = −0.792, p < 0.001). Despite these findings, no significant changes were found in salivary NO3− and NO2− over time (all p > 0.05). Conclusions: Periodontal treatment induced an immediate increase in the relative abundance of health‐associated NO2−‐producing bacteria. This increase persisted throughout periodontal healing. Future studies should test the effect of periodontal treatment combined with NO3− intake on periodontal and cardiovascular health. [ABSTRACT FROM AUTHOR]

Water quality management is a critical factor in recirculating aquaculture systems (RASs) that significantly influences the growth and health of fish. The present research aimed to investigate the effects of humic acid (HA) added at three concentrations (0, 1.5, and 3 mg L−1) to water on total ammonia nitrogen (TAN) removal efficiency of biofilter unit, growth performance, and some blood biochemical indices of Nile tilapia (Oreochromis niloticus) in a water recirculating system. The Nile tilapia fish with an average weight of 83.44 ± 1.32 g were cultured in nine individual experimental units for 30 days. The removal efficiency of the biofilter for TAN reached to 81.23% and 82.76% in the systems with 1.5 mg L−1 and 3 mg L−1 HA, respectively. The systems with HA had higher nitrate (NO3−) concentration than the the system without HA (control) (p < 0.05). HA adding to the water increased the fish final body weight and the specific growth rate (SGR) compared to the control group (p < 0.05). The feed conversion ratio (FCR) in the HA-groups was significantly lower than the control (p < 0.05). The highest crude protein content of muscle tissue was observed in the fish cultured in the system with 3 mg L−1 HA (p < 0.05). There were no significant differences in the plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) concentrations among treatment groups (p > 0.05). The plasma glucose concentration was significantly lower in the fish exposed to HA compared to the control (p < 0.05). The highest plasma triglyceride concentration was recorded in the HA-3 mg L−1 (p < 0.05). These results indicated that the addition of low-cost commercial HA to RASs has a high potential to improve water quality and fish growth performance. [ABSTRACT FROM AUTHOR]

Vegetable soybean has high nutritional value and offers functional benefits to human body. However, its use in cooking is still limited, mainly due to the lack of knowledge about its properties. In addition, the availability of cultivars for human consumption is reduced. Therefore, this study was conducted in Botucatu, Brazil, to assess the potential of grain soybean (GS) and dual-purpose soybean (DPS) cultivars for consumption as vegetable soybean (VS). Pods were harvested at R6 stage, and the contents of bioactive compounds (total phenolic compounds, flavonoids, antioxidant activity and proteins) and antinutritional components (nitrates, oxalate, alkaloids and tannins) were evaluated. The cultivars showed the same protein content, not differing statistically from each other, as well as for nitrate and oxalate. The content of phenolic compounds and total antioxidant activity of the SG cultivar differed statistically from the content of the DPS and VS cultivars, respectively. According to the results, the GS cultivar, with pods harvested at R6 stage, showed nutraceutical quality and contents of antinutritional compounds similar to those of the two cultivars proposed for the vegetable soybean. [ABSTRACT FROM AUTHOR]

Long-term effects of coronavirus disease 2019 (long COVID) develop in a substantial number of people following an acute COVID-19 episode. Red beetroot juice may have positive effects on multiple pathways involved in long COVID. The aim of this pilot study was to explore the impact of beetroot juice supplementation on physical function, gut microbiota, and systemic inflammation in adults with long COVID. A single-center, double-blind, placebo-controlled randomized trial was conducted to test the effects of 14 days of beetroot juice supplementation, rich in nitrates and betalains, on functional and biological outcomes in adults aged between 20 and 60 years with long COVID. Participants were randomized 1:1 to receive either daily oral supplementation with 200 mL beetroot juice (∼600 mg nitrate) or placebo (∼60 mg nitrate) for 14 days. The primary endpoint was the change from baseline to day 14 in a fatigue resistance test. Secondary outcomes included the distance walked on the 6-min walk test, handgrip strength, and flow-mediated dilation. Secondary endpoints also included changes from baseline in circulating inflammatory mediators and metagenomic and fecal water metabolomic profiles. Partial least squares discriminant analysis (PLS−DA) models were built to evaluate the differences in biological variables associated with the interventions. Thirty-one participants were randomized in the study. Twenty-five of them (median (interquartile range) age 40 (10), 14 [56 %] women), received either beetroot juice (15) or placebo (10) and completed the study. At 14 days, fatigue resistance significantly improved from baseline (mean difference [standard error]: +21.8 [3.7] s; p < 0.001) with no significant differences between intervention groups. A significant increase from baseline in the distance walked on the 6-min walk test was observed (mean difference [standard error]: +30.0 [9.4] m; p = 0.03), which was not different between groups. Flow-mediated dilation did not differ between participants who received beetroot juice and those on placebo. PLS–DA models allowed correct classification of participants with 92.2 ± 4.4 % accuracy. Those who ingested red beetroot juice had a greater abundance of bacteria with well-known beneficial effects, including Akkermansia , Oscillospira , Prevotella , Roseburia , Ruminococcaceae , and Turicibacter , compared with placebo. Participants allocated to beetroot juice supplementation were also characterized by significantly higher levels of fecal nicotinate, trimethylamine, and markers of beetroot juice intake (e.g., 5,6-dihydroxyindole). Finally, higher levels of interferon gamma and macrophage inflammatory protein-1β were found in participants who consumed beetroot juice. Beetroot juice supplementation for two weeks did not to induce significant improvements in functional outcomes in adults with long COVID compared with placebo. Beneficial effects were observed in both gut microbiota composition (i.e., increase in probiotic species) and inflammatory mediators. Trial was registered under ClinicalTrials.gov. Identifier no. NCT06535165. [ABSTRACT FROM AUTHOR]

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The eastern Niger Delta region in Nigeria is a hotspot for reactive nitrogen pollution due to extensive animal husbandry, pit latrine usage, and agricultural practices. Despite the high level of human activity, the sources and processes affecting nitrogen in groundwater remain understudied. Groundwater nitrate (NO3−) concentrations are highly variable, with some areas recording values well above the safe drinking water threshold of 50 mg/L. This is particularly true near municipal sewage systems. Elevated nitrite (NO2−) and ammonium (NH4+) concentrations were also detected in the study area. Sewage analysis revealed NO3− concentrations ranging from 1 to 145 mg/L, NO2− from 0.2 to 2 mg/L, and notably high NH4+ concentrations. A comparison of major ions indicated that 71%, 90%, 87%, and 92% of groundwater samples surpassed reference site levels for calcium (Ca2+), sodium (Na+), potassium (K+), and chloride (Cl−), respectively, pointing to sewage as a likely source of contamination. The NO3−/Cl− ratios at several sites suggested that most groundwater NO3− originates from human waste. Stable isotope analysis of NO3− showed a general enrichment in 15N and, in some cases, a depletion in 18O, indicating that the NO3− originates from sewage-derived NH4+ nitrification. Although denitrification, a process that reduces NO3−, is present, the high dissolved oxygen (DO) and NO3− levels in the groundwater suggest that denitrification is insufficient to fully mitigate NO3− pollution. Consequently, there is a risk of NO3− leaching from shallow aquifers into the Niger Delta's surface waters and ultimately into the coastal ocean. [ABSTRACT FROM AUTHOR]

