Release Of Nitrates Research Articles

Electrochemical Nitrate-to-Ammonia Conversion Enabled by Carbon-Decoration of Ni─GaOOH Synthesized via Plasma-Assisted CO2 Reduction.

The release of nitrates into the environment leads to contaminated soil and waterthat poses a health risk to humans and animals. Due to thetransition to renewable energy-based technologies, an electrochemical approach is an emerging option that can selectively produce valuable ammonia from nitrate sources. However, traditional metal-based electrocatalysts often suffer from low nitrate adsorption that reduces NH3production rates. Here, aNi-GaOOH-C/Ga electrocatalyst for electrochemical nitrate conversion into NH3 is synthesized via a low energy atmospheric-pressure plasma process that reduces CO2into highly dispersed activated carbon on dispersed Ni─GaOOH particles produced from a liquid metal Ga─Ni alloy precursor. Nitrate conversionrates of up to 26.3µgh-1mg-1 catareachieved with good stability of up to 20h. Critically, the presence of carbon centers is central to improved performance whereboth Ni─C and NiO─C interfaces act as NO3-adsorption and reduction centers during thereaction. Density functional theory (DFT) calculations indicate that the NiO─C and Ni─C reaction sites reduce the Gibbs free energy required for NO3-reduction to NH3compared to NiO and Ni. Importantly, catalysts without carbon centers do not produce NH3, emphasizing the unique effects of incorporating carbon nanoparticles into the electrocatalyst.

Synthesis, characterization, cytotoxicity and antimicrobial activity of a nanostructured mineral clay

Clay minerals nanostructured appear as an alternative to increase textural property and mechanical strength, such as montmorillonite (MMT-NPs). Nanocomposites are nanomaterials made up of a matrix and reinforcement, to obtain a higher quality nanomaterial. In parallel, (agro)industrial waste constitutes a major socio-environmental problem, such as rice husk (RH - a source of silica) and residual sludge (RS – a source of silica and aluminum). In this context, the present work aims to synthesize and characterize montmorillonite nanoparticles (MMT-NPs) for use as nanocomposite support to evaluate the safety profile in 293T embryonic kidney human and antimicrobial activity against E. coli, S. aureus and P. aeruginosa strains. X-ray diffraction (XRD) showed the presence of characteristic peaks of montmorillonite in the crystalline phases of the neighborite, muscovite, kaolinite and quartz low. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectra indicated the stretching of Si-O-Si (at 991.29 cm−1) and Si-O-Al at 470.54 cm−1. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) micrographs indicated a heterogeneous morphology with a semicube shape and composition containing sodium, aluminum, potassium, and magnesium. MMT-NPs showed type V isotherms with H3 hysteresis (mesoporous characteristics) and SBET = 18 ± 0.2 m2 g−1, Dp = 33.5 ± 0.5 nm with zeta potential (ZP) of the −18.2 ± 0.4 mV and a contact angle around 26.1°. Biological results showed a minimal antibacterial inhibition concentration against S. aureus, E. coli and P. aeruginosa of the 15.6, 500 and 500 mg L−1, respectively. Furthermore, the safety profile of MMT-NPs using 293T cells indicated the 100% concentration as safe (>60% cells) and showed the release of reactive oxygen species and nitrates and nitrites similar to the negative control. Therefore, it was possible to synthesize montmorillonite nanoparticles from rice husk and residual sludge for use as a nanocomposite matrix, correlating sustainability and environmental nanotechnology.

Overfeeding During Lactation in Rats is Associated with Cardiovascular Insulin Resistance in the Short-Term.

Childhood obesity is associated with metabolic and cardiovascular comorbidities. The development of these alterations may have its origin in early life stages such as the lactation period through metabolic programming. Insulin resistance is a common complication in obese patients and may be responsible for the cardiovascular alterations associated with this condition. This study analyzed the development of cardiovascular insulin resistance in a rat model of childhood overweight induced by overfeeding during the lactation period. On birth day, litters were divided into twelve (L12) or three pups per mother (L3). Overfed rats showed a lower increase in myocardial contractility in response to insulin perfusion and a reduced insulin-induced vasodilation, suggesting a state of cardiovascular insulin resistance. Vascular insulin resistance was due to decreased activation of phosphoinositide 3-kinase (PI3K)/Akt pathway, whereas cardiac insulin resistance was associated with mitogen-activated protein kinase (MAPK) hyperactivity. Early overfeeding was also associated with a proinflammatory and pro-oxidant state; endothelial dysfunction; decreased release of nitrites and nitrates; and decreased gene expression of insulin receptor (IR), glucose transporter-4 (GLUT-4), and endothelial nitric oxide synthase (eNOS) in response to insulin. In conclusion, overweight induced by lactational overnutrition in rat pups is associated with cardiovascular insulin resistance that could be related to the cardiovascular alterations associated with this condition.

