Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4555705 | Environmental and Experimental Botany | 2007 | 10 Pages |
Abstract
The interception by crop canopies of radionuclides in rainfall can be important in determining radiation exposures to animals and man. Data were obtained on the sorption and desorption of radionuclides on the adaxial surfaces of fully expanded bean leaves by exposing them to ionic forms of caesium (Cs+), iodine (Iâ) or sulphur (SO42â) over a six order of magnitude concentration range. The accumulation of each element was determined as a time course over a 48Â h period using radioactive labels (137Cs, 125I or 35S, respectively). Time- and concentration-dependent sorption of each element to the leaf surface was analysed to determine: (a) the leaf surface-solution distribution coefficient (Kd) at equilibrium and (b) the sorption and desorption rate coefficients for each element over the range of concentrations investigated. It was expected that Cs+ would show a stronger tendency to sorb to the leaf surface than both Iâ and SO42â because of the cation exchange properties of the cuticular membrane. The Kd for Cs+ was approximately 90Ã greater than that for SO42â but 5Ã less than that for Iâ. This is thought to be due to either (a) the highly organophilic nature of iodide and the relatively high iodine number of cuticular waxes on plant leaf surfaces or (b) the possible oxidation of Iâ to I0 or IO3â, with consequently enhanced leaf surface sorption. Based on data obtained in this study, ranges and best estimates of sorption and desorption rate coefficients are presented for Cs+, Iâ and SO42â for use in modelling the interception of radioactive Cs, I and S in rainfall by crops.
Related Topics
Life Sciences
Agricultural and Biological Sciences
Ecology, Evolution, Behavior and Systematics
Authors
G. Shaw, L.K. Scott, R.P. Kinnersley,