An analysis of vegetation interception data pertaining to close-in weapons test fallout.

This paper reports an analysis of literature data pertaining to the fraction of particles resulting from regional weapons fallout intercepted by vegetation. A simple model for the interception parameter, alpha, was developed that predicted an increasing interception fraction with increasing distance from detonation site. The predicted values of alpha close to the detonation site are much smaller than most accepted values that pertain to aerosols and gases. The apparent dependence of the interception parameter on distance is believed to partially reflect the changes of the particle-size distribution of the fallout cloud with the time aloft and the ability of vegetation surfaces to better retain particles of small size. The validity of a set of predicted values was tested using an assessment model and literature data of radioiodine concentrations in milk following a nuclear test.