Contributions of natural sources to high PM10PM10 and PM2.5PM2.5 events in the eastern Mediterranean

In total 562 daily PM10PM10 and PM2.5PM2.5 samples were collected from April 2001 to April 2002 at a rural site (Erdemli) located on the coast of the Eastern Mediterranean. The annual mean PM10PM10 and PM2.5PM2.5 levels were 36.4±27.836.4±27.8 and 9.7±5.9μgm-3, respectively. PM10PM10 and PM2.5PM2.5 concentrations indicated orders of magnitude change from day to day (PM10=2–326μgm-3; PM2.5=0.5–28μgm-3). The highest levels of PM10PM10 were observed during the transition period (March, April and May) due to mineral dust transported from North Africa and during winter due to sea spray generation. However, PM2.5PM2.5 levels exhibited higher concentrations during summer resulting from an enhanced production of secondary aerosols. The PM2.5/PM10PM2.5/PM10 ratio (0.25) and categorization of air mass back trajectories indicated that PM10PM10 at the study area is dominated by primary aerosol emissions (mineral dust particles from the Saharan Desert and sea salt particles from the Mediterranean Sea itself). During the whole sampling period 28 and 51 events exceeded the recommended maximum values of 50 and 15μgm-3 for PM10PM10 and PM2.5PM2.5, respectively. Source apportionment analysis indicated that PM10PM10 exceedances originated as a consequence of natural events (mineral dust ∼40%∼40%; sea salt ∼50%∼50%) whereas PM2.5PM2.5 exceedances were accounted primarily by pollution events (in 90% of the cases).