Ana Vicente

Emission of trace gases and organic components in smoke particles from a wildfire in a mixed-evergreen forest in Portugal

On May 2009, both the gas and particulate fractions of smoke from a wildfire in Sever do Vouga, central Portugal, were sampled. Total hydrocarbons and carbon oxides (CO(2) and CO) were measured using automatic analysers with flame ionisation and non-dispersive infrared detectors, respectively. Fine (PM(2.5)) and coarse (PM(2.5-10)) particles from the smoke plume were analysed by a thermal-optical transmission technique to determine the elemental and organic carbon (EC and OC) content. Subsequently, the particle samples were solvent extracted and fractionated by vacuum flash chromatography into different classes of organic compounds. The detailed organic speciation was performed by gas chromatography-mass spectrometry. The CO, CO(2) and total hydrocarbon emission factors (g kg(-1) dry fuel) were 170 ± 83, 1485 ± 147, and 9.8 ± 0.90, respectively. It was observed that the particulate matter and OC emissions are significantly enhanced under smouldering fire conditions. The aerosol emissions were dominated by fine particles whose mass was mainly composed of organic constituents, such as degradation products from biopolymers (e.g. levoglucosan from cellulose, methoxyphenols from lignin). The compound classes also included homologous series (n-alkanes, n-alkenes, n-alkanoic acids and n-alkanols), monosaccharide derivatives from cellulose, steroid and terpenoid biomarkers, and polycyclic aromatic hydrocarbons (PAHs). The most abundant PAH was retene. Even carbon number homologs of monoglycerides were identified for the first time as biomarkers in biomass burning aerosols.

Polycyclic aromatic hydrocarbons and their derivatives (nitro-PAHs, oxygenated PAHs, and azaarenes) in PM2.5 from Southern European cities

Atmospheric particulate matter (PM2.5) samples were collected over two one month periods during winter and summer in three Southern European cities (Oporto - traffic site, Florence - urban background, Athens - suburban). Concentrations of 27 polycyclic aromatic hydrocarbons (PAHs), 15 nitro-PAHs (NPAHs), 15 oxygenated-PAHs (OPAHs) and 4 azaarenes (AZAs) were determined. On average, the winter-summer concentrations of ΣPAHs were 16.3-5.60, 7.75-3.02 and 3.44-0.658ngm-3 in Oporto, Florence and Athens, respectively. The corresponding concentrations of ΣNPAHs were 15.8-9.15, 10.9-3.36 and 15.9-2.73ngm-3, whilst ΣOPAHs varied in the ranges 41.8-19.0, 11.3-3.10 and 12.6-0.704ngm-3. Concentrations of ΣAZAs were always below 0.5ngm-3. Irrespective of the city, the dominant PAHs were benzo[b+j+k]fluoranthene, retene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene. The most abundant OPAH in all cities was 1,8-naphthalic anhydride, whereas 5-nitroacenaphthene was the prevailing NPAH. The ΣOPAHs/ΣPAHs and ΣNPAHs/ΣPAHs were higher in summer than in winter, suggesting increasing formation of derivatives by photochemical degradation of PAHs. Molecular diagnostic ratios suggested that, after traffic, biomass burning was the dominant emission source. Apart from being influenced by seasonal sources, the marked differences between winter and summer may indicate that these diagnostic ratios are particularly sensitive to photodegradation, and thus should be applied and interpreted cautiously. The lifetime excess cancer risk from inhalation was, in part, attributable to PAH derivatives, acclaiming the need to include these compounds in regular monitoring programmes. On average, 206, 88 and 26 cancer cases per million people were estimated, by the World Health Organisation method, for the traffic-impacted, urban background and suburban atmospheres of Oporto, Florence and Athens, respectively.

