Depth profile of 236U/238U in soil samples in La Palma, Canary Islands

► Vertical distribution of 236U/238U in La Palma region. ► The isotopic ratio 240Pu/239Pu indicated a global fallout signature. ► The 236U concentrations [atoms/g] at each surface layer were surprisingly high compared to deeper layers (two orders of magnitude lower). ► Due to the 240Pu/239Pu results the isotopic ratio 236U/239Pu enabled us to derive the global fallout as the probable source for 236U. ► The obtained value for 236U/239Pu of around 0.2 is within the expected range for this contamination source.