Increasing nitrate concentration on surface and groundwater due to anthropogenic activities is an environmental concern. In this study, Tg(fli1: EGFP) zebrafish embryos were exposed to nitrate (NO3−) and nitrite (NO2−), and their cardiovascular development were investigated. Exposure to 10 mg/L NO3-N and 1 and 10 mg/L NO2-N decreased heart rate at 48–96-h post-fertilization (hpf), ventricular volume, and red blood cell flow rate at 96 hpf. Similar concentrations increased the number of embryos and larvae with pericardial edema and missing intersegmental and parachordal vessels in the caudal region at 48–96 hpf. Addition of ICI 182,720 (ICI) reversed the effects of nitrate and nitrite, suggesting estrogen receptors (ER) are involved. 10 mg/L NO3-N and 1 mg/L NO2-N decreased cardiovascular-related genes, gata4,5,6, hand2, nkx2.5, nkx2.7, tbx2a, tbx2b, and fgf1a. Gene expressions of ovarian aromatase and brain aromatase (cyp19a1a and cyp19a1b, respectively) decreased in the exposed groups, whereas ERs (esr1, esr2a, and esr2b) and nitric oxide synthase 2a (nos2a) increased. The effects on gene expression were also reversed by addition of ICI. Taken together, nitrate and nitrite disrupt cardiovascular system through ER in developing zebrafish, implying that environmental nitrate and nitrite contamination may be harmful to aquatic organisms. [ABSTRACT FROM AUTHOR]

Electrocatalytic ammonia oxidation reaction (eAOR) is of significance to ammonia fuel economy and the production of valuable N-containing products, such as nitrite, nitrate and hydrazine. The study of well-defined molecular catalysts offers rich insights in terms of the detailed mechanism of ammonia oxidation. This review analyzes the thermodynamics of ammonia oxidation reactions and summarizes the current progress in molecular electrocatalysts in this booming field. We emphasized the factors that influence the selectivity of products and further discussed the challenges in designing efficient catalysts. [ABSTRACT FROM AUTHOR]

Six 0.1‐ha earthen ponds with 45 kW/ha of aeration capacity were stocked with hybrid catfish (Ictalurus punctatus x I. furcatus) ranging from 15,000 to 90,000 fish ha−1 in 15,000 fish ha−1 increments to analyze the effect of nitrogen loading on ammonia accumulation and fish production. Minimum dissolved oxygen (DO) concentration was maintained above 3.0 mg O2 L−1 to prevent hypoxia‐induced appetite reduction. Stocking density did not impact survival but decreased average fish harvest weight and increased food conversion ratio (FCR). Gross production increased with stocking density and ranged from 7249 to 35,674 kg ha−1. Average total (TAN) and un‐ionized ammonia (NH3) were not different among stocking densities despite greater nitrogen inputs in ponds with higher feeding rates. Nitrite (NO2−) and nitrate (NO3−) concentrations were significantly higher in ponds with higher stocking densities, suggesting that nitrification increased with nitrogen loading. Phytoplankton assimilation of ammonia is the primary ammonia removal process in traditional catfish ponds with modest fish densities and feeding rates. However, in intensively aerated ponds with high feeding rates, nitrification can become an important process for ammonia removal. These data indicate that small earthen hybrid catfish ponds with high aeration capacities can increase catfish production without ammonia accumulating. [ABSTRACT FROM AUTHOR]

Nitrate is a well‐known regulator of several processes in plants, including seed germination. It generally induces germination, but its effect is species‐specific, and germination of some species is even inhibited. It is not clear what drives these differences. Nevertheless, it is striking that the germination of initially mycoheterotrophic orchids is generally inhibited by nitrate, indicating that this may be an adaptive trait allowing the seeds to detect sites with low nutrient availability, favourable for mycoheterotrophic plants. Whether this unusual negative response to nitrate is a general feature of mycoheterotrophic plant germination remains unknown. We focused on the family Ericaceae, which contains lineages that are either fully or initially mycoheterotrophic together with autotrophic ones, and we tested the germination response of selected species to nitrate. We found high variability in the germination responses even within members of this family. Fully and initially mycoheterotrophic species reacted more negatively to nitrate compared to autotrophic species. However, the species responses to nitrate also strongly correlated with seed dimensions. As a control, we also tested responses to another common nitrogen form, ammonium ion, but these showed little or no correlations with the tested predictors indicating that the observed germination responses are specific to nitrate. Two factors may be responsible for the negative response of mycoheterotrophic species of both Ericaceae and orchids to nitrate: seed size and the mode of carbon acquisition (mycoheterotrophy); nevertheless, both factors are closely linked. Thus, mycoheterotrophic plants in general, which nearly all produce tiny dust seeds, are likely to be negatively affected by nitrate. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

An efficient oxidation of stilbenes to α‐diketones co‐catalyzed by bismuth nitrate and iodine is reported. The utilization of molecular oxygen as a terminal oxidant and water as the reaction solvent provides a low‐cost and environmentally friendly approach to preparing the α‐diketone derivatives from readily available stilbenes. Isotope labeling experiments suggest that the two oxygen atoms of the α‐ diketone products mainly originate from water. The method displays high functional group tolerance and we have demonstrated a concise route for preparing trifenagrel and HIV‐1 integrase inhibitors from 1,2‐diphenylethene. [ABSTRACT FROM AUTHOR]

Photocatalytic utilization of methanol and nitrate as carbon and nitrogen sources for the direct synthesis of amino acids could provide a sustainable way for the valorization of green "liquid sunlight" and nitrate waste. In this study, we develop an efficient photochemical method to synthesize glycine directly from methanol and nitrate, which cascades the C−C coupling to form glycol, nitrate reduction to NH3, and finally C−N coupling to generate glycine. Interestingly, the involved photocatalytic tandem reactions show a synergistic effect, in which the presence of nitrate is the dominant factor to enable the overall reaction and reach high synthetic efficiency. Ba2+−TiO2 nanoparticles are confirmed as a feasible and efficient catalyst system for the photosynthesis of glycine with a remarkable glycine photosynthesis rate of 870 μmol gcat−1 h−1 under optimal conditions. This work establishes a novel catalytic system for amino acid synthesis from methanol and nitrate under mild conditions. These results also allow us to further suppose the formation pathways of amino acids on the primitive earth, as an extension to proposals based on the Miller‐Urey experiments. [ABSTRACT FROM AUTHOR]

