238U and 232Th decay chains in relation to cryoconite. On the left a scheme presenting the decay chain of 238U and the interactions between 210Pb and cryoconite. On the right the activity of radionuclides belonging to the 238U chain (upper part, logarithmic scale) and to the 232Th one (lower part). Data about two cryoconite samples (CR3 and CR5) are shown. Chains are partial and represented from left to right. Detection limits (red bars) and observed activities (blue bars) are presented with relative errors. Black (grey) line(s) refers to mean (st. dev.) activity of the entire decay chains. In the case of Pb-210 supported (blue bar) and unsupported (orange bar) fractions are highlighted.