Fukushima radiation detected in Tillamook Bay, Gold Beach — K5

” For the first time, seaborne radiation from Japan’s Fukushima nuclear disaster has been detected on the West Coast of the United States.

Cesium-134, the so-called fingerprint of Fukushima, was measured in seawater samples taken from Tillamook Bay and Gold Beach in Oregon, researchers from the Woods Hole Oceanographic Institution are reporting.

Because of its short half-life, cesium-134 can only have come from Fukushima.

Also for the first time, cesium-134 has been detected in a Canadian salmon, the Fukushima InFORM project, led by University of Victoria chemical oceanographer Jay Cullen, is reporting.

In both cases, levels are extremely low, the researchers said, and don’t pose a danger to humans or the environment.

Massive amounts of contaminated water were released from the crippled nuclear plant following a 9.0 magnitude earthquake and tsunami in March 2011. More radiation was released to the air, then fell to the sea.

Woods Hole chemical oceanographer Ken Buesseler runs a crowd-funded, citizen science seawater sampling project that has tracked the radiation plume as it slowly makes its way across the Pacific Ocean.

The Oregon samples, marking the first time cesium-134 has been detected on U.S. shores, were taken in January and February of 2016 and later analyzed. They each measured 0.3 becquerels per cubic meter of cesium-134.

Buesseler’s team previously had found the isotope in a sample of seawater taken from a dock on Vancouver Island, B.C., marking its landfall in North America.

Meanwhile, in Canada, Cullen leads the InFORM project to assess radiological risks to that country’s oceans following the nuclear disaster. It is a partnership of a dozen academic, government and non-profit organizations, including Woods Hole.

Last month, the group reported that a single sockeye salmon, sampled from Okanagan Lake in the summer of 2015, had tested positive for cesium-134.

The level was more than 1,000 times lower than the action level set by Health Canada, and is no significant risk to consumers, Cullen said.

Buesseler’s most recent samples off the West Coast also are showing higher-than background levels of cesium-137, another Fukushima isotope that already is present in the world’s oceans because of nuclear testing in the 1950s and 1960s.

Those results will become more important in tracking the radiation plume, Buesseler said, because the short half-life of cesium-134 makes it harder to detect as time goes on.

Cesium-134 has a half-life of two years, meaning it’s down to a fraction of what it was five years ago, he said. Cesium-137 has a 30-year half-life.

A recent InFORM analysis of Buesseler’s data concluded that concentrations of cesium-137 have increased considerably in the central northeast Pacific, although they still are at levels that pose no concern.

“It appