Ultralow-Content Pd In-Situ Incorporation Mediated Hierarchical Defects in Corner-Etched Cu2O Octahedra for Enhanced Electrocatalytic Nitrate Reduction to Ammonia

2022 ◽  
pp. 121094
Author(s):  
You Xu ◽  
Kaili Ren ◽  
Tianlun Ren ◽  
Mingzhen Wang ◽  
Ziqiang Wang ◽  
...  
Keyword(s):  
Nitrate Reduction

In situ grown Fe3O4 particle on stainless steel: A highly efficient electrocatalyst for nitrate reduction to ammonia

Nano Research ◽  
2021 ◽  
Author(s):  
Xiaoya Fan ◽  
Lisi Xie ◽  
Jie Liang ◽  
Yuchun Ren ◽  
Longcheng Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Nitrate Reduction ◽  
Fe3o4 Particle ◽  
Highly Efficient

Relation Between CO2 Evolution and in situ Reduction of Nitrate in Wheat Leaves

1981 ◽  
Vol 8 (6) ◽  
pp. 515 ◽  
Author(s):  
MS Naik ◽  
DJD Nicholas
Keyword(s):  
Citric Acid ◽  
Nitrate Reduction ◽  
Citric Acid Cycle ◽  
Nitrate Assimilation ◽  
Co2 Evolution ◽  
In Situ Reduction ◽  
Acid Cycle ◽  
Nitrite Production ◽  
Wheat Leaves

In wheat leaf discs the evolution of 14CO2 from exogenously supplied 14C-labelled citric acid cycle intermediates was stimulated during the in situ anaerobic reduction of nitrate in the dark. Under these conditions, however, [1,4-14C]succinate was not metabolized. Similarly, when leaves were allowed to assimilate 14CO2 in the dark, thus producing endogenously labelled organic acids, the subsequent evolution of 14CO2 from discs prepared from these leaves was strongly dependent on nitrate reduction. A 1 : 1 stoichiometry between nitrite production and CO2 evolution was recorded during this in situ reduction of nitrate. The in situ reduction of nitrate was inhibited by malonate and D-malate and this effect was reversed by fumarate, probably by generating L-malate within the mitochondria. Mitochondrial NAD-malic enzyme (decarboxylating) (EC 1.1.1.38) was similarly inhibited competitively by malonate and D-malate, but not by succinate. These results indicate that the citric acid cycle dehydrogenases which generate CO2 supply NADH for nitrate reduction in wheat leaves. It is likely that, under anaerobic conditions, nitrate acts as an alternative oxidant to O2 for the NADH generated by the citric acid cycle dehydrogenases resulting in simultaneous evolution of CO2. This ensures that the citric acid cycle operates at the required rate for nitrate assimilation.

scholarly journals A Study on the Mechanism and Kinetic of Nitrate Reduction by the nZVI-g-C3N4/TiO2  Composite Under the Simulated Sunlight

2021 ◽  
Author(s):  
Linyu Wei ◽  
Jing Tian ◽  
Qing Wang ◽  
Yuanyuan Liu ◽  
Yi Yu ◽  
...  
Keyword(s):  
Nitrate Reduction ◽  
Reduction Method ◽  
Nitrate Removal ◽  
Simulated Sunlight ◽  
Photoelectric Properties ◽  
Phase Reduction ◽  
Reduction Efficiency ◽  
Initial Ph ◽  
Lamp System

Abstract g-C3N4/TiO2 composite has excellent photoelectric properties and is considered as a good carrier of nanoparticles. A novel composite of nZVI-g-C3N4/TiO2 was successfully synthesized through in-situ growth nZVI on the surface of g-C3N4/TiO2 with liquid phase reduction method. The composite was characterized by TEM, XRD, EDS and evaluated its nitrate removal efficiency. The effects of composite dosage, solution initial pH and HCOOH concentration on nitrate reduction were investigated. The results showed that nitrate was rapidly reduced by nZVI-g-C3N4/TiO2 composite. The dosage of 4 g/L nZVI-g-C3N4/TiO2 composite and 3.0 mM of HCOOH concentration was more suitable for nitrate reduction. Solution initial pH had little impact on the nitrate reduction efficiency, but affected the proportion of the nitrate reduction products. The mechanism of nitrate reduction in the nZVI-gC3N4/TiO2/HCOOH-Xe-lamp system was proposed. The nZVI-gC3N4/TiO2 composite could be considered as a viable and promising technology for water pollution remediation.