Plants require essential macronutrients such as nitrogen (N), phosphorus (P), and potassium (K), but their availability in soil is often inefficient due to evaporation, leaching, and binding. Controlled‐release fertilizers (CRFs) provide a solution by regulating nutrient release over time. This study evaluates the effects of two coating materials, polyethylene glycol (PEG) and humic acid, on the release patterns of N, P, and K during an 18‐week incubation using Inceptisol from Bogor, Indonesia. Various CRF treatments were tested, including uncoated (A1, A2), PEG‐coated (B1, B2), and humic acid–coated (C1, C2) formulations. Results showed that CRF with PEG (B2) demonstrated slower N release, with ammonium levels decreasing from 32.22% in week 1 to 9.36% by week 18. Nitrate release increased steadily from 26.37% to 37.36% between weeks 3 and 18. In contrast, CRF with humic acid (C2) showed slower nitrate release, reaching 36.26% by the end of incubation. P release patterns were similar across treatments, while K release was lowest in the humic acid–coated treatment (C2) at 24.48%. These findings underline the potential of coating materials like PEG and humic acid to optimize nutrient release, enhancing agricultural efficiency. [ABSTRACT FROM AUTHOR]

Recent findings of NO near Gale Crater on Mars have been explained by two pathways: formation of nitric acid (HNO3) in a warm climate or formation of peroxynitric acid (HO2NO2) in a cool climate. Here, we put forth two hitherto unexplored pathways: (a) deposition of nitric/peroxynitric acid onto ice particles in a cold atmosphere, which settle quickly onto Mars' surface and (b) solar energetic particle‐induced production of nitric/peroxynitric acid. The deposition rates are enhanced and NO production is more efficient under the higher atmospheric pressures typical of Mars' ancient atmosphere. Depending on the unknown rate at which nitric/peroxynitric acid is lost from the surface, the new pathways could result in larger NO‐levels than those detected by the Mars Science Laboratory. We predict a 2:1 ratio of nitrite:nitrate would have deposited in cool surface climates with an icy atmosphere, whereas orders of magnitude more nitrate than nitrite is expected from warm surface climates. Plain Language Summary: The nitrogen oxides discovered in present‐day soil on Mars likely formed in the atmosphere before being deposited on the ground. Two possible mechanisms are deposition of nitric acid (HNO3) when Mars had a warm climate and deposition of peroxynitric acid (HO2NO2) during cold climate. The latter scenario involves processes that have not been considered previously and leads to a much faster deposition rate for nitrogen oxides than was reported in previous studies: solar energetic particles splitting N2 in the middle atmosphere, reactions of nitrogen oxides on the surfaces of ice particles in the atmosphere, and deposition of peroxynitric acid onto the Martian surface when surface pressure was higher. Depending on the unknown rate at which they are lost from the surface due to UV photolysis, the maximum accumulation rate for nitrogen oxides could be much larger than is required to explain the present day measurements. We predict that more nitrite would form than nitrate in a cool climate with an icy atmosphere, whereas in a warm climate much more nitrate than nitrite is expected. So, an investigation of the relative amounts of NO2:NO3 in the soil in the present‐day measurements could reveal the climate state under which the salts formed. Key Points: In a cold climate, heterogeneous reactions with atmospheric ice particles would cause faster deposition of HNOx than dry depositionFormation of HNOx species is faster for earlier Martian climates of larger surface pressureModeled NO accumulates to amounts greater than present‐day measurements, so we propose there may be a loss mechanism that is unidentified [ABSTRACT FROM AUTHOR]

Monoclinic single crystals of Cd5(TeO3)4(NO3)2 (space group P21/c), penta­cadmium tetra­kis­[oxidotellurate(IV)] dinitrate, and of Cd4Te5O14 (space group C2/c), tetra­cadmium penta­oxidotellurate(IV), were obtained under the same hydro­thermal conditions. Whereas the crystal structure of Cd5(TeO3)4(NO3)2 is distinctively layered, that of Cd4Te5O14 exhibits a tri-periodic framework. In Cd5(TeO3)4(NO3)2, the three CdII atoms have coordination numbers (CN) of 7, 6 and 6. The two types of [CdO6] and the [CdO7] polyhedra [bond lengths range from 2.179 (3) to 2.658 (2) Å] share corners and edges, resulting in layers extending parallel to (100). Both TeIV atoms are coordinated by three oxygen atoms in a trigonal–pyramidal shape. The oxygen atoms of the isolated [TeO3] groups [bond lengths range from 1.847 (3) to 1.886 (3) Å] all are part of the cadmium–oxygen layer. The electron lone pairs ψ of the TeIV atoms are directed away from the layer on both sides. The available inter­layer space is co-occupied by the nitrate group, which is directly connected with two of its O atoms to the layer whereas the third O atom is solely bonded to the N atom and points towards the adjacent layer. In Cd4Te5O14, all three unique CdII atoms are coordinated by six oxygen atoms, considering Cd—O distances from 2.235 (2) to 2.539 (2) Å. By edge- and corner-sharing, the distorted [CdO6] polyhedra form an open framework that is partially filled with three different stereochemically active TeIV atoms. All of them exhibit a CN of 4, with Te—O bonds in a range from 1.859 (2) to 2.476 (2) Å. The corresponding [TeO4] units are linked to each other by corner- and edge-sharing, forming infinite helical ¹∞[Te10O28] chains extending parallel to [203]. The connectivity in the chains can be described as (⋯–⋄–⋄=⋄–⋄–⋄–⋄–⋄=⋄–⋄–⋄–⋯)n where ‘⋄’ denotes a [TeO4] unit, ‘–’ a linkage via corners and ‘=’ a linkage via edges. Such a structural motif is unprecedented in the crystal chemistry of oxidotellurate(IV) compounds. [ABSTRACT FROM AUTHOR]

