Category Archives: Potassium

Fukushima Derived Contamination of Whales and Dolphins in Northern Japan

By Jay T. Cullen

Pacific white sided dolphins (Photo from the Nakamura et al. (2015) study published in MEPS)


The purpose of this post is to report on a recently published, peer-reviewed study documenting the contamination of whales and dolphins in northern Japan following the Fukushima Dai-ichi Nuclear Power Plant disaster in March 2011. This post is the most recent in an ongoing series that documents scientific research into the impacts of the FDNPP disaster on the health of the marine environment. The paper by Nakamura and colleagues investigated the levels of artificial radionuclides 134Cs (half life ~ 2 years) and 137Cs (half life ~30 years) and naturally occurring 40K (half life 1.25 x 109 years) in stranded whales and dolphins in 2011 and 2012 following the disaster. While there was little radiocesium present in the seawater around the northern island of Hokkaido after the disaster some of the animals had detectable levels of radiocesium from the FDNPP in the months following the disaster. By 2012 most stranded animals did not have detectable levels of FDNPP derived radiocesium. According to the authors, the sudden rise in radiocesium levels in the animals following the disaster suggests that the contamination in the animals reflected the seawater activities of the radionuclides through which they swam north rather than bioconcentration through the marine food web. Levels of artificial radionuclides were about 10-fold lower than naturally occurring isotopes in the organisms and are not likely to be causing negative health impacts but may be useful for helping to better understand the migration routes of these animals. Continue reading Fukushima Derived Contamination of Whales and Dolphins in Northern Japan

Background Ionizing Radiation Dose Through Geologic Time

By Jay T. Cullen

The purpose of this post is to review how the background dose of ionizing radiation has changed through geologic time until the present. I was motivated to write this by questions and misinformed statements made to me regarding the likelihood that the low levels of ionizing radiation now added to the Pacific Ocean might harm marine microbes and effectively kill the base of the oceanic food chain – given levels being measured this is for all intents and purposes impossible. This post is part of an ongoing series that summarizes the results of scientific research into the impact of the Fukushima Dai-ichi nuclear disaster on the health of the marine environment and residents of the west coast of North America. Life on Earth has been exposed to ionizing radiation since the first organisms began leaving chemical signs of their existence almost 4 billion years ago. In a paper published in 1999 Karam and Leslie calculated how the dose experienced by organisms from naturally radioactive geological and biological materials has changed over time. They find that overall the annual beta and gamma dose experienced by organisms has dropped from about 7 millisievert (mSv = 0.001 Sv) 4 billion years ago to about 1.4 mSv today. Given the similarity of repair mechanisms that organisms use to cope with damage from ionizing radiation it is likely that these mechanisms evolved early in Earth’s history which may explain why organisms are capable of dealing with higher than background doses in the environment today. Continue reading Background Ionizing Radiation Dose Through Geologic Time