Search

In this study, the results of hydrochemical measurement aboard the RV Kavoshgar Khalij Fars in the Persian Gulf (PG) in September 2018, May, and November 2019 are discussed. Nitrate, nitrite, ammonium, phosphate, and silicate concentrations, salinity, temperature, dissolved oxygen, and pH in the water column of a 1000-km transect in the PG were studied to determine the present status of nutrient regimes of this region. Nitrate, phosphate, and silicate were more concentrated at the bottom layer and showed a maximum just below the thermocline in summer and autumn. Seasonal distribution of nutrient ratios (N:P, N:Si, Si:P) indicates P limitation in autumn, N limitation in spring, P limitation and poor Si in summer throughout the upper layer. The results of this study do not infer eutrophication in the upper layer of the PG waters in autumn and summer. [ABSTRACT FROM AUTHOR]

This study aimed to use colloidal silver nanoparticles (AgNPs) for ammonium adsorption. Several factors were considered, including pH value, contact time, amount of adsorbent, and beginning ammonium content. The ideal parameters for ammonium adsorption onto the AgNPs were an a pH of 9, a contact period of 60 minutes, a concentration of 1.824 mg AgNPs/25 mL of ammonium solution, and a starting concentration of 80 mL, as determined. The optimum ammonium adsorption capacity onto the AgNPs was 276.84 mg/g, and the Langmuir model described the isotherm adsorption with R2, KL, and calculated qmax values of 0.9339, 0.518 L/mg, and 263.37 mg/g, respectively. The experimental data were most closely matched by the Elovich model, as seen by its R2, α, and β values of 0.885, 0.055, and 0.180, respectively. Temperature release values for the exothermic adsorption were 23,084 kJ/mol at 20°C, −23872 kJ/mol at 30°C, and 24,660 kJ/mol at 40°C. [ABSTRACT FROM AUTHOR]

The aim of this work was to assess effect of saturated constructed wetland-Microbial fuel cell system on dissolved oxygen gradient, electricity generation and ammonium removal. Two laboratory-scale systems, one planted with Schoenoplectus californicus (SCW1-MFC) and other without plant (SCW2-MFC), were fed discontinuously with synthetic wastewater over 90 days. Both systems were operated at different organic loading rate (12 and 28 g COD/m2d) and ammonium loading rate (1.6 and 3.0 g NH4+– N/m2 d) under open circuit and close circuit mode. The results indicate that between lower and upper zones of wetlands the average values were in the range of 1.22 ± 0.32 to 1.39 ± 0.27 mg O2/L in SCW1-MFC and 1.28 ± 0.24 to 1.56 ± 0.31 mg O2/L in SCW2-MFC. The effect of operating mode (closed and open circuit) and vegetation on DO was not significant (p > 0.05). Chemical oxygen demand (COD) removal efficiencies, fluctuated between 90 and 95% in the SCW1-MFC and 82 and 94% in the SCW2-MFC system. Regarding NH4+- N, removal efficiencies were above 85% in both systems reaching values maximus 98%. The maximum power density generated was 4 and 10 mW/m2 in SCW1-MFC, while SCW2-MFC recorded the highest values (12 and 22 mW/m2). [ABSTRACT FROM AUTHOR]

An incubation experiment was conducted to study the effect of clay content and composition on organic nitrogen mineralization. The experiment measured the mineralization of organic nitrogen from alfalfa residues, enzyme activities, and microbial biomass nitrogen in mixtures of sand, kaolinite, and non-layered colloids (NLCs) with sand as a control. The study found that as the contents of kaolinite and NLCs increased, the mineralization of organic nitrogen and enzyme activity decreased, but microbial biomass nitrogen increased. The maximum decrease in organic nitrogen mineralization was 88.6%, and microbial biomass nitrogen increased from 4.7 to 15.5%. The acid and alkaline phosphatase activities also decreased by 86.0 and 93.6%, respectively, with an increase in clay content. The specific surface area (SSA) of the mixtures showed an inverse relationship with enzyme activity and mineralization of organic nitrogen. Inactivation of extracellular enzymes by adsorption on the surfaces of kaolinite and NLCs, and decreased accessibility of organic nitrogen substrate molecules due to adsorption, reduced the mineralization of organic nitrogen. Microbial biomass nitrogen increased as the water holding capacity of the mixtures increased, indicating the importance of water-filled pores in accommodating active microbial biomass and protecting it from desiccation and predators. [ABSTRACT FROM AUTHOR]

Partial nitrification is known as first and critical step for autotrophic nitrogen removal in high strength nitrogenous wastewater. Phosphorylated polyvinyl alcohol gel entrapment was used for suppressing oxygen to nitrite-oxidizing bacteria (NOB) in the gel matrix. The study investigated the effect of the size of gel matrix on partial nitrification. Results show that ammonia-oxidizing bacteria (AOB) proportion in the inoculum rather than the size of gel matrix governed ammonia oxidation. Nitrite oxidation depended on the size of gel matrix not the relative proportions of NOB and AOB in the inoculum. Larger size of gel matrix lead to less in situ oxygen penetration and available for NOB resulting in higher nitrite accumulation. This finding gains a better understanding of using suitable inoculum to control partial nitrification that is beneficial for the preparation of anaerobic ammonium oxidation-suited effluent. [ABSTRACT FROM AUTHOR]

Waste rolling oil (WRO) can be regenerated by polymer flocculation-adsorption. Poly diallyl dimethyl ammonium chlorid (PDADMAC) is a linear high polymer with quaternary ammonium cations which was selected as an polymer flocculant. Effects of different treatment conditions on the performance of the recycled oil were investigated. Results indicated that the recycled oil achieved optimum quality under the following conditions: mass ratios of PDADMAC-WRO, KOH-WRO of 0.02 and 0.075, refining time, 20 min, refining temperature, 40 °C, stirring speed, 500 rpm, respectively. Compared with traditional regeneration methods, this flocculation method has higher effectiveness and can reduce the treatment time and cost. [ABSTRACT FROM AUTHOR]

The aftermath of mining weathered crust elution-deposited rare earth ore produces a large amount of residual ammonium leaching solution, which causes ammonia and nitrogen pollution to the mine site. Recently, denitrification by heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria has attracted much attention. However, limited studies exist regarding the denitrification process of HN-AD bacteria. In this study, we combined four strains of HN-AD bacteria, Pseudomonas fulva K3, Pseudomonas mosselii K17, Klebsiella oxytoca A12, and Enterobacter hormaechei A16, obtained from rare earth element leaching sites, to select the best microbial consortium for ammonia nitrogen removal. We designed an ammonia removal process applicable to HN-AD bacteria to directly remove ammonia nitrogen from acidic leaching solutions. The experimental results demonstrated that the most efficient microbial consortium for ammonia nitrogen removal to be K3 + K17 + A16, with a removal efficiency of 89.68% for 8 h. In this process, considering the influencing factors of the ammonia removal process, the larger the influent flow rate and influent ammonia nitrogen concentration, the greater the ammonia nitrogen accumulation and pH decrease in the reactor. In consecutive multi-batch experiments, the ammonia removal process was used to remove ammonia nitrogen, at concentrations of 100–600 mg/L, from the simulated leaching solution at pH 4–7, whereby the effluent ammonia nitrogen concentration was lower than 15 mg/L. The results demonstrate that the ammonia removal process is highly feasible and stable. These findings will provide new ideas for the application of HN-AD bacteria and new methods for the removal of ammonia nitrogen from acidic leaching solutions. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of feeding silage to pigs on nitrogen (N) utilization and ammonia (NH3) volatilization. In total, 128 Yorkshire × Hampshire (30–110 kg) pigs were fed commercial feed (Control) or commercial feed mixed with dried, milled silage in pelleted form (Pellet-S), fresh, chopped silage (Silage-Ch) or intensively treated silage (Silage-Pr). Silage replaced 20% of the crude protein (g/kg). Diet affected daily N excretion, which was higher for pigs fed Silage-Ch and Silage-Pr than for pigs in the Pellet-S and Control treatments. Ammonium nitrogen (NH4-N) content in the manure and NH3 volatilization from fresh manure were higher for Control pigs than for pigs in the other treatments. Overall, these results show that pre-treatment of silage influences N utilization and excretion. Furthermore, the results indicate that feeding silage to pigs can reduce NH3 volatilization from fresh manure. [ABSTRACT FROM AUTHOR]

The preferable N source for tropical grasses and its effects on the nutritional status are still matters of priority investigation. This study aimed to explore the effects of N sources and N deprivation on growth and uptake of elements in a newly-released ruzigrass cultivar, BRS Integra. Plants were grown under controlled conditions in vermiculite and were supplied with nutrient solution containing either NH4+, NH4++NO3-, NO3- or no N added in solution making. Plant biomass, chlorophyll content, transpiration, N status, and levels of selected elements were evaluated. NH4+ improved biomass production and aboveground N contents. Other elements exhibited high (N, K and Na), medium (Mn), low (Ca, Cd, Cr, Cu, Mg, Ni and Zn) or non-detected (Al and Fe) translocation. Cd was included in the study because of its hazardous concentrations in agricultural soils in Brazil and its influence on N uptake and translocation in the genus Urochloa. All N sources increased the uptake of whole plant Cu and K and Al, and root Fe and Mg. Other favorable relations prevailed in the roots, specifically of NO3- on Ca and Ni, NH4+ and NH4++NO3- on Cr, and NH4+ on Cd. Removal of N supply caused increases on Mn and Na aboveground and Zn in roots. Overall, the more evident N source-induced uptakes were, in order of decrease, of NO3- on Ca, NH4++NO3- on Ni, and NH4+ on Cr, Cu and Mn. It is concluded that NH4+ is more efficient for fertilizing ruzigrass by improving growth and N uptake compared to NH4++NO3- or NO3-. In addition, the diverse effects of varying N sources on the uptake of 12 elements indicate such interactions should be taken into account to further improve fertilizer formulations. [ABSTRACT FROM AUTHOR]

One of the practices which could mitigate the negative effects of drought stress is ammonium nutrition. Nitrification inhibitor (DMPP) can keep ammonium concentrations high in the soil for several weeks. Although there are contradictory reports regarding the priority of NH4+ uptake and its toxicity effects on wheat, it is necessary to understand better how to apply DMPP to increase drought tolerance without any negative effects. The field experiment was conducted using 15N trace technology. The fertilizers treatment included (15NH4)2SO4 and (15NH4)2SO4 with DMPP at four drought stress levels. Available soil mineral nitrogen was measured, as well as yield components and 15N recovery. The results showed that DMPP application at full irrigation and moderate drought stress caused an increase in grain yield of 13% and 10%, respectively. DMPP application at full irrigation, moderate and severe drought stress caused a significant increase in nitrogen use efficiency of 19%, 11%, and 17%, respectively. It seems DMPP application at the stem elongation stage, promoted NH4+ assimilation and transfer to the shoots, which has created relative resistance to drought stress conditions. In conclusion, it is recommended that farmers use DMPP at stem elongation to avoid wheat yield reduction and nitrogen recovery under drought stress. [ABSTRACT FROM AUTHOR]

In this study, sucrose and ammonium polyphosphate (APP) were utilized as the raw materials to prepare an environmentally-friendly plywood adhesive. The bonding performance results showed that the optimal synthesis conditions of the sucrose-ammonium polyphosphate (SAPP) adhesive were an 80/20 mass ratio (sucrose/APP) at 115 oC for 3 h, and the optimal manufacturing conditions were 170 oC for 7 min. In addition, the maximum wet shear strength of the obtained three-ply plywood was 0.81 MPa, which satisfied the China National Standard GB/T 9846–2015 (wet shear strength≥0.7 MPa). The insoluble mass proportion was positively associated with the heating temperature and time. The TG and DSC analysis showed that a rapid mass loss of the SAPP adhesive occurred at 143.4 oC, and endothermic peaks appeared at 136.2 and 156.4 oC. The 13C NMR spectra showed that the adhesive contained monosaccharides, oligosaccharides, ketones, HMF, Schiff bases, and various other unknown substances. This implies that hydrolysis, caramelization, and the Amadori rearrangement occurred during synthesis. Furthermore, the FT-IR and Py-GC/MS results indicated that the cured SAPP adhesive was a complex polymer containing furan and nitrogenous compounds, which were connected by dimethylene ether bridges. [ABSTRACT FROM AUTHOR]

A symbiotic microalgal-bacterial system may be an optional technology for wastewater treatment. It was composed of microalgae and activated sludge and established in the SBR to explore the effect of different dosing ratios of algae and sludge on the removal of nitrogen and phosphorus from simulated wastewater containing ammonium. It can be seen from the result that varied algae–sludge dosing ratios had a higher removal effect on COD removal, but the difference was not significant. The algal-bacterial symbiosis system had a 100% removal rate for ammonium removal on the 8th day. Relatively speaking, the removal of nutrients and related mechanisms vary with environmental conditions (inoculation rate). In general, when the additive ratio was 5:1 (algae: AS), the removal rate of TN and TP was the highest, reaching 53.85% and 85.13% in the shortest time (14 days), among them, the removal rate of ammonium and COD was 100%, and the reduction rates of Nitrite nitrogen and Nitrate nitrogen were 362.99% and 73.42%, respectively. In addition, 16S rDNA gene analysis results demonstrated that the microbial community in the reactor with algal sludge inoculation ratio of 5:1 had differences in three stages of the initial reaction, the middle reaction and the end of the reaction. Comamonadaceae, Flavobacterium, Paenarthrobacter, Mesorhizobium, Nitrobacter were enriched during the reaction operation. [ABSTRACT FROM AUTHOR]

We evaluated the effects of isoforms of ammonium transporters (AMT) and amino acid transporters (AAT) on three rice varieties cultivated with different levels of ammonium (NH4+) and its biochemical responses. The rice varieties used were IAC-47 (improved), Manteiga and Piauí (landraces), cultivated under 0.2 mM NH4+ (low N, LN), 1 mM NH4+ (sufficient N, SN) or resupply with 1 mM of NH4+ after three days without nitrogen (N). When cultivated with LN, the Piauí variety presented a higher expression of AAT (Lysine-Histidine Transporter 4 (OsLHT4) and GABA Transporters (OsGAT1)) in roots, while Manteiga and IAC-47 presented higher expression of the Amino Acid Permease 1 (OsAAP1) and Ammonium Transporter 1.1 (OsAMT1.1), respectively. Additionally, Piauí had the higher expression of glutamine synthetase (OsGS1.1 and OsGS1.3) in shoots cultivated with LN or resupply. The Piauí variety displayed higher glutamine synthetase activity and amino acid content under resupply. Manteiga and Piauí presented a lower reduction in fresh weight of leaves and sheaths under LN compared to IAC-47. The results suggest that the improved variety IAC-47 is more efficient when cultivated with SN, while, under LN or resupply, the landrace varieties were superior. Overall, the molecular responses were different among the varieties, which may affected their nitrogen metabolism. [ABSTRACT FROM AUTHOR]

