A GENERIC DYNAMIC-MODEL OF CS-137 TURNOVER IN NORDIC LAKES

The purpose of this study was to design a generic model for long-term predictions of the Cs-137 concentration in lakes, emphasizing the seco ndary, load of radiocaesium to the waterbody from lake sediments and d rainage area, If the concentration of Cs-137 in lake waters can be acc urately predicted, estimates of concentration in fish will be more rel iable. The inflow from the drainage area is estimated from the fractio n of outflow areas, whereas resuspension from lake sediments is estima ted from the maximum depth and surface area. The model is based on com partment theory. Modelling results for six lakes are presented. There was very good agreement between model results and observed values, for both water and lake sediments, although there were minor discrepancie s for sediments in the deepest lakes, Analyses of the model results sh owed that, for deep lakes, the main contribution maintaining the conce ntration in lake waters is inflows from the drainage area, whereas for shallow lakes, the main factor is resuspension for caesium rich sedim ents. (C) 1997 Elsevier Science Ltd.