Publications (8)3.46 Total impact
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Article: Urban NH3 levels and sources in a Mediterranean environment
Atmospheric Environment. 01/2012; -
Book: Reporting on natural events in the EU Member States under Directive 2008/50/EC: years 2008-2009.
12/2011; -
Article: Size and time-resolved roadside enrichment of atmospheric particulate pollutants
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ABSTRACT: Size and time-resolved roadside enrichments of atmospheric particulate pollutants in PM10 were detected and quantified in a Mediterranean urban environment (Barcelona, Spain). Simultaneous data from one urban background (UB), one traffic (T) and one heavy traffic (HT) location were analysed, and roadside PM10 enrichments (RE) in a number of elements arising from vehicular emissions were calculated. Tracers of primary traffic emissions (EC, Fe, Ba, Cu, Sb, Cr, Sn) showed the largest REs (>70%). Other traffic tracers (Zr, Cd) showed lower but still consistent REs (25–40%), similar to those obtained for mineral matter resulting from road dust resuspension (Ca, La, Ce, Ti, Ga, Sr, 30–40%). The sum of primary and secondary organic carbon showed a RE of 41%, with contributions of secondary OC (SOC) to total OC ranging from 46% at the HT site, 63% at the T site, and 78% in the UB. Finally, other trace elements (As, Co, Bi) showed unexpected but consistent roadside enrichments (23% up to 69%), suggesting a link to traffic emissions even though the emission process is unclear. Hourly-resolved PM speciation data proved to be a highly resourceful tool to determine the source origin of atmospheric pollutants in urban environments. At the HT site, up to 62% of fine Mn was attributable to industrial plumes, whereas coarse Mn levels were mainly attributed to traffic. Similarly, even though Zn showed on average no roadside enrichment and thus was classified as industrial, the hourly-resolved data proved that at least 15% of coarse Zn may be attributed to road traffic emissions. In addition, our results indicate that secondary nitrate formation occurs within the city-scale, even in the absence of long atmospheric residence times or long-range atmospheric transport processes.Atmospheric Chemistry and Physics Discussions. 01/2011; -
Article: On the quantification of atmospheric carbonate carbon by thermal/optical analysis protocols
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ABSTRACT: Carbonaceous species, usually classified into two categories, organic carbon (OC) and elemental carbon (EC), constitute an important component of the atmospheric aerosol. Carbonate carbon (CC), or inorganic carbon, another constituent of carbonaceous material, is often not considered in many atmospheric chemistry studies. The reason for this may be its low contribution to fine particle mass in most areas studied, along with the difficulties in its analytical determination in atmospheric aerosols. The objective of this study was the quantification of atmospheric carbonate concentrations using the thermal optical transmittance method (Sunset Laboratory, Inc.). Three different temperature protocols (two modified NIOSH protocols and the EUSAAR-2 protocol) were tested on filter samples containing known amounts of CC. Moreover, the performance of the two most widely used protocols across European countries (NIOSH and EUSAAR-2) was also checked on two different instruments namely the semi-continuous OCEC analyzer and the laboratory OCEC analyzer. NIOSH-840 thermal protocol (NIOSH protocol with a maximum temperature of 840 °C in the He-mode) can be used for the detection and quantification of atmospheric carbonate concentrations. CC was determined in ambient PM10 and PM2.5 samples From Athens and Barcelona by using the NIOSH-840 thermal protocol. The results confirm that in South European countries CC may constitute a significant fraction of carbonaceous aerosols (~15%), thus it should not be neglected. However, the NIOSH-840 protocol seems to overestimate the OC concentrations when compared to the EUSAAR-2 protocol. The results suggest that during dust episodes, common for the Southern Europe, the analytical laboratories could use the NIOSH-840 protocol as a suitable method for the carbonate determination and manually integrate the sharp peak that appears in the maximum temperature step in the inert mode. Afterwards, carbonate should be evaporated by a fumigation method and one could then apply the EUSAAR-2 protocol for the precise determination of OC and EC fractions.Atmospheric Measurement Techniques Discussions. 01/2010; -
Article: Ultrafine particle formation in the inland sea breeze airflow in Southwest Europe
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ABSTRACT: Studies on ultrafine particles (diameter < 100nm) and air quality have mostly focused on vehicle exhaust emissions and on new particle formation in "clean" ambient air. Here we present a study focused on the processes contributing to ultrafine particle concentrations in a city (Huelva, SW Spain) placed close to a coastal area where significant anthropogenic emissions of aerosol precursors occur. The overall data analysis shows that two processes predominantly contribute to the number of particles coarser than 2.5 nm: vehicle exhaust emissions and new particle formation due to photo-chemical activity. As typically occurs in urban areas, vehicle exhaust emissions result in high concentrations of black carbon (BC) and particles coarser than 2.5 nm (N) during the morning rush hours. The highest N concentrations were recorded during the 11:00–17:00 h period, under the sea breeze regime, when low BC concentrations were registered and photochemical activity resulted in high O3 levels and in new particle formation in the aerosol precursors' rich inland airflow. In this period, it is estimated that about 80% of the number of particles are linked to sulfur dioxide emissions. The contributions to N of "carbonaceous material and those compounds nucleating/condensing immediately after emission" and of the "new particle formation processes in air masses rich gaseous precursors (e.g. SO2)" were estimated by means of a relatively novel method based on simultaneous measurements of BC and N. A comparison with two recent studies suggests that the daily cycles of "new particle formation" during the inland sea breeze is blowing period seem to be a feature of ultrafine particles in coastal areas of South-west Europe.Atmospheric Chemistry and Physics. 01/2010; -