In Situ Dissimilatory Nitrate Reduction to Ammonium in a Paddy Soil Fertilized with Liquid Cattle Waste

Pedosphere ◽  
2012 ◽  
Vol 22 (3) ◽  
pp. 314-321 ◽  
Author(s):  
Wei-Wei LU ◽  
S. RIYA ◽  
Sheng ZHOU ◽  
M. HOSOMI ◽  
Hai-Lin ZHANG ◽  
...  
Keyword(s):  
Paddy Soil ◽  
Nitrate Reduction ◽  
Dissimilatory Nitrate Reduction

Comparison and Evaluation of in-situ Bio-Denitrification Systems for Nitrate Reduction in Groundwater

1993 ◽  
Vol 28 (3-5) ◽  
pp. 359-368 ◽  
Author(s):  
M. F. Dahab
Keyword(s):  
Nitrate Reduction ◽  
Laboratory Experiments ◽  
Nitrate Contamination ◽  
Field Scale ◽  
Water Turbidity ◽  
The World ◽  
Management Schemes ◽  
Careful Management ◽  
The U.S

Nitrate contamination of groundwater is a growing problem in the U.S. and throughout the world. This paper examines the potential application of in-situ bio-denitrification to reduce nitrates in groundwater to an acceptable level as well as pertinent parameters that control the process. Results from laboratory experiments designed to simulate in-situ bio-denitrification using an aquifer model are compared to results of experiments reported in the literature. The results indicate that while denitrification can be effective in reducing nitrates in contaminated groundwater, serious aquifer plugging problems can be expected. Furthermore, the avoidance of the plugging problem requires that careful management schemes be implemented during in-situ treatment The results of field-scale experiments in Europe and other areas generally confirm the efficacy of bio-denitrification. However, aquifer plugging was not reported by some of these studies or appeared to be downgraded by others. In some cases, this problem was reported as having serious ramifications on the success or failure of bio-denitrification. In addition to aquifer plugging, other problems can be expected. These include residual organics and the presence of large bacterial counts in the treated water with subsequent potential effects on the water turbidity, disinfection requirements, and public health acceptability.

scholarly journals The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study

2017 ◽  
Vol 14 (2) ◽  
pp. 285-300 ◽  
Author(s):  
Stefano Bonaglia ◽  
Astrid Hylén ◽  
Jayne E. Rattray ◽  
Mikhail Y. Kononets ◽  
Nils Ekeroth ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Nitrate Reduction ◽  
Organic N ◽  
Fixed Nitrogen ◽  
Coastal Station ◽  
Solute Fluxes ◽  
The Baltic ◽  
The Impact

Abstract. Over the last decades, the impact of human activities on the global nitrogen (N) cycle has drastically increased. Consequently, benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while in oligotrophic systems its understanding is still scarce. Here we report on benthic solute fluxes and on rates of denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located in the northern part of the Baltic Sea. Rates of N burial were also inferred to investigate the fate of fixed N in these sediments. Most of the total dissolved fixed nitrogen (TDN) diffusing to the water column was composed of organic N. Average rates of dinitrogen (N2) production by denitrification and anammox (range: 53–360 µmol N m−2 day−1) were comparable to those from Arctic and subarctic sediments worldwide (range: 34–344 µmol N m−2 day−1). Anammox accounted for 18–26 % of the total N2 production. Absence of free hydrogen sulfide and low concentrations of dissolved iron in sediment pore water suggested that denitrification and DNRA were driven by organic matter oxidation rather than chemolithotrophy. DNRA was as important as denitrification at a shallow, coastal station situated in the northern Bothnian Bay. At this pristine and fully oxygenated site, ammonium regeneration through DNRA contributed more than one-third to the TDN efflux and accounted, on average, for 45 % of total nitrate reduction. At the offshore stations, the proportion of DNRA in relation to denitrification was lower (0–16 % of total nitrate reduction). Median value and range of benthic DNRA rates from the GOB were comparable to those from the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well-oxygenated sediments with low organic carbon loading. However, the mechanisms behind the variability in DNRA rates between our sites were not resolved. The GOB sediments were a major source (237 kt yr−1, which corresponds to 184 % of the external N load) of fixed N to the water column through recycling mechanisms. To our knowledge, our study is the first to document the simultaneous contribution of denitrification, DNRA, anammox, and TDN recycling combined with in situ measurements.

