The Tōhoku earthquake and tsunami of March 11, 2011, resulted in unprecedented radioactivity releases from the Fukushima Dai-ichi nuclear power plants to the Northwest Pacific Ocean. Results are presented here from an international study of radionuclide contaminants in surface and subsurface waters, as well as in zooplankton and fish, off Japan in June 2011. A major finding is 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, and unique to this study we also find 110mAg in zooplankton. Vertical profiles are used to calculate a total inventory of ∼2 PBq 137Cs in an ocean area of 150,000 km2. Our results can only be understood in the context of our drifter data and an oceanographic model that shows rapid advection of contaminants further out in the Pacific. Importantly, our data are consistent with higher estimates of the magnitude of Fukushima fallout and direct releases [Stohl et al. (2011) Atmos Chem Phys Discuss 11:28319–28394; Bailly du Bois et al. (2011) J Environ Radioact, 10.1016/j.jenvrad.2011.11.015]. We address risks to public health and marine biota by showing that though Cs isotopes are elevated 10–1,000× over prior levels in waters off Japan, radiation risks due to these radionuclides are below those generally considered harmful to marine animals and human consumers, and even below those from naturally occurring radionuclides.
However, although radioactive iodine quickly decays to undetectable levels, the risk to those exposed remains elevated for a lifetime, so the number of excess thyroid cancers will continue to climb, he added.
TOKYO (Kyodo) — The government said Thursday that a panel of experts has set a quantitative standard for approval of shipments of radioactive cesium-tainted gravel and crushed stones from quarries in Fukushima Prefecture, home of the crippled Fukushima complex.
“There may be a risk of developing cancer, but the risk is small. As long as we take care in selecting food, I think it’s OK,” said student Wataru Sugeno.
KAMAKURA, Kanagawa Pref. — Lingering concerns about radiation a year into the Fukushima nuclear crisis have prompted people even as far away as the Tokyo area, some 100 to 250 km from the Fukushima No. 1 power plant, to move away.
Asked to write in a free description section what Fukushima will be like in 30 years, the children’s reactions were mixed. A second-year middle-school girl wrote, ”It will be safe just like the days before the nuclear accident,” while a second-year middle-school boy said Fukushima will be powered mainly by renewable energy. Those who aired pessimistic views said Fukushima would remain deserted or that radiation fears will persist.