Mário Cerqueira

Size distribution of polycyclic aromatic hydrocarbons in a roadway tunnel in Lisbon, Portugal

Atmospheric aerosols of four aerodynamic size ranges were collected using high volume cascade impactors in an extremely busy roadway tunnel in Lisbon (Portugal). Dust deposited on the tunnel walls and guardrails was also collected. Average particle mass concentrations in the tunnel atmosphere were more than 30times higher than in the outside urban background air, revealing its origins almost exclusively from fresh vehicle emissions. Most of the aerosol mass was concentrated in submicrometer fractions (65%), and polycyclic aromatic hydrocarbons (PAH) were even more concentrated in the finer particles with an average of 84% of total PAH present in sizes smaller than 0.49μm. The most abundant PAH were methylated phenanthrenes, fluoranthene and pyrene. About 46% of the total PAH mass was attributed to lower molecular weight compounds (two and three rings), suggesting a strong influence of diesel vehicle emissions on the production of local particulate PAH. The application of diagnostic ratios confirmed the relevance of this source of PAH in the tunnel ambient air. Deposited dust presented PAH profiles similar to the coarser aerosol size range, in agreement with the predominant origin of coarser aerosol particles from soil dust resuspension and vehicle wear products.

Source assessment of particulate air pollutants measured at the southwest european coast

Abstract Aerosol particles and gaseous species were measured in air masses transported to the west coast of Portugal, between November 1993 and August 1994. Samples were taken during four monitoring campaigns distributed along the various seasons of the year, integrated in the EC Project: BMCAPE. Aerosol particles were collected with separation in two size fractions and analysed in relation to total mass, water soluble ions, trace elements and black/organic carbon. Local micro-meteorological parameters and air mass backward trajectories were compared with analytical results in order to define characteristic air mass types and to evaluate the origin of pollutants. Average concentrations on the Portuguese west coast, even in maritime air masses, are higher than values observed in remote oceanic locations. This is probably a consequence of continental European air masses recirculation through the eastern Atlantic Ocean, reinforced by situations of mesoscale transport from the Iberian Peninsula. Principal Component Analysis permitted the identification of five source groups for the fine and coarse aerosol fractions, namely combustion plus road traffic, sea salt spray, secondary aerosol production, soil and possibly non-ferrous metallurgy industries. In the aerosol fine fraction road traffic and combustion contribute on average with 25% of the total fine aerosol mass, while sea spray and secondary production represent 14% and 31%, respectively of the mass loading. Sea spray is by far the major contributor to the coarse fraction with an average of 88% of the suspended coarse aerosol mass.

Outdoor/indoor air quality in primary schools in Lisbon: a preliminary study

Simultaneous measurements of outdoor and indoor pollution were performed at three schools in Lisbon. Volatile organic compounds (VOCs), formaldehyde and NO2 were passively monitored over a two-week period. Bacterial and fungal colony-forming units and comfort parameters were also monitored at classrooms and playgrounds. The highest indoor levels of CO2 (2666 μg/m3), NO2 (40.3 μg/m3), VOCs (10.3 μg/m3), formaldehyde (1.03 μg/m3) and bioaerosols (1634 CFU/m3), and some indoor/outdoor ratios greater than unity, suggest that indoor sources and building conditions might have negative effects on air indoors. Increasing ventilation rates and use of low-emission materials would contribute towards improving indoor air quality.

Volatile organic compounds in rural atmospheres of central Portugal

Atmospheric concentrations of volatile organic compounds were measured at two rural sites in central Portugal. The sites were chosen to be in line with the summer northwesterly sea breezes in order to study the evolution of the chemical composition of air masses during transport to inland areas. The most abundant non-oxygenated hydrocarbon in the ambient air was isoprene and the monoterpenes alpha-pinene, beta-pinene and 1,8 cineol. The maximum isoprene levels (6-7 ppb) were recorded at the most inland site, suggesting an enrichment of coastal air masses with biogenic emissions during transport over eucalyptus forests. Formaldehyde was the most prominent carbonyl compound in the atmosphere but acetaldehyde and acrolein were also abundant. Concentrations of carbonyl compounds had a tendency to be higher inland, particularly for glyoxal, methyl glyoxal, methyl vinyl ketone, metacrolein and pentanal. The observed increases indicate that carbonyls were produced by photochemical oxidation of biogenic hydrocarbons in aged air masses with coastal origin. Isoprene, monoterpenes and various carbonyls exhibited pronounced diurnal variations, which are explained on the basis of emissions from vegetation, oxidation pathways of biogenic hydrocarbons and meteorological conditions.

Sulphur and nitrogen compounds in variable marine/continental air masses at the southwest European coast

Measurements of atmospheric sulphur and nitrogen species were made on the west coast of Portugal, within the framework of BMCAPE project. Four research intensive campaigns took place between November 1993 and August 1994 and revealed pronounced seasonal cycles for DMS and MSA. Surprisingly high levels of DMS were detected during autumn (mean concentration: 776ngSm−3), possibly as a consequence of a later algae bloom or local marsh emissions. COS displayed a slight seasonal variation with mean concentrations ranging from 741 ng S m−3 in autumn up to 903 ng S m−3 in summer. On the basis of backward air mass trajectories and local meteorological data, samples were assigned into different classes of air masses. The lowest concentrations of SO2, nssSO42−, NH3, NH4+, HNO3, N03− and NO2 were found in air masses transported over the Atlantic Ocean and were about 3–10 times lower than those recorded in air masses from continental origin. Nevertheless, for many of the species, the mean concentrations in maritime air were still significantly higher than those previously recorded in remote marine sites, presumably owing to long-range transport of pollutants or contamination induced by mesoscale wind circulation.