This study was to investigate the possibility of nutrient removal from landfill leachate using Chlorella sp. and its potential as agricultural fertilizer. Chlorella sp. was inoculated to a leachate suspension (1:1 ratio). Phosphate, ammonium and nitrate concentrations in the suspension and the dry cell weight of algae were measured at 0, 2, 4, 6 and 8 days of incubation. Then, the harvested microalgae biomass was mixed with a nutrient-poor soil at three levels: 0 (A0), 2 (A2) and 4 (A4) g 100 g−1. The mixtures were incubated for 2 months, and soil biochemical properties, including soil organic carbon (OC), available phosphorus (Pava), mineral nitrogen (Nmin), microbial basal respiration (MBR) and microbial biomass carbon (MBC), were determined in soil at 7, 14, 28, 35, 42, 49 and 56 days of incubation. The dry cell weight of the microalgae increased over time and removed ammonium, phosphate and nitrate from the leachate by 98.7, 92.7 and 56.9%, respectively. The added microalgae biomass to soil caused positive and significant changes in soil OC, Pava, Nmin, MBR and MBC. Therefore, it seems that Chlorella sp. cultivated in landfill leachate can be used as an agricultural fertilizer in soil. [ABSTRACT FROM AUTHOR]

Vertical up-flow-constructed wetlands integrating with microbial fuel cell (VFCW-MFC) were evaluated for N H 4 + -N removal and bioelectricity recovery. The experiments were carried out in lab-scale VFCW-MFC microcosms treating synthetic domestic wastewater under different operational conditions of pH, hydraulic retention time, and mass loading rate. Effects of wild ornamental grass (Cenchrus setaceus) on treatment performance and voltage output were investigated simultaneously. Experiments demonstrated that the neutral pH of influents favoured N H 4 + -N removal and power generation. Extended retention time improved treatment capacity and power output but likely depended on the substrate availability. COD removal and power output increased, while N H 4 + -N removal decreased with increasing mass loading rates. At the loading rate of 88.31 mg COD/L.day, planted VFCW-MFCs exhibited better N H 4 + -N treatment performance (36.9%) and higher voltage output (132%–143%) than unplanted systems. Plants did not affect the COD removal efficiency of VFCW-MFCs (>95%). Power density was in the range of 1.26–1.59 mW/m2 in planted microcosms with a maximum CE of 13.6%. The anode layer accounted for a major proportion of N H 4 + -N removal in VFCW-MFCs. This study implies that N H 4 + -N in domestic wastewaters with relatively high COD:N ratios can be treated effectively in up-flow CW-MFCs via anaerobic processes, including anammox and heterotrophic denitrifying processes. The mass loading rate could be a critical parameter to balance different microbial processes, thus, coincidently determining the potential of power recovery from wastewaters. [ABSTRACT FROM AUTHOR]

Residual aluminium from the coagulation–sedimentation process in the treatment of surface water can decrease the catalytic activity of a manganese co-oxide filter film (MeOx) used for ammonium and manganese removal. To solve this problem, a MeOx filter was used as a pretreatment process to filtrate source water directly before the coagulation and sedimentation treatment. The removal performance and the mechanism of change in the activity of MeOx were investigated. The experimental results indicated that the MeOx filter removed ammonium and manganese from surface water sources effectively, and its manganese removal activity was enhanced. The characteristics of MeOx were investigated via SEM, EDS, XPS, and the BET surface area. Analysis of the experimental results showed that the increase in the content of Al under this condition was much lower than that under treatment with the coagulation–sedimentation process. After long-term operation, the amount and surface area of MeOx coated on the filter sand increased significantly, leading to an increase in the catalytic activity. However, in cold water, the catalytic activity of MeOx decreased, and more Mn(II) was obtained on the surface of MeOx. Thus, the morphology of MeOx changed. Fortunately, when water temperature increases, the removal activity can recover immediately. By inactivating microorganisms and comparing the removal performance with that under other conditions, the MeOx activity of the pretreatment process is preserved effectively and no strengthening measures are required. This study will provide a new strategy for the use of the MeOx catalytic technology. [ABSTRACT FROM AUTHOR]

A new cyclo-pentazolate anion-based energetic cocrystal NH4N5 · 1/6NH4Cl was synthesized. The structure, thermal behavior, sensitivity, and detonation properties of NH4N5 · 1/6NH4Cl were studied. Cube-shaped NH4N5 · 1/6NH4Cl crystallizes in the Fd-3 m space group, and is formed by hydrogen bonding interactions. DSC-TG-MS combined techniques show that NH4N5 · 1/6NH4Cl has better thermal stability than NH4N5. The cocrystal exhibits low impact and friction sensitivity, and largely reduces the mechanical sensitivity of NH4N5. Furthermore, the cocrystal is predicted to have a detonation velocity of about 8.3 km s−1 and a detonation pressure of about 21.4 GPa, respectively, indicating excellent detonation performance. [ABSTRACT FROM AUTHOR]

The current work aimed to investigate the removal mechanism of NH4+ from wastewater treatment plant effluent (WWTPE) onto the zeolite in the plug-flow column reactor (PFCR). The adsorption process was optimised as a function of length (2–15), time (0.5–202 min), and accumulation (0.05–2.4 mg/g) using response surface methodology (RSM). The optimal operating parameters for the adsorption were recorded after 134.89 min with 1.52 mg/L of zeolite with 6.685 cm of the column length where the predicted and actual removal was 99.79 vs. 98.00% of NH4+ from WWTPE. The bed depth service time (BDST), Thomas, and Yoon-Nelson models were used to explain the adsorption behaviour. In contrast, the mass transfer factor (MTF) model was carried out to determine the internal and external removal mechanism. The findings revealed that PFCR exhibited an efficiency for removing NH4+ from WWTPE. The dynamic adsorption behaviour was satisfactorily described by the BDST, Thomas, and Yoon-Nelson models. These findings confirmed that the empirical models had verified the suitable of PFCR for removing NH4+ from WWTPE. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is involved not only in the regulation of plant growth, development, and stress responses but also in the regulation of plant-microbe interactions. Here, we demonstrate that Piriformospora indica can induce tobacco nitrate reductase to produce a NO signal in roots which enhances nitrogen uptake capacity by inducing the expression of ammonium and nitrate transporter genes and the development of lateral root and root hair, thereby promoting tobacco growth. In addition, the NO signal induced by P. indica is significantly different from that induced by the pathogen Phytophthora nicotianae. Inoculation with P. indica did not produce H2O2 and maintained high expression of Phytoglobin 1 in roots, resulting in a significantly lower NO level than in the roots inoculated with P. nicotianae. These findings suggest that an appropriate NO level is the likely basis of plant-P. indica symbiosis, which promotes the growth of host plants. [ABSTRACT FROM AUTHOR]

In extent of this study, ammonium removal from wastewater through biological nitrification process was performed in upflow biofilm reactors. The effects of hydraulic retention time (HRT) and nitrogen loading rate (NLR) on the nitrification process were investigated. For the nitrification process, the optimum HRT and NLR were determined to be 80 hr and 0.044 kg/m3.day, respectively. It is observed that the efficiency increased from 53% to 96% along with the increase in HRT from 22 hr to 80 hr and the decrease in NLR from 0.165 kg/m3.day to 0.044 kg/m3.day.The substrate consumption kinetics were studied in the attached growth reactor, and the Monod kinetic model, first-order kinetic model, modified Stover-Kincannon and Grau second-order kinetic models were examined. For the substrate consumption kinetic study, experimental studies were performed at 125, 150, 175, 200, 225 mg NH4-N/L substrate concentrations and 62 hr at HRT during the nitrification process. As a result of the considering kinetic studies, it was determined that the kinetic study was suitable for the modified Stover-Kincannon kinetic model that had the highest coefficient of regression by 0.997 and when the effluent NH4-N concentrations and NH4-N removal efficiencies calculated using kinetic models were examined, it was observed that the results closest to the experimental results (4.5, 10.1, 19.7, 26.2 and 42.3 mg NH4-N/L) were obtained through the modified Stover-Kincannon model (4.16, 10.71, 18.92, 28.12 and 39.51 mg NH4-N/L). [ABSTRACT FROM AUTHOR]

