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Ozone application in water sources: effects of operational parameters and water quality variables on ozone residual profiles and decay rates

LAGE FILHO, F. A.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
371.8331%
Systematic ozonation tests were conducted by means of a mobile pilot plant. Water source 1 was a low turbidity stream with very low solids content and very low turbidity, apparent color and alkalinity. Water source 2 was reservoir water with higher turbidity, solids content and alkalinity than source 1. The ozone plant was a counter-current contactor composed of four columns in series. Variations in contact time, in the feed gas concentration (in terms of percent by weight of ozone) and in splitting of the total applied ozone dosage between columns 1 and 2 were tested. Concentration - time (CT) products were calculated and decay coefficients K were estimated from experimental data. The relative importance of water quality and certain operational parameters with regard to CT products and ozone decay was assessed. Total CT values seemed to increase with: (a) total applied ozone dosage, (b) percent by weight of ozone in the feed gas to the bubble contactor, (c) increasing contact time and (d) higher water quality, with regard to turbidity, apparent color, total organic carbon and particle counts. As the total applied ozone dosage was increased, the more important the contact time and ozone dosage configuration became for the total CT value. The apparent first order ozone decay rate constant (K) decreased with increasing total applied ozone dosage. The contact time appeared to exert a much stronger influence on total CT values than on K values...

Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load

KUHN, U.; GANZEVELD, L.; THIELMANN, A.; DINDORF, T.; SCHEBESKE, G.; WELLING, M.; SCIARE, J.; ROBERTS, G.; MEIXNER, F. X.; KESSELMEIER, J.; LELIEVELD, J.; KOLLE, O.; CICCIOLI, P.; LLOYD, J.; TRENTMANN, J.; Artaxo Netto, Paulo Eduardo; ANDREAE, M. O.
Fonte: COPERNICUS GESELLSCHAFT MBH Publicador: COPERNICUS GESELLSCHAFT MBH
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
369.6251%
As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O(3), NO, NO(2), CO, VOC, CO(2), and H(2)O. Aerosol loads were characterized by concentrations of total aerosol number (CN) and cloud condensation nuclei (CCN), and by light scattering properties. Measurements over pristine rainforest areas during the campaign showed low levels of pollution from biomass burning or industrial emissions, representative of wet season background conditions. The urban plume of Manaus City was found to be joined by plumes from power plants south of the city, all showing evidence of very strong photochemical ozone formation. One episode is discussed in detail, where a threefold increase in ozone mixing ratios within the atmospheric boundary layer occurred within a 100 km travel distance downwind of Manaus. Observation-based estimates of the ozone production rates in the plume reached 15 ppb h(-1). Within the plume core...

Effect of low-dose gaseous ozone on pathogenic bacteria

Fontes, Belchor; Heimbecker, Ana Maria Cattani; Brito, Glacus de Souza; Costa, Silvia F; van der Heijden, Inneke M; Levin, Anna S; Rasslan, Samir
Fonte: BIOMED CENTRAL LTD Publicador: BIOMED CENTRAL LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
369.6251%
Background: Treatment of chronically infected wounds is a challenge, and bacterial environmental contamination is a growing issue in infection control. Ozone may have a role in these situations. The objective of this study was to determine whether a low dose of gaseous ozone/oxygen mixture eliminates pathogenic bacteria cultivated in Petri dishes. Methods: A pilot study with 6 bacterial strains was made using different concentrations of ozone in an ozone-oxygen mixture to determine a minimally effective dose that completely eliminated bacterial growth. The small and apparently bactericidal gaseous dose of 20 mu g/mL ozone/oxygen (1: 99) mixture, applied for 5min under atmospheric pressure was selected. In the 2nd phase, eight bacterial strains with well characterized resistance patterns were evaluated in vitro using agar-blood in adapted Petri dishes (10(5) bacteria/dish). The cultures were divided into 3 groups: 1-ozone-oxygen gaseous mixture containing 20 mu g of O-3/mL for 5 min; 2- 100% oxygen for 5 min; 3- baseline: no gas was used. Results: The selected ozone dose was applied to the following eight strains: Escherichia coli, oxacillin-resistant Staphylococcus aureus, oxacillin-susceptible Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis...

