A four-year size-segregated characterization study of particles PM 10, PM 2.5 and PM 1 depending on air mass origin at Melpitz

Abstract

PM 10 measurements were started in November 1992 at Melpitz site. The mean PM 10 concentration in 1993 was 38 μg m −3 in the summer season (May until October) and about 44 μg m −3 in the winter season (November until April). The mean PM 10 level decreased until 1999 and varies now in ranges from 20–34 μg m −3 to 17–24 μg m −3 (minimum and maximum mean values for 1999–2008) in winter and summer seasons, respectively. High volume filter samples of particles PM 10, PM 2.5 and PM 1 were characterized for mass, water-soluble ions, organic and elemental carbon from 2004 until 2008. The percentage of PM 2.5 in PM 10 varies between summer (71.6%) and winter seasons (81.9%). Mean concentrations of PM 10, PM 2.5 and PM 1 in Melpitz were 20, 15, and 13 μg m −3 in 2004, 22, 18, and 13 μg m −3 in 2005, 24, 19, and 12 μg m −3 in 2006 and 22, 17, and 12 μg m −3 in 2007, respectively. In the four winters the rural background concentration PM 10 at Melpitz exceeded the daily 50 μg m −3 limit for Europe on 8, 8, 7 and 6 days, respectively. Findings for a simple two-sector-classification of the samples (May 2004 until April 2008) using 96-h backward trajectories for the identification of source regions are: Air masses were transported most of time (60%) from the western sector and secondly (17%) from the eastern sector. The lowest daily mean mass concentration PM 10 were found during western inflow in summer (17 μg m −3) containing low amounts of sulphate (2.4 μg m −3), nitrate (1.7 μg m −3), ammonium (1.1 μg m −3) and TC (3.7 μg m −3). In opposite the highest mean mass concentration PM 10 was found during eastern inflow in winter (35 μg m −3) with high amounts of sulphate (6.1 μg m −3), nitrate (5.4 μg m −3), ammonium (3.8 μg m −3) and TC (9.4 μg m −3). An estimation of secondary formed OC (SOA) shows 0.8–0.9 μg m −3 for air masses from West and 2.1–2.2 μg m −3 from East. The seasonal difference can be neglected. The half-hourly measurements of the particle mass concentration PM 10 evaluated as mean daily courses using a TEOM ® show low values (14–21 μg m −3) in summer and winter for air masses transported from West and the highest concentrations (31–38 μg m −3) in winter for air masses from East. The results demonstrate the influence of meteorological parameters on long-range transport, secondary particle mass formation and re-emission which modify mass concentration and composition of PM 10, PM 2.5 and PM 1. Melpitz site is located in the East of Germany faraway from strong local anthropogenic emissions (rural background). Therefore, this site is suitable for investigation of the influence of long-range transport of air pollution in continental air masses from the East with source regions inside and outside of the European Union.