Mutagenicity assessment of aerosols in emissions from domestic combustion processes

Domestic biofuel combustion is one of the major sources of regional and local air pollution, mainly regarding particulate matter and organic compounds, during winter periods. Mutagenic and carcinogenic activity potentials of the ambient particulate matter have been associated with the fraction of polycyclic aromatic hydrocarbons (PAH) and their oxygenated (OPAH) and nitrogenated (NPAH) derivatives. This study aimed at assessing the mutagenicity potential of the fraction of this polycyclic aromatic compound in particles (PM10) from domestic combustion by using the Ames assays with Salmonella typhimurium TA98 and TA100. Seven biofuels, including four types of pellets and three agro-fuels (olive pit, almond shell and shell of pine nuts), were tested in an automatic pellet stove, and two types of wood (Pinus pinaster, maritime pine, and Eucalyptus globulus, eucalypt) were burned in a traditional wood stove. For this latter appliance, two combustion phases—devolatilisation and flaming/smouldering—were characterised separately. A direct-acting mutagenic effect for the devolatilisation phase of pine combustion and for both phases of eucalypt combustion was found. Almond shell revealed a weak direct-acting mutagenic effect, while one type of pellets, made of recycled wastes, and pine (devolatilisation) presented a cytotoxic effect towards strain TA100. Compared to the manually fired appliance, the automatic pellet stove promoted lower polyaromatic mutagenic emissions. For this device, only two of the studied biofuels presented a weak mutagenic or cytotoxic potential.

Organic tracers in aerosols from the residential combustion of pellets and agro-fuels

The consumption of pellets and alternative biofuels, such as some agricultural residues, has experienced a tremendous growth in Mediterranean countries, which has changed the panorama of biomass burning emissions. To apply source apportionment models, specific chemical signatures for smoke aerosols are necessary. In this study, filter samples of fine particles (PM2.5) from the combustion of four different types of pellets and three agro-fuels (shell of pine nuts, olive pit and almond shell) in a pellet stove were collected. The PM2.5 samples were extracted with dichloromethane/methanol and the dried extracts were silylated before injection into the gas chromatograph-mass spectrometer (GC-MS). The analysis included monosaccharide anhydrides, resin acids, methoxyphenols and sterols. The amounts emitted were highly variable and dependent on both biofuel and combustion temperature. On average, the anhydrosugar particle mass fractions for the seven biofuels were 30 to 70 times lower than the values reported for manually fired systems. The highest levoglucosan emissions were observed for olive pit. Levoglucosan to mannosan ratios ranged from values around 2 for pellets and shell of pine nuts to much higher quotients, similar to those reported for hardwood combustion. Irrespective of biofuel, vanillin and vanillic acid were always present in the smoke samples. Coniferyl alcohol was only detected in samples from the combustion of olive pit and pellets with the highest softwood content. Sinapyl alcohol was exclusively emitted by olive pit. Dehydroabietic and isopimaric acids were represented in emissions whether from all type of pellets or from shell of pine nuts, whilst abietic acid was only quantifiable in PM2.5 from the combustion of pellets made of coniferous wood. Sitosterol was solely detected in smoke particles from shell of pine nuts and olive pit.

Chemical profiling of PM 10 from urban road dust

Road dust resuspension is one of the main sources of particulate matter with impacts on air quality, health and climate. With the aim of characterising the thoracic fraction, a portable resuspension chamber was used to collect road dust from five main roads in Oporto and an urban tunnel in Braga, north of Portugal. The PM10 samples were analysed for: i) carbonates by acidification and quantification of the evolved CO2, ii) carbonaceous content (OC and EC) by a thermo-optical technique, iii) elemental composition by ICP-MS and ICP-AES after acid digestion, and iv) organic speciation by GC-MS. Dust loadings of 0.48±0.39mgPM10m-2 were obtained for asphalt paved roads. A much higher mean value was achieved in a cobbled pavement (50mgPM10m-2). In general, carbonates were not detected in PM10. OC and EC accounted for PM10 mass fractions up to 11% and 5%, respectively. Metal oxides accounted for 29±7.5% of the PM10 mass from the asphalt paved roads and 73% in samples from the cobbled street. Crustal and anthropogenic elements, associated with tyre and brake wear, dominated the inorganic fraction. PM10 comprised hundreds of organic constituents, including hopanoids, n-alkanes and other aliphatics, polycyclic aromatic hydrocarbons (PAH), alcohols, sterols, various types of acids, glycerol derivatives, lactones, sugars and derivatives, phenolic compounds and plasticizers. In samples from the cobbled street, these organic classes represented only 439μgg-1PM10, while for other pavements mass fractions up to 65mgg-1PM10 were obtained. Except for the cobbled street, on average, about 40% of the analysed organic fraction was composed of plasticizers. Although the risk via inhalation of PAH was found to be insignificant, the PM10 from some roads can contribute to an estimated excess of 332 to 2183 per million new cancer cases in adults exposed via ingestion and dermal contact.

Organic compounds in particulate and gaseous phase collected in the neighbourhood of an industrial complex in São Paulo (Brazil)

São Paulo, a megacity in South America, is the largest consumer of fossil fuels in Brazil. The petrochemical products play an important role in the Brazilian economy and in the energy matrix. The compounds emitted when oil is used or processed can affect air quality and endanger human health. Particulate matter and gaseous samples were collected simultaneously in 2015 at an urban site highly impacted by anthropogenic activities, in the city of Santo André, São Paulo Metropolitan Area. Samples were analysed for elemental and organic carbon, hopanes, n-alkanes, alkenes polycyclic aromatic hydrocarbons and their oxygenated and nitrated derivatives. Among the polycyclic aromatic hydrocarbon, phenanthrene presented the highest concentration in PUF and benzo(b)fluoranthene was dominant in PM. The carcinogenic equivalents for benzo(a)pyrene were 2.1 for PAH and 1.2 for nitro-PAH. The results showed that local activities as vehicular and industrial activities affected the air quality.

Recognizing salt-structures on the basis of geophysical and remote sensing data: the case of monte real salt-structure (onshore west-central portugal)

Remote sensing data from Monte Real sub-basin (onshore West-Central Portugal), collected by the LANDSAT 7 ETM+, JERS-1 (SAR) and Envisat (ASAR) satellites, are used with the purpose to give new insights relatively to the Monte Real salt-structure. The recognized pattern of the diapir and of the structural lineaments is in agreement with the geophysical and geological data.

Hydrocarbons in particulate samples from wildfire events in central Portugal in summer 2010

In summer 2010, twenty eight (14 PM2.5 samples plus 14 samples PM2.5-10) smoke samples were collected during wildfires that occurred in central Portugal. A portable high-volume sampler was used to perform the sampling, on quartz fibre filters of coarse (PM2.5-10) and fine (PM2.5) smoke samples. The carbonaceous content (elemental and organic carbon) of particulate matter was analysed by a thermal-optical technique. Subsequently, the particulate samples were solvent extracted and fractionated by vacuum flash chromatography into three different classes of organic compounds (aliphatics, polycyclic aromatic hydrocarbons (PAHs) and carbonyl compounds). The organic speciation was performed by gas chromatography-mass spectrometry (GC-MS). Emissions were dominated by the fine particles, which represented around 92% of the PM10. A clear predominance of carbonaceous constituents was observed, with organic to elemental carbon (OC/EC) ratios ranging between 1.69 and 245 in both size fractions. The isoprenoid ketone 6,10,14-trimethyl-2-pentadecanone, a tracer for secondary organic aerosol formation, was one of the dominant constituents in both fine and coarse particles. Retene was the most abundant compound in all samples. Good correlations were obtained between OC and both aliphatic and PAH compounds. Pyrogenic processes, thermal release of biogenic compounds and secondary processing accounted for 97% of the apportioned PM2.5 levels.

Structural lineaments in a volcanic island evaluated through remote sensing techniques The case of Santiago Island (Cape Verde)

The remote sensing data (optical and radar) was used with the purpose of identify the structural lineaments that crosscut the geological formations that composed the bedrock of the south part of Santiago island (Cape Verde). Besides tectonics, this study also provided new insights to the understanding of the hydrogeological system of the volcanic island.

Application of optical and microwave remote sensing data to the tectonics and lithostratigraphy of metasedimentary rocks: the case of Douro Region (Northeastern Portugal)

The lithostratigraphy and the tectonics of Douro region, mainly composed by metasedimentary rocks of Neoproterozoic to Lower Cambrian age, has been studied with support of optical and microwave data collected by the Landsat 7 ETM+, Jers-1 and Envisat satellites. The lithologies already characterized from field data where recognized in the images which also show that they are organized under a normal sequence.