Plutonium isotope measurements from across continental Australia

The 240Pu/239Pu ratio of the global plutonium fallout from atmospheric nuclear weapons testing is typically in the range 0.17–0.19. However, the influence of regional nuclear installations or nearby weapons test sites can lead to local values outside this range. We report 240Pu/239Pu ratios at 14 representative sites across the Australian continent, and find that the weapons tests carried out in Australia appear to have made a significant contribution to the total fallout in the center of the continent, despite their relatively small explosive yield.