Search results for "Nitrogen"
showing 10 items of 1200 documents
Effect of defoliation management and plant arrangement on yield and N2 fixation of berseem-annual ryegrass mixture
2005
The research was carried out in a Mediterranean semi-arid environment on berseem clover, annual ryegrass and their mixture to study the effect of defoliation management [date of first cut (FC) 85, 119, 140, 169 days after sowing] and different plant arrangements (sowing the two components in alternate rows or in the same row) on yields, N content, N2 fixation and N transfer. The experimental design was a split-plot with four replications. The 15 N isotope dilution technique was used (8 kg N ha –1 as ammonium sulphate at 10 atom% 15 N excess) to evaluate the N2 fixation. Total seasonal DM yield was, on average, significantly higher for FC119 and FC140 (approx. 12.3 t ha –1 ) than for FC85 and FC…
Nitrogen Adsorption on Graphene Sponges Synthesized by Annealing a Mixture of Nickel and Carbon Powders
2017
The present research has been supported by the National Research Programme for 2014–2017 “Multifunctional Materials and Composites, Photonics and Nanotechnologies”.
UCT-MBR vs IFAS-UCT-MBR for Wastewater Treatment: A Comprehensive Comparison Including N2O Emission
2017
In this study the performance (in terms of carbon and nutrient removal) and N2O emission of two plant configurations adopting innovative technologies were investigated. With this regards, an University Cape Town (UCT) membrane bioreactor (MBR) plant and an Integrated Fixed Film Activated Sludge (IFAS) -UCT-MBR plant were monitored. Both plants treat real wastewater under two different values of the influent carbon nitrogen ratio (C/N = 5 mgCOD/mgN and C/N = 10 mgCOD/mgN). Results have shown the highest carbon and nutrients removal efficiencies for the IFAS-UCT-MBR configuration during both the two investigated C/N values. Furthermore, the lowest N2O emission occurred for the IFAS-UCT-MBR.
A globally relevant stock of soil nitrogen in the Yedoma permafrost domain
2022
AbstractNitrogen regulates multiple aspects of the permafrost climate feedback, including plant growth, organic matter decomposition, and the production of the potent greenhouse gas nitrous oxide. Despite its importance, current estimates of permafrost nitrogen are highly uncertain. Here, we compiled a dataset of >2000 samples to quantify nitrogen stocks in the Yedoma domain, a region with organic-rich permafrost that contains ~25% of all permafrost carbon. We estimate that the Yedoma domain contains 41.2 gigatons of nitrogen down to ~20 metre for the deepest unit, which increases the previous estimate for the entire permafrost zone by ~46%. Approximately 90% of this nitrogen (37 gigaton…
Determination of lead on the airborne particulates of urban Valencia city
1991
A method for the determination of lead in airborne particulates by graphite furnace atomic absorption spectrometry after extraction with HCl-HNO3 (120–150°C) is described. Particulate lead levels in the atmosphere have been measured in samples collected throughout a year, sampling has been made at eleven sites within the city of Valencia. The results obtained in this study show that annual means of lead levels are within the range of 0.526 to 7.033 μg/m3 depending upon the sampling site. Lead levels are higher in winter and autumn. Lead and nitrogen oxide levels are well correlated.
A remarkable selectivity in the N-functionalization of polyaza[n]paracyclophanes. Synthesis of N-(4-picolyl)-substituted 2,6,9,13-tetraaza[14]paracyc…
1997
Abstract Interaction of cationic host species, in particular Zn 2+ salts, with polyaza[n]paracyclophanes (i.e. 2,6,9,13-Tetraaza[14]paracyclophane, B323 (1a) ) directs their selective N-functionalization. In this way compounds mono- or difunctionalized with ArCH 2− groups at the benzylic nitrogen atoms can be easily obtained. Direct reaction with the alkylating agent, in the absence of the Zn 2+ species, produces, in general, very complex mixtures of mono- and polyalkylated compounds except when 4-picolyl chloride is used. In this case, mono-, di-, tri- and tetra N-substituted derivatives of D323 can be isolated depending on the amount of the alkylating agent used. In this case, the mono- a…
Developmental speed affects ecological stoichiometry and adult fat reserves in Drosophila melanogaster
2020
Abstract The elemental composition of organisms belongs to a suite of functional traits that change during development in response to environmental conditions. However, associations between adaptive variations in developmental speed and elemental body composition are not well understood. We compared body mass, elemental body composition, food uptake and fat metabolism of Drosophila melanogaster male fruit flies in relation to their larval development speed. Slowly developing flies had higher body carbon concentration than rapidly developing and intermediate flies. Rapidly developing flies had the highest body nitrogen concentration, while slowly developing flies had higher body nitrogen lev…
Die Wirkung unterschiedlicher Lichtintensitäten auf die Nitratreduktase-Aktivität, den Gehalt an löslichen Proteinen und löslichen reduzierenden Zuck…
1977
Summary Plants of Sinapis alba (white mustard) grown under strong light conditions have a higher content of soluble reducing sugars, of soluble proteins and a higher dry wight during growth from germination to flowering. Furthermore, in these plants the nitrate reductase activity is essentially higher during the vegetative development, but before the beginning of the flowering phase the activity is less than the level of plants grown under low light intensities. The results obtained indicate a direct correlation between nitrate reductase activity and the content of soluble proteins. In the high-light plants both components show distinct maxima 13—14 days after sowing the seeds. The enhancem…
Improvement of the nitrogen uptake induced by titanium (iv) leaf supply in nitrogen‐stressed pepper seedlings
1996
Abstract The beneficial effect of titanium (Ti) on plant metabolism can result in more profitable use of fertilizer applied to a crop. A crop chamber experiment with paprika pepper (Capsicum annuum L., cv. Bunejo) seedlings under differential nitrogen (N) concentration levels in a nutrient solution (100% N, 75% N, 50% N, and 25% N) was performed. A third of the seedlings growing under each N support level remained Ti‐untreated and were used as the reference. Another third of the seedling received one and two 0.042 mM Ti(TV) ascorbate, pH 6.0, leaf spray treatments, respectively. The biomass production of the Ti‐untreated plants was only affected by the N supply of 50% or less. The Ti(IV) le…
Investigation on the Nitrogen Metabolism of Spruce Needles in Relation to the Occurrence of Novel Forest Decline
1988
Summary In order to obtain information on the nitrogen metabolism of undamaged and damaged spruce ( Picea abies ), investigations were performed in 1985 and 1986 on the activity of glutamine synthetase and on the content of free ammonium and soluble proteins in spruce needles. In addition, the chlorophyll content was determined. Needles from the second needle year and the seventh whorl were used. The investigations were carried out in pair comparison on a 20-year-old spruce plantation and in comparison with damage classes on an 80-year-old spruce plantation. Both the pair comparison and the contrasting of different damage groups show an unequivocal decrease of the chlorophyll content correl…