Seven years on, since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, it is useful to start to bring together information from scientific studies of the impact of the contamination on the North American environment and its people. I recently wrote to communicate the most recent results of the Integrated Fukushima Ocean Radionuclide (InFORM) project. This post summarizes a recently published, peer-reviewed paper by colleagues lead by Dr. Krzyzstof Starosta of Simon Fraser University in BC working in parallel to InFORM. The open access paper was published in the Canadian Journal of Chemistry and was recently recognized with the “Best Paper Award” by the journal. They studied the concentrations of anthropogenic radioisotopes (134Cs half-life ~2 years, 137Cs half-life ~30 years) and naturally occurring radioisotope 40K (half-life 1.25 billion years) in Pacific salmon (sockeye, chum and chinook) and in soil and roof debris collected in southern British Columbia to determine the local impact of the FDNPP accident. Their results were as follows:
- 134Cs (a fingerprint of Fukushima contamination) was not detected in any of the salmon samples
- 137Cs was not detected in sockeye or chum salmon but was detected in all chinook with an average level of ~0.2 Bq kg-1
- Annual dose from artificial radionuclides to a human consumer of chinook salmon was estimated to be ~1/300 of the dose owing to naturally occurring isotopes in the fish and ~1/30,000 of the annual dose experienced for all other natural sources by the average Canadian
- Most soil samples contained 134Cs and 137Cs which was delivered to the region by atmospheric transport shortly after the disaster
- Levels of Fukushima radioisotopes in soil did not approach levels known to be harmful to living organisms
Consistent with other monitoring in the area the results of the study indicate that given the trace levels of contamination present the impact of the FDNPP accident on ecosystem and public health in North America will be insignificant. Continue reading Monitoring Fukushima Contamination in Pacific Salmon and Soil in British Columbia
The Fukushima Daiichi Nuclear Power Plant (FDNPP) and surroundings before the tragic events of March 11, 2011
By Jay T. Cullen
The purpose of this post is to bring the community up to date on monitoring efforts aimed at understanding the impact of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on environmental and public health. This post is part of an ongoing series and will focus on North American monitoring, summarizing work carried out by the Integrated Fukushima Ocean Radionuclide Monitoring (InFORM) project. Seven years since the peak in releases to the environment our project continues to measure environmental levels of radioisotopes that could represent a radiological health risk to living things. InFORM makes measurements of levels in seawater and common marine organisms as consumption of seafood is one of the most likely ways that residents of North America could be exposed to Fukushima derived contamination. Maximum contamination levels in seawater from Fukushima measured in waters offshore and onshore British Columbia and in the Arctic Ocean are about 8 to 10-fold lower than levels present in the North Pacific during the height of atmospheric nuclear weapons testing in the 1950’s and 1960’s. These levels are roughly 1000-fold below the maximum allowable drinking water standards for these isotopes. Levels in marine organisms have not changed significantly since before the disaster. As was reported in 2015 in this comprehensive study by Health Canada and backed up by measurements made by the international scientific community the release of radioisotopes from Fukushima will have no measurable impact on the health of the marine ecosystem in the northeast Pacific nor on public health in North America.
On March 11, 2011 all eyes were on Japan and I was watching too and feeling acutely the loss of life that the earthquake and tsunami brought on the Japanese people. A little later I watched as events at the FDNPP began to unfold and it became clear that a major nuclear accident was underway. I wondered what it meant for me and my family and friends in Victoria, BC Canada. I catalogued all the monitoring data coming in in 2011 I could find from the international scientific community and kept careful watch on the scientific literature. In 2013 I began communicating with the public about what the triple meltdowns at the FDNPP meant for the health of our marine ecosystem and public health because much of the information getting to the public was not scientifically sound, misinformed the public in general and overestimated the risk to people living in North America. The short of the story then was that nothing in the measurements of air, soil and water suggested any significant risk to public or environmental health. But it was clear that many in the public were being mislead by information online. To address the lack of quality information getting to the public I and other scientists in Canada and the USA, non-Governmental Organizations and citizen scientist volunteers put together the InFORM network. This is what we have found so far.
