Ultrafine particle formation in the inland sea breeze airflow in Southwest Europe
1University of Huelva, Joint Research Unit to CSIC "Atmospheric Pollution", Campus El Carmen, 21071 Huelva, Spain
2Estación Experimental del Zaidín, CSIC, C/ Profesor Albareda 1, 18008 Granada, Spain
3Izaña Atmospheric Research Centre, AEMET Joint Research Unit to CSIC "Studies on Atmospheric Pollution", La Marina 20, planta 6, Santa Cruz de Tenerife, 38071, Canary Islands, Spain
4Institute of Environmental Assessment and Water Research (IDǼA), CSIC, Jordi Girona, 18–26, 08034, Barcelona, Spain
Abstract. Studies on ultrafine particles and air quality have mostly focused on vehicle exhaust emissions and on new particle formation in "clean" ambient air. Here we present a study of the processes contributing to ultrafine particle concentrations in an urban coastal area (Huelva, SW Spain) 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 11–17 h period, under the sea breeze regime, when photochemical activity resulted in high O3 levels and 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 period when the inland sea breeze is blowing period seem to be a feature of ultrafine particles in coastal areas of South-west Europe.