On the presence of plutonium in Madagascar following the SNAP-9A satellite failure.

This study examined the Pu and Pu activity concentration and the Pu/Pu atomic ratio in peat bogs sampled in 2012 from marshlands in central Madagascar. The purpose was to investigate the presence of plutonium isotopes, Pu, from the 1964 satellite failure carrying a SNAP-9A radiothermal generator. With an average Pu/Pu activity ratio of 0.165 ± 0.02 (decay corrected to 1964), the peat bogs in Madagascar exhibit similar values as the ones found in the southeastern African continent, except they are one order of magnitude higher than expected (0.025) from global fallout in the Southern Hemisphere. The Pu/Pu atomic ratio showed a distinct decrease for layers dating back to the mid-1960s (down to 0.069 compared with an anticipated ratio of 0.17 for global fallout), indicating that the SNAP-9A failure also resulted in an elevated deposition of Pu. The obtained results demonstrate that further Pu analysis in Madagascar and in southeastern continental Africa is necessary to fully account for the regional Pu deposition from the SNAP-9A event.