Fukushima: Dilution of radioactivity at sea
These two maps show the change in caesium-137 concentrations in the sea off Fukushima between April 2011, just after the main discharges, and June 2011. The change in the concentrations reveals highly effective dilution of the seawater contamination within two months. This dilution is the result of the marked waters being carried by strong currents towards the centre of the North Pacific. (NB: This IRSN map was prepared from an Ifremer model; the small coloured squares correspond to the available measurements).