Isoscapes of 134, 135, 137Cs and 239, 240Pu for part of the Fukushima prefecture surrounding FDNPP. The green marker is used to highlight an anomalous 240Pu/239Pu atom ratio of 0.64. R1, R2 and R3 correspond to ORIGEN estimated isotope ratio values for Reactor Units 1, 2 and 3, respectively27. SW indicates the mean value for the Cs isotope ratios measured to the southwest of FDNPP by Snow et al.19. 240Pu/239Pu atom ratio for Northern Hemisphere integrated global fallout is denoted by NHF28.