Measurements of the Deposition of Iodine Onto Vegetation and of the Biological Half-life of Iodine on Vegetation

Publisher Website
Google Scholar
Abstract
The deposition velocity of elemental I onto vegetation, measured by field experiments at the Juelich Nuclear Research Center, can be described by a semi-empirical equation as proportional to the dry weight of vegetation per unit area, to the relative atmospheric humidity, to the friction velocity and to a biological quality factor. The fallout deposition onto moist grass surfaces is greater by more than a factor of 2 than the deposition onto dry grass surfaces. On clover, the deposition of elemental I is greater by about a factor of 2 than onto grass. The deposition velocity of elemental I onto dry grass surfaces, averaged over the grazing period, was estimated to be 2 cm/s in West Germany. Taking into account that the surface of the vegetation is periodically moist because of dew and rain, the average value of the deposition is increased to about 3 cm/s. The deposition velocity of aerosols is lower by about a factor of 20 than that of elemental I. The deposition velocity of methyl iodide, measured in the laboratory, is only about 0.5% of that of elemental I. By field experiments, the biological half-life of I on grass was seen to be 7.5 days. Deposition is the point of entry in the atmosphere-pasture-cow-milk-thyroid food chain, the critical exposure pathway for infants.

This publication has 0 references indexed in Scilit: