The contamination of the marine environment has occurred both through atmospheric fallout or washout with precipitation, and through discharges of contaminated water into the sea
Authorised discharge of low level contaminated water (4 April)
Japanese institutes continue to perform measurements in seawater at 30 m and 330 m off the discharge points of Dai-ichi NPP, as well at 10 km and 20 km off-shore and along two North-South transects situated 15 and 30 km off-shore
Seawater sampling offshore Fukushima carried out by Japanese Authorities Seawater sampling locations of Japanese Authorities
Transect about 30 km offshore, sampling points separated by 10 kilometres, surface and bottom seawater sampled
Additional sampling stations at 10 and 20 km offshore, for which both surface and bottom seawater are sampled (M9-M10)
The highest levels are still measured close to the coast, namely 30 m, 330 m and 10 km near-shore.
Concentration data from about 30 km off-shore show a generally decreasing time trend
It can be expected that, if no additional releases occur, the levels measured at the stations 30 km off-shore will continue to decrease significantly by dilution into deeper layers and dispersion by ocean currents
Conclusions The number of marine sampling points has been increased with a new North-South transect 15 km offshore One marine expert from IAEA Environmental Laboratories, Monaco has been in Japan to review and advise on marine sampling and measurements (back yesterday night) .