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.

Cation export by overland flow in a recently burnt forest area in north-central Portugal.

The current fire regime in the Mediterranean Basin constitutes a serious threat to natural ecosystems because it drastically enhances surface runoff and soil erosion in the affected areas. Besides soil particles themselves, soil cations can be lost by fire-enhanced overland flow, increasing the risk of fertility loss of the typically shallow and nutrient poor Mediterranean soils. Although the importance of cations for land-use sustainability is widely recognized, cation losses by post-fire runoff have received little research attention. The present study aimed to address this research gap by assessing total exports of Na(+), K(+), Ca(2+) and Mg(2+) in a recently burnt forest area in north-central Portugal. These exports were compared for two types of planted forest (eucalypt vs. maritime pine plantations), two types of parent materials (schist vs. granite) and for two spatial scales (micro-plot vs. hill slope). The study sites were a eucalypt plantation on granite (BEG), a eucalypt plantation on schist (BES) and a maritime pine plantation on schist (BPS). Overland flow samples were collected during the first six months after the wildfire. Cation losses differed strikingly between the two forest types on schist, being higher at the eucalypt than pine site. This difference was evident at both spatial scales, and probably due to the extensive cover of a needle cast from the scorched pine crowns. The role of parent material in cation export was less straightforward as it varied with spatial scale. Cation losses were higher for the eucalypt plantation on schist than for that on granite at the micro-plot scale, whereas the reverse was observed at the hill slope scale. Finally, cation yields were higher at the micro-plot than slope scale, in agreement with the general notion of scaling-effect in runoff generation.

A one-year record of carbonaceous components and major ions in aerosols from an urban kerbside location in Oporto, Portugal

PM2.5 aerosol samples were collected from January 2013 to January 2014 on the kerbside of a major arterial route in the city of Oporto, Portugal, and later analyzed for carbonaceous fractions and water soluble ions. The average concentrations of organic carbon (OC), elemental carbon (EC) and water soluble organic carbon (WSOC) in the aerosol were 6.2μg/m(3), 5.0μg/m(3) and 3.8μg/m(3), respectively, and fit within the range of values that have been observed close to major roads in Europe, Asia and North America. On average, carbonaceous matter accounted for 56% of the gravimetrically measured PM2.5 mass. The three carbon fractions exhibited a similar seasonal variation, with high concentrations in late autumn and in winter, and low concentrations in spring. SO4(2-) was the dominant water soluble ion, followed by NO3(-), NH4(+), Cl(-), Na(+), K(+), oxalate, Ca(2+), Mg(2+), formate, methanesulfonate and acetate. Some of these ions exhibited a clear seasonal trend during the study period. The average OC/EC ratio for the entire set of samples was 1.28±0.61, which was consistent with a significant influence of vehicle exhaust emissions on aerosol composition. On the other hand, the average WSOC/OC ratio was 0.67±0.23, reflecting the influence of other emitting sources. WSOC was highly correlated with nssK(+), a tracer of biomass combustion, and was not correlated with nssSO4(2-), a species associated with secondary processes, suggesting that the main source of WSOC was biomass burning. Most of the SO4(2-) was anthropogenic in origin and was closely associated with NH4(+), pointing to the formation of secondary aerosols. Na(+), Cl(-) and methanesulfonate were clearly associated with marine sources while NO3(-) was related with combustion of both fossil and non-fossil fuels. Mixed sources explained the occurrence of the other water soluble ions.

LISBON AIR QUALITY - EVALUATING TRAFFIC HOT-SPOTS

This paper presents an air quality study in an urban traffic hot-spot in Lisbon, Portugal, by comparing the atmospheric pollutant concentrations obtained by a numerical model with measured values. Results indicate that the mean variation of particle and gaseous concentrations followed the traffic flow rate, evidencing the occurrence of PM10 concentrations greater than the respective air quality limit. SO2 and CO results fulfil the national legislation. The performed simulations showed that current methodologies for PM10 dispersion modelling allow to obtain acceptable results on air quality assessment within complex urban areas.

Impact of water quality on bacterioplankton assemblage along Cértima River Basin (central western Portugal) assessed by PCR–DGGE and multivariate analysis

The information on bacterial community composition (BCC) in Portuguese water bodies is very scarce. Cértima River (central western Portugal) is known to have high levels of pollution, namely organic. In the present work, the BCC from a set of 16 water samples collected from Cértima River Basin and its main tributaries was characterized using 16S rDNA–denaturing gradient gel electrophoresis, a culture-independent molecular approach. Molecular data were related to environmental parameters through multivariate analysis to investigate potential impact of water pollution along the river. Principal component analysis using environmental data showed a water quality gradient from more pristine waters (at the mountain tributaries) to waters with increasingly eutrophic potential (such as Fermentelos Lake). This gradient was mainly defined by factors such as organic and inorganic nutrient sources, electrical conductivity, hydrogen carbonate concentration, and pH. Molecular results showed variations in BCC along Cértima River Basin but in the main river section, a Bacteroidetes phylotype (Flavobacterium sp.) proved to be dominant throughout the river course. Multivariate analysis suggests that spatial variation of BCC along the Cértima River Basin depended mainly on parameters such as Chl a, total suspended solid (TSS), total organic carbon, electrical conductivity, and HCO