Ammonium polyphosphate (APP) is a type of fire-fighting material that has excellent performance; however, it also has the disadvantage of facile deliquescence. Microcapsule technology is therefore employed in this study to use melamine resin as encasing material in the preparation of melamine–formaldehyde resin-microencapsulated APP. The performance of prepared microcapsules is characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric experiments. The experimental results show that the same APP characteristic peaks (e.g., N-H stretching vibration peaks) and characteristic absorption peaks of melamine-formaldehyde (MF) resin (e.g., vibration peak of MF ring) are exhibited by the microcapsules. Furthermore, the coated microcapsule surface is rough because of the adsorption of solid particles, indicating that the wall material successfully covers the core material. Thermogravimetric analysis shows that the microcapsules can effectively increase and decrease the maximum weight loss rate temperature and maximum weight loss rate, respectively. When the microcapsule content constitutes 15% of the total sample mass, the maximum weight loss rate and coal temperature decrease and increase by 0.58%/min and 13°C, respectively. This significantly inhibits the composite coal-oxygen process, indicating the improved fire-fighting performance afforded by microcapsules. The Research provides a new direction for the development of fire-fighting materials. [ABSTRACT FROM AUTHOR]

Nitrogen and water should be applied at the right time and amount to obtain optimum crop yield in arid and semi-arid regions. The study was carried out in 2017–2018 to investigate the effects of different supplementary irrigation levels applied after harvests, and different nitrogen sources on water use efficiency (WUE), yield and quality characteristics of sun-cured tobacco. The study included five different nitrogen sources (N1: zero-nitrogen, N2: ammonium nitrate, N3: ammonium sulfate, N4: calcium ammonium nitrate, and N5: urea) and four different irrigation treatments (I0:No irrigation; I33:66% deficit, I66:33% deficit and I100:100% full irrigation). The effects of nitrogen sources and supplementary irrigation treatments on plant height, leaf number, leaf width, leaf height, yield, quality grade, sugars, nicotine, phenolics, WUE and irrigation water use efficiency (IWUE) were statistically significant. Seasonal crop evapotranspiration values ranged between 117.7 and 235.3 mm. The highest WUE 1.65 kg m−3 and IWUE: 10.48 kg m−3 were recorded in I33 treatment. Plant characteristics were different between nitrogen sources; however, the results did not indicate a prominent nitrogen form. The results for supplementary irrigation revealed that the I100 treatment in semi-arid conditions increased the sun-cured tobacco yield by 22% with acceptable quality improvements. The gross income increased 1705 $ ha−1 with the increase in tobacco yield and sale price per hectare. [ABSTRACT FROM AUTHOR]

Ammonium (NH4+) oxidation is crucial for nitrogen (N) removal, contributing to regional and global N cycles, but is regarded as limited to a few biological pathways. A novel pathway for NH4+ oxidation and the N cycle is provided in the microbial anaerobic NH4+ oxidation coupled with Fe(III) (ferric iron) reduction, called ferric ammonium oxidation (Feammox). Over the past few years, Feammox, which results in significant loss of N in natural environments, has been detected widely in both terrestrial and aquatic ecosystems. Researchers have revealed various Feammox pathways, end products of nitrate (NO3-), nitrite (NO2-), and gaseous nitrogen (N2), and the interactions within the nitrogen and iron-cycle-related microbial communities, which might offer some novel alternative processes for wastewater treatment. However, there are substantial variations among different studies in terms of the key functional microorganisms. The underlying mechanisms of Feammox, as well as the effect of environmental factors, remain poorly understood. In this review of the emerging process, we detail the end-products and microbes involved in the Feammox process and discuss possible mechanisms and the main influential factors. In particular, we assess the potential applications in wastewater treatment based on previous experimental studies and highlight knowledge gaps and future research opportunities. [ABSTRACT FROM AUTHOR]

Catharanthus roseus belongs to the Apocynaceae family and is known as an important medicinal plant that produces several valuable terpenoid indole alkaloids. Reserpine is an indole alkaloid utilized in the treatment of paranoia, schizophrenia, and hypertension. In this study, we aimed to examine the effects of different concentrations of urea fertilizer and substrates on reserpine production by C. roseus plants. These plants were cultivated in pots containing either soil-humus-quartz, soil-perlite-quartz, or sand-quartz and treated with urea (60, 100, and 120 kg ha − 1) for 12 days. The experiment was performed based on a completely randomized factorial design with three replications. Different physiological parameters and reserpine concentrations were measured. Overall, results showed that the soil-humus-quartz substrate and 60 kg ha − 1 concentration of urea led to superior physiological and growth parameters (i.e., number of leaves, root length, root biomass, shoot length and shoot biomass) and the highest reserpine concentrations (605.8 ± 4.3 μg g − 1). It seemed that the soil-humus-quartz substrate contained organic materials and microorganisms which contributed to the generation of three nitrogen sources (i.e., urea, nitrate, and ammonium), enhanced the secondary metabolic pathways, and led to the highest production of reserpine in C. roseus plants. Supplemental data for this article is available online at https://doi.org/10.1080/11263504.2021.1986587. [ABSTRACT FROM AUTHOR]

This work explores the techno-economic aspects of landfill leachate treatment by an integrated scheme composed of microfiltration (MF), nanofiltration (NF), and zeolite application for carbon and nitrogen removal. In bench-scale experiments, MF and NF were investigated, and zeolite batch tests were carried out to determine optimum conditions. A preliminary economic analysis is presented for a 200 m3 d−1 full-scale treatment facility based on the data obtained from experimental tests and literature surveys. The maximum removals of 92%, 94%, and 79% for chemical oxygen demand (COD), absorbance at 254 nm, and ammonium nitrogen (NH4+-N) were achieved in bench experiments, respectively. It was possible to reach the local discharge standard for COD (200 mg L−1), but it was not possible to reach the Brazilian disposal requirement for NH4+-N (20 mg L−1). The total cost of the integrated MF + NF + zeolite system was estimated at 19.89 US$m−3. In this study, the costs of the zeolite application account for around 70% of the total costs of the integrated scheme. Membrane process integration was an adequate strategy for removing organic compounds at low operating costs; However, further NH4+-N depuration is needed to meet discharge requirements. [ABSTRACT FROM AUTHOR]