Ozone sounding in the Metropolitan Area of Sao Paulo, Brazil: Wet and dry season campaigns of 2006

de Fatima, Andrade Maria; Fornaro, Adalgiza; Dias de, Freitas Edmilson; Mazzoli, Caroline R.; Martins, Leila Droprinchinski; Boian, Claudia; Lopes Oliveira, Marcio Gledson; Peres, Jean; Carbone, Samara; Alvala, Plinio; Leme, Neusa Paes
Fonte: PERGAMON-ELSEVIER SCIENCE LTD; OXFORD Publicador: PERGAMON-ELSEVIER SCIENCE LTD; OXFORD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
370.69492%
In the Metropolitan Area of Sao Paulo (MASP), located in southeastern Brazil, surface ozone concentrations are often well above the national air quality standards. In this experimental study, we attempted to characterize the vertical profile of atmospheric ozone and transport of the ozone plume in the boundary layer, using data from the first ozone soundings ever taken in the MASP. In 2006, we launched fifteen ozonesondes: eight from 15 to 18 May (dry season); and seven from 30 October to 1 November (wet season). Vertical ozone mixing ratios in the troposphere were approximately 40 ppb, reaching maximum values of approximately 60 ppb during the dry-season campaign and approximately 100 ppb during the wet-season campaign. In the first and second campaigns, the mean tropospheric ozone column abundance was 28.2 and 41.3 DU, respectively, which can be attributed to the considerable variation in the annual temperature cycle over the region. To determine the effect that biomass burning has on ozone concentrations over the MASP, we analyzed wind trajectories and satellite-derived fire counts. We cannot state unequivocally that biomass burning contributed to higher ozone concentrations above the boundary layer during the experimental campaigns. In the boundary layer...

Effect of low-dose gaseous ozone on pathogenic bacteria

Fontes, Belchor; Heimbecker, Ana Maria Cattani; Brito, Glacus de Souza; Costa, Silvia F; Heijden, Inneke M van der; Levin, Anna S; Rasslan, Samir
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
369.6251%
Abstract Background Treatment of chronically infected wounds is a challenge, and bacterial environmental contamination is a growing issue in infection control. Ozone may have a role in these situations. The objective of this study was to determine whether a low dose of gaseous ozone/oxygen mixture eliminates pathogenic bacteria cultivated in Petri dishes. Methods A pilot study with 6 bacterial strains was made using different concentrations of ozone in an ozone-oxygen mixture to determine a minimally effective dose that completely eliminated bacterial growth. The small and apparently bactericidal gaseous dose of 20 μg/mL ozone/oxygen (1:99) mixture, applied for 5min under atmospheric pressure was selected. In the 2nd phase, eight bacterial strains with well characterized resistance patterns were evaluated in vitro using agar-blood in adapted Petri dishes (105 bacteria/dish). The cultures were divided into 3 groups: 1- ozone-oxygen gaseous mixture containing 20 μg of O3/mL for 5 min; 2- 100% oxygen for 5 min; 3- baseline: no gas was used. Results The selected ozone dose was applied to the following eight strains: Escherichia coli...

Sensibilidade da formação do ozônio troposférico às emissões veiculares na região metropolitana de São Paulo; Tropospheric ozone formation sensitivity to vehicle emission in the Metropolitan Area of São Paulo

Martins, Leila Droprinchinski
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 02/02/2007 PT
Relevância na Pesquisa
370.69492%
Este trabalho teve como objetivo avaliar a sensibilidade da formação do ozônio troposférico às emissões veiculares de compostos orgânicos voláteis (COVs) e NOx na Região Metropolitana de São Paulo (RMSP). Essa avaliação foi realizada através de modelagem numérica com modelo de qualidade do ar fotoquímico tridimensional. Para a determinação da especiação dos COVs veiculares foram realizadas duas campanhas intensivas de medidas em túneis da cidade de São Paulo, constituindo portanto em um esforço na melhoria do inventário de emissões da RMSP. Das medidas de concentração dos COVs, CO, NOx e SO2 foram calculados fatores de emissão e com base na relação entre as concentrações dos COVs emitidos pela exaustão veicular, juntamente com informações obtidas previamente da composição do combustível líquido e das emissões evaporativas foi construído um inventário dos COVs emitidos pela gasolina, álcool e diesel na RMSP, utilizado nas simulações de qualidade do ar. Foram realizadas simulações de referência utilizando o modelo fotoquímico densenvolvido no Caltech Institute of Technology (CIT) e Carnegie Mellon University, e as concentrações obtidas das simulações foram comparadas às concentrações observadas pela rede de monitoramento da Companhia de Tecnologia de Saneamento Ambiental (CETESB) para três períodos distintos...

Contribuições da atividade canavieira para as concentrações de ozônio troposférico em Araraquara, SP; Contributions of the Sugarcane Industry to Tropospheric Ozone Concentrations in Araraquara, SP

Francisco, Ana Paula
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 20/09/2012 PT
Relevância na Pesquisa
370.69492%
Objetivo: Avaliar a influência da atividade canavieira nas concentrações de ozônio troposférico em área urbana de Araraquara, SP. Método: Foram realizadas coletas passiva de ozônio e COV (Compostos Orgânicos Voláteis), na safra e entressafra de cana-de-açúcar 2011 2012, em 6 locais na área urbana, com exposição de 5 dias. Coleta ativa de COV foi realizada na área central durante 6 dias, não consecutivos, utilizando 24 coletores por dia com exposição de 1 hora cada um, totalizando 144 amostras. Coletas passivas de COV também foram realizadas em 3 situações: durante e após a queima de canavial e em área urbana, durante 1 hora cada, totalizando 9 amostras. A quali e quantificação dos COV foram realizadas por cromatografia gasosa, utilizando como pré-tratamento da amostra dessorvedor térmico e criogenia. A determinação de ozônio foi feita por cromatografia iônica com a quantificação de íons nitrato, produto da reação do ozônio com o absorvente químico. Além disso, foi realizada estimativa de emissões atmosféricas da atividade canavieira e urbanas para avaliar a participação dessas fontes de poluição na emissão de precursores de ozônio. Resultados: Concentrações médias de ozônio estiveram na faixa de 42...

A New and Simple Visual Technique Based on Indigo Dye for Determination of Ozone in Ambient Air

Garcia, Gabriel; Allen, Andrew George; Cardoso, Arnaldo Alves
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 9
ENG
Relevância na Pesquisa
371.50055%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Episodes of pollution resulting from high concentrations of environmental ozone frequently occur in different parts of the world. The ozone can affect human health, natural vegetation, and agricultural productivity. The monitoring of ozone concentrations is essential to aid investigation of its effects and it is also required to assess progress in public management of this pollutant. A new effective and simple technique is presented for the determination of ambient ozone concentrations using a visual procedure. The method is based on the reaction between the dye indigo and ozone, with the formation of colorless products. The bleaching intensity is proportional to the amount of ozone. An indigo color standard scale was developed with the utilization of digital image-based (DIB) calibration and printed as a wheel-chart test kit. Ozone sampling is performed using a passive sampler containing a filter impregnated with indigo. The amount of reacted ozone can be determined by visual comparison using the wheel-chart test kit. The method enables determination of ozone concentrations from 2 to 97 ppb, with intervals of 3 ppb. It does not require an energy source or any post-sampling chemical treatment or analysis...

Avaliação do tratamento com agua ozonizada para higienização de alface (Lactuca sativa); Tratment evaluation with ozone water for iceberg lettuce sanitization

Daniel Augusto Cavalcante
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/06/2007 PT
Relevância na Pesquisa
369.6251%
A etapa de sanitização é critica e de suma importância para a qualidade microbiológica de vegetais. É importante que o sanitizante seja além de eficaz, seguro do ponto de vista toxicológico. O uso do ozônio durante o processamento de vegetais prolonga a vida de prateleira, preserva os atributos sensoriais e não produz resíduos tóxicos. O objetivo deste trabalho foi estudar a eficiência o ozônio como sanitizante em hortaliças folhosas. Em um primeiro momento foi verificada a ação do sanitizante in vitro em Escherichia coli O157:H7 e Bacillus subtilis. O ozônio foi utilizado nas concentrações de 0,6, 0,8 e 1,0 mg L-1 nos tempos de 1, 3 e 5 minutos para cada concentração. Na seqüência observou-se a ação de água ozonizada durante um minuto na sanitização de alface americana inoculada com E. coli O157:H7 na concentração de 1,0 mgL-1 e, para completar o estudo, foi verificado o comportamento da hortaliça durante dez dias de armazenamento a 2ºC, sob ação de 1,0 mg L-1 de água ozonizada nos tempos de 1, 2 e 3 minutos. No estudo in vitro a E. coli O157:H7 e o Bacillus subtilis, no tempo de 3 minutos de exposição a 1,0 mg L-1 de água ozonizada, apresentaram uma redução de 6,6 e 6,3 ciclos logarítmicos...

