Suchergebnisse

17 páginas, 8 figuras. ; PM1 (particulate matter with an aerodynamic diameter <1 µm) non-refractory components and black carbon were measured continuously together with additional air quality and atmospheric parameters at an urban background site in Barcelona, Spain, during March 2009 (campaign DAURE, Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). Positive matrix factorization (PMF) was conducted on the organic aerosol (OA) data matrix measured by an aerosol mass spectrometer, on both unit mass (UMR) and high resolution (HR) data. Five factors or sources could be identified: LV-OOA (low-volatility oxygenated OA), related to regional, aged secondary OA; SVOOA (semi-volatile oxygenated OA), a fresher oxygenated OA; HOA (hydrocarbon-like OA, related to traffic emissions); BBOA (biomass burning OA) from domestic heating or agricultural biomass burning activities; and COA (cooking OA). LV-OOA contributed 28 % to OA, SV-OOA 27 %, COA 17 %, HOA 16 %, and BBOA 11 %. The COA HR spectrum contained substantial signal from oxygenated ions (O:C: 0.21) whereas the HR HOA spectrum had almost exclusively contributions from chemically reduced ions (O:C: 0.03). If we assume that the carbon in HOA is fossil while that in COA and BBOA is modern, primary OA in Barcelona contains a surprisingly high fraction (59 %) of non-fossil carbon. This paper presents a method for estimating cooking organic aerosol in ambient datasets based on the fractions of organic mass fragments at m/z 55 and 57: their data points fall into a V-shape in a scatter plot, with strongly influenced HOA data aligned to the right arm and strongly influenced COA data points aligned to the left arm. HR data show that this differentiation is mainly driven by the oxygen-containing ions C3H3O + and C3H5O + , even though their contributions to m/z 55 and 57 are low compared to the reduced ions C4H + 7 and C4H + 9 . A simple estimation method based on the markers m/z 55, 57, and 44 is developed here and allows for a first-order-estimation of COA in urban air. This study emphasizes the importance of cooking activities for ambient air quality and confirms the importance of chemical composition measurements with a high mass and time resolution. ; We thank the organizers of the DAURE project, including Mar Viana and everybody else at ICTJA for their work and help. We acknowledge the CCES project IMBALANCE and the EU-FP7 project EUCAARI for financial support and 'Accion Complementaria DAURE' from the Spanish Ministry of Science and Innovation (CGL2007-30502-E/CLI) for infrastructure support. P. F. DeCarlo is grateful for the postdoctoral support from the US-NSF (IRFP# 0701013). J. Penuelas and R. Seco were sup- ˜ ported by the Spanish Government projects CGL2010-17172 and Consolider Ingenio Montes CSD2008-00040, and by a postdoctoral grant from Fundacion Ram ´ on Areces to R. Seco. The National ´ Center for Atmospheric Research is sponsored by the National Science Foundation. J. L. Jimenez was supported by NSF ATM- 0919189 and DOE (BER, ASR program) DE-FG02-11ER65293. ; Peer reviewed

In many large cities of Europe standard air quality limit values of particulate matter (PM) are exceeded. Emissions from road traffic and biomass burning are frequently reported to be the major causes. As a consequence of these exceedances a large number of air quality plans, most of them focusing on traffic emissions reductions, have been implemented in the last decade. In spite of this implementation, a number of cities did not record a decrease of PM levels. Thus, is the efficiency of air quality plans overestimated? Do the road traffic emissions contribute less than expected to ambient air PM levels in urban areas? Or do we need a more specific metric to evaluate the impact of the above emissions on the levels of urban aerosols? This study shows the results of the interpretation of the 2009 variability of levels of PM, Black Carbon (BC), aerosol number concentration (N) and a number of gaseous pollutants in seven selected urban areas covering road traffic, urban background, urban-industrial, and urban-shipping environments from southern, central and northern Europe. The results showed that variations of PM and N levels do not always reflect the variation of the impact of road traffic emissions on urban aerosols. However, BC levels vary proportionally with those of traffic related gaseous pollutants, such as CO, NO2 and NO. Due to this high correlation, one may suppose that monitoring the levels of these gaseous pollutants would be enough to extrapolate exposure to traffic-derived BC levels. However, the BC/CO, BC/NO2 and BC/NO ratios vary widely among the cities studied, as a function of distance to traffic emissions, vehicle fleet composition and the influence of other emission sources such as biomass burning. Thus, levels of BC should be measured at air quality monitoring sites. During morning traffic rush hours, a narrow variation in the N/BC ratio was evidenced, but a wide variation of this ratio was determined for the noon period. Although in central and northern Europe N and BC levels tend to vary simultaneously, not only during the traffic rush hours but also during the whole day, in urban background stations in southern Europe maximum N levels coinciding with minimum BC levels are recorded at midday in all seasons. These N maxima recorded in southern European urban background environments are attributed to midday nucleation episodes occurring when gaseous pollutants are diluted and maximum insolation and O3 levels occur. The occurrence of SO2 peaks may also contribute to the occurrence of midday nucleation bursts in specific industrial or shipping-influenced areas, although at several central European sites similar levels of SO2 are recorded without yielding nucleation episodes. Accordingly, it is clearly evidenced that N variability in different European urban environments is not equally influenced by the same emission sources and atmospheric processes. We conclude that N variability does not always reflect the impact of road traffic on air quality, whereas BC is a more consistent tracer of such an influence. However, N should be measured since ultrafine particles (<100 nm) may have large impacts on human health. The combination of PM10 and BC monitoring in urban areas potentially constitutes a useful approach for air quality monitoring. BC is mostly governed by vehicle exhaust emissions, while PM10 concentrations at these sites are also governed by non-exhaust particulate emissions resuspended by traffic, by midday atmospheric dilution and by other non-traffic emissions. ; This work was funded by the Spanish Ministry of Science and Innovation (VAMOS CGL2010-19464/CLI; DAURE CGL2007-30502-E/CLI, GRACCIE-CSD2007-00067), Department of Inovation, Science and Enterprise of the Andalusian Autonomous Government (AER-REG-P07-RNM-03125), the Ministry of the Environment and Rural and Marine Affairs, and the 7th FP from the EC project SAPUSS (Marie Curie intra-European Fellowship). The authors acknowledge the Departament de Territori i Sostenibilitat from Generalitat de Catalunya, Gobierno de Canarias and Junta de Andalucia (Spain), DEFRA (UK) and the Swiss Federal Office for the Environment (FOEN) for providing the data.