Roots are important plant organs that absorb water and nutrients. Root length responses are influenced by the plants' sources of nitrogen (N), such as ammonium (NH4+) and nitrate (NO3−) ions and their concentrations. Here, to determine the genetic resources with the potential to improve the root system of rice (Oryza sativa L.), the root development traits of a core set of 334 introgression lines (ILs) were assessed in plants grown in hydroponic culture medium containing low (5 μM) or high (500 μM) concentrations of N in the form of NH4+ or NO3−. ILs were classified into three clusters. The mean value of maximum root length (MRL) in cluster I was significantly higher than that in the other two clusters under all conditions. Root number (RN) differed significantly between clusters IIa and IIb, with the mean RN being higher in cluster IIa. In addition, the order of the mean total root length of the clusters was cluster I > IIa > IIb. Therefore, ILs in cluster I are considered genetic resources for improving root development traits under all tested N conditions. Among the ILs, YTH187 – which is derived from YP5 as a donor – had a longer MRL under all conditions. Quantitative trait loci (QTL) analyses, performed using recombinant inbred lines derived from a cross between IR 64 and YTH187, revealed that qRL5.3-YP5 and qRL6.5-YP5 were detected under all N conditions. In contrast, qRL4.1-YP5 was detected only under low KNO3 concentrations, whereas qRL8.1-YP5 was detected under high concentrations of NH4Cl and KNO3. YP5 alleles at these QTLs increased MRL. QTLs for root length in rice grown in hydroponic culture have not previously been detected in the vicinity of qRL8.1-YP5; thus, this may be a novel QTL that controls root length in rice. Moreover, qRL8.1-YP5 and qRL4.1-YP5 could be useful QTLs to determine the mechanism of root elongation under KNO3 conditions because such QTLs have not yet been detected under these conditions in rice. In future studies, further fine-mapping and characterization of qRL8.1-YP5 could reveal the mechanism of root elongation under high KNO3 concentration conditions. [ABSTRACT FROM AUTHOR]

Anti-oxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions. Benzimidazoles and their derivatives make up an important class of heterocyclic compounds which have a wide range of therapeutic and pharmacological properties, including anti-oxidant,[1] antimicrobial,[[2]] antihelmintic,[4] anticancer,[5] antihypertensive,[6] anti-inflammatory,[7] analgesic,[8] and antiprotozoal activities.[9] The classical synthesis of benzimidazoles involves the reaction between an I ortho i -phenylendiamine and a carboxylic acid (or derivative, such as a nitrile, amidate, or orthoester) under harsh dehydrating conditions.[10] A survey of the recent literature reveals several methods for the synthesis of benzimidazoles using sulfamic acid,[11] DDQ,[12] air,[13] Oxone,[14] FeCl SB 3 sb /Al SB 2 sb O SB 3 sb ,[15] In(OTf) SB 3 sb , [16] Yb(OTf) SB 3 sb ,[17] Sc(OTf) SB 3 sb ,[18] KHSO SB 4 sb ,[19] IL,[20] or PBBS.[21] Oxidation reactions can produce free radicals. Some of the compounds displayed moderate anti-oxidant activity using the DPPH radical assay. Several compounds from fruits and vegetables were recently found to possess anti-oxidant activities.[23] In this vein, heterocyclic compounds obtained by synthesis are also reported to possess anti-oxidant activity.[24] Benzimidazoles have been studied in this regard and are used, for example, as radical scavengers.[25] As part of our systematic research on synthesis methodology,[[26], [28], [30]] we now report a selective synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzimidazoles in water and under solvent-free conditions. [Extracted from the article]

In this study, two experiments were conducted to evaluate the plant response of Brachiaria brizantha cv. MG5 to nitrogen forms and different pH of nutrient solution. For this, nutrient solutions containing ammonium and ammonium nitrate were fixed at pH 4, 6 or 8, and nutrient solution containing nitrate was fixed at pH 6. The pH adjustment was done by different compounds including MES, calcium hydroxide, calcium carbonate and sulfuric acid. In another experiment the seedlings were grown in nutrient solution with different N forms, but without pH adjustment. The results showed that plants in ammonium or ammonium nitrate at pH = 4 had better growth and performance, followed by pH = 6, compared to plants grown at pH = 8 (buffered with calcium carbonate). Calcium carbonate (bicarbonate) especially in higher amounts in nutrient solution (pH = 8) significantly reduced plant growth particularly root growth as the toxic effects were visible on the roots. The adverse effect of carbonate at high pH was more than those at low pH. High concentration of carbonate in presence of ammonium also was toxic for plants probably due to additional toxic effect of ammonia. However, plants were able to grow normally with different N forms under hydroponics culture, independent of pH effect. When pH was not controlled under different N-forms, there was no significant difference between root and shoot biomass production or leaf SPAD value and protein concentration. So, the presence of carbonate but not pH, was determined as an inhibiting factor for growth of Palisadegrass plants. [ABSTRACT FROM AUTHOR]

The present investigation deals with separation of various types of nitrophenols using SILM technique. Several ionic liquids were developed and the SILM parameters such as role of ILs, feed and strip phase concentration, wastewater pH, salt effect and mixture of pollutants were thoroughly investigated. The percentage extraction and stripping, flux, apparent rate constants and selectivity were evaluated. The selected ammonium IL being more polar than the imidazolium IL showed better separation of 2-nitrophenol. The SILM constituting an ammonium IL with SCN anion exhibited extraction efficiency of >96% and Ka: 0.264 h−1. The change in feed concentration showed maximum transport of nitrophenol at 300 ppm concentration (Ka: 0.673 h−1). The membranes were repeated for 4 cycles which demonstrated good stability for runs of more than 48 hours. The selectivity of 2-nitrophenol, 2,4-dinitrophenol, 2,4,6- trinitrophenol over nitrobenzene was 26, 36 and 58, respectively. The morphology of membranes was studied by using FTIR and FE-SEM and the transport mechanism was elucidated. With the optimized parameters, a concentration factor of 7 can be achieved in the present SILM system. The application of SILM including ammonium IL with SCN anion shows a promising potential for the treatment of various types of nitrophenol bearing wastewater. [ABSTRACT FROM AUTHOR]

It is effective to adsorb phosphate and ammonium from water by sludge-based biochar, while the desorption performance has not been studied systematically. Biochar in this study was prepared through the co-pyrolysis of sludge and walnut shells to remove N H 4 + and P O 4 3 − from water. The desorption characteristics of N H 4 + and P O 4 3 − from the post-adsorption sludge-based biochar were investigated. The effects of the adsorption condition (concentration of adsorption solution) and desorption conditions (pH value of desorption solution and desorption temperature and time) on desorption performance were examined. Several techniques were performed to characterise the properties of the post-adsorption sludge-based biochar. The adsorption amount of the pure sewage sludge biochar (SBC) for P O 4 3 − and the biochar derived from the co-pyrolysis of sewage sludge and walnut shell with the mixing ratio of 3:1 (MBC3-1) for N H 4 + were 14.19/ 23.75 mg/g and 9.28/ 16.23 mg/g, respectively, when the concentrations of the adsorbates were 100 and 500 mg/L. The desorption experiments showed that the acidic condition (pH = 2) was beneficial for P O 4 3 − and N H 4 + desorption. The highest desorption ratio reached 7.58% for P O 4 3 − and 2.18% for N H 4 + . The desorption of P O 4 3 − was endothermic, whereas that of N H 4 + was exothermic. The desorption amounts of P O 4 3 − and N H 4 + decreased and increased, respectively, with the increase in desorption time. This study of the desorption characteristics of P O 4 3 − and N H 4 + in sludge-based biochar provides a theoretical basis for the subsequent utilisation of sludge-based biochar. [ABSTRACT FROM AUTHOR]

Article title: Tolerance of anammox reactor packed with zeolite to partial supply of nitrite or ammonium using purified livestock wastewaterAuthors: Miyoko Waki, Kaoru Abe, Tomoko Yasuda and Yasuyuki FukumotoJournal:ENVIRONMENTAL TECHNOLOGYBibliometrics: Volume 41, Number 11, pages 1411–1418DOI:http://dx.doi.org/10.1080/09593330.2018.1537307This article was originally published with few wrong entries in Table 3. This error was detected after publication, and for this reason we have corrected Table 3 and republished the article. [Extracted from the article]