Effect of ozone on the quality of fresh-cut green beans (Phaseolus vulgaris L.) and bell peppers (Capsicum annuum L.)

Alexandre, Elisaberte M. C.; Fundo, Joana; Santos, Dora M.; Brandão, Teresa R. S.; Silva, Cristina L. M.
Fonte: Instituto Superior Politécnico de Viseu - Escola Superior Agrária Publicador: Instituto Superior Politécnico de Viseu - Escola Superior Agrária
Tipo: Conferência ou Objeto de Conferência
Publicado em //2005 ENG
Relevância na Pesquisa
369.6251%
Ozone is a potent oxidant and disinfectant agent with multiple industrial applications. The efficacy of ozone treatments has been recognised in the sanitation of equipments and water disinfections. Recently, ozone started to be used as an innovative food processing technology that guarantees product safety. The objective of this work was to study the effect of ozone on the quality of fresh-cut green beans (Phaseolus vulgaris, L.) and green and red bell peppers (Capsicum annuum, L.). The quality factors analysed were enzyme (peroxidase) activity, colour and texture for green beans, and colour, texture and pH for bell peppers. Experiments were carried out in pilot equipment. An ozone generator was interconnected to a container filled with tap water. Ozone was continuously incorporated in water and its content was indirectly measured by potential difference. Green beans and bell peppers were cut in small portions. Samples were immersed in ozonated and non-ozonated water baths and removed after different times till a maximum of 180 minutes. Data from both treatments were compared by analysis of variance. For green beans, results showed that ozone treatment did not affect the colour, but significantly influenced texture (firmness) and peroxidase inactivation (at 7% significance level). After 40 minutes enzyme activity was reduced approximately 20%. This inactivation was verified for the rest of the sampling times. Ozone treatment affected pH and texture (fracturability) of red bell peppers (at 1% significance level). The other quality factors were not significantly influenced by ozone.

Long-term trends of total ozone column over the Iberian Peninsula for the period 1979e2008

Antón, Manuel; Bortoli, Daniele; Kulkarni, Pavan; Costa, Maria João; Domingues, Ana Filipa; Loyola, Diego; Silva, Ana Maria; Alados-Arboledas, Lucas
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
370.69492%
The objective of this work is to analyze the total ozone column (TOC) trends over the Iberian Peninsula during the last 30 years (1979e2008). This study is carried out using TOC data derived from the Multi Sensor Reanalysis (MSR), Total Ozone Mapping Spectrometer (TOMS) and Global Ozone Monitoring Experiment (GOME). The analysis of the long-term ozone trends is focused on two sub-periods (1979e1994 and 1995e2008) in order to detect changes in the ozone trend pattern. The results show that the ozone depletionwas statistically significant at the 95% confidence level during the first sub-period (1979e1994) in the entire region of study (except in the Southerner locations), with linear trends from 4.5%/decade to 2.5%/decade. These linear trends present a clear dependence on latitude, being higher for the Northerner locations than for the Southerner. By contrast, the analysis of the second sub-period of study (1995e2008) shows positive ozone trends over the Iberian Peninsula, with the highest values (þ2.5%/decade) in the Northeast of this region. This result indicates that the ozone layer may be responding as expected to the controls on ozone-depleting substances imposed by theMontreal Protocol. Additionally, a seasonal trend analysis is performed using the average of the deseasonalized monthly values for each season of the year. The seasonal analysis showed that the negative ozone trends during the first sub-period of study were statistically significant in the spring and winter...

