Simulated inventory and distribution of 137 Cs released from multiple sources in the global ocean.

Radioactive cesium (137 Cs) is distributed in the world's oceans as a result of global fallout from atmospheric nuclear weapons tests, releases from fuel reprocessing plants, and inputs from nuclear power plant accident. In order to detect future radionuclide contamination, it is necessary to establish a baseline global distribution of radionuclides such as 137 Cs and to understand the ocean transport processes that lead to that distribution. In order to aid in the interpretation of the observed database, we have conducted a suite of simulations of the distribution of 137 Cs using a global ocean general circulation model (OGCM). Simulated 137 Cs radioactivity concentrations agree well with observations, and the results were used to estimate the changes in inventories for each ocean basin. 137 Cs activity concentration from atmospheric nuclear weapons tests are expected to be detectable in the world ocean until at least 2030.