853 resultados para Contaminació atmosfèrica


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Fluoride concentration was determined in rainwater, ground water and soil in the zone of fertilizer industry in the city of Rio Grande. In contaminated rainwater fluorine concentration was registered up to the value of 4,4 mg.L-1. Fluorine concentration in the shallow ground water in general reflects its distribution in the atmosphere, but cannot be used as marker of atmosphere contamination in the urban area due to dissolving influence of residential effluents. The 0,01% HCl extracts from the set of surface soil samples demonstrates fluoride distribution in the zone of influence of industrial emissions, which coincides to the numerical simulation of fluorides dispersion in the air.

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The oxidation process of sulfur(IV) species by oxygen, ozone and nitrogen oxides, catalysed by trace metal ions, can play an important role in atmospheric chemistry processes like acid rain, visibility degradation and health hazard. An overview of the more relevant investigations on emissions sources, aqueous phase conversion process and environmental impact is presented.

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Ammonia is the most common alkaline gas of the atmosphere, being important in the neutralization of various processes that occur in the atmosphere. Its main sources of emission are the decomposition of organic matter and dejections of animals. Ammonia is used by man in diverse activities of production, therefore it is a gas that can contaminate work environments. Measurements of ammonia concentration in some parts of the world have shown great spatial and weather variation. This large variability makes it difficult to estimate the input of reduced nitrogen to different ecosystems from measurements.

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In atmospheric aerosol sampling, it is inevitable that the air that carries particles is in motion, as a result of both externally driven wind and the sucking action of the sampler itself. High or low air flow sampling speeds may lead to significant particle size bias. The objective of this work is the validation of measurements enabling the comparison of species concentration from both air flow sampling techniques. The presence of several outliers and increase of residuals with concentration becomes obvious, requiring non-parametric methods, recommended for the handling of data which may not be normally distributed. This way, conversion factors are obtained for each of the various species under study using Kendall regression.

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The present work is a preliminary study of total and wet precipitation in the Candiota region, RS. The samples were collected from January to June 2001 at four different sites. The following variables were analysed: pH, conductivity, alkalinity, Cl-, NO3-, F-, SO4(2-), Na+, K+, Mg2+, NH4+, Ca2+ and Zn, Cu, Fe, Al, Mn. The results showed slightly acidic precipitation and higher concentrations of NH4+, Na+, Cl- and SO4(2-). Factor analysis applied to the variables studied allowed identifying the major sources. Na+, Cl- and Mg2+ have their origin in sea salts and NH4+, Ca2+, K+, SO4(2-) and NO3- are from local anthropogenic sources.

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The performances of eight kinds of insulators from electrical distribution lines in Salvador-BA, Brazil, were evaluated considering the chemical and physical local environmental pollution. The parameters that were chosen as characteristic for the insulators' properties were leakage current and partial electrical discharge. A data storage processing system and a communication link to the lab were built for data acquisition. The results show that the main contribution to the poor performance of the insulators is settleable magnetite particulate matter on the insulator in addition to the long term wetness time, t4.

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Atmospheric chemistry in Brazil from 1790 to 1853. Scarcely any mention is made today of investigations carried out in Brazil during the period above on the science of the atmosphere. Yet the study of these cases reveals much about the milieu of a few devoted men who laboured to pursue a scientific career. That such an arcane topic has been the concern of investigators at such an early date may come as a surprise to many. The subject was an oddity as a field of study anywhere at the time, and its history deserves the attention of present-day chemists.

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Two sampling points were chosen and forty samples were collected between January and December 2006 at Alto Sorocaba basin. The rainwater pH varied from 5.46 to 6.36 (Ibiúna) and 5.26 to 6.81 (Itupararanga), being Ca2+ the main ion responsible for controlling the rainwater pH. The ionic concentrations decreased in the following order: Ca2 +>Na+> Mg2+>K+ for cations and SO4(2-)>HCO3->NO 3->Cl- >PO4(3-) for anions. The annual atmospheric deposition appeared to be controlled mostly by following sources: mining activities and cement factories (Ca2+ and HCO3-), natural soil dust (Na+, Mg2+ and HCO3-), fossil fuel burning (SO4(2-)) and agriculture activities (K+, NO3- and PO4(3-)).