Analysis of total ozone trends in the Iberian Peninsula using satellite data

Antón, Manuel; Bortoli, Daniele; Kulkarni, Pavan; Costa, Maria João; Domingues, Ana Filipa; Loyola, Diego; Silva, Ana Maria; Alados-Arboledas, Lucas
Fonte: Global Conference on Global Warming - GCGW 2011 Publicador: Global Conference on Global Warming - GCGW 2011
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
370.20055%
This work is focused on the study of the total ozone column (TOC) trends over the Iberian Peninsula during the last 30 years (1979-2009). This analysis is carried out using satellite TOC data and it is divided into two sub-periods in order to detect changes in the ozone trend pattern: from 1979 to 1994 using the NASA Total Ozone Mapping Spectrometer (TOMS) and from 1995 to 2009 by means of the ESA Global Ozone Monitoring Experiment (GOME). The analysis of the long-term ozone trends is performed using annual mean time series derived from the average of the deseasonalized monthly TOC series. The results show that the ozone depletion was statically significant at the 95% confidence level during the first sub-period (1979-1994) in the entire region of study, with linear trends from -4.5 %/decade to -2.9 %/decade. These linear trends presented a clear dependence on latitude, being higher for the Northerner locations than for the Southerner. By contrast, the analysis of the second sub-period of study (1995-2009) presented positive ozone trends from +0.6 %/decade to +1.8 %/decade (only statically significant in four of nine locations of study), indicating that the ozone layer may be responding as expected to the controls on ozone-depleting substances imposed by the Montreal Protocol. Additionally...

Influence of the ozone profile above Madrid (Spain) on Brewer estimation of ozone air mass factor

Antón, Manuel; López, M.; Costa, Maria João; Serrano, Antonio; Bortoli, Daniele; Bañón, M.; Vilaplana, Jose Manuel; Silva, Ana Maria
Fonte: Copernicus Publications Publicador: Copernicus Publications
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
371.8331%
The methodology used by Brewer spectroradiometers to estimate the ozone column is based on differential absorption spectroscopy. This methodology employs the ozone air mass factor (AMF) to derive the total ozone column from the slant path ozone amount. For the calculating the ozone AMF, the Brewer algorithm assumes that the ozone layer is located at a fixed height of 22 km. However, for a real specific site the ozone presents a certain profile, which varies spatially and temporally depending on the latitude, altitude and dynamical conditions of the atmosphere above the site of measurements. In this sense, this work address the reliability of the mentioned assumption and analyses the influence of the ozone profiles measured above Madrid (Spain) in the ozone AMF calculations. The approximated ozone AMF used by the Brewer algorithm is compared with simulations obtained using the libRadtran radiative transfer model code. The results show an excellent agreement between the simulated and the approximated AMF values for solar zenith angle lower than 75°. In addition, the relative differences remain lower than 2% at 85°. These good results are mainly due to the fact that the altitude of the ozone layer assumed constant by the Brewer algorithm for all latitudes notably can be considered representative of the real profile of ozone above Madrid (average value of 21.7±1.8 km). The operational ozone AMF calculations for Brewer instruments are limited...

Effect of ozone oxidative preconditioning in preventing early radiation-induced lung injury in rats

Bakkal,B.H.; Gultekin,F.A.; Guven,B.; Turkcu,U.O.; Bektas,S.; Can,M.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2013 EN
Relevância na Pesquisa
369.6251%
Ionizing radiation causes its biological effects mainly through oxidative damage induced by reactive oxygen species. Previous studies showed that ozone oxidative preconditioning attenuated pathophysiological events mediated by reactive oxygen species. As inhalation of ozone induces lung injury, the aim of this study was to examine whether ozone oxidative preconditioning potentiates or attenuates the effects of irradiation on the lung. Rats were subjected to total body irradiation, with or without treatment with ozone oxidative preconditioning (0.72 mg/kg). Serum proinflammatory cytokine levels, oxidative damage markers, and histopathological analysis were compared at 6 and 72 h after total body irradiation. Irradiation significantly increased lung malondialdehyde levels as an end-product of lipoperoxidation. Irradiation also significantly decreased lung superoxide dismutase activity, which is an indicator of the generation of oxidative stress and an early protective response to oxidative damage. Ozone oxidative preconditioning plus irradiation significantly decreased malondialdehyde levels and increased the activity of superoxide dismutase, which might indicate protection of the lung from radiation-induced lung injury. Serum tumor necrosis factor alpha and interleukin-1 beta levels...