Clopyralid degradation using solar-photocatalytic/ozone process with olive stone activated carbon

Clopyralid degradation in ultrapure water was investigated by homogeneous ozonation (O3), catalytic ozonation with Olive Stone Activated Carbon (O3/OSAC), under simulated sunlight radiation by photolytic ozonation (O3/Daylight) and photocatalytic ozonation (O3/OSAC/Daylight). The OSAC was characterized by several analytical techniques, such as Nitrogen adsorption desorption at 77 K, Scanning Electron Microscopy (SEM-EDX), determination of pHpzc and X-ray Photoelectron Spectroscopy (XPS). This herbicide exhibited a rapid oxidation rate in the simultaneous presence of ozone, activated carbon and simulated sunlight. The combined process led to a complete removal of clopyralid in less than 30 min. Solar-photocatalytic ozonation was the most efficient process both in terms of clopyralid elimination rate and mineralization. Clopyralid degradation mainly occurs through hydroxyl radical in those systems involving ozone. For comparison purposes, the different processes can be modelled by simple first-order kinetics in clopyralid concentration (rate constants khomo = 0.0159 min−1, homogeneous ozonation; kO3/Daylight = 0.0410 min−1, kO3/OSAC = 0.0705 min−1, kO3/OSAC/Daylight = 0.1433 min−1). 90% of Total Organic Carbon (TOC) removal after 3 h was reached in photocatalytic ozonation (O3/OSAC/Daylight) and photolytic ozonation (O3/Daylight) compared to about 70% using O3/OSAC. Single ozonation just led to 20% TOC reduction under similar operating conditions. Furthermore, small oxygenated organic and inorganic by-products were analyzed by ionic chromatography. As a rule of thumb, TOC removal led to the formation of low weight carboxylic acids, taking place the release of chlorides and nitrates. Finally, toxicity evolution during O3, O3/OSAC, O3/Daylight and O3/OSAC/Daylight were monitored considering phytotoxicity trials of Lactuca Sativa germination. Phytotoxicity assays indicate almost total detoxification after the photocatalytic ozonation treatment.

Geographical Analysis of Agro-Environmental Measures for Reduction of Chemical Inputs in Tuscany

The agro-environmental policies included in rural development plans are getting increasing importance in European Community strategies. These policies represent the meeting point between demand and supply of positive externalities. The difficulty of assessing real environmental efficiency is one of the elements characterizing agro-environmental measures. This difficulty is related to the identification of suitable parameters for evaluating farms according to their impact on the territory. This impact is mainly related both to chemical inputs and to the territorial characteristics of the farm. Different types of fertilizers, pesticides and herbicides are currently used in production processes; however, the analysis has focused only on nitrates, as they represent the most critical types of chemicals related to soil pollution. A case study is provided by analysis of agro-environmental measures in Tuscany for the reduction of nitrates in organic and integrated farms. Using spatial multicriteria analysis, integrated and organic farms were classified according to their geographical locations and their release of nitrates into the soil. This classification permits the highlighting of farms that make the greatest economic efforts to reduce pollution and therefore it could determine environmental benefits. Considering that the trend of policy strategies is toward a reduction of monetary resources, the classification could help decision makers choose the right allocation of future resources.

