Chernobyl134Cs,137Cs, and210Pb in high mountain lake sediment: Measurements and modeling of mixing process

We have measured the /sup 134/Cs, /sup 137/Cs, /sup 137/Cs and /sup 210/Pb vertical distributions in a lake sediment core. A value of 0.042 Bq cm/sup -2/ has been estimated for the atmospheric /sup 137/Cs fallout originating in Chernobyl release on the Alpine area: it represents 15% of the residual /sup 137/Cs activity due to nuclear tests. Mixing process and sedimentation rate have been deduced from /sup 134/Cs and /sup 210/Pb distribution. Distribution of /sup 137/Cs has been simulated for slow and rapid mixing processes and for various mixing thicknesses. Comparison with the experimental distribution indicates values of mixing thickness and sedimentation rate in agreement with the previously measured ones. copyright American Geophysical Union 1988