More results from InFORM’s 2016 biotic monitoring results are now available and reveal that Fukushima contamination was not detected in sampled BC salmon after initial testing. These results are an update to the earlier report on the first 20 of the 123 fish donated by First Nations from 10 rivers in British Columbia and Yukon in 2016. Nine fish did have individual levels of 137Cs detected near the minimum detectable concentration (MDC). These levels (<0.7 Bq kg-1) are not known to present a significant health risk and are ~1,400x lower than the national and international action level (1000 Bq kg-1). For perspective, you would need to consume 1000-1500 kg of salmon at this concentration of cesium to receive the same radiation dose acquired during a single cross country flight. There has not been a significant increase to the total 137Cs concentration in BC salmon since InFORM monitoring began in 2014.
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
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
The measurements undertaken as part of the InFORM project to look for Fukushima derived radionculides in fish during our first of three years of monitoring are now complete. Sockeye salmon (Oncorhynchus nerka) and Steelhead Trout (Oncorhynchus mykiss) (as well as some Chinook, Chum and Pink Salmon) were caught off the west coast of Canada in Summer 2014 as they were returning to 9 different streams and rivers up and down the coast of British Columbia Canada. These results add to the first 19 fish which we reported on in December of 2014.