Distribution of Tritium and 137CS in South Indian Ocean Waters - Implications of Water Transport Processes

The World Ocean, and specifically the Indian Ocean, plays a significant role in the better understanding of the climate. The distribution of global fallout 3H, 14C, 90Sr, 129I and 137Cs in the seawater of the Indian Ocean, after their main injection from atmospheric nuclear weapons tests during the 1960s, have been investigated. Results obtained in the framework of the SHOTS (Southern Hemisphere Ocean Tracer Studies) project are evaluated and compared with previously published data. The enhanced 3H and 137Cs levels observed in the south Indian ocean indicate transport of water masses labelled with these radionuclides from the central Pacific Ocean via the Indonesian Seas to the Indian Ocean. The observed surface gradients and presence of several water masses in the south Indian ocean makes this ocean one of the most dynamic parts of the World ocean. (author)