FCT (DCEA) - Capítulos de Livros em Editoras Internacionais
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Browsing FCT (DCEA) - Capítulos de Livros em Editoras Internacionais by Author "Barros, Nelson"
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- Impact of Oporto Metropolitan Area carbon dioxide emissions over the adjacent coastal zonePublication . Carvalho, Rogério; Barros, Nelson; Duarte, PedroConcerns about global warming over the last years have stimulated a large number of studies regarding atmospheric and oceanic carbon dioxide (CO2) concentration and its consequences. In spite of the available data on global atmospheric CO2, there is only limited knowledge on CO2 variability at regional scales. Moreover, there is an important gap in our understanding of the contribution of high CO2 emission regions, such as metropolitan areas, to CO2 concentrations over nearby coastal areas–considered by several authors as an important CO2 sink. A possible working hypothesis is that, large littoral metropolitan areas may have a significant influence on CO2 atmospheric concentrations over those areas and exert an important influence on sea-air CO2 exchanges. Therefore, the main objective of this study is to estimate CO2 concentration at a regional scale, under the influence of Oporto Metropolitan Area (OMA) emissions as a first test of this hypothesis. To fulfil this objective, an emission database was built and used to force, together with meteorological synoptic data, a mesoscale atmospheric dispersion model. The model was used to simulate several weather scenarios and estimate CO2 concentrations along a ca. 90 km stretch of the Portuguese northern shore. The results obtained suggest that emissions from OMA have an important influence on CO2 atmospheric concentrations up to 6–12 km offshore, particularly in autumn and winter. However, this CO2 increase does not seem to have the potential to significantly affect sea-air CO2 exchanges, although this is just a preliminary conclusion that has to be tested by field work.
- Learning from 24 years of ozone data in PortugalPublication . Barros, Nelson; Silva, M.P.; Fontes, Tânia; Manso, M. Conceição; Carvalho, Ana CristinaOzone (O3) is a secondary pollutant mainly produced in the troposphere by photochemical reactions with high impact on human health. In this work hourly average O3 concentrations from the Portuguese air quality network collected during 24 years (1988–2011) were analysed. The background time series were assessed by environment type (urban, suburban and rural) and considering several criteria: the annual mean O3 concentration, the Directive 2008/50/EC O3 long-term objective and the 2005 WHO Guideline for protection of human health and, finally, the hourly information threshold exceedances. The trend of annual mean O3 concentration data and the maximum daily eight-hour mean ozone concentration data were both annually compared using an one-way ANOVA followed by a Tamhane post-hoc comparison test. In both series, although of an instable trend, a tendency for an increase of the mean O3 concentrations was found. On the other hand, after 2006, for all stations types, the normalized number of exceedances for public O3 information are significantly decreasing (p<0.05). In this paper, the O3 trend will be analyzed and discussed, contributing to improve knowledge of long time series of O3 concentrations in Portugal.
- Ozone deposition modelling in a portuguese coastal zonePublication . Valinhas, Maria José; Borrego, Carlos; Barros, Nelson; Carvalho, Ana CristinaThe deposition of pollutants from the atmosphere to ecosystems is the cause of some present environmental problems: acidification, eutrophication and, indirectly, ground level ozone. Related with these issues is the critical loads/levels concept, widely accepted in Europe as basis for pollution control strategies. The knowledge of atmospheric pollutants deposition on ecosystems is needed to setup this methodology. This paper presents the parameterisation done in the deposition module of the system of models MAR IV which is adequate to simulate the transport, dispersion and removal of pollutants, including ozone production for mesoscale application. The ozone surface resistance (Rc) pararneterisation was applied to Lisbon region and the modelk performance was assessed with ozone deposition experimental data observed in the study area during the fieldwork LisbEx 97. The influence of parameterisation became evident with the good fit between modelled results and measured data. Based on an empirical method described by the Stockholm Environmental Institute report a Critical Load map, for non-forested areas, was calculated for Pomgal. The methodology is based on the kind of soil and its buffer capacity to acid compounds, The results show that around 70°/0of the country is in sensitive areas reinforcing the need for the application of this concept.
- Population exposure to urban highway traffic emissionsPublication . Barros, Nelson; Fontes, Tânia; Brás, C.; Cunha, L. M.In this paper is presented firstly the traffic and emission characterization of Via de Cintura Interna (VCI), an urban highway at Oporto city, Portugal, with more than 4 000 vehicles/hour during rush hours. Emission estimates were carried through on the basis of emission factors to road transport published in the Atmospheric Emission Inventory Guidebook. A weighed emission factor has been calculated for nitrogen oxides (NOx) and vehicle class, according to the Portuguese fleet composition (vehicles age, type of engine and average speed). Furthermore, during a three-week period, an outdoor nitrogen dioxide (NO2) monitoring campaign was carried out in a domain around the VCI (100 m for each side), in particular near residential buildings. The results demonstrate that higher NO2 concentrations are seen in the sub-domain with higher circulation of heavy-duty vehicles and where buildings are adjacent to VCI hindering pollutant dispersion. Meteorological conditions, such as wind intensity and direction, temperature and solar radiation were monitorized too. The NO2 concentrations obtained by the monitoring campaign have been used to create scenarios of population exposure to NO2, having taken into account the time-activity patterns of residents. It was verified that higher exposures occur when the population lives in Boavista, in contrast with the favourable scenario that corresponds to life in Prelada and those working in Espinho city. The work and results presented in this paper are a part of the methodology used in the scope of the ImpactAir Project. This project, started in 2003 in Oporto city, has the main objective of evaluating the impact of urban highway (VCI) traffic emissions on air quality and the health of the local population.
- Spatial prediction of air quality in an urban sensitive area: a seasonal overviewPublication . Fontes, Tânia; Barros, Nelson