Post-World War II uranium changes in dated Mont Blanc ice and snow

Recent controversies concerning the possibility of environmental contaminat ion due to the use of uranium in classical weaponry have led us to realize that there is a lack of time series for this metal from environmental archi ves. We have therefore performed analysis of a dated 140 m-long ice/snow co re that was drilled in 1994 at a cold high altitude site (4250 m) near the summit of Mont Blanc in the French-Italian Alps. Ultraclean analytical proc edures were employed in our analyses. Uranium concentrations were determine d by inductively coupled plasma sector field mass spectrometry. In ice dati ng from before the 1940s, uranium concentrations are found to have remained fairly constant and can be explained simply by a crustal contribution. For the post-World War II layers, on the other hand, the data show large exces ses above crustal contributions. These uranium excesses are attributed to t ropospheric transport of dust emitted during extensive mining and milling o perations which took place in the GDR and to a smaller extent in France at that time. There is no enhancement in uranium concentrations in the ice lay er in which fallout from the 1986 Chernobyl accident was previously identif ied from a gross beta activity vs depth profile.