Foliar absorption of resuspended 137Cs relative to other pathways of plant contamination

The foliar absorption of 137Cs sorbed to suspended soil particles was quantified at two Ukranian locations contaminated by different forms of Chernobyl fallout. Our experimental design, allowed us to separate the pathways of foliar absorption, root uptake, and contamination adhering to plant surfaces. Foliar absorption, root uptake, and the quantity of soil-attached 137Cs adhering to leaves were greater at a loamy sand site contaminated with condensation-type fallout (Polesskoye), than at a sandy site contaminated with fuel-particles (Chistogolavka) (0.7 vs 0.04kBqkg−1; 20.8 vs 0.9kBqkg−1; and 3.2 vs 1.1mBqcm−2, respectively). We found that when 137Cs was very mobile in soils, root uptake grossly dominated all other plant contamination pathways. As the plant/soil concentration ratio decreased, a relative increase in foliar absorption from resuspension occurred, but it was quickly surpassed in importance by soil adhering to plant surfaces. The data suggest that although foliar absorption of 137Cs from suspended soil is measurable, it is inconsequential relative to other plant contamination pathways, and does not need to be considered as a critical pathway in routine radionuclide transport models.