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The aim of this review is to take a look at Cold War era nuclear tests signatures found in Brazilian coastal sediments. Both137Cs and 240+239Pu signatures have been documented in mangrove, coastal mudflats and continental shelf sediments, associated with above ground nuclear tests beginning in the 1950's. The dates associated to the anthropogenic radionuclide signatures 137Cs and 240+239Pu along sediment columns are confirmed by 210Pb geochronology in many of the studies highlighted in this review. The results outlined in this review characterize the extent to which nuclear fallout products reach the Brazilian coast in quantities sufficient for detection, allowing the use of these radioisotopes as geochronometers.

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Tesis (Maestro en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales ) U.A.N.L.

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Tesis (Maestría en Ciencias con orientación en Procesos Sustentables) UANL, 2014.

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L’ objectiu principal d’ aquest treball és l’ anàlisi de l’ evolució de l’ impacte ambiental produït per l’ emissió de gasos contaminants procedents de la incineradora de Campdorà (Girona). Els gasos contaminants objecte d’ estudi són: partícules de suspensió totals, clorur d’ hidrogen, diòxid de nitrogen, monòxid de carboni i diòxid de sofre. S’ ha realitzat la simulació de la dispersió atmosfèrica dels contaminants emesos per la incineradora de Campdorà mitjançant el programa informàtic ISC-AERMOD View. Com a resultat, s’ obtenen una sèrie de mapes de concentració on es mostren els diferents nivells d’ immissió detectats en la zona objecte d’ estudi. Els resultats mostren com la incorporació de noves tecnologies i tractaments de gasos en la incineradora de Campdorà han representat una reducció dels nivells d’ immissió de la zona, millorant la qualitat de l’ aire i disminuint l’ impacte ambiental que produeixen les emissions contaminants

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El prop??sito de este grupo de trabajo es integrar la ense??anza en el ??mbito de la naturaleza a trav??s de una serie de actividades por medio de las cuales el alumno pueda valorar por s?? mismo la importancia que tiene la conservaci??n y preservaci??n del medio ambiente. Participan 16 profesoras-es cuyos centros son de bachillerato y formaci??n profesional, todos ellos ubicados en la isla de Lanzarote. El total de alumnos de todos los centros es de 100. Objetivos: -Concienciar e implicar al alumno en la preservaci??n y conservaci??n del medio ambiente por medio del estudio de distintas zonas de la isla. -Despertar el inter??s por el estudio del ecosistema mediante la elaboraci??n de sus propias conclusiones. -Que el alumno aprenda a tratar adecuadamente los ecosistemas rurales y urbanos, haciendo hincapi?? en el deterioro medioambiental que presenten. -Fomentar la interdisciplinariedad con el fin de conseguir soluciones a los diversos problemas de la sociedad actual potenciando grupos de estudio por parte de los alumnos con el suficiente conocimiento sobre la materia tratada para promover dichas soluciones. -Saber aplicar los conocimientos te??ricos a la realidad por medio del an??lisis y comprensi??n de los textos. Desarrollar la capacidad cr??tica y anal??tica sobre el entorno. Se preparan con antelaci??n las unidades did??cticas eligiendo y seleccionando los textos y cuestiones pertinentes. El grupo de trabajo considera conveniente que las actividades de campo se organicen en forma de peque??os grupos de alumnos. Las experiencias a realizar consisten en salidas a dos zonas rurales del norte de la isla y a dos zonas urbanas de los alrededores de Arrecife, su capital. Cada unidad tem??tica estar?? englobada en un bloque de unidades relacionadas entre s??; se evaluar?? en conjunto mediante: la apreciaci??n personal del profesor mediante la observaci??n permanente del aprovechamiento del alumno, la evaluaci??n del trabajo en grupo de los cuadernos de campo y la realizaci??n de un ejercicio evaluativo consistente en una serie de cuestiones acerca de conceptos asumidos. La evaluaci??n realizada por los profesores participantes fue positiva, ya que se trabaj?? muy bien consigui??ndose pr??cticamente todos los objetivos..

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Crédito variable de Enseñanza Secundaria para el área de Ciencias Experimentales en el que se pretende que el alumno tome contacto de forma científica con la problemática derivada de la contaminación, así como conseguir la adquisición por parte de éste de elementos conceptuales y técnicas de trabajo para evaluar crítica y científicamente el impacto medioambiental de la actividad humana. Se sugieren 37 actividades de aprendizaje así como actividades de evaluación.