Deposition and retention of 141Ce and 134Cs aerosols on cool desert vegetation.

Abstract

Deposition velocities and retention times were obtained for submicron aerosols of 141Ce and 13l4Cs deposited on two cool desert plant species, big sagebrush (Artemisia tridentata) and bottlebrush grass (Sitanion hystrix). Mean deposition velocities for sagebrush were 0.18 cm/s (141Ce) and 0.13 cm/s (134Cs). Mean deposition velocities for grass were 0.022 (141Ce) and 0.023 cm/s (134Cs). Species differences were significant (p less than 0.05), however, nuclide differences were not significant. The loss of activity on the vegetation consisted of two components. A rapid initial loss was found with effective half-times of approx. 1 d (1-8 d for 141Ce and 0.6 d for 134Cs) on sagebrush and approx. 2 d (2.8 d for 141Ce and 2.3 d for 134Cs) on grass. This was followed by a slower, long-term loss with effective half-times ranging from 11 d for 141Ce and 15 d for 134Cs on sagebrush to 9 d for 141 Ce and 11 d for 134Cs on grass.