1 super(2) super(9)I measurements in lake water for an estimate of regional super(1) super(2) super(9)I depositions

Estimates of super(1) super(2) super(9)I depositions from super(1) super(2) super(9)I releases of reprocessing plants are so far based on measurements of soil and rain water samples. Because super(1) super(2) super(9)I concentrations in these samples show a highly temporal and spatial variability, the super(1) super(2) super(9)I deposition values deduced from single measurements cannot be seen as representative for a larger area. Here it is proposed to use lake water as an archive for former super(1) super(2) super(9)I depositions, to overcome these limitations. If the limnological parameters of any lake are known, the local super(1) super(2) super(9)I deposition flux can be deduced which is temporally averaged over the flushing time, and spatially averaged over the catchment area of the lake. Samples were collected from various European lakes and from Lake Baikal (Russia). The super(1) super(2) super(9)I concentration in these samples was measured by means of accelerator mass spectrometry, and values between 0.3 and 8.1x10 super(8) at/l were obtained. Deduced super(1) super(2) super(9)I deposition fluxes averaged over the flushing times of the lakes range from 0.3 to 9.3x10 super(1) super(2) at/m super(2) y. The super(1) super(2) super(9)I deposition fluence measured for Lake Baikal is attributed predominantly to releases from the former Soviet reprocessing facilities Chelyabinsk, Tomsk and Krasnoyarsk, while the super(1) super(2) super(9)I deposition fluxes deduced for all other lakes are attributed to releases from the European reprocessing activities at Sellafield, Marcoule and La Hague.