Prof. Aoyama from Institute of Environmental Radioactivity of Fukushima University reported that the radioactive material discharged from Fukushima plant circulated in the Pacific to come back to Japan offshore.
He implemented seawater analysis at 71 points from 11. 2015 to 2. 2016. The analysis is partially completed to show radioactive material has spread to the South West offshore of Japan. 2 Bq/m3 of Cs-137 was detected in seawater from South West offshore of Kyushu. 1.83 Bq/m3 was detected even offshore of the west coast of Japan.
0.38 Bq/m3 of Cs-134 was also measured to prove this is from Fukushima accident.
It is assumed that the discharged Cs-134/137 travelled to the east in the Northern Pacific. It was carried to the South and West to come back to Japan by taking 2 ~ 3 years.
He comments it is possible that the density of radioactive material increases from now.