Article: Oxidative properties of ambient PM2.5 and elemental composition: Heterogeneous associations in 19 European cities
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ABSTRACT: We assessed the extent to which constituents of PM2.5 (transition metals, sodium, chloride) contribute to the ability to generate hydroxyl radicals (OH) in vitro in PM2.5 sampled at 20 locations in 19 European centres participating in the European Community Respiratory Health Survey. PM2.5 samples (n = 716) were collected on filters over one year and the oxidative activity of particle suspensions obtained from these filters was then assessed by measuring their ability to generate OH in the presence of hydrogen peroxide. Associations between OH formation and the studied PM constituents were heterogeneous. The total explained variance ranged from 85% in Norwich to only 6% in Albacete. Among the 20 centres, 15 showed positive correlations between one or more of the measured transition metals (copper, iron, manganese, lead, vanadium and titanium) and OH formation. In 9 of 20 centres OH formation was negatively associated with chloride, and in 3 centres with sodium. Across 19 European cities, elements which explained the largest variations in OH formation were chloride, iron and sodium.Atmospheric Environment 01/2009; 43(30):4595-4602. · 3.46 Impact Factor -
Article: Toward a standardised thermal-optical protocol for measuring atmospheric organic and elemental carbon: the EUSAAR protocol
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ABSTRACT: Thermal-optical analysis is a conventional method for determining the carbonaceous aerosol fraction and for classifying it into organic carbon, OC, and elemental carbon, EC. Unfortunately, the different thermal evolution protocols in use can result in a wide elemental carbon-to-total carbon variation by up to a factor of five. In Europe, there is currently no standard procedure for determining the carbonaceous aerosol fraction which implies that data from different laboratories at various sites are of unknown accuracy and cannot be considered comparable. In the framework of the EU-project EUSAAR (European Supersites for Atmospheric Aerosol Research), a comprehensive study has been carried out to identify the causes of differences in the EC measured using different thermal evolution protocols; thereby the major positive and negative biases affecting thermal-optical analysis have been isolated and minimised to define an optimised protocol suitable for European aerosols. Our approach to improve the accuracy of the discrimination between OC and EC was essentially based on four goals. Firstly, charring corrections rely on faulty assumptions – e.g. pyrolytic carbon is considered to evolve completely before native EC throughout the analysis –, thus we have reduced pyrolysis to a minimum by favoring volatilisation of OC. Secondly, we have minimised the potential negative bias in EC determination due to early evolution of light absorbing carbon species at higher temperatures in the He-mode, including both native EC and combinations of native EC and pyrolytic carbon potentially with different specific cross section values. Thirdly, we have minimised the potential positive bias in EC determination resulting from the incomplete evolution of OC during the He-mode which then evolves during the He/O2-mode, potentially after the split point. Finally, we have minimised the uncertainty due to the position of the OC/EC split point on the FID response profile by introducing multiple desorption steps in the He/O2-mode. Based on different types of carbonaceous PM encountered across Europe, we have defined an optimised thermal evolution protocol, the EUSAAR_2 protocol, as follows: step 1 in He, 200°C for 120 s; step 2 in He 300°C for 150 s; step 3 in He 450°C for 180 s; step 4 in He 650°C for 180 s. For steps 1–4 in He/O2, the conditions are 500°C for 120 s, 550°C for 120 s, 700°C for 70 s, and 850°C for 80 s, respectively.Atmospheric Measurement Techniques Discussions. 01/2009; -
Article: PM speciation and sources in Mexico during the MILAGRO-2006 Campaign
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ABSTRACT: Levels of PM10, PM2.5 and PM1 and chemical speciation of PM10 and PM2.5 were measured during the MILAGRO campaign (1 to 31 March 2006, but extended in some cases until 6 April) at four urban, one suburban, two rural, two rural background sites with different degree of industrial influence in the Mexico City Metropolitan Area (MCMA) and adjacent regions. PM10 and PM2.5 daily levels varied between 50–56 μg/m³ and 24–46 μg/m³ at the urban sites, 22–35 μg/m³ and 13–25 μg/m³ at the rural sites, and 75 μg/m³ and 31 $mu $g/m³ at the industrial hotspot, respectively; lower than those recorded at some Asian mega-cities and similar to those recorded at other South American cities. At the urban sites, hourly PM2.5 and PM1 concentrations showed a marked impact of road traffic emissions (at rush hours), with levels of coarse PM remaining elevated during daytime. At the suburban and rural sites, different PM daily patterns were registered according to the influence of the pollution plume from MCMA and also on local soil resuspension. The speciation studies showed that mineral matter accounted for 25–27% of bulk PM10 at the urban sites and a higher proportion (up to 43%) at the suburban and rural sites. This pattern is repeated in PM2.5, with 15% at urban and 28% at suburban and rural sites. Carbonaceous compounds accounted for a similar proportion at the urban sites (24–32% in PM10, and up to 37% in PM2.5), markedly reduced at the suburban and rural sites (17% in PM10, and 23–38% in PM2.5). The secondary inorganic aerosols accounted for 10–20% of bulk PM10 at urban, suburban, rural and industrial sites, with a higher proportion (40%) at the industrial background site. A relatively high proportion of nitrate in rural sites was present in the coarse fraction. Typically anthropogenic elements (As, Cr, Zn, Cu, Pb, Sn, Sb, Ba, among others) showed considerably high levels at the urban sites; however levels of particulate Hg and crustal trace elements (Rb, Ti, La, Sc, Ga) were generally higher at the suburban site. Principal component analysis identified three common factors: crustal, regional background and road traffic. Moreover, some specific factors were obtained for each site.Atmospheric Chemistry and Physics Discussions. 01/2007;
