99/03222 Providing for transmission in times of scarcity: an ISO cannot do it all

Abstract

For a period of 10 years (1993–2002) daily PM10 samples were collected on quartz filters by a PM10 high-volume sampler (Sierra-Andersen). In addition, since 1995 weekly filter samples of PM10, PM2.5 and since 1999 PM1 filter samples were collected by a low-volume sampler (‘Partisol 2000’, Rupprecht and Patashnik) on Teflon filters at the IfT research station Melpitz (12°56′E, 51°32′N) located in the downwind plume of the Leipzig conurbation in central Europe. The resulting time series were compared based on weekly means (particle mass r=0.90, NO3− mass r=0.94, SO42− mass r=0.92 and NH4+ mass r=0.90) and integrated in a historical mass trend (since 1983) for Saxony. In the data (1983–1990) the total particle mass concentration (TSP) shows big scatter with a mean of about 75 μg m−3. Since the re-unification of Germany in 1990 a decrease in PM10-concentration to a mean of 20–30 μg m−3 is observed. The mass concentration of PM10 shows a decreasing trend from a yearly maximum value in 1996 (39 μg m−3) to a mean value for 1999–2002 of about 23 μg m−3. The highest values were observed just before the winter of 1997/1998. No pronounced concentration peaks were found in the following winters. Reasons are the rapid modernization of power plants and the decreasing number of coal heating systems in the Leipzig conurbation and its surroundings as well as a lack of strong inversion situations. The NO3−/SO42−-ratio shows a typical increasing trend caused by the decreasing SO42−-mass concentration in PM10 which originates in the dramatic decrease of SO2 concentrations. From the weekly low-volume samples the mass contributions of PM1, PM2.5–PM1 and PM10–PM2.5 to PM10 (100%) for 1999–2002 were about 61%, 20% and 19% for winter and 42%, 13% and 45% for summer, respectively. Most of the PM2.5 mass is PM1. During summers the weekly ratio of coarse particles (PM10–PM2.5) to fine particles (PM2.5) was higher (about 1.4) than the winter value (about 0.3). An additional impactor for PM1 at the low-volume sampler contains a quartz filter for the weekly determination of organic carbon (OC) and elemental carbon (EC) using a thermographic method. About 30% of the PM1 mass is total carbon (TC=OC+EC). The percentage of EC to TC seems to be increasing in the summer from 1999 to 2002.