The response of pepper (Capsicum annuum L.) to Ammonium-N was studied in a multispan greenhouse under soilless culture using coir fiber as substrate. Ammonium-N application rates were 0, 2, 4, 6 and 8 mM with a total-N concentration of 13 mM. The total content of the rest of all macronutrients in the nutrient solution was maintained from the beginning of the experiment until the end. The highest water uptake was recorded at 2 mM ammonium concentration in the nutrient solution. Compared to nitrate, ammonium nitrogen caused a decrease in nitrate absorption, but led to an increase when applying 8 mM ammonium. Despite a progressive increase in ammonium content in the nutrient solution, potassium absorption was constant below the ammonium concentration of 8 mM. Under a high N-NH4 content (from 6 to 8 mM) in the nutrient solution, high toxicity was found, deriving in the appearance of deformed or noncommercial fruits. There was a significant benefit by the use of ammonium as a component in the nutrient solution. The optimum yield ammonium concentrations were found in the range from 2 to 4 mM. Nevertheless, concentrations higher than 6 mM led into a decrease in commercial production, with the production of increasing deformed fruit, out of size and/or blossom-end rot. [ABSTRACT FROM AUTHOR]

In our preview research, four novel quaternary ammonium hybrids were isolated from the Stereum hirsutum FP-91666. To further discover this type of compounds, S. hirsutum was fermented in 30 L YMG broth, and eight hybrid compounds including four new quaternary ammoniums were obtained, which are sesquiterpenes combined with α-amino acids. Their structures were elucidated by extensive spectroscopic analyses, including 1D- and 2D-NMR, and HR-MS experiments. [ABSTRACT FROM AUTHOR]

Cationic quaternary ammonium gemini surfactants were synthesized by mixing N,N-dimethylcetylamine and α,ω-dibromoalkane. The synthesized products were characterized by C, H, N elemental and 1H NMR analyses. The critical micelle concentration (CMC) of these surfactants with and without additives was calculated by means of the conductivity technique. The role of the synthesized quaternary ammonium geminis in the reaction was investigated by a UV–vis spectroscopy. The rate constant (kψ) was determined at different gemini concentrations and plotted graphically as kψ vs. [16–s–16]. Additionally, the influence of other reaction parameters (viz., reactants, pH, and temperature) was investigated. The binding constants were also determined (KA for [Cu(II)–His]+ and KB for ninhydrin). The resulting kψ–[16–s–16] plot can be understood in terms of a pseudo-phase model of micelles. [ABSTRACT FROM AUTHOR]

Ammonium (NH4+) is a major nitrogen source for tea plant growth. Although NH4+-induced growth of tea plants were reported, it was still unclear to elucidate the mechanism of proteins in tea plants in responding to NH4+ resupply. In the present study, the proteomic profiles of tea leaves under N deficiency/resupply were investigated by using LC-MS/MS and PRM technique. Compared with N deficiency, there were 247 and 328 proteins significantly expressed after 3 h and 3d of N resupplied, respectively. And compared with 3 h of N resupplied, there were 186 proteins significantly expressed after 3d of N resupplied. According to bioinformatics analysis, the results showed that different expressed proteins participated in various biological processes, such as PsbO, Pbs27, PsaN, and PsaF were involved in photosynthesis, ADH1, AOC3, URE, GDH1-2, and argD were involved in amino acid metabolism, CHI and ANR were involved in flavonoid biosynthesis, GSTF9, APX, and GSS were involved in glutathione metabolism, and PdxT and PdxS were involved in vitamin B6 metabolism. Through PPI analysis, the results showed that the interactions between different expressed proteins mainly occurred in the photosynthetic pathway. Ammonium supply has a profound impact on photosynthesis, amino acid metabolism, flavonoid biosynthesis, glutathione metabolism, and vitamin B6 metabolism. [ABSTRACT FROM AUTHOR]

Most of nitrogen emissions can be ascribed to agro-industrial activities. Since digestate produced by fermentation of agro-industrial residues can be difficult to dispose of due to its high ammonium content, advanced technical- and cost-effective technologies must be developed and applied in order to significantly reduce its impact on the environment. In this study, aerobic granules were successfully cultivated in a granular sludge sequencing batch reactor (GSBR) fed with the ammonium-rich (approx. 2500 mg L−1) effluent of a 3-stage anaerobic digester treating agro-industrial residues. The peculiar characteristics of such wastewater required a 2-step operating strategy aimed at the selection of nitrifying biomass (Step 1) and the formation of aerobic granular sludge (Step 2). During Step 1, nitrifying biomass selection was achieved by properly regulating the cycle length: N H 4 + - N removal rates progressively increased from 42 to 109 mgN L−1d−1, and a corresponding increase in N H 4 + - N specific removal rates from 8 to 24 mgN gVSS−1d−1 was also observed. During Step 2, the increase in selective pressures (i.e. minimum settling velocity and volumetric organic loading rate) led to the formation of compact (average diameter, 1.02 ± 0.43 mm) and well-settling granules (SVI5, 28.6 ± 3.8 mL gTSS−1), which were able to remove up to 89 ± 2% of organic matter (as COD), 79 ± 3% of N H 4 + - N and 59 ± 4% of nitrogen (as a sum of N H 4 + - N , N O 2 – - N and N O 3 – - N ). The 2-step operating strategy played a key role in biomass selection and subsequent granule formation and maintenance in the GSBR, and may be successfully adopted for the treatment of different ammonium-rich wastewaters. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the growth and nutrient removal efficiency of a mixed microalgal culture with and without the addition of low concentrations (0.5, 1, and 5 g L-1 of total liquid volume in the reactor) of natural zeolite. A control test in which only zeolite was added into a similar membrane photobioreactor was also conducted. The addition of 0.5 g L−1 zeolite to a continuously-fed membrane photobioreactor increased the microalgal biomass concentration from 0.50 to 0.90–1.17 g particulate organic carbon per L while the average ammonium removal efficiency increased from 14% to 30%. Upon microscopic inspection, microalgal cells were observed growing on the surface of zeolite particles, which indicates that zeolite can support attached microalgal growth. With higher zeolite doses (1 and 5 g L−1) inside the reactor, however, the breaking apart of added zeolite particles into finer particles dramatically increased solution turbidity, which likely was not beneficial for microalgal growth and ammonium removal due to reduced light penetration. This work shows that low doses of zeolite can be used as microcarriers to enhance microalgal biomass concentration and ammonium removal efficiency, while minimizing zeolite dose would likely reduce the turbidity effects. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is one of the most produced cereals in the world. Among the essential nutrients required by this crop, nitrogen (N) is of paramount importance to achieve optimum yields. In paddy fields, ammonium (NH4+) represents the main source of N. This work aimed to evaluate the root morphology, ammonium uptake kinetics and N accumulation in two upland rice varieties, Piauí and Manteiga from Maranhão – Brazil. The varieties were cultivated in hydroponic conditions and submitted to three different doses of ammonium: 1 – constant treatment with 0.2 mM NH4+, 2 – constant treatment with 1 mM NH4+ and 3 – constant treatment with 1 mM NH4+, followed by N starvation during 72 h and resupply with 1 mM NH4+. The varieties present contrasting behaviors when submitted to different doses of NH4+. Piauí showed higher biomass and root length under the treatment with 0.2 mM NH4+. The favorable kinetics parameters observed contributed to a higher N accumulation by Piauí in low dose of NH4+. Under 1 mM NH4+, a higher root biomass and favorable kinetics parameters was recorded by Manteiga. This variety presented a better performance with higher doses of N. Under the treatment of N resupply, Piauí variety showed to be more adapted, due to the greater root plasticity observed. For one hand, the results suggest that Piauí variety presents greater growth in environments with low dose or seasonal flux of NH4+. On the other hand, Manteiga variety presents better growth when submitted to higher levels of NH4+. [ABSTRACT FROM AUTHOR]