AbstractInsoluble humic substances-humin (HM) are ubiquitous in the environment and often coexist with iron reducers. Previous research has focused on the electron-donating process from HM to iron reducers; however, the reduction process of HM by iron reducers and its impact on the fate of typical contaminants are still poorly understood. In this study, Shewanella oneidensis MR-1 was selected as a model iron reducer, and its ability to reduce HM and the potential environmental impact of bioreduced HM were investigated. The results showed that S. oneidensis MR-1 reduced HMs extracted from different sources to different extents. This process is highly dependent on lactate concentration, salinity, pH, and dissolved oxygen concentration. Alginate bead experiments indicated that the indirect pathway accounted for 40% of the total electrons transferred from S. oneidensis MR-1 to HM. Electrochemical and spectrochemical analyses further revealed that in addition to flavin, c-type cytochrome may mediate electron transfer. The quinone and iron components may be the main functional groups of HM that accept electrons. Finally, we showed that after being reduced by S. oneidensis MR-1, HM can act as an electron donor for microbial nitrate reduction and the chemical reduction of Cr(VI), with electron-mediation efficiencies of 93% and 56%, respectively. [ABSTRACT FROM AUTHOR]

Monoclinic single crystals of Cd5(TeO3)4(NO3)2 (space group P21/c), penta­cadmium tetra­kis­[oxidotellurate(IV)] dinitrate, and of Cd4Te5O14 (space group C2/c), tetra­cadmium penta­oxidotellurate(IV), were obtained under the same hydro­thermal conditions. Whereas the crystal structure of Cd5(TeO3)4(NO3)2 is distinctively layered, that of Cd4Te5O14 exhibits a tri-periodic framework. In Cd5(TeO3)4(NO3)2, the three CdII atoms have coordination numbers (CN) of 7, 6 and 6. The two types of [CdO6] and the [CdO7] polyhedra [bond lengths range from 2.179 (3) to 2.658 (2) Å] share corners and edges, resulting in layers extending parallel to (100). Both TeIV atoms are coordinated by three oxygen atoms in a trigonal–pyramidal shape. The oxygen atoms of the isolated [TeO3] groups [bond lengths range from 1.847 (3) to 1.886 (3) Å] all are part of the cadmium–oxygen layer. The electron lone pairs ψ of the TeIV atoms are directed away from the layer on both sides. The available inter­layer space is co-occupied by the nitrate group, which is directly connected with two of its O atoms to the layer whereas the third O atom is solely bonded to the N atom and points towards the adjacent layer. In Cd4Te5O14, all three unique CdII atoms are coordinated by six oxygen atoms, considering Cd—O distances from 2.235 (2) to 2.539 (2) Å. By edge- and corner-sharing, the distorted [CdO6] polyhedra form an open framework that is partially filled with three different stereochemically active TeIV atoms. All of them exhibit a CN of 4, with Te—O bonds in a range from 1.859 (2) to 2.476 (2) Å. The corresponding [TeO4] units are linked to each other by corner- and edge-sharing, forming infinite helical ¹∞[Te10O28] chains extending parallel to [203]. The connectivity in the chains can be described as (⋯–⋄–⋄=⋄–⋄–⋄–⋄–⋄=⋄–⋄–⋄–⋯)n where ‘⋄’ denotes a [TeO4] unit, ‘–’ a linkage via corners and ‘=’ a linkage via edges. Such a structural motif is unprecedented in the crystal chemistry of oxidotellurate(IV) compounds. [ABSTRACT FROM AUTHOR]

Introduction: The production of high-quality food for the growing world population on the one hand and the reduction of chemical-synthetic pesticides on the other hand represents a major challenge for agriculture worldwide. The effectiveness of a combination of microbial and non-microbial biostimulants (BSs) with various nitrogen (N) forms in pathogen defense is discussed as a promising, but still poorly understood bio-based alternative for crop protection. Methods: For this reason, nitrate and stabilized ammonium fertilizer both combined with a consortium of Pseudomonas brassicacearum , Bacillus amyloliquefaciens , and Trichoderma harzianum as soil treatment or with a mixture of seaweed extract (Ascophyllum nodosum) together with chitosan-amended micronutrient fertilizer as foliar spray application were compared under controlled greenhouse conditions. Furthermore, a combination of microbial and different non-microbial BSs (seaweed extracts + chitosan) and micronutrients with nitrate or with stabilized ammonium fertilizer was tested under field conditions to improve nutrient availability, promote plant growth, and suppress Zymoseptoria tritici (Zt) in winter wheat. Results and discussion: While plant-protective effects against Zt by the microbial consortium application could be observed particularly under ammonium fertilization, the application of seaweed extract–chitosan mixture expressed plant defense against Zt more strongly under nitrate fertilization. In the field trial, the combination of microbial consortium with the seaweed extract–chitosan mixture together with micronutrients zinc (Zn) and manganese (Mn) showed positive effects against Zt under ammonium fertilization, associated with increased levels of defense metabolites. Furthermore, the additional input of Zn and copper (Cu) from the chitosan application improved the micronutrient status by minimizing the risk of Zn and Cu deficiency under controlled and field conditions. The use of BSs and the inoculation of Zt did not show any effects on plant growth and yield neither under controlled greenhouse conditions nor in the field. Summarized, microbial and non-microbial BSs separately applied or even combined together as one treatment did not influence plant growth or yield but made a positive contribution to an N form-dependent promotion of pathogen defense. [ABSTRACT FROM AUTHOR]

Background: Environmental contaminants may play a significant role in the development of migraine. Perchlorate, nitrate, and thiocyanate were selected for this study due to their known impact on thyroid function, which is closely linked to neurological processes. Disruptions in thyroid function have been associated with various neurological disorders, including migraines. However, there is currently no evidence linking exposure to these specific chemicals to migraine. The study aims to evaluate the association between urinary concentrations of perchlorate, nitrate, and thiocyanate with the prevalence of severe headache or migraine in U.S. adults. Methods: A cross-sectional study was conducted using data from the National Health and Nutrition Examination Survey (NHANES) 2001–2004. Utilizing electrospray tandem mass spectrometry in conjunction with ion chromatography, urinary concentrations of perchlorate, nitrate, and thiocyanate urine were measured. Multiple logistic regression models were employed to evaluate the linear correlation between perchlorate, nitrate, and thiocyanate exposure and severe headache or migraine. The non-linear relationship is described analytically using a fitted smoothing curve and a two-piecewise regression model. Subgroup analyses were used to further clarify the stability of this relationship across different populations. Results: There were 1,446 participants in this population-based study, ranging in age from 20 to 85. After adjusting for potential confounding variables, the multiple logistic regression findings demonstrated that thiocyanate was significantly positively associated with the prevalence of migraine (odds ratio [OR] = 1.18; [1.06, 1.30]; p < 0.001). There was consistency in this connection across different subgroups (p for interaction >0.05). Furthermore, there was a non-linear correlation between urinary thiocyanate and migraine. Using a fitted smoothing curve and a two-piecewise regression model, it was found that the correlation between urinary thiocyanate and migraine was U-shaped (p for Log-likelihood ratio = 0.002). According to the findings of the multiple regression analysis, there was no significant correlation between urinary perchlorate and nitrate and migraine (both p > 0.05). Conclusion: We should limit our exposure to thiocyanate by keeping it within a reasonable range, as indicated by the U-shaped correlation between urinary thiocyanate and migraine. [ABSTRACT FROM AUTHOR]

