Elements presenting an enrichment in cryoconite with respect to moraine sediments. In panel a the average concentration of cationic elements in cryoconite, normalized with respect to moraine sediment composition, is shown. Elements are ordered following their affinity for clay minerals42, 43. In panel b full data about the anthropic elemental group, an additional crustal element (Ce, light blue bars) is included for comparison. For each element data are presented as absolute concentration (bars, lower part) and as enrichment factor with respect to UCC (black curve, upper parts). Moraine sediment data are also presented (grey bars). Asterisks are referred to values below the detection limit.