FCAA - Faculdade de Ciências Agrárias e do Ambiente
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Browsing FCAA - Faculdade de Ciências Agrárias e do Ambiente by Author "Afonso, Joana"
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- Climatology of aerosol composition (organic versus inorganic) at nonurban sites on a west-east transect across EuropePublication . Pio, Casimiro; Legrand, Michel; Oliveira, Tiago S.; Afonso, Joana; Santos, C.; Caseiro, A.; Fialho, Paulo; Barata, Filipe; Puxbaum, Hans; Sanchez-Ochoa, A.; Kasper-Giebl, Anne; Gelencsér, András; Preunkert, Susanne; Schock, M.In the framework of the European CARBOSOL project (Present and Retrospective State of Organic versus Inorganic Aerosol over Europe: Implications for Climate), atmospheric aerosol was continuously sampled for 2 years at six sites along a west-east transect extending from Azores, in the mid-Atlantic Ocean, to K-Puszta (Hungary), in central Europe. Aerosols were analyzed for ²¹°Pb, inorganic ions, elemental (EC) and organic (OC) carbon, water soluble organic carbon (WSOC), macromolecular type (humic-like) organic substances (HULIS), C2–C5 diacids, cellulose, and levoglucosan. Pooled aerosol filters were also used for the identification of different families of organic compounds by gas chromatography/mass spectrometry, GC/MS, as well as 14C determinations. The data resulted in a climatological overview of the aerosol composition over Europe in the various seasons, from west to east, and from the boundary layer to the free troposphere. The paper first summarizes the characteristics of the sites and collected samples and then focuses on the aerosol mass partitioning (mass closure, inorganic versus organic, EC versus OC, water soluble versus insoluble OC), giving an insight on the sources of carbonaceous aerosol present in rural and natural background areas in Europe. It also introduces the main role of other companion papers dealing with CARBOSOL aerosol data that are also presented in this issue.
- Monitorização do Carbono Negro no Arquipélago dos AçoresPublication . Barata, Filipe; Fialho, Paulo; Pio, Casimiro; Afonso, Joana; Oliveira, Tiago S.; Henriques, Diamantino; Carvalho, FernandaA presence do aerosol Carbono Negro tem sido analisada em dois locais do Arquipélago dos Açores. Um pretende reflectir as condições na troposfera livre da região do Atlântico Norte (PICO-NARE – 38.471º N, 27.404º W, 2225m de altitude), o outro as condições de fronteira maritime na mesma região (CLIMAAT-TERCEIRA-NARE – 38.691º N, 27.354º W, 50 m de altitude) (INTERREG IIIB – Projecto CLIMAAT-MAC 2.3/A3). No PICO-NARE utilizou-se um Etalómetro em amostragem continua (usualmente amostragem no período de 24 horas) e análise, em intervalos de 5 minutos, do equivalente de concentração de massa de Carbono Negro. No CLIMAAT-TERCEIRA-NARE instalou-se um Etalómetro nas mesmas condições e também um Colector de Partículas de Grande Caudal para amostragem de aerossóis em períodos contínuos de 7 dias, amostras que posteriormente foram enviadas para análise da concentração de massa de Carbono Negro por técnica Termo-Óptica, na Universidade de Aveiro. Os resultados médios obtidos, para o período de Julho de 2001 a Janeiro de 2004, de equivalents de concentração de massa de Carbono Negro, foram de: 85.85 ± 33.83 ng/m³ (max: 201.20 ng/m³, min: 41.57 ng/m³) para CLIMAAT-TERCEIRA-NARE e 37.48 ± 18.99 ng/m³ (max: 84.94 ng/m³, min: 12.65 ng/m³) para PICO-NARE. Para a concentração de massa de carbono negro, no CLIMAAT-TERCEIRA-NARE, obteve-se a media mensal de 49.01 ± 27.77 ng/m³ (max: 130.75 ng/m³, min: 1.55 ng/m³).
- Particulate carbon in precipitation at European background sitesPublication . Cerqueira, Mário; Pio, Casimiro; Legrand, Michel; Puxbaum, Hans; Kasper-Giebl, Anne; Afonso, Joana; Preunkert, Susanne; Gelencsér, András; Fialho, PauloThe particulate carbon content of precipitation was investigated in samples collected at five background sites located over a west-east European transect, from the Azores, in the mid-Atlantic Ocean, to the Hungarian plain, in central Europe. Sampling was performed on an event basis and the particulate carbon (elemental carbon, EC, and water insoluble organic carbon, WIOC) content was concentrated on quartz filters for the subsequent analysis by a thermal optical method in order to separate the EC and WIOC fractions. The average EC concentrations range from low values at the Azores (2.8±4.3 μg C L−1) and at the high mountain site of Sonnblick (5.2±3.7 μg C L−1) to high values at the more inland sites of Schauinsland (28±38 μg C L−1) and K-Puszta (24±24 μg C L−1). The average WIOC concentrations range from 98±56 μg C L−1 at the coastal site of Aveiro and 113±78 μg C L−1 at the Azores to 358±194 μg C L−1 at the continental site of K-Puszta. These results are discussed in terms of factors affecting the spatial distribution of particulate carbon, such as emissions from surrounding areas and prevalent meteorological conditions. EC is found to be a minor contributor to total particulate carbon present in rain and snow samples (from 2.5% to 15%). This is particularly true at the remotes sites, where the EC contribution to total particulate carbon is <6.5%, consistent with a negligible impact of anthropogenic combustions locally. The EC and WIOC scavenging ratios were estimated and compared with those of sulfate, also evaluated at the same sampling sites. The results indicated that EC is removed from the atmosphere by wet deposition less efficiently than WIOC, and in turn this species is removed less efficiently than sulfate.
- Seasonal variation of particulate lipophilic organic compounds at nonurban sites in EuropePublication . Oliveira, Tiago S.; Pio, Casimiro; Alves, Célia A.; Silvestre, Armando J. D.; Evtyugina, M.; Afonso, Joana; Fialho, Paulo; Legrand, Michel; Puxbaum, Hans; Gelencsér, AndrásAtmospheric aerosol samples, collected continuously during a sampling period longer than 1 year at six rural and background sites representing oceanic, rural and continental environments across Europe, were extracted, fractionated and analyzed by gas chromatography/mass spectrometry. The detailed organic speciation of the aerosol samples enabled the choice of some key compounds to assess the contribution of different sources. Lipophilic molecular markers were identified, including vehicle exhaust constituents, meat smoke tracers, phytosterols of higher photosynthetic plants and wood smoke components, especially from coniferous vegetation. The lowest concentrations and a quasi absence of seasonal cycle were observed at the oceanic background site of Azores. The highest values and a greater number of compounds were registered at the two continental lower-level sites. Aveiro (a rural site close to the small coastal Portuguese city of Aveiro) and K-puszta (Hungarian plains) both presented a seasonal variation with winter maxima attributable to a sizable contribution of wood-burning and meat-cooking sources. At the mountain sites (Puy de Dôme, Schauinsland and the high alpine summit of Sonnblick), concentrations maximized during summer as a result of the decoupling of the lower layers from the midtroposphere with wintry weather and the influence of boundary layer air masses during the warm season.