129I concentration in a high-mountain environment

The environmental abundance of I-129 has been significantly increased in the Nuclear Age starting from the 1950s. Tons of anthropogenic I-129 have been discharged into the environment through anthropogenic nuclear activities. This fact allows the relative dating of spring water samples, where low concentrations of I-129 indicate waters with no surface contact since the 50s. In this regard, the present study aims to identify the relative age of spring waters in the Kaunertal Valley in Western Austria. More than fifty water samples were derived from precipitation collectors, springs, and directly from the Gepatschferner glacier. Measurement results cover I-129 concentrations ranging from 1 x 10(6) to 5 x 10(8) atoms per litre. The variability of six springs, which were tested in July and September, was found to be negligible given the associated measurement uncertainties. No altitudinal dependence was found along the topographic gradient. Significant differences between high I-129 concentrations of precipitation and low I-129 contents of glacier samples were found and are considered beneficial to ascribe spring waters to pre-nuclear (older than 1950) or modern times of formation. Additional tritium analyses of selected water samples partly support the usage of I-129 for relative dating.