Constructed wetlands are standard conservation practices used to reduce nitrate loads in agricultural watersheds. Many studies have examined the efficiency of denitrification in wetlands under various scenarios, but quantifying the watershed-scale impact of wetlands on downstream nitrate levels is rarely done using field observations. In this study, we estimated nitrate removal in a constructed wetland in the headwaters of Mud Creek, a HUC12 watershed in eastern Iowa, from May-September 2022 and May-September 2023 (a tenmonth period). We also measured nitrate loads at four successive downstream sites, three along Mud Creek and one below its confluence with the larger Cedar River. The wetland removed 6,200 kg of nitrate (74% of total inputs). At the three downstream locations in Mud Creek, the percentage of each site's total nitrate load removed by the wetland decreased to 19, 8.6, and 4.1%--this latter value represents the wetland's influence on nitrate removal in the entire Mud Creek basin. The wetland's impact of nitrate loads in the Cedar River was negligible (reduction of 0.02%). The percentage of a site's drainage area treated by the wetland approximately followed a 1:1 relationship to that site's percent reduction in nitrate. Profiles of nitrate concentrations in Mud Creek notably varied pre- and post-wetland. Concentrations before the installation steadily decreased along the waterway, while post-wetland concentrations rapidly decreased directly downstream of the wetland and steadily increased at each succeeding site. Our results demonstrate that while the wetland successfully lowered local nitrate levels, its effect on the basin's overall nitrate loads was minimal. Achieving nutrient reduction goals at the watershed scale solely using constructed wetlands appears infeasible given that the required number of practices greatly exceeds current efforts. [ABSTRACT FROM AUTHOR]

Sulfate and nitrate are important components of atmospheric PM2.5, which is the main contributor of haze. Therefore, studying the sources and formation mechanisms of atmospheric sulfate and nitrate is very important for the prevention and control of haze formation. Stable isotopes of sulfate and nitrate, including isotopic compositions of sulfur, oxygen, and nitrogen, can be comprehensively used to study the sources and formation pathways of sulfate and nitrate in PM2.5, and to evaluate the contribution of each source and each formation pathway. This paper briefly reviews the determination methods for sulfur, oxygen and nitrogen isotopes in sulfate and nitrate, focuses on the application of the above isotopes in identifying the sources and formation pathways of sulfate and nitrate in atmospheric PM2.5, and puts forward research prospects. [ABSTRACT FROM AUTHOR]

Field studies suggest that NO3− photolysis may play a more significant role than previously thought. In this study, we concurrently measured HONO, NO2, and NO2− in situ to gain a deeper understanding of the photogenerated HONO transfer to air and to better constrain the rate constants of NO3− photolysis. The presence of fatty acids (e.g., nonanoic acid, NA), which are naturally present in the environment, significantly increases the production of photogenerated HONO and NO2. With an increase in oxygen percentage, the release rate of photoinduced HONO slowed, while the release rate of NO2 accelerated. The measured J N O 3 − value averaged 1.65 × 10−5 s−1, which is two orders of magnitude higher than values reported in similar systems. The HONO transfer rate from the solutions increased from 2.3 × 10−4 s−1 to 5.6 × 10−4 s−1 as the NA concentration increased from 0.1 to 20 mM. This can be attributed to the accumulation of NO2− induced by NA at the interface. Within this interfacial region, NO2− in the solutions becomes more prone to transfer into gaseous HONO, suggesting that photogenerated NO2− hosted in atmospheric droplets may serve as a temporary reservoir of atmospheric HONO without illumination, influencing the atmospheric oxidizing capacity in the region for hours. Therefore, simultaneous measurements of both gas and particle phase photoproducts are recommended to better constrain the rate constants of NO3− photolysis, thereby enhancing the accuracy of predicting the photochemical production of HONO in the atmosphere. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction enables the recovery of nitrate from water under mild conditions and generates ammonia for nitrogen fertilizer feedstock in an economical and green means. In this paper, Co/biomass carbon (Co/BC) composite catalysts were prepared by co-carbonization of straw and metal–organic framework material ZIF-67 for electrocatalytic nitrate reduction using hydrothermal and annealing methods. The metal–organic framework structure disperses the catalyst components well and provides a wider specific surface area, which is conducive to the adsorption of nitrate and the provision of more reactive active sites. The introduction of biomass carbon additionally enhances the electrical conductivity of the catalyst and facilitates electron transport. After electrochemical testing, Co/BC-100 exhibited the best performance in electrocatalytic nitrate reduction to ammonia, with an ammonia yield of 3588.92 mmol gcat.−1 h−1 and faradaic efficiency of 97.01% at −0.5 V vs. RHE potential. This study provides a promising approach for the construction of other efficient cobalt-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Nitrate pollution is one of the major environmental issues in reservoirs. Small and medium-sized reservoirs are the sources of drinking water more sensitive to seasonal variations in diffuse pollution. This study aims to analyze the changes in nitrate sources in a reservoir in a hilly watershed under agricultural cultivation in different periods. The Qiaodian Reservoir basin was selected as the study area. 16 sites were set to collect the water samples in January (freeze-up period), March (ablation period), June (pre-flood period), August (high water period), and November (low water period) in 2023. These samples were examined for water quality indicators, major ion compositions, and nitrogen and oxygen isotopes. Different sources of nitrate contamination in the water and their contributions were identified using hydrochemistry analysis, the nitrogen and oxygen isotope tracer technique, and the Bayesian stable isotope mixing model (MixSIAR). Hydrochemical analysis showed that the hydrochemistry was dominated by the HCO3 ·SO4 -Ca type in the study area, where the dissolution of rock weathering seriously controlled the ionic composition. The ionic sources were enhanced by water-rock interaction during the abundant water period. There were relatively consistent trends in the TN and NO3 - -N concentrations, with NO3 - -N emerging as the primary form of dissolved inorganic nitrogen. Hydrometeorological conditions, land use patterns, and anthropogenic activities primarily contributed to the fluctuations in the nitrate concentrations. There was dry land (of the watershed area) with various crops. Livestock farming existed in the villages, where more animal manure was applied to the farmland. The rest types of land use were forest land and grassland. Temporally, the nitrate concentrations declined in the descending order of freeze-up period (3.83 mg/L), high water period (3.57 mg/L), ablation period (3.51 mg/L), low water period (2.54 mg/L), pre-flood period (1.90mg/L). At the spatial scale, NO3 - -N concentrations were more variable in the upper and middle reaches of the watershed, while the downstream NO3 - -N concentrations were close to those in the reservoir area. The δ15N-NO3 - mean values of nitrate were 9.61‰, 9.11‰, 8.1‰, 7.18‰, and 6.04‰ in the pre-flood, ablation, low water, freeze-up, and high water periods, respectively. The δ18O-NO3 - mean values of nitrate were 9.52‰, 4.25‰, 3.74‰, 3.46‰, and 1.96 ‰ in the pre-flood, low water, high water, freeze-up, and ablation periods, respectively. The range of δ15N-NO3 - and δ18O-NO3 - values varied outstandingly in the different periods, indicating the multiple sources of nitrate. Various analyses showed that soil nitrogen, manure, and sewage were the pivotal contributors to nitrate concentration shifts within the reservoir basin. MixSIAR model was used to quantitatively assess the contribution rates of different nitrate sources. Nitrate was derived mainly from the soil nitrogen, manure, and sewage during the freeze-up, ablation, and low water periods. The proportions of nitrate sources were more consistent between the freeze-up and the low water period. Specifically, soil nitrogen contributed the highest proportion of nitrate to the watershed, 37% and 36%, respectively. Nitrate depended on the atmospheric deposition during the pre-flood period, accounting for 13%. There was the most severe loss of soil nitrogen during the high water period, when the highest contribution rates of nitrate from soil nitrogen and chemical fertilizer were 41% and 31%, respectively. This finding can provide a scientific basis for preventing and controlling surface pollution in the small and medium-sized reservoir watersheds in hilly agricultural areas. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, [Ni(C8H20N4)(NO3)]NO3, at room temperature, has monoclinic (P21/n) symmetry. The structure displays inter-molecular hydrogen bonding. The nickel displays a distorted bipyramidal geometry with the symmetric bidentate bonded nitrate occupying an equatorial site. The 1,4,7,10-tetraazacyclododecane (cyclen) backbone has the [4,8] configuration, with three nitrogen-bound H atoms directed above the plane of the nitrogen atoms towards the offset nickel atom with the fourth nitrogen-bound hydrogen directed below from the plane of the nitrogen atoms. The nitrate anion O atoms are seen to hydrogen bond to the H atoms bound to the N atoms of the ligand. [ABSTRACT FROM AUTHOR]

