AN INVESTIGATION OF POSSIBLE PROCESSES OF RADIOCESIUM RELEASE FROM ORGANIC UPLAND SOILS TO WATER BODIES

A series of samples taken during a rain storm from two streams feeding into a small lake were analysed for major ions and radiocaesium. Chan ges in Cs-137 content in both streams showed no relationship to ammoni a or dissolved organic carbon concentrations, suggesting that neither competition at illitic frayed-edge sites nor chelation of radiocaesium were important remobilization processes. One stream contained signifi cantly higher dissolved radiocaesium concentrations than the other. In the former stream, peaks and troughs in radiocaesium concentrations c orresponded with changes in calcium, pH and alkalinity. However the pH was related directly with the radiocaesium, whereas the proposed mech anism of humic mediated sorption to solids would infer an inverse rela tionship with pH. The positive Ca and pH relationships with radiocaesi um implied that, in the flooded fibrous-peat soils (peat bogs) encount ered in its subcatchment, radiocaesium was sorbed to the soils by simp le ion exchange processes.