NATURAL AND ARTIFICIAL RADIOACTIVITY IN THE SVALBARD GLACIERS

Natural and artificial radioactivity in the snow of 10 Svalbard glacie rs has been measured from 31 ice core samples, drilled between 1981 an d 1993. Of these ice cores, seven exhibit the well-known level arising from the fallout of the 1961-62 atmospheric thermonuclear tests. The second level, due to the Chernobyl accident (26 April 1986), has been detected in all the studied glaciers, the maximum Cs-137 fallout reach es 22 Bq kg(-1) and shows a high variability. The natural radioactivit y, mostly due to Pb-210, shows art indepth variation which is not gove rned by its half-life (22.2 years). These measurements serve many glac iological purposes: absolute dating of the snow layers; air-snow trans fer and fallout studies; the determination of mean annual mass balance s in the accumulation area of glaciers and their associated spatio-tem poral variations.