RETENTION OF RADIOACTIVE CESIUM BY DIFFERENT SOILS IN THE CATCHMENT OF A SMALL LAKE

Cs-137 activity levels in Devoke Water Cumbria (UK) remained high for much longer than was expected after the Chernobyl accident. This is shown to be due to the release of dissolved Cs-137 from the catchment to the lake. Cs-137 inventories in different soil types suggest that fibrous peat soils loose Cs rapidly. Rankers and amorphous peats loose smaller amounts and podzols the least. The concentration of Cs-137 at any time in the streams is given by either: log A = -0.001064 time(days) + 0.302003 log flow(m3 s-1) + constant or: log A = -0.001064 time(days) + constant depending on the size of the constant, where the constant is given by: constant = (0.0473%) fibrous peat + 4.383) X deposition (kBq/m2)/9.8. Possible release mechanisms are discussed.