In June 2011, an international WHOI-led study of radionuclide contaminants off the coast of Japan in surface and subsurface waters, as well as in zooplankton was conducted. (RM) A major finding was the detection of Fukushima-derived 134Cs and 137Cs throughout waters 30–600 km offshore, with the highest activities associated with near-shore eddies and the Kuroshio Current acting as a southern boundary for transport. Fukushima-derived Cs isotopes were also detected in zooplankton and mesopelagic fish.
Vertical profiles were used to calculate a total inventory of ∼2 PBq 137Cs in an ocean area of 150,000 km2.
Our results were place in the context of drifter data and an oceanographic model that shows rapid advection of contaminants further out in the Pacific. Importantly, our data were consistent with higher estimates of the magnitude of Fukushima fallout and direct releases