In many intensively used agricultural regions nitrate leaching into the groundwater is a major concern. To elucidate the effects of a nitrification inhibitor (3,4-dimethylpyrazole phosphate = DMPP) and a cation binding mineral (zeolite) on nitrogen leaching, yield and nitrogen uptake of spring wheat a pot experiment was conducted. The experiment was arranged based on a randomized complete block design with 7 treatments and 4 replications: control (without N fertilizer), ammonium sulfate alone, ammonium sulfate + DMPP and ammonium sulfate + zeolite (30, 36, 42 and 48 g pot−1). Excess water was applied 25, 50, 75 and 100 days after seeding to provoke leaching. While at the first leaching event nitrate leaching was drastically reduced due to the application of DMPP, ammonium leaching was highest. At later leaching events losses for both mineral N forms was rather low with no significant differences between treatments. Contrary to expectations zeolite applications resulted in higher nitrate leaching losses compared to the AS treatment, however, ammonium losses were lower. Neither residual soil mineral N nor grain yield showed any differences between the N treatments. The significantly highest amount of nitrogen uptake by the above ground plant was observed for the AS + DMPP treatment. Overall the effects of zeolite compared to a pure ammonium sulfate application on total N recovery were rather small. It might be worthwhile to get a better understanding of the ammonium adsorption and desorption processes induced after zeolite application during the early phase of the growing period when plant N uptake is less dominating. [ABSTRACT FROM AUTHOR]

During the past two decades, interest has developed in regard to the possibility that plant roots can take up organic N compounds directly, a concept which challenges the conventional wisdom that soil inorganic N forms ( NH 4 + and NO 3 − ) are the sole primary sources of N absorbed by plant roots. We reviewed the literature based on single or dual (15N, 13C) stable isotope labelling techniques to test the hypothesis of direct uptake. Both isotopically enriched and natural abundance approaches were reviewed. Of the methods examined, the dual enrichment technique, when combined with compound specific and position-specific stable isotope analysis, provided incontrovertible evidence for direct uptake of simple amino acids. We demonstrate that dual labelling lacks overall sensitivity due to the high C concentration in plant tissue relative to N, and the higher natural abundance of 13C cf. 15N, which limits the period of measurement due to isotope dilution, and hence an assessment of the long-term contribution of direct uptake to the N economy of plant communities. [ABSTRACT FROM AUTHOR]

An attempted isolation of the elusive diammonium tetraoxidotungstate (NH4)2[WO4] as its imidazole (Im) adduct resulted in the serendipitous formation of hepta(ammonium) penta(1H-imidazol-3-ium) paratungstate B tetrahydrate having formula [NH4]7[ImH]5[W12O42]·4H2O (1). The synthesis, vibrational spectra, crystal structure and thermal study of the mixed cationic paratungstate tetrahydrate 1 are reported. The structure of 1 consists of a centrosymmetric paratungstate [W12O42]12– anion devoid of internal hydrogen atoms, which is charge balanced by ammonium and 1H-imidazol-3-ium cations. One of the four unique NH4+ cations and one of the three crystallographically independent 1H-imidazol-3-ium cations are disordered around a center of inversion. The cations, [W12O42]12– anion and the unique lattice water molecules are joined with the aid of five varieties of hydrogen bonding interactions. A comparative study of twenty-three partaungstates is described. Thermal decomposition of 1 results in the formation of monoclinic tungsten trioxide WO3. [ABSTRACT FROM AUTHOR]

Sandy soil is typically poor in organic matter. When areas with sandy soil are used for pasture prior to soybean cultivation, the availability of nitrogen (N) for plants is limited even further. Our objective was to evaluate if inoculation combined with N fertilization increases N content in the soil and N supply to soybean plants in post-pasture and post-soybean areas. Four experiments were conducted in degraded post-pasture and post-soybean areas in a sandy soil (Rhodustult), between 2016 and 2018, in Brazil. Treatments used a combination of inoculant (zero, 4, 8 and 12 rates ha−1) and mineral N (0, 25, 50, and 100 kg ha−1) with four replicates. It was using the soybean cultivar TMG 7062 IPRO. The post-soybean area had higher N content in the soil than the post-pasture area; 33, 32, and 21% for total N, microbial biomass nitrogen (MBN), and inorganic nitrogen (IN), respectively. Soybean shoots from the post-soybean area also had greater accumulations of N (86 kg ha−1 of N). Increased N fertilization linearly raised levels of N in the soil (total N, MBN, and IN). In both areas, the effect of inoculation was restricted by the increase of total N in the soil. Inoculation combined with moderate rates of N in soybeans (50 kg ha−1) increased levels of N in the soil and N supply to plants in post-pasture areas. In post-soybean areas, inoculation alone fulfilled the N soybean need. [ABSTRACT FROM AUTHOR]

The effect of applying different hydraulic retention times (HRTs) was investigated for a lab-scale membrane bioreactor (MBR) treating domestic wastewater. The submerged flat-type ultrafiltration MBR was operated under three HRTs (576 min, 462 min, and 372 min) corresponding to three operating periods to investigate its efficiency in removing organic content and nutrients from domestic wastewater. The chemical oxygen demand (COD) decreased from 99 to 96.5% with the HRT decreased from 576 min to 462 min. The bacteria performing nitrification were affected by the HRT change: the ammonium (NH4-N) removal dropped from 98.5% (HRT of 576 min) to 74.2% (HRT of 462 min). With the HRT adjusted to the lowest value of 372 min, the COD and NH4-N removals were 94.4% and 55.8%, respectively. The phosphate (PO4-P) removal was 59.1%, 34.4%, and 28% during periods 1, 2 and 3, respectively. In terms of the COD removal efficiency, the treated effluent met the Turkish limits for discharge to the receiving water during all of the operating periods. The system performance was suitable in terms of NH4-N removal for periods 1 (HRT of 576 min) and 2 (HRT of 462 min). However, applying the operating conditions of period 2 (i.e., maintaining the HRT at 462 min) requires additional post-treatment (e.g., low-cost chemical precipitation) to enhance the PO4-P removal. [ABSTRACT FROM AUTHOR]

Nutrients were extracted from digester supernatant sampled from a full-scale enhanced biological phosphorus removal (EBPR) wastewater treatment plant. A four-compartment selectrodialysis setup was used to extract ammonium and phosphate in two separate compartments. The initial phosphate recovery rate was measured to be 0.072 mmol m−2 s−1 and the initial ammonium recovery rate was measured to be 1.31 mmol m–2 s–1. The ammonium recovery rate was 18 times higher than that for phosphate, whereas the molar concentration of ammonium in the feed was 10 times higher than that of phosphate. An average recovery of 72 ± 1% and 90 ± 10% for ammonium and phosphate was observed after 3 h of operation. A monovalent anion selective (MVA) membrane was used to avoid ammonium and reduce the concentration of monovalent anions in the phosphorus stream. The pH in the phosphorus stream was kept at 10 so phosphate did not pass the MVA membrane. A membrane area of 26 m2 per m3 digester supernatant was required to recover 70% of phosphate and ammonium for the digester supernatant that contained 6 mM phosphate and 105 mM ammonium. [ABSTRACT FROM AUTHOR]