We interpret here the variability of levels of carbonaceous aerosols based on a 12 yr database from 78 monitoring stations across Spain specially compiled for this article. Data did not evidence any spatial trends of carbonaceous aerosols across the country. Conversely, results show marked differences in average concentrations from the cleanest, most remote sites (around 1 μg m−3 of non-mineral carbon (nmC), mostly made of organic carbon (OC) with very little elemental carbon (EC), around 0.1 μg m−3; OC / EC = 12–15), to the highly polluted major cities (8–10 μg m−3 of nmC; 3–4 μg m−3 of EC; 4–5 μg m−3 of OC; OC / EC = 1–2). ; This study was supported by the Ministry of Agriculture, Food and the Environment of Spain, the Ministry of Economy and Competitivity (MINECO) of Spain and FEDER funds under the projects VAMOS (CGL2010-19464/CLI), PRISMA (CGL2012-39623-C02-01), GRACCIE (CSD 2007- 00067), POLLINDUST (CGL2011-26259) and UHU (CGL2011- 28025); and by AGAUR-Generalitat de Catalunya (2009 SGR 00008) and LIFE + AIRUSE (LIFE11-ENV/ES/000584). The Montseny site forms part of the ACTRIS network (European Union Seventh Framework Programme (FP7/2007-2013) project no. 262254), formerly EUSAAR (EUSAAR R113-CT-2006-026140). Funding was also received for the Andalucía sites from projects 2007-RNM027329 and 2011-RNM7800 (Department of Innovation Science and Enterprise, Andalusia Autonomous Government).

We interpret here the variability of levels of carbonaceous aerosols based on a 12 yr database from 78 monitoring stations across Spain specially compiled for this article. Data did not evidence any spatial trends of carbonaceous aerosols across the country. Conversely, results show marked differences in average concentrations from the cleanest, most remote sites (around 1 μg m−3 of non-mineral carbon (nmC), mostly made of organic carbon (OC) with very little elemental carbon (EC), around 0.1 μg m−3; OC / EC = 12–15), to the highly polluted major cities (8–10 μg m−3 of nmC; 3–4 μg m−3 of EC; 4–5 μg m−3 of OC; OC / EC = 1–2). ; This study was supported by the Ministry of Agriculture, Food and the Environment of Spain, the Ministry of Economy and Competitivity (MINECO) of Spain and FEDER funds under the projects VAMOS (CGL2010-19464/CLI), PRISMA (CGL2012-39623-C02-01), GRACCIE (CSD 2007- 00067), POLLINDUST (CGL2011-26259) and UHU (CGL2011- 28025); and by AGAUR-Generalitat de Catalunya (2009 SGR 00008) and LIFE + AIRUSE (LIFE11-ENV/ES/000584). The Montseny site forms part of the ACTRIS network (European Union Seventh Framework Programme (FP7/2007-2013) project no. 262254), formerly EUSAAR (EUSAAR R113-CT-2006-026140). Funding was also received for the Andalucía sites from projects 2007-RNM027329 and 2011-RNM7800 (Department of Innovation Science and Enterprise, Andalusia Autonomous Government).