scholarly journals Anammox, denitrification and fixed-nitrogen removal in sediments from the Lower St. Lawrence Estuary

2012 ◽  
Vol 9 (11) ◽  
pp. 4309-4321 ◽  
Author(s):  
S. A. Crowe ◽  
D. E. Canfield ◽  
A. Mucci ◽  
B. Sundby ◽  
R. Maranger
Keyword(s):  
Nitrate Reduction ◽  
Sediment Cores ◽  
Oxygen Demand ◽  
N Cycling ◽  
Fixed Nitrogen ◽  
Lawrence Estuary ◽  
Hypoxic Conditions ◽  
Nitrate And Nitrite ◽  
St Lawrence Estuary

Abstract. Incubations of intact sediment cores and sediment slurries reveal that anammox is an important sink for fixed nitrogen in sediments from the Lower St. Lawrence Estuary (LSLE), where it occurs at a rate of 5.5 ± 1.7 µmol N m−2 h−1. Canonical denitrification occurs at a rate of 11.3 ± 1.1 µmol N m−2 h−1, and anammox is thus responsible for up to 33% of the total N2 production. Both anammox and denitrification are mostly (> 95%) fueled by nitrate and nitrite produced in situ through benthic nitrification. Nitrification accounts for > 15% of the benthic oxygen demand and may, therefore, contribute significantly to the development and maintenance of hypoxic conditions in the LSLE. The rate of dissimilatory nitrate reduction to ammonium is three orders of magnitude lower than denitrification and anammox, and it is insignificant to N-cycling. NH4+ oxidation by sedimentary Fe(III) and Mn(III/IV) in slurry incubations with N isotope labels did not occur at measurable rates; moreover, we found no evidence for NH4+ oxidation by added Mn(III)-pyrophosphate.

scholarly journals Combined Gel Probe and Isotope Labeling Technique for Measuring Dissimilatory Nitrate Reduction to Ammonium in Sediments at Millimeter-Level Resolution

2010 ◽  
Vol 76 (18) ◽  
pp. 6239-6247 ◽  
Author(s):  
Peter Stief ◽  
Anna Behrendt ◽  
Gaute Lavik ◽  
Dirk De Beer
Keyword(s):  
Quartz Sand ◽  
Nitrate Reduction ◽  
Isotope Labeling ◽  
Sediment Cores ◽  
Isotopic Labeling ◽  
Physical Disturbance ◽  
Sediment Pore Water ◽  
Dissimilatory Nitrate Reduction ◽  
The Vertical Distribution

ABSTRACT Dissimilatory NO3 − reduction in sediments is often measured in bulk incubations that destroy in situ gradients of controlling factors such as sulfide and oxygen. Additionally, the use of unnaturally high NO3 − concentrations yields potential rather than actual activities of dissimilatory NO3 − reduction. We developed a technique to determine the vertical distribution of the net rates of dissimilatory nitrate reduction to ammonium (DNRA) with minimal physical disturbance in intact sediment cores at millimeter-level resolution. This allows DNRA activity to be directly linked to the microenvironmental conditions in the layer of NO3 − consumption. The water column of the sediment core is amended with 15NO3 − at the in situ 14NO3 − concentration. A gel probe is deployed in the sediment and is retrieved after complete diffusive equilibration between the gel and the sediment pore water. The gel is then sliced and the NH4 + dissolved in the gel slices is chemically converted by hypobromite to N2 in reaction vials. The isotopic composition of N2 is determined by mass spectrometry. We used the combined gel probe and isotopic labeling technique with freshwater and marine sediment cores and with sterile quartz sand with artificial gradients of 15NH4 +. The results were compared to the NH4 + microsensor profiles measured in freshwater sediment and quartz sand and to the N2O microsensor profiles measured in acetylene-amended sediments to trace denitrification.

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