Search results for "Nitrogen"
showing 10 items of 1200 documents
Variación espacial de la exposición a contaminación atmosférica en la ciudad de Valencia y su relación con un índice de privación
2013
Objetivo: Evaluar la variación espacial de la exposición a dióxido de nitrógeno (NO2) en la ciudad de Valencia y su relación con la privación socioeconómica y la edad. Métodos: La población por sección censal (SC) procede del Instituto Nacional de Estadística. Los niveles de NO2 se midieron en 100 puntos del área de estudio, mediante captadores pasivos, en tres campañas entre 2002 y 2004. Se utilizó regresión por usos del suelo (LUR) para obtener el mapa de los niveles de NO2. Las predicciones del LUR se compararon con las proporcionadas por: a) el captador más cercano de la red de vigilancia, b) el captador pasivo más cercano, c) el conjunto de captadores en un entorno y d) kriging. Se asi…
Variación espacial de la exposición a contaminación atmosférica en la ciudad de Valencia y su relación con un índice de privación The spatial distrib…
2013
Objetivo: Evaluar la variación espacial de la exposición a dióxido de nitrógeno (NO2) en la ciudad de Valencia y su relación con la privación socioeconómica y la edad. Métodos: La población por sección censal (SC) procede del Instituto Nacional de Estadística. Los niveles de NO2 se midieron en 100 puntos del área de estudio, mediante captadores pasivos, en tres campañas entre 2002 y 2004. Se utilizó regresión por usos del suelo (LUR) para obtener el mapa de los niveles de NO2. Las predicciones del LUR se compararon con las proporcionadas por: a) el captador más cercano de la red de vigilancia, b) el captador pasivo más cercano, c) el conjunto de captadores en un entorno y d) kriging. Se asi…
Detection of reactive nitrogen containing particles in the tropopause region? Evidence for a tropical nitric acid trihydrage (NAT) belt
2008
The detection of nitric acid trihydrate (NAT, HNO<sub>3</sub>&times;3H<sub>2</sub>O) particles in the tropical transition layer (TTL) harmonizes our understanding of polar stratospheric cloud formation. Large reactive nitrogen (NO<sub>y</sub>) containing particles were observed on 8 August 2006 by instruments onboard the high altitude research aircraft M55-Geophysica near and below the tropical tropopause. The particles, most likely NAT, have diameters less than 6 &mu;m and concentrations below 10<sup>-4</sup> cm<sup>&minus;3</sup>. The NAT particle layer was repeatedly detected at altitudes between 15.1 and 17.5 km ove…
Faba bean grain yield, N2 fixation, and weed infestation in a long-term tillage experiment under rainfed Mediterranean conditions
2012
Background and Aims Long-term experiments could provide valuable information to determine the effects of an agronomic practice on agro-ecosystem productivity and stability. This study evaluated the long-term (18-year) impact of different tillage systems on faba bean (Vicia faba L.) productivity, including weed and broomrape incidence, and N2 fixation. Methods The experiment was carried out on a Vertisol under rainfed Mediterranean conditions. It was set up as a strip plot design. The tillage systems were: conventional tillage (CT) with moldboard plow, reduced tillage (RT) with chisel plow, and no tillage (NT). Nitrogen fixation was estimated over 2 years in the final phase of the experiment…
Organic and chemical N fertilization on coriander (Coriandrum sativum L.)
2014
Coriander (Coriandrum sativum L.) is an annual herbaceous Medicinal and Aromatic Plant (MAP) dealing with a great industrial interest because of its strongly-scented fruits (“seeds”). The role of N fertilization in coriander seed yield is matter of debate as far; information is missing, for instance, about the effects of organic N fertilization, a mandatory technique when the organic cropping management is chosen. Organic and chemical N fertilizers have been supplied on coriander from 2001–2002 to 2006–2007 in a Mediterranean semi-arid environment, and their effects on the formation of biomass and seeds yield have been evaluated. Different organic fertilizers, allowed by EU regulations conc…
N use and partitioning in coriander (Coriandrum sativum L.) after organic and conventional N fertilization
2010
In coriander, a well known spice herb, many studies concerning the effect of N fertilization have been conducted in special areas where the cultivation of such plant has a major importance, such as India. Limited information is available as concerns the response of coriander to N fertilization under Mediterranean climatic conditions, above all when organic N fertilizers (mandatory when organic cropping management is chosen) are used. This work refers about some observations realised from 2004 to 2006 by an experiment on organic and mineral N fertilization techniques in coriander, carried on in the experimental farm “Sparacia” (Cammarata, AG, Sicily). Similarly to what suggested for other sp…
Nitrogen fertilisation in coriander (Coriandrum sativumL.): a review and meta-analysis
2009
Nitrogen (N) fertilisation is one of the most important external inputs in assessing coriander seed yield and plant growth. Recent concerns related to the misuse of N fertilisers in agricultural environments, however, stress the opportunity for a fine-tuning of N management in order to optimise the use of this element, avoiding losses and reducing environmental hazards. In this study, some results from the literature concerning N fertilisation in coriander are reviewed and, by means of statistical analysis, an attempt is made to derive from them some general suggestions about practices of N fertilisation. In most cases examined, N fertilisation allowed a 10–70% increase in seed yields in co…
Measurements of relative line strengths in N I multiplets for transition arrays 3s–np (n=3, 4, 5)
2008
Abstract Applying the emission method, intensities of 60 spectral lines of neutral nitrogen (N I) belonging to 15 multiplets originating from 3s–np (n=3, 4, 5) transition arrays have been measured. A wall-stabilized arc, operated at atmospheric pressure in helium with some admixture of nitrogen was applied as the excitation source. From measured line intensities, relative line strengths within multiplets have been evaluated. For transitions with Δn=1 and 2, significantly larger discrepancies from LS coupling results are found if compared to transitions 3s–3p (Δn=0). The measured relative line strengths within 3s–3p multiplets are compared with older measurements, recent calculations and wit…
Relationship between N-cycling communities and ecosystem functioning in a 50-year-old fertilization experiment.
2009
The relative importance of size and composition of microbial communities in ecosystem functioning is poorly understood. Here, we investigated how community composition and size of selected functional guilds in the nitrogen cycle correlated with agroecosystem functioning, which was defined as microbial process rates, total crop yield and nitrogen content in the crop. Soil was sampled from a 50-year fertilizer trial and the treatments comprised unfertilized bare fallow, unfertilized with crop, and plots with crop fertilized with calcium nitrate, ammonium sulfate, solid cattle manure or sewage sludge. The size of the functional guilds and the total bacterial community were greatly affected by …
Two-Stage Anaerobic Digestion of Energy Crops: Methane Production, Nitrogen Mineralisation and Heavy Metal Mobilisation
2006
Energy crops (willow, sugar beet and grass silage) were digested in pilot scale two-stage anaerobic digesters. The specific methane yields obtained were 0.16, 0.38 and 0.39 m3 kg(-1) added volatile solids (VSadded) for willow, sugar beet and grass, respectively, corresponding to yearly gross energy yields of 15, 53 and 26 megawatt-hours (MWh) per hectare. With grass and sugar beets as substrate, 84-85% of the harvestable methane was obtained within 30 days. In pilot scale two-stage digestion of willow and sugar beet, 56 and 85% of the laboratory scale methane yields were obtained, but digestion of grass in two-stage reactors yielded 5% more methane than digestion in laboratory scale complet…