Impacts of the Fukushima Nuclear Power Plants on Marine Radioactivity

TLDR

The impacts on the ocean of releases of radionuclides from the Fukushima Dai‑ichi nuclear power plants remain unclear. The study aims to draw basic conclusions about relative levels of radionuclides released from Fukushima and compare them to prior ocean studies to address dose consequences. The authors use publicly available data on iodine and cesium concentrations near the discharge point to perform this comparison. Peak ocean discharges occurred in early April, followed by a 1000‑fold drop the next month, yet concentrations remained elevated through July, with 137Cs levels exceeding 10,000‑fold 2010 levels, indicating continued releases; dose calculations suggest minimal direct impact on marine biota or humans, though further study of biological uptake and seafood consumption is warranted. Published in this journal.

Abstract

The impacts on the ocean of releases of radionuclides from the Fukushima Dai-ichi nuclear power plants remain unclear. However, information has been made public regarding the concentrations of radioactive isotopes of iodine and cesium in ocean water near the discharge point. These data allow us to draw some basic conclusions about the relative levels of radionuclides released which can be compared to prior ocean studies and be used to address dose consequences as discussed by Garnier-Laplace et al. in this journal. (1) The data show peak ocean discharges in early April, one month after the earthquake and a factor of 1000 decrease in the month following. Interestingly, the concentrations through the end of July remain higher than expected implying continued releases from the reactors or other contaminated sources, such as groundwater or coastal sediments. By July, levels of 137Cs are still more than 10 000 times higher than levels measured in 2010 in the coastal waters off Japan. Although some radionuclides are significantly elevated, dose calculations suggest minimal impact on marine biota or humans due to direct exposure in surrounding ocean waters, though considerations for biological uptake and consumption of seafood are discussed and further study is warranted.