INTERCEPTION OF CESIUM-CONTAMINATED RAIN BY VEGETATION

A series of experiments were carried out to quantify the interception of rain-borne caesium by crops of grass (Lolium perenne), broad beans (Vicia faba) and wheat (Triticum aestivum) under rainfall intensities typical of those encountered in the U.K. (1-18 mm h(-1)). The fraction of contamination deposited on the vegetation decreased with time, as the plant surface approached a saturation level of contamination. Surf ace contamination was dependent upon the total amount of rainfall rath er than the rainfall intensity. The total surface water storage capaci ty of wheat and beans was determined, and found to approach a saturati on level as total rainfall increased in a manner similar to the measur ed contamination levels. Total accumulation of caesium from aqueous so lution onto bean leaves was found to increase linearly with time over the range of concentrations tested (0.0001-10 mM), the rate of accumul ation increasing with concentration according to a power law. The comb ination of results obtained suggests that deposition of rain-borne con taminants could be modelled appropriately by a water storage capacity term and a ''chemical term'' derived from the contaminant concentratio n and its affinity for a particular plant surface. (C) 1997 Elsevier S cience Ltd.