“…Radioactive isotopes of noble gases are considered as powerful and sensitive tracers for environmental studies. In particular, 85 Kr (half-life 10.76 years), 39 Ar (269 years) and 81 Kr (229,000 years) have been used for age dating of groundwaters [1][2][3][4][5][6][7][8] and polar ice sheets, [9] for studying transport processes in the oceans, [10,11] and the atmosphere, for monitoring nuclear fuel reprocessing activities [12][13][14] and for checking 85 Kr radioactivity in solar neutrino detector systems. [15,16] Because of their chemical inertness, noble gases have the great advantage to be easily extracted with high efficiency from a large quantity of environmental samples (atmosphere, water, ice).…”