Algae characterization and multistep pyrolysis mechanism

This paper presents a new characterization method and a multistep kinetic mechanism for describing the pyrolysis process of algae fuels. Since third generation biomasses are still largely unexplored, we first organized a database by collecting literature information on the nature and main features of algal biomass. The algal species, both macro- and micro-algae, are constituted by proteins, carbohydrates and lipids, present in various amounts depending on the taxonomy and growing conditions. Noteworthy, algae contain higher levels of proteins, lipids, nitrogen and ashes compared to vegetal biomasses. Starting from the ultimate analysis and ash content, the biochemical composition of each algal species is defined in terms of proteins, carbohydrates, and lipids. To this aim, a limited number of representative reference species is first defined, based on atomic mass balances. The predicted biochemical compositions fairly agree with experimental information. Then, a multi-step semi-detailed kinetic mechanism of algae pyrolysis has been developed for the different reference components, following the same approach successfully applied for lignocellulosic biomasses. Moreover, a further release of ammonium, nitrates, and carbonates groups is estimated and related to the ash content. Despite the reduced number of reference species and the rough assumptions to reduce the complexity of the overall problem, the model is already able to satisfactorily predict the pyrolysis behavior of micro- and macro-algae. To our knowledge, and despite all the strong simplifications, this is the first method to characterize algae species, as well as the first kinetic model able to predict the algae pyrolysis process.

Peritumoral adipose tissue as a source of inflammatory and angiogenic factors in colorectal cancer.

Obesity is a risk factor for the development of human colorectal cancer (CC). The aim of this work is to report the inflammatory and angiogenic scenario in lean (BMI < 25 kg/m2) and obese (BMI > 30 kg/m2) patients with and without CC and to assess the role of peritumoral adipose tissue in CC-induced inflammation. Patients were divided in four experimental groups: obese patients with CC (OB-CC), lean patients with CC (LEAN-CC), obese patients without CC (OB), and lean patients without CC (LEAN). Plasma levels of pro-inflammatory cytokines (interleukin (IL)-6, IL-4, IL-8) and granulocyte-macrophage colony-stimulating factor (GM-CSF) were increased in OB-CC patients. Peritumoral adipose tissue (TF) explants and cultured mature adipocytes secreted higher amounts of nitrites and nitrates than did control and non-tumoral (NTF) adipose tissue both alone and in response to lipopolysaccharide (LPS). Nitrite and nitrate secretion was also increased in TF explants from OB-CC patients compared with that from LEAN-CC patients. Gene expression of adiponectin, tumor necrosis factor alpha (TNF-α), insulin-like growth factor type I (IGF-I), cyclooxygenase-2 (COX-2), and peroxisome proliferator-activated receptor γ (PPAR-γ) was increased in TF explants from CC patients. LPS increased the gene expression of IL-6, IL-10, TNF-α, vascular endothelial growth factor (VEGF), and COX-2 in OB and in TF explants from OB-CC patients. COX-2 and PPAR-γ inhibition further increased LPS-induced release of nitrites and nitrates in TF explants and adipocytes from OB-CC patients. In conclusion, OB-CC patients have increased plasma levels of pro-inflammatory and angiogenic factors. TF from OB-CC patients shows an increased secretion of inflammatory markers compared with both TF from LEAN-CC and non-tumoral adipose tissue (AT) through a COX-2- and PPAR-γ-independent mechanism.

Studies of Decomposition rate and release of nutrients Ammonium, Nitrates, Nitrites, and Phosphatesions during the decomposition of Oryza coarctata in the laboratory experiment.

he vegetation, other than the mangroves in Indus delta, for example Oryza coarctata is also the source of nutrients for the adjacent coastal environment. The O. coarctata is the major vegetation on the tidal mudflatds of Keti- Bunder (Hajambro creek), Indus delta, other than the Avicennia marina and Rhizophora mucronataplanted mangrove forest. This is the first report of decomposition rates of O. coarctata in the laboratory. The decomposition of O. coarctata. was conducted to evaluate the nutrients (ammonium, nitrate, nitrites, phosphates) during the decomposition. The decomposition rate was more rapid during this early phase and O. coarctata. decomposed up to 40 % during the first 7 days. Afterwards, the Oryzasp. decomposed slowly and gradually and remained up to 40% of the dry mass. Therefor e, about 60% of the organic matter present in the O. coarctatacan decompose completely in the aerobic conditions of the aquatic environment. The ammonium ions concentration was found 2.75 μM/L at 7th day and highest value was 6.38 μM/L at 124th day of exp eriment. So the amount of ammonium ions increased during the phase of decomposition. The nitrate ions concentration was 1.95 μM/L at 7th day and increased to 2.71 μM/L at 15th day of decomposition, and afterwards the concentration of nitrate decreased gradually and lowest value 0.129 μM/L was recorded in the last day of the experiment. The nitrite ions concentration was found 1.80 μM/L and gradually increased to 3.33 μM/L at 60th day and the lowest value was 3.05 μM/L. The initial concentration of the phosphate ions was 0.84 and decresed gradually during the phase of decomposition to its lowest value at 0.7 μM/L. The concentration of the nitrogen in the O. coarctata was initially between 1- 1.5 mg DW, which increased to about 2 mg DW at the 7th day of the decomposition. The % DW nitrogen contents than decreased suddenly at 15th day reaching up to about 1 mg DW of the decomposed material. This decrease of the t otal DW Nitrogen is very important, as it is the source of the nutrients to the adjacent ecosystem. The results are also strongly correlated with the nutrients values.