Ozone application in water sources: effects of operational parameters and water quality variables on ozone residual profiles and decay rates

Lage Filho,F. A.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
Relevância na Pesquisa
371.8331%
Systematic ozonation tests were conducted by means of a mobile pilot plant. Water source 1 was a low turbidity stream with very low solids content and very low turbidity, apparent color and alkalinity. Water source 2 was reservoir water with higher turbidity, solids content and alkalinity than source 1. The ozone plant was a counter-current contactor composed of four columns in series. Variations in contact time, in the feed gas concentration (in terms of percent by weight of ozone) and in splitting of the total applied ozone dosage between columns 1 and 2 were tested. Concentration - time (CT) products were calculated and decay coefficients K were estimated from experimental data. The relative importance of water quality and certain operational parameters with regard to CT products and ozone decay was assessed. Total CT values seemed to increase with: (a) total applied ozone dosage, (b) percent by weight of ozone in the feed gas to the bubble contactor, (c) increasing contact time and (d) higher water quality, with regard to turbidity, apparent color, total organic carbon and particle counts. As the total applied ozone dosage was increased, the more important the contact time and ozone dosage configuration became for the total CT value. The apparent first order ozone decay rate constant (K) decreased with increasing total applied ozone dosage. The contact time appeared to exert a much stronger influence on total CT values than on K values...

Ozone production in transpacific Asian pollution plumes and implications for ozone air quality in California

Hudman, R. C.; Jacob, Daniel James; Cooper, O. R.; Evans, M. J.; Heald, C. L.; Park, R. J.; Fehsenfeld, F.; Flocke, F.; Holloway, J.; Hübler, G.; Kita, K.; Koike, M.; Kondo, Yasuyuki; Neuman, Aaron Drake; Nowak, Jonathan Andrew; Oltmans, S.; Parrish, D.;
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
EN_US
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370.69492%
We examine the ozone production efficiency in transpacific Asian pollution plumes, and the implications for ozone air quality in California, by using aircraft and surface observations in April–May 2002 from the Intercontinental Transport and Chemical Transformation 2002 (ITCT 2K2) campaign off the California coast and the Pacific Exploration of Asian Continental Emission–B (PEACE-B) campaign over the northwest Pacific. The observations are interpreted with a global three-dimensional chemical transport model (GEOS-CHEM). The model reproduces the mean features observed for CO, reactive nitrogen oxides (NOy), and ozone but underestimates the strong (∼20 ppbv) stratospheric contribution to ozone in the middle troposphere. The ITCT 2K2 aircraft sampled two major transpacific Asian pollution plumes, one on 5 May at 5–8 km altitude with CO up to 275 ppbv but no elevated ozone and one on 17 May at 2.5–4 km altitude with CO up to 225 ppbv and ozone up to 90 ppbv. We show that the elevated ozone in the latter plume is consistent with production from peroxyacetylnitrate (PAN) decomposition during subsidence of the plume over the northeast Pacific. This production is particularly efficient because of the strong radiation and low humidity of the subsiding environment. We argue that such PAN decomposition represents a major and possibly dominant component of the ozone enhancement in transpacific Asian pollution plumes. Strong dilution of Asian pollution plumes takes place during entrainment in the U.S. boundary layer...

Climate response to the increase in tropospheric ozone since preindustrial times: A comparison between ozone and equivalent CO 2 forcings

Mickley, Loretta J.; Jacob, Daniel James; Field, D; Rind, D
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
372.1291%
We examine the characteristics of the climate response to anthropogenic changes in tropospheric ozone. Using a general circulation model, we have carried out a pair of equilibrium climate simulations with realistic present-day and preindustrial ozone distributions. We find that the instantaneous radiative forcing of 0.49 W m−2 due to the increase in tropospheric ozone since preindustrial times results in an increase in global mean surface temperature of 0.28°C. The increase is nearly 0.4°C in the Northern Hemisphere and about 0.2°C in the Southern Hemisphere. The largest increases (>0.8°C) are downwind of Europe and Asia and over the North American interior in summer. In the lower stratosphere, global mean temperatures decrease by about 0.2°C due to the diminished upward flux of radiation at 9.6 μm. The largest stratospheric cooling, up to 1.0°C, occurs over high northern latitudes in winter, with possibly important implications for the formation of polar stratospheric clouds. To identify the characteristics of climate forcing unique to tropospheric ozone, we have conducted two additional climate equilibrium simulations: one in which preindustrial tropospheric ozone concentrations were increased everywhere by 18 ppb, producing the same global radiative forcing as present-day ozone but without the heterogeneity; and one in which CO2 was decreased by 25 ppm relative to present day...

