This study has provided insight into the potential fate of radioactively contaminated material released into the South Pacific marine environment. Releases of large quantities of radionuclides into the South Pacific Ocean could have large-scale and long-term consequences, with elevated levels of radioactivity being the result for Pacific Island, South American and Australasian nations within 10 years of initial release.
The fate of radioactive material contained within the geological structure of Moruroa Atoll in the event of its escape varies as a function of the depth to which it is released, the rate of its release, and the oceanic climate into which it is released. Instantaneous surface releases remain most highly concentrated at the surface in French Polynesia when seasonal variability is incorporated into the tracer model, while longer-term average velocity fields used in this and previous model studies see maximum concentrations advected towards the south eastern Pacific. Vertical mixing, subsurface transport, and topographically induced upwelling also influence the fate of contaminants released from Moruroa. These lead to the appearance of radionuclides in the coastal waters of Australia within seven years of its release. The concentration of radioactive material if gradually released through hydrogeological processes, remains highest near the source. The concentration is dependent upon the strength of currents, and thus closely linked to ocean circulation variability. The worst case scenario for the nations in the vicinity of French Polynesia would be an instantaneous release during an ENSO year. This would see weak local currents having only a small effect on dispersing the pollutant. While previous studies have suggested that maximum radionuclide concentrations would be found in the relatively unpopulated eastern South Pacific following an instantaneous release, we show that seasonal variability can result in maximum concentrations remaining within French Polynesia.
http://www.maths.unsw.edu.au/~doughaze Page created by Douglas R. Hazell 7/6/2001 Last update of this page: 1/8/2001