Nitrogen cycling and relationships between ammonia oxidizers and denitrifiers in a clay-loam soil

This study investigated the effect of municipal solid waste (MSW) compost (0, 50, and 100 t/ha) on N cycling and the microorganisms involved in it, in a clay-loam soil. After a release of nitrates (NO3(-)-N) in the first 6 days after compost incorporation, soil NO3(-)-N content remained constant in all the treatments until day 62, suggesting N immobilization induced by the soil used in this study. Then, soil NO3(-)-N content increased in all treatments and especially in the highest compost dose, providing evidence that immobilization effect has been at least partially relieved. amoA gene copies of ammonia-oxidizing archaea (AOA) and bacteria (AOB) followed the overall pattern of soil NO3(-)-N content; however, no differences were found in amoA gene copies among treatments, except in the last sampling, an effect attributed to the slight differences in the potential nitrification rate among them. Ammonia oxidizer pattern provided evidence that both groups were involved in ammonia oxidation and changes in their abundance can be used as 'indicator' to predict changes in soil nitrification status. Moreover, the strong correlation between AOA and AOB amoA copies (R(2) = 0.94) and the high slope (13) of the curve suggest that AOA had probably an important role on ammonia oxidation. Denitrifying genes (nirS, nirK, nosZ) also followed the general pattern of soil NO3(-)-N, and they were strongly correlated with both groups of ammonia oxidizers, and particularly AOA, suggesting strong interrelationships among them. Losses of N through denitrification, as they were estimated by total nitrogen, were inversely related to soil NO3(-)-N content. Similar to ammonia oxidizers, denitrifying gene copies did not differ among compost treatments an effect that could be probably explained by the low availability of organic-C in the MSW compost and hence the competition with aerobic heterotrophs.

Nitrate and nitrite in leek and spinach from Urmia district and their changes as affected by boiling

Aims: This study was carried out to determine nitrite and nitrate levels in fresh leek and spinach from different greengrocers' shops of Urmia (Iran) and then the effect of boiling and the effect of aqueous boiling pH were studied. Materials and Methods: Nitrite and nitrate content of 15 market samples of leek and spinach from Urmia region were determined by spectrophotometric method. Effect of boiling and their pH levels at home processing condition were studied. Results: Results showed that the fresh vegetables had only traces of nitrite and the level of nitrate was 36-328 ppm KNO 3 . In the most of samples, nitrite and nitrate contents in spinach were greater than in leek, but lower than standard International Organization for Standardization levels in Iran. Boiling process was carried out, according to home conditions and it caused a decrease in nitrate levels between 23% and 61% in leak and spinach samples, respectively. T-test analysis of the boiled vegetables showed a significant reduction about 75% in nitrate content (in dry weight vegetable content), in the samples, but an increase in nitrate content in the boiled water of the sample was observed. The effect pH of boiling (4-8) shows that with an increase in pH, there was a decrease in nitrate contents of boiled water. Conclusion: The experiment showed that the leek and spinach marketed in Urmia region were safe for consumption and boiling of vegetables caused the release of nitrates from vegetables to water after the cooking process. It is of particular importance not to use the vegetable cooking water for use in pureeing homemade baby foods.