In order to improve the activity of copper (Cu) towards electrolytic reduction of nitrate, thin films of magnesium hydroxide (Mg(OH)2) were deposited on Cu substrate. For the first time, these films were synthesized by electrochemical deposition in a potassium sulfate bath containing Mg2+ at 70 °C. The effect of various experimental parameters, such as deposition time and potential, on the electrocatalytic activity for the nitrate reduction was investigated. Surface analysis techniques (SEM, EDX and XRD) were used to get information on the morphology, the composition and the structure of the deposits. The activity of the modified electrode was studied by cyclic voltammetry, and amperometric method. The modified Mg(OH)2/Cu sensor exhibited a good electrocatalytic behavior towards the reduction of nitrates with high reproducible reduction peak currents. In addition, the sensor exhibits a linear answer for concentration in nitrate between 0.125 to 7 mM, combined with high sensitivity (24.6 µA mM−1 cm−2) and limit of detection (225.35 µM) values. When common interfering molecules were added to the solution, Mg(OH)2/Cu electrodes have kept their good selectivity. They demonstrated acceptable detection levels for nitrates in tap water. [ABSTRACT FROM AUTHOR]

SUMMARY: Hydathodes are small organs found on the leaf margins of vascular plants which release excess xylem sap through a process called guttation. While previous studies have hinted at additional functions of hydathode in metabolite transport or auxin metabolism, experimental support is limited. We conducted comprehensive transcriptomic, metabolomic and physiological analyses of mature Arabidopsis hydathodes. This study identified 1460 genes differentially expressed in hydathodes compared to leaf blades, indicating higher expression of most genes associated with auxin metabolism, metabolite transport, stress response, DNA, RNA or microRNA processes, plant cell wall dynamics and wax metabolism. Notably, we observed differential expression of genes encoding auxin‐related transcriptional regulators, biosynthetic processes, transport and vacuolar storage supported by the measured accumulation of free and conjugated auxin in hydathodes. We also showed that 78% of the total content of 52 xylem metabolites was removed from guttation fluid at hydathodes. We demonstrate that NRT2.1 and PHT1;4 transporters capture nitrate and inorganic phosphate in guttation fluid, respectively, thus limiting the loss of nutrients during this process. Our transcriptomic and metabolomic analyses unveil an organ with its specific physiological and biological identity. Significance Statement: Hydathodes are vascular discontinuities at leaf margins of all vascular plants which allow the release of excess water during a process known as guttation. The physiology of this organ is poorly characterised. We conducted comprehensive transcriptomic, metabolomic and physiological analyses of mature hydathodes of Arabidopsis and demonstrated that those organs are sites of auxin accumulation and active nutrient scavenging. [ABSTRACT FROM AUTHOR]

Exogenous nitrate ingestion can improve exercise performance. This study investigated whether an isotonic beetroot drink could improve jump and sprint performance in active individuals. Twenty-three physically active participants (17 males, 6 females) (mean ± SD; age: 26 ± 4 years; body mass index: 22.4 ± 1.9 kg/m2) completed a double-blind, randomized, cross-over study where they consumed 570mL of either beetroot juice drink (BR) or isotonic beetroot juice drink (ISO-BR) three hours before performing countermovement (CMJ) and standing broad jump (SBJ) tests and a 30-second all-out sprint on a cycle ergometer. Both drinks contained equal nitrate (12.9 mmol) and carbohydrate (6.1g per 100mL) content but differed in osmolality (BR: 420 mOsm/kg vs. ISO-BR: 315 mOsm/kg). Salivary total nitrate and nitrite concentrations (NOx) 3 hours post-ingestion were significantly higher after consuming ISO-BR than BR. ISO-BR significantly improved peak power output compared to BR by 3.9% (ISO-BR: 11.4 ± 2.5 W/kg vs. BR: 11.0 ± 2.3 W/kg, p =.04) but not time to peak power (ISO-BR: 2.8 ± 1.7 s vs. BR: 2.9 ± 1.6 s, p =.62) or mean power output (ISO-BR: 7.3 ± 1.5 W/kg vs. BR: 7.3 ± 1.5 W/kg, p =.37). There were no significant differences in CMJ or SBJ between trials (p >.05). Sensory evaluation indicated that ISO-BR was preferred by 91% (n = 21) of participants compared with BR (average score; ISO-BR: 5.52 vs. BR: 3.52, p <.05). An ISO-BR drink improved peak power output during sprint cycling but not jump performance compared with BR alone, potentially via increased NOx. [ABSTRACT FROM AUTHOR]

