Partitioning of major and trace components in PM 10–PM 2.5–PM 1 at an urban site in Southern Europe

Abstract

Partitioning of major and trace components in PM 10–PM 2.5–PM 1 at an urban site in Barcelona (Spain) in the Western Mediterranean was studied in the period 2005–2006. Particular attention was paid to the partitioning of mineral matter and to the evidence of possible interactions of mineral matter with other pollutants (gaseous pollutants and secondary PM). The results showed a high contribution of mineral matter (mainly anthropogenic, but sporadically associated with African dust outbreaks) in levels of both PM 10 and PM 2.5. A high proportion of nitrate was also present in the coarse fractions as a result of the interaction of mineral matter with gaseous pollutants. As at most urban sites in Europe, sulphate and carbonaceous aerosols are mainly present in the finer PM fractions. The PM 1–2.5 fraction resembled that of PM 10 in composition. The chemically unaccounted fraction (mostly bounded water) had also a fine grain size, probably because of the fine size of the hygroscopic aerosol components. The data series follow an increasing trend for PM 1 levels (and less clearly for PM 2.5) from 1999 to 2006, whereas no trend is observed for PM 10. The contributions of African dust and regional soil resuspension to the annual PM 10 levels has been estimated in around 1–2 and 2–3 μg m −3 in this part of Spain. The African dust outbreaks accounted for around 15–20 exceedances of the European daily PM 10 limit value. Finally, the data obtained were compared with data from selected European sites to highlight major differences in levels and speciation of PM.