Offshore Monitoring of Seawater Contamination
The levels of radionuclide contamination in seawater is important to understand as the levels that ultimately are found in marine organisms is set by seawater levels. InFORM recently published a peer-reviewed paper in Environmental Science and Technology summarizing our results to date. Offshore levels of Fukushima derived isotopes have peaked and are now decreasing at our westernmost stations 1000-1500 kilometers from the North American coast. The peak levels are well below levels measured in the same waters during the 1950’s and 1960’s when atmospheric nuclear weapons tests were common. The study area is shown in the figure below along with the prevailing currents that brought the contaminated seawater to North America.
Measurements of radiocesium isotopes help scientists determine how much impact Fukushima has had on seawater at any given location on the globe. Off North America levels peaked at about 10 Bq per cubic meter of seawater (a Bq = Becquerel is one decay of an atom per second). This peak contamination is about 10-fold below levels measured here in the middle of the 20th century and 1000-fold below levels allowed in drinking water in Canada. The figure below shows how Fukushima derived contamination arrived in the upper ~400 meters of seawater from June 2013 until August of 2016.
The figure below shows the change in contamination with time and the levels in comparison to historical levels in the eastern North Pacific Ocean.
Levels measured now and predicted to arrive along the coast in the future will not approach levels known to represent a significant risk to the health of marine organisms or human beings.
Coastal Monitoring Efforts by InFORM Citizen Scientists
Every month since about December 2014 volunteer citizen scientists in 15 coastal communities up and down the shores of British Columbia have collected seawater samples at the beach and returned them to our laboratories for analysis. The sampling network is shown below.
Since monitoring began coastal seawater concentrations have increased as the Fukushima contamination plume arrives. The first detection of Fukushima contamination at the coast occurred in Feb. 2015 in the coastal community of Ucluelet on the west coast of Vancouver Island. Since that time levels have increased moderately and likely reflect that fact that the mixing of freshwaters coming from the land with the contaminated oceanic waters tend to insulate the coast from higher levels of contamination measured offshore. At the coastal locations contamination levels of human-made isotopes (which are a very small fraction of the radioactive elements in seawater) have increased 2-4 times relative to the pre-Fukushima levels.
Our coastal ecosystem and food supply are not at risk from these low levels of radioisotope contamination.
Monitoring of Pacific Salmon and Other Marine Organisms
Since 2014 we have collected and analyzed ~100 Pacific salmon and steel head trout per year returning to rivers up and down the BC coast from the Pacific Ocean. There has been no statistically significant increase in the levels of human-made isotopes in the fish since before the Fukushima disaster. The dose of ionizing radiation experienced by consumers of Pacific fish and shellfish is still dominated by the presence of naturally occurring radioisotopes in the Uranium and Thorium decay series (principally 210-Polonium) and remains well below levels that might represent a health risk. Our results are summarized in the following two figures.
The ionizing dose from consuming these fish is insignificant relative to other sources of ionizing radiation dose experienced by members of the public in North America. No measurable health impacts are expected.
Our intensive monitoring of environmental levels of contamination from Fukushima here in North America indicate that there is insignificant risk to ecosystem or public health resulting from the levels of radioisotopes detected in seawater and marine organisms. A summary of our program results thus far and monitoring of conditions off of Fukushima in Japan are given in the following figure.
Consistent with model predictions and the measurements made by scientists around the globe, the FDNPP accident will not have measurable negative impacts on North America’s marine ecosystems or public health. Levels of contamination are simply too far below those known to represent a threat to wildlife or human health. The InFORM project will continue its monitoring efforts into March 2019 and will continue to report its results and make them available to the public as soon as possible. I am available and happy to answer and questions related to the project, its goals and results. As always on this somber anniversary I think about the incredible loss of life from the tsunami and wish the best for the recovery of Japan’s coastal communities.
January 19, 2018
by Mari Yamaguchi
Originally published by Phys.org
The operator of Japan’s crippled Fukushima nuclear plant said Friday that a long telescopic probe successfully captured images of what is most likely melted fuel inside one of its three damaged reactors, providing limited but crucial information for its cleanup. Continue reading Melted nuclear fuel seen inside second Fukushima reactor
Laboratories outside Japan have validated the results. Marine radioactivity levels from the nuclear disaster have fallen, but questions remain years after the meltdown. Continue reading IAEA Affirms Japan’s Fukushima-Related Radioactivity Monitoring