Suchergebnisse

A long-term series (2001–2008) of chemical analysis of atmospheric particulate matter (PM10 and PM2.5) collected in the city of Huelva (SW Spain) is considered in this study. The impact of emission plumes from one of the largest Cu-smelters in the world on air quality in the city of Huelva is evidenced by the high daily and hourly levels of As, other potentially toxic elements (e.g. Cu, Zn, Cd, Se, Bi, and Pb) in particulate matter, as well as the high levels of some gaseous pollutants (NO2 and SO2). Mean arsenic levels in the PM10 fraction were higher than the target value set by European Directive 2004/ 107/EC (6 ngAs m 3) for 1st January 2013. Hourly peak concentrations of As and other metals and elements (Zn, Cu, P and Se) analyzed by PIXE can reach maximum hourly levels as high as 326 ngAs m 3, 506 ngZn m 3, 345 ngCu m 3, 778 ngP m 3 and 12 ngSe m 3. The contribution of Cu-smelter emissions to ambient PM is quantified on an annual basis in 2.0–6.7 mg m 3 and 1.8–4.2 mg m 3 for PM10 and PM2.5, respectively. High resolution outputs of the HYSPLIT dispersion model show the geographical distribution of the As ambient levels into the emission plume, suggesting that the working regime of the Cu-smelter factory and the sea breeze circulation are the main factors controlling the impact of the Cu-smelter on the air quality of the city. The results of this work improve our understanding of the behaviour of industrial emission plumes and their impact on air quality of a city, where the population might be exposed to very high ambient concentrations of toxic metals during a few hours. ; This work was developed within the framework of project CGL2005-05693-C03-01 and was funded by the Spanish Ministry of Science and Innovation, and Project CS2007-0067 GRACCIE by the Spanish Ministry of Science and Innovation. Also, we would like to thank the Autonomous Government of Andalusia for financing this work (Projects 2007-RNM 02729 and RNM-03125). We would like to thank the NOAA Air Resources Laboratory (ARL) for providing the HYSPLIT transport and dispersion model. Thanks also go to the NASA/Goddard Space Flight Center, Laboratory for Atmospheres, Greenbelt (MD, USA), the Atmospheric Modeling and Weather Forecasting Group from the University of Athens and NASA's SeaWIFS Project for the valuable information supplied by the TOMS and SKIRON aerosol maps and satellite images.

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.