Browsing by Author "Oliveira, Tiago S."
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- Characterisation of carbonaceous aerosols from the Azorean island of TerceiraPublication . Alves, Célia A.; Oliveira, Tiago S.; Pio, Casimiro; Silvestre, Armando J. D.; Fialho, Paulo; Barata, Filipe; Legrand, MichelAerosol samples were collected from 2002 to 2003 in Terceira, one of the islands of the Azores archipelago in the north-eastern Atlantic. The atmospheric samples have been analysed for its carbonaceous content and for lipid class compounds. The major constituents that comprise plant wax are n-alkanes (C23–C33, with and odd-to-even carbon predominance and carbon maxima at 29 or 31), n-alkanols (C22–C30, even-to-odd) and n-alkanoic acids (C22–C30, even-to-odd), with minor amounts of n-alkanals and polycyclic biomarkers, such as phytosterols. Some alkanedioic acids and phthalates were also detected. The occurrence of short-chain homologues may indicate an additional marine source, probably introduced into the atmosphere via sea spray. Changes in the composition of the homologous series derived from terrestrial plants throughout the observation period may be related to alterations in the regional sources and transport pathways. These terrestrial lipids contributed up to 47% of the total compound mass, while the marine input was estimated to be inferior to 19%, both of them being more representative in summer. Biomass burning sources represented approximately 1% of the total inputs to the organic aerosol for the most part of the year, excepting during the spring, when it contributed to 10%. Petroleum products and plasticizers presented higher contributions (up to 19%) during the winter months. Secondary constituents resulting from oxidation during transport varied from 14% to 37% of the apportioned organic mass. The fraction derived from soil resuspension accounted for 2–16%.
- 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).
- 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.