Pollutant pathways between Mururoa and other polynesian islands, based on numerical model trajectories

Abstract

We address the question of which Polynesian islands would be most vulnerable to exposure from radio-nuclide material as a result of past nuclear testing at Mururoa and Fangataufa, should some of the material now stored in the atolls find its way into the ocean. We use an ocean circulation model of the Polynesian region with 26.5 km resolution and four open boundaries to find advective pathways from Mururoa to other islands. The model is driven by monthly mean wind stress and by the large-scale circulation determined from the wind stress curl at the northern and southern boundaries. Surface trajectories vary strongly with the seasons but always indicate southward or south-westward movement. Trajectories at 50 m and 100 m follow the South Equatorial Current westward. According to the model, no islands in the main island groups north of the latitude of Mururoa (22°S) are on a direct (advective) pathway with Mururoa or Fangataufa at any time. The islands most in danger of exposure to material from the two nuclear test sites are those in the Austral Group.