Heavy metal pollution is rapidly increasing in the environment. It has been shown that exposure to vanadium and chromium is able to alter the immune response. Nevertheless, the mechanisms by which these metal pollutants mediate their immunomodulatory effects are not completely understood. Herein, we examined the effect of ammonium metavanadate and potassium dichromate on the development of an inflammatory response caused by subcutaneous injection of turpentine oil. We demonstrated that pretreatment of rats with ammonium metavanadate and potassium dichromate for two weeks prior to initiation of the inflammatory response resulted in a wider zone of necrosis surrounding the site of inflammation. The acute inflammatory process in the combined model was characterized by elevated serum levels of IL-10 and decreased serum levels of IL-6 as compared to rats not treated with ammonium metavanadate and potassium dichromate. Ammonium metavanadate and potassium dichromate administration induced a decrease in the proportion of splenic His48HighCD11b/c+ myeloid cells accompanied by a reduced infiltration of the wound with neutrophils. Further analysis showed decreased proportions of CD3+CD4+IFNγ+ and CD3+CD4+IL-4+ T cells in the rats with combined model as compared to inflamed rats not treated with ammonium metavanadate and potassium dichromate. The data suggest that consumption of vanadium and chromium compounds disrupts the inflammatory response through an altered balance of pro- and anti-inflammatory cytokines and inhibition of effector T cell activation and neutrophil expansion. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is the mineral nutrient required in greater quantities by plants with deficiencies affecting crop production. Nitrate (NO3-) and ammonium (NH4+) are the inorganic N forms most readily available for plant uptake. We investigated the influence of ammonium and nitrate rates on growth, nutritional status, chlorophyll production, and nutritional efficiency in mahogany seedlings, grown in an Oxisol soil under greenhouse conditions. Treatments were five N rates (50, 100, 150, 200, and 400 mg dm−3 N) in ammonium and nitrate forms and control treatment (0 mg dm−3 N), in a factorial design with five replications. The plants were harvested for evaluation at 150 days after transplanting. N supply affected mahogany growth, mainly in the production of leaf tissue. The maximum economic efficiency of N rates for production of leaf tissue was around 190 mg dm−3 N. The ammonium supply enhanced leaf tissue production, with a 20% increase in leaf area and 15% in leaf dry matter compared to nitrate. Furthermore, the plants showed a preference for ammonium uptake in rates above 200 mg dm−3 N, which indicates that the preference for N form was dependent on the concentration of N in the soil. The ammonium supply enhanced nutritional status, mainly phosphorus, demonstrating high synergism on uptake of this nutrient. Conversely, a strong antagonism between nitrate and phosphorus uptake was observed. Thus, ammonium enhanced the growth and nutritional status of mahogany seedlings and must be prioritized in its fertilization. [ABSTRACT FROM AUTHOR]

Macroalgal growth in temperate coastal ecosystems is primarily regulated by light and inorganic nitrogen availability. The effect of light (photon irradiance) on NO3- and NH4+ uptake, and NO3- - assimilation, were studied in the red macroalga, Hemineura frondosa, which does not operate a carbon concentrating mechanism (non-CCM). Non-CCM macroalgae grow in low and high light environments but become increasingly dominant with depth, suggesting a mechanism for 'preserving energy' under low light levels. H. frondosa was acclimated to limiting (30 µmol photons m-2 s-1) and saturating (150 µmol photons m-2 s-1) irradiances for 8 days. Then, NO3- and NH4+ uptake rates were measured under limiting and saturating irradiances at six concentrations ranging from 2--64 µM. NO3- uptake did not follow saturating uptake kinetics at both irradiances suggesting multiple uptake mechanisms. NH4+ uptake saturated at concentrations <32 µM under limiting but not under saturating irradiance. Saturating irradiance resulted in greater maximum uptake rates of both NO3- and NH4+. There was no evidence that irradiance regulated NO3- reduction by nitrate reductase. Also illustrated is the importance of measuring nitrate reductase activity on fresh material, as freezing in liquid nitrogen and storage at -80°C for 7 days caused a 65% decline in activity. Photosynthetic pigments, soluble tissue nitrogen and % total tissue nitrogen were all higher in limiting irradiance. In this first study of the nitrogen physiology of a non-CCM seaweed, we show that light regulates NO3- and NH4+ uptake but not NO3- assimilation. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) is a promising biological nitrogen removal process, due to its advantages of high efficiency and low cost. However, problems remain in the application, such as long startup period and susceptibility to environmental variations. Quorum sensing (QS), as a means of bacterial communication, attracts more attentions in regulating aggregation behavior and microbial density. Many physiological characteristics of anammox bacteria have been confirmed to be associated with QS, including specific anammox activity, growth rate and the production of extracellular polymeric substances (EPS), which directly affect the performance of anammox process. Therefore, a comprehensive understanding of the QS in anammox process is prerequisite. This work systematically reviewed the role and application of QS in the anammox process with the focus on mechanism. Additionally, current challenges and research needs were proposed. [ABSTRACT FROM AUTHOR]

The carbon isotopic composition (δ13C) of foliage is often used as proxy for plant performance. However, the effect of N O 3 – vs. N H 4 + supply on δ13C of leaf metabolites and respired CO2 is largely unknown. We supplied tobacco plants with a gradient of N O 3 – to N H 4 + concentration ratios and determined gas exchange variables, concentrations and δ13C of tricarboxylic acid (TCA) cycle intermediates, δ13C of dark-respired CO2, and activities of key enzymes nitrate reductase, malic enzyme and phosphoenolpyruvate carboxylase. Net assimilation rate, dry biomass and concentrations of organic acids and starch decreased along the gradient. In contrast, respiration rates, concentrations of intercellular CO2, soluble sugars and amino acids increased. As N O 3 – decreased, activities of all measured enzymes decreased. δ13C of CO2 and organic acids closely co-varied and were more positive under N O 3 – supply, suggesting organic acids as potential substrates for respiration. Together with estimates of intra-molecular 13C enrichment in malate, we conclude that a change in the anaplerotic reaction of the TCA cycle possibly contributes to 13C enrichment in organic acids and respired CO2 under N O 3 – supply. Thus, the effect of N O 3 – vs. N H 4 + on δ13C is highly relevant, particularly if δ13C of leaf metabolites or respiration is used as proxy for plant performance. [ABSTRACT FROM AUTHOR]

Chemical preparation, X-ray diffraction data collection on a single crystal and IR spectroscopy studies of the monophosphate (C7H4NH3OOH)H2PO4, meta-carboxyphenyl ammonium dihydrogenophosphate crystal (m-CPAMP) were developped at room temperature. The title compound crystallizes in the monoclinic system, with the centrosymmetric space group P21/c (Z = 4). Its unit-cell dimensions are a = 12.9361 (7) (Å), b = 11.7735 (6) (Å), c = 6.5764 (4) (Å), β = 102.668 (2)° and V = 977.22 (9) Å3. The structure determined gives a clear description of the hydrogen bonds connecting the hydrogen phosphate H2PO4- with the organic matrix. In the structure of this compound, each (H2PO4)− aggregates with cation through hydrogen-bond interactions of O-H----O(P) and N-H····O(P) types, and with another (H2PO4)− via hydrogen bonding O1-H····O3, forming symmetrical (H4P2O8)2− anionic units.The Infrared spectrum of (C7H4NH3OOH)H2PO4 compound is studied in comparison to that of the cation C7H4NH3OOH considered in its free symmetry. [ABSTRACT FROM AUTHOR]