The relationship between tritiated water activities in air, vegetation and soil under steady-state conditions.

Abstract

Radiation dose estimates to man from chronic, atmospheric releases of tritiated water (HTO) are routinely calculated under the assumption that the specific activity of /sup 3/H in the water of exposed vegetation is 50% of the specific activity of water in the air. The specific activity, as used in this paper, is the activity of tritium (curies) in a given mass of a compound (grams of water). A related subject is the ratio of the specific activity between the soil-water and the water in leaves when the source of HTO is in the soil. In this paper a simple model will be used to describe the relationship of the steady-state specific activity of HTO in leaves as it is affected by the specific activity of HTO in the soil-water and atmospheric moisture. The results indicate the specific activity ratio for either atmospheric or soil releases can vary greatly depending on the r.h. and other factors which affect the movement of water through the vegetation.