Resuspension of coarse particles in the region of Chernobyl

Measurements of resuspension into air in the coarse particle range (> 10 mu m in aerodynamic diameter) were performed as part of a field measurement e xperiment at four sites around Chernobyl during wind-driven and anthropogen ic enhanced resuspension (agricultural activities). Caesium-137 was used to quantify the magnitude of resuspension. The mean resuspension factor of co arse particles was between 1 x 10(-10) and 6 x 10(-10) m(-1) for wind-drive n resuspension. During agricultural activities, the resuspension increased by up to three orders of magnitude. Coarse particles comprised about one-th ird of the total amount of resuspended Caesium-137. The activity size distr ibution of Caesium-137 was not uniform in the coarse particle range: approx imately 44% of the activity was found in the range 10-20 mu m aerodynamic d iameter. The determination of the number concentration of particles > 20 mu m aerodynamic diameter showed a linear relation between particle number an d activity: the mean activity per particle was 0.75 +/- 0.15 mu Bq at the s ite Novozybkov, Russia. The resuspension factor was found to decrease expon entially with increasing relative soil moisture content. At higher soil hum idity, the portion of coarse particles of the total resuspended activity wa s larger. (C) 1999 Elsevier Science Ltd. All rights reserved.