Tropospheric ozone, respiratory effects and Australian air quality goals

Woodward, A.; Guest, C.; Steer, K.; Harman, A.; Scicchitano, R.; Pisaniello, D.; Calder, I.; McMichael, A.
Fonte: British Medical Association Publicador: British Medical Association
Tipo: Artigo de Revista Científica
Publicado em //1995 EN
Relevância na Pesquisa
370.20055%
OBJECTIVE: To review the health effects of tropospheric ozone and discuss the implications for public health policy. DESIGN: Literature review and consultation with scientists in Australia and overseas. Papers in English or with English language abstracts were identified by Medline search from the international peer reviewed published reports. Those from the period 1980-93 were read systematically but selected earlier papers were also considered. Reports on ozone exposures were obtained from environmental agencies in the region. RESULTS: Exposure to ozone at concentrations below the current Australian air quality goal (0.12 ppm averaged over one hour) may cause impaired respiratory function. Inflammatory changes in the small airways and respiratory symptoms result from moderate to heavy exercise in the presence of ozone at levels of 0.08-0.12 ppm. The changes in respiratory function due to ozone are short lived, vary with the duration of exposure, may be modified by levels of other pollutants (such as sulphur dioxide and particulates), and differ appreciably between individuals. Bronchial lavage studies indicate that inflammation and other pathological changes may occur in the airways before reductions in air flow are detectable, and persist after respiratory function has returned to normal. It is not known whether exposures to ozone at low levels (0.08-0.12 ppm) cause lasting damage to the lung or...

Ozone Exposure of a Weed Community Produces Adaptive Changes in Seed Populations of Spergula arvensis

Landesmann, Jennifer Brenda; Gundel, Pedro Emilio; Martinez Ghersa, M. Alejandra; Ghersa, Claudio Marco
Fonte: Public Library Science Publicador: Public Library Science
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
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Tropospheric ozone is one of the major drivers of global change. This stress factor alters plant growth and development. Ozone could act as a selection pressure on species communities composition, but also on population genetic background, thus affecting life history traits. Our objective was to evaluate the consequences of prolonged ozone exposure of a weed community on phenotypic traits of Spergula arvensis linked to persistence. Specifically, we predicted that the selection pressure exerted by high ozone concentrations as well as the concomitant changes in the weed community would drive population adaptive changes which will be reflected on seed germination, dormancy and longevity. In order to test seed viability and dormancy level, we conducted germination experiments for which we used seeds produced by S. arvensis plants grown within a weed community exposed to three ozone treatments during four years (0, 90 and 120 ppb). We also performed a soil seed bank experiment to test seed longevity with seeds coming from both the four-year ozone exposure experiment and from a short-term treatment conducted at ambient and added ozone concentrations. We found that prolonged ozone exposure produced changes in seed germination, dormancy and longevity...

Effect of gaseous ozone and hot water on microbial and sensory quality of cantaloupe and potential transference of Escherichia coli O157:H7 during cutting

Selma, María Victoria; Ibáñez, Ana María; Allende, Ana; Cantwell, Marita; Suslow, Trevor
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 259768 bytes; application/pdf
ENG
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7 pages, 3 tables, 1 figure.; The effect of gaseous ozone and hot water, alone or in combination, on the sensory and microbial quality of cantaloupe melon was investigated. Escherichia coli O157:H7 transmission from the rind to edible melon flesh during cutting practices was also investigated. Four different treatments consisting of hot water (75 °C, 1 min), gaseous ozone (10,000 ppm, 30 min), gaseous ozone supplied by carbon monoxide gas and the combination of hot water and gaseous ozone were evaluated. Sensory quality and growth evolution of aerobic mesophilic and psychrotrophic bacteria, coliforms and molds were studied. In general, hot water, gaseous ozone, and the combination of hot water and gaseous ozone were effective in reducing total microbial population. The combination of hot water and gaseous ozone was the most effective treatment to control microbial growth achieving 3.8, 5.1, 2.2 and 2.3 log reductions for mesophilic and psychrotrophic bacteria, molds and coliforms, respectively. However no significant differences were observed between gaseous ozone and gaseous ozone supplied by with carbon monoxide gas. There was no evidence of damage in melons treated with hot water, ozone or their combination and they maintained initial texture and aroma. Therefore...