Nitrogen mineralization and phosphorus solubilization due to rewetting of forest and paddy soils

Rewetting of soils may cause an increase in phosphorus solubilization and nitrogen mineralization resulting in the release of bioavailable phosphates and nitrates which are vital for crop growth but are also associated with eutrophication of surface waters. The study was conducted to evaluate P solubilization and N mineralization due to drying and rewetting of forest and paddy soils under laboratory conditions. Forest and paddy soils were tested for water extractable P and mineralizable N (NH4+ and NO3–) after being subjected to drying and rewetting cycles for 7 and 14 days of drying. Soil samples were also analyzed for pH, OM, total N, total P, available P, and clay contents. Results indicated a significant increase in water-extractable P and total mineralized N for all the samples tested. N mineralization and P solubilization were correlated with OM, total N, available P, and clay. Findings also revealed that NH4+ concentration increased while that of NO3– decreased significantly for all the samples tested. The amounts of water-extractable P and NO3– released due to rewetting could potentially accelerate eutrophication if transported to bodies of water. They could also however benefit the growing plant.

Soil and vegetable crop response to addition of different levels of municipal waste compost under Mediterranean greenhouse conditions

In the soil thematic strategy of the European Union Commission, a soil organic carbon content of 2% is indicated as a threshold below which a reduction in soil chemical, biological and physical fertility, and increase in erosion can be observed. Composting of organic matter ‘exogenous’ to soil (such as from municipalities, industries and agriculture sources) is recommended as an effective way to ensure the return of biomass to soil and the return of the soil organic matter losses. The composting of municipal solid wastes is seen as a strategy to divert organic waste materials from landfills. A municipal source-separated solid waste compost was used in a study carried out during 2003–2006 in Southern Italy. An annual tomato-snap bean-lettuce rotation was planted on a sandy loam soil with 26 g kg−1 organic carbon under greenhouse conditions. Different rates of compost (15-30-45 tha−1 on a dry weight basis) and combinations of compost at a rate of 15 t ha−1 with reduced doses of mineral N fertilizer (1/2 or 1/4 of optimal supply) were compared with an untreated control and a N, P, K fertilized control. We found that: (1) increasing compost rates produced increasing positive soil organic carbon balances. The C conversion efficiency was 23 and 36% with 15 and 30 t ha−1, respectively, but declined to 28% with the highest rate of compost. Indeed, the higher the compost amounts applied, the higher the soil organic carbon losses. (2) Under tunnel-greenhouse conditions, all the fertilization strategies, except compost at a rate of 15 t ha−1, increased soil nitrate concentrations by up 100 to 400 mg kg−1 dry weight of soil, particularly in the spring-summer seasons. In the same period, nitrate contents in the untreated control reached 100 mg kg−1. (3) The average yield of marketable tomato for the four-year period was 114 t ha−1 and did not vary significantly among treatments. No differences in snap bean yields were detected among the fertilization treatments. In lettuce cultivation, however, 30 and 45 t ha−1 of compost yielded more than other treatments. In the tunnel-greenhouse environment, a high initial content of soil organic matter resulted in high vegetable yields over all four years, even without mineral or organic fertilizer supply. However, among the various fertilization strategies, the best solution able to restore annual soil carbon mineralization was the supply of 15 t ha−1 of compost. In addition, this rate reduced the hazards linked to the high release of nitrates in soil caused by 30 and 45 t ha−1 rates of compost or mineral fertilization.

Kinetics of uptake of phosphates and nitrates by marine multicellular algae Gelidium latifolium (Grev.) Born. et Thur.

We studied nonstationary kinetics of the uptake of phosphates and nitrates by the red marine algae Gelidium latifolium (Grev.) Born et Thur. and calculated constants of the Michaelis-Menten equation for these elements. In the area of 0-3 microM, the kinetics of phosphate consumption had the following coefficients: maximum rate of uptake 0.8 micromol/(g x h), constant of half-saturation 1.745 microM. For nitrate nitrogen at 0-30 microM, an adaptive strategy of uptake kinetics was noted with change of the equation parameters with time: after 1 h, the maximum rate of uptake was 5.1 micromol/(g x h) and constant of half-saturation 19 gM, while within 2 h, the maximum rate of uptake significantly increased. This could be related to the synthesis of nitrate reductase. Coupled with the uptake of nitrates, nonstationary kinetics of the release of nitrates in the surrounding medium had a one-peak pattern: the maximum concentration of nitrites in the medium and the time of its achievement increased with the initial concentration of nitrates. The maximum concentration of nitrites was 6 to 14% of the initial concentration in the medium.

