Foliar leaching of 137Cs from Eriophorum vaginatum L., Scirpus caespitosus L. and Erica tetralix L.

Evidence of extensive leaching losses of nutrients, particularly of K, suggest that loss of 137Cs by foliar leaching could be considerable and could stimulate further root uptake and redistribution of 137Cs in plants. This study investigated the foliar leaching of 137Cs from two deciduous graminoid species, Eriophorum vaginatum and Scirpus caespitosus and one evergreen shrub, Erica tetralix. Plants were labelled with 137Cs via the roots and subjected to a leaching treatment in August and November and changes in both leachate and plant 137Cs activity were determined. Leaching losses were significantly reduced in November compared with August in the deciduous species, but not in the evergreen E. tetralix. A reduction in the total activity of 137Cs of leached plants was observed not only in leaves but also in stems and roots in some instances, suggesting that 137Cs from these organs had been redistributed to replenish that lost by leaching from the leaves. The data suggest that leaching losses were greater from older and senescent leaves than from younger leaves of E. vaginatum. The extent to which this is an accurate representation of foliar leaching of field-grown plants by rainfall, and the likely fate of 137Cs lost by foliar leaching are discussed.