Rainwater composition over a rural area with special emphasis on the size distribution of insoluble particulate matter

The rainwater composition in the vicinity of Mainz, FRG, has been investigated with special emphasis on insoluble constituents. The number size distribution was determined in the range from 0.1 m up to 100 m radius. For particles with r>0.5 m radius the shape of the size distribution of insoluble particles in rain follows the shape of the average urban and rural aerosol. In this particular size range no major size selective removal processes could be seen. For r<0.5 m the number size distribution tends to flatten compared to the average aerosol. This might be the indication of a size selective removal process (Greenfield Gap).