Sonolytic, photocatalytic and sonophotocatalytic degradation of malachite green in aqueous solutions

The degradation of malachite green (MG) in water by means of ultrasound irradiation and its combination with heterogeneous (TiO2) and homogeneous photocatalysis (photo-Fenton) was investigated. Emphasis was given on the effect of key operating conditions on MG conversion and mineralization rates and the elucidation of major reaction by-products. Eighty-kilohertz of ultrasound irradiation was provided by a horn-type sonicator, while a 9W lamp was used for UV-A irradiation. The extent of sonolytic degradation increased with increasing ultrasound power (in the range 75–135W) and decreasing initial concentration (in the range 2.5–12.5mgL−1), while the presence of TiO2 in the dark generally had little effect on degradation. Sonolysis under argon was substantially faster than under air, oxygen or helium leading to complete MG degradation after 120min at 10mgL−1 initial concentration and 135W ultrasound power. On the other hand, TiO2 photocatalysis or photo-Fenton led to complete MG degradation in 15–60min with the rate increasing with increasing catalyst loading (in the range 0.1–0.5gL−1 for TiO2 and 7–20mgL−1 for Fe3+) and also depending on the gas used. TiO2 sonophotocatalysis was always faster than the respective individual processes due to the enhanced formation of reactive radicals as well as the possible ultrasound-induced increase of the active surface area of the catalyst. For instance, the pseudo-first order rate constant for the sonophotocatalytic degradation at 0.5mgL−1 TiO2 under air was 136.7×10−3min−1 with the respective values for photocatalysis and sonolysis being 112.6×10−3 and 11.6×10−3min−1. Irrespective of the process employed, mineralization was slower than MG decomposition implying the formation of stable by-products accompanied by the release of nitrates in the solution. GC/MS analysis verified the identity of primary intermediates and a reaction pathway based on them was proposed. Depending on the conditions employed, ecotoxicity of MG to marine bacteria was partly or fully eliminated.

Nitrate occlusion studies in Y zeolite and in a clay pillared with aluminium oxide

The occlusion of nitrates is a subject that is important, for instance, in soil amendment, as far as the control of the release of nitrates to the environment is concerned. In this work, the occlusion of molten nitrates was studied in the sodium form of zeolite Y and, to our knowledge, for the first time, in a pillared clay. The samples were characterized by different techniques, such as low-temperature nitrogen adsorption, X-ray diffraction, differential scanning calorimetry, FTIR, 23Na MAS NMR and 15N MAS NMR. From the different techniques evidence was obtained that supports the existence of occluded nitrates in the studied samples. Both materials, i.e., zeolite Y and the clay from Wyoming pillared with aluminum oxide, seem to have a potential in the release of nitrates for use in soil amendment.

Bile acid induced colonic irritation stimulates intracolonic nitric oxide release in humans.

To measure the intracolonic release of nitric oxide end products (nitrates plus nitrites) and eicosanoids in response to intraluminal irritation with deoxycholic acid (DCA). Seven patients with irritable bowel syndrome. The left colon was perfused with a solution with or without 3 mM deoxycholic acid. Aspirates were assayed for eicosanoids by specific radioimmuno-assay, and for nitrates plus nitrites by the Griess reaction. To confirm that stimulated colonic mucosa can produce nitric oxide (NO), ancillary studies were performed in vitro using samples of normal mucosa obtained from five surgically resected colons. Samples were incubated for 30 minutes in Kreb's solution, 3 mM DCA or DCA with 1 mM L-nitro-arginine-methyl-ester (L-NAME) to inhibit the NO synthase. Finally, NO synthase activity was measured in five samples of human colonic mucosa. Intracolonic release of nitrates plus nitrites was basally undetectable in six of seven patients. Bile acid considerably increased the release of prostaglandin E2 and nitrates plus nitrites (p < 0.01). By contrast, no increase in thromboxane and leukotriene was seen. In vitro mucosal incubation with DCA increased the production of NO synthase products, which was blocked by L-NAME. Activity of Ca+2 independent NO synthase was detectable in four of five samples of human colonic mucosa. The human colonic mucosa responds to bile acid induced irritation by a surge in NO generation via NO synthase.