In the last couple decades, more use of nitrogenous chemical fertilizers and improper disposable of wastewater has harmed water and it cause water pollution. Low concentrated Nitrite (NO 2) is the one of hazardous pollution and it is difficult to remove through biological processes, while it occurs in low concentration. Many technologies have been developed to accumulate NO 2 in the mainstream. However, most of them use chemical inhibitors for nitrite oxidizing bacteria (NOB). In past studies high concentrated reactor performance have been modeled using mathematical models. In this study, machine learning application (MLA) was applied to model the performance of reactors. The reactor was low concentrated, continuous stirred tank reactor (CSTR) with in-fluent total ammonia nitrogen (TAN) concentration was (∼30PPM-TAN and ∼50PPM-TAN) and lower output TAN concentration was (∼1PPM-TAN). However, 216 days of water treatment data from CSTR were used, and the CSTR's efficiency (%) of nitrite accumulation was estimated using in-fluent and effluent quantities. Then efficiency is predicted with 70 % of the data that is used to train the algorithms. Confusion matrix was used to access the performance of algorithms and actual and predicted classes (efficiencies) were compared. The DTC and XGB over-performed other algorithms. [Display omitted] • A novel machine learning application was applied to model the performance of reactors. • More use of nitrogenous chemical fertilizers has harmed groundwater and soil composition. • DTC and XGB are the most accurate, followed by RF and LR, while KNN is the least accurate. [ABSTRACT FROM AUTHOR]

Context Diabetes is a global health concern, and diet is a contributing factor to diabetes. Findings regarding the connection between nitrate, nitrite, and nitrosamine and diabetes risk are inconsistent. Objective The aim was to examine the effects of these dietary compounds on diabetes risk. Data Sources The data were sourced from PubMed, EMBASE, Scopus, and Web of Science until February 28, 2023. Studies that reported individual-level consumption of these compounds were included. Review articles or ecological studies were excluded. Data Extraction The number of events and total observations were recorded. Data Analysis The pooled odds ratio (OR) was calculated and displayed in a forest plot. Subgroup and sensitivity analyses were predefined. A dose–response meta-analysis was conducted to determine the exposure intervals that may increase the risk of disease. Six observational reports that met the inclusion criteria were included, involving 108 615 individuals. Participants in the highest quantile of nitrite intake had a greater risk of diabetes compared with those in the lowest quantile (OR, 1.61; 95% confidence interval [CI], 1.08–2.39; I2 = 74%, P = 0.02). Higher nitrosamine consumption tended to increase diabetes risk (OR, 1.52; 95% CI, 0.76–3.04; I2 = 76%; P = 0.24). The relationship was stronger for type 1 (OR, 1.79; 95% CI, 1.20–2.67; I2 = 58%; P < 0.01) than for type 2 diabetes (OR, 1.42; 95% CI, 0.86–2.37; I2 = 71%; P = 0.17). Additionally, nitrite consumption had a dose-dependent association with both phenotypes. No association was found between diabetes risk and high nitrate intake (OR, 1.01; 95% CI, 0.87–1.18; I2 = 28%; P = 0.87). Conclusion Attention should be paid to the consumption of nitrite-containing foods. Systematic Review Registration PROSPERO registration no. CRD42023394462 (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=394462). [ABSTRACT FROM AUTHOR]

Diabetes is a common, chronic, and complex disorder that leads to several disabilities and serious complications. Certain nutrients can be effective in the management of diabetes mellitus. In the present study, we aimed to investigate the effects of dietary nitrate, nitrite, dietary total antioxidant capacity (DTAC), and nitric oxide (NO) index on some cardiometabolic parameters in patients with diabetes. This cross-sectional study was conducted on 100 participants with type 2 diabetes. A validated, semi-quantitative, food frequency questionnaire was collected to evaluate dietary intakes. Anthropometric parameters, blood pressure, and biochemical parameters, including glycemic indices, lipid profile, high-sensitive C-reactive protein (hs-CRP), and serum NO were measured using standard methods. Higher intakes of nitrate and nitrite in our study were primarily attributed to drinking water, vegetables, grains (for nitrate), dairy products, and legumes (for nitrite) rather than higher meat intakes. After adjustment for total energy, MET, BMI, and age, higher intake of nitrate was related to lower HbA1C (p = 0.001) and hs-CRP (p = 0.0.23), and greater HDL-C (p < 0.001) and serum NO (p = 0.008). Moreover, a greater nitrite intake was associated with lower DBP (p = 0.017), HbA1C (p = 0.040), FPG (p = 0.011), and higher serum NO values (p = 0.001). Higher amounts of DTAC and NO index were also related to greater DBP (p < 0.001, and p = 0.004, respectively) and lower hs-CRP (p = 0.004, and p = 0.009, respectively). High intakes of dietary nitrate and nitrite, in the context of high DTAC, are significantly associated with the improvement of some cardiometabolic parameters in patients with diabetes. HIGHLIGHTS: A higher intake of nitrite is related to improving glycemic indices. A higher intake of nitrate is related to increasing HDL-C and decreasing hs-CRP. A higher intake of nitrate and nitrite, with a high DTAC index, is related to reduced cardiometabolic parameters. [ABSTRACT FROM AUTHOR]

Nitrate is a nutrient and signal that regulates gene expression. The nitrate response has been extensively characterized at the organism, organ, and cell‐type‐specific levels, but intracellular mRNA dynamics remain unexplored. To characterize nuclear and cytoplasmic transcriptome dynamics in response to nitrate, we performed a time‐course expression analysis after nitrate treatment in isolated nuclei, cytoplasm, and whole roots. We identified 402 differentially localized transcripts (DLTs) in response to nitrate treatment. Induced DLT genes showed rapid and transient recruitment of the RNA polymerase II, together with an increase in the mRNA turnover rates. DLTs code for genes involved in metabolic processes, localization, and response to stimulus indicating DLTs include genes with relevant functions for the nitrate response that have not been previously identified. Using single‐molecule RNA FISH, we observed early nuclear accumulation of the NITRATE REDUCTASE 1 (NIA1) transcripts in their transcription sites. We found that transcription of NIA1, a gene showing delayed cytoplasmic accumulation, is rapidly and transiently activated; however, its transcripts become unstable when they reach the cytoplasm. Our study reveals the dynamic localization of mRNAs between the nucleus and cytoplasm as an emerging feature in the temporal control of gene expression in response to nitrate treatment in Arabidopsis roots. Summary statement: Transcriptome analysis of nuclear and cytoplasmic fractions in response to nitrate revealed transcripts with specific subcellular localization, revealing a novel layer of gene regulation. The dynamic interplay between mRNA localization, synthesis, and decay is crucial for the adaptive response of Arabidopsis roots to nitrate. [ABSTRACT FROM AUTHOR]

Water resources face challenges such as climate change and human activities. Sustainable water management is extremely important to solve this problem. More and more people are using artificial intelligence, especially machine learning, to predict and manage water quality. These AI methods are excellent at identifying patterns in water data and improving water quality management. This study examines the water quality of the Maroon River using a combination of factor analysis and machine learning. Data on various water quality parameters were collected from three stations over a period of ten years and the water quality index was calculated. Then, different machine learning algorithms were used to predict the water quality index. In a further step, factor analysis was performed to extract the important features of the input for the optimal algorithm. The performance of the studied algorithms was determined at each step using evaluation criteria. The results showed that in the first step, the Random Forest algorithm (R² (0.78), RMSE (2.65)) had the best performance in predicting water quality index. It was also found that among the three algorithms studied, nitrate is the most important input parameter, while acidity is the least important. By reducing the number of inputs to 3 important parameters, the performance of the Random Forest algorithm (R2 (0.74), RMSE (2.86)) almost reached the level of 8 input parameters. Combining insights from factor analysis and feature importance analysis can provide a more comprehensive understanding of the complex relationships among water quality parameters and help develop more effective water management [ABSTRACT FROM AUTHOR]

The San Antonio segment of the karstic Edwards Aquifer provides an example of the impact of aggregate quarries on nitrate loads in karst aquifers. Previous published reports have not evaluated aggregate quarries as a possible cause of nitrate concentrations in the Edwards Aquifer above normal background levels and instead attribute nitrate to recent urban development directly over the aquifer's recharge zone. Quarries are known to be sources of nitrate pollution of groundwater resulting from use of ammonium nitrate fuel--oil (ANFO) mixtures as explosives in mining operations. Ammonium nitrate is highly soluble and leaches readily into the formation being mined. Large quantities are used, up to 30 percent of which is not consumed by blasting, thus constituting a potential groundwater pollutant. Groundwater data from the Texas Water Development Board and stream data from the Texas Commission on Environmental Quality show that urbanization cannot explain the geographic distribution and historical changes of nitrate in the aquifer. The geographic distribution of numerous limestone quarries fits with the data, and nitrate concentrations in the Edwards Aquifer have risen since ANFO use as an explosive began on a large scale, which indicates quarries are a major contributor of nitrate to the aquifer. Water-quality measurements of nitrate in the Edwards Aquifer mostly remain at a level safe for humans. However, some freshwater aquatic organisms are harmed by prolonged exposure to lower nitrate levels. Recent nitrate measurements show that most measurements have reached a level that might be harmful to some groundwater species. [ABSTRACT FROM AUTHOR]

Over the last decades, as a consequence of wastewater discharges and other anthropogenic sources, severe nitrate (NO3−) pollution has developed in municipal environment causing global concern. Thus, eliminating the potential sources of pollution is one of the major challenges of the twenty-first century, whereby sanitation services are essential for ensuring public health and environmental protection. In the present study, long-term monitoring (2011–2022) of shallow groundwater NO3− contamination in municipal environment was carried following the construction of the sewerage network (2014) in the light of the pre-sewerage situation. Our primary aim was to assess the long-term effects of sewerage on nitrate NO3− levels in the shallow groundwater and evaluate the efficiency of these sanitation measures over time. Based on the results, significant pollution of the shallow groundwater in the municipality was identified. During the pre-sewer period, NO3− concentrations exceeded the 50 mg/L limit in the majority of monitoring wells significantly, upper quartile values ranged between 341 and 623 mg/L respectively. Using Nitrate Pollution Index (NPI) and interpolated NO3− pollution maps, marked spatial north–south differences were detected. In order to verify the presence of wastewater discharges in the monitoring wells, the isotopic ratio shifts (δ) for 18O and D(2H) were determined, confirming municipal wastewater effluent. Variations in NO3−/Cl− molar ratios suggest also contamination from anthropogenic sources, including septic tank effluent from households and the extensive use of manure. Data series of 7 years (2015–2022) after the investment indicate marked positive changes by the appearance of decreasing trends in NO3− values confirmed by Wilcoxon signed rank test and ANOVA. By comparing the pre- and post-sewerage conditions, the mean NO3− value decreased from 289.7 to 175.6 mg/L, with an increasing number of monitoring wells with concentrations below the limit. Our results emphasise the critical role of sanitation investments, while also indicating that the decontamination processes occur at a notably slow pace. Detailed, long-term monitoring is therefore essential to ensure accurate follow-up of the ongoing changes. The results can provide information for local citizens and authorities to improve groundwater management tools in the region. [ABSTRACT FROM AUTHOR]

Metal-assisted catalyzed etching (MACE) technology is convenient and efficient for fabricating large-area silicon nanowires at room temperature. However, the mechanism requires further exploration, particularly the dynamic effect of various ions in the acid-etching solution. This paper investigated the MACE of silicon wafers predeposited with metal nanofilms in an HF-M(NO3)x-H2O etching solution (where M(NO3)x is the nitrate of the fourth-period elements of the periodic table). The oxidizing ability of Fe3+ and NO3− was demonstrated, and the dynamic influence of metal ions on the etching process was discussed. The results show that the MACE of silicon can be realized in various HF-M(NO3)x-H2O etching solutions, such as KNO3, Al(NO3)3, Cr(NO3)3, Mn(NO3)2, Ni(NO3)2, Co(NO3)2, HNO3, and Ca(NO3)2. It is confirmed that the concentration and type of cations in the etching solution affect the etching rate and morphology of silicon. Fe3+ and NO3− act as oxidants in catalytic etching. The fastest etching rate is about 5~6 μm/h in Ni(NO3)2, Co(NO3)2, and Ca(NO3)2 etching solutions. However, a high concentration of K+ hinders silicon etching. This study expands the application of MACE etching solution systems. [ABSTRACT FROM AUTHOR]