PM10 and PM2.5 Levels in the Eastern Mediterranean (Akrotiri Research Station, Crete, Greece)

Abstract

Particulate matter measurements (PM10, PM2.5) using a beta radiation attenuation monitor were performed at the Akrotiri research station (May 2003–March 2006) on the island of Crete (Greece). The mean PM10 concentration during the measuring period (05/02/03–03/09/04) was equal to 35.0 ± 17.7 μg/m3 whereas the mean PM2.5 concentration (03/10/04–04/02/06) was equal to 25.4 ± 16.5 μg/m3. The aerosol concentration at the Akrotiri station shows a large variability during the year. Mean concentrations of particulate matter undergo a seasonal change characterised by higher concentrations during summer [PM10, 38.7 ± 10.8 μg/m3 (2003); PM2.5, 27.9 ± 8.7 μg/m3 (2004) and 27.8 ± 9.7 μg/m3 (2005)] and lower concentrations during winter [PM10, 28.7 ± 22.5 μg/m3 (2003/2004); PM2.5, 21.0 ± 13.0 μg/m3 (2004/2005) and 21.4 ± 21.9 μg/m3 (2005/2006)]. Comparative measurements of the PM10 concentration between the beta radiation attenuation monitor, a standardized low volume gravimetric reference sampler and a low volume sequential particulate sampler showed that PM10 concentrations measured by the beta radiation attenuation monitor were higher than values given by the gravimetric samplers (mean ratio 1.17 ± 0.11 and 1.21 ± 0.08, respectively). Statistical and back trajectory analysis showed that elevated PM concentrations (PM10, 93.8 ± 49.1 μg/m3; PM2.5: 102.9 ± 59.9 μg/m3) are associated to desert dust events. In addition regional transport contributes significantly to the aerosol concentration levels whereas low aerosol concentrations were observed during storm episodes.