Size distribution measurements of the natural radioactivity in aerosols and its application as a tracer for dry deposition

The natural radioactivity in the ground-level air can be used as a tracer for dry deposition processes. The main factors influencing the deposition velocity are the particle size and the wind speed. Both show a high degree of variability in the real canopy. We have developed and tested a simple device to sample particles in four size classes. The inertial impactor and filter substrates are suitable for alpha-spectroscopy and XRFA after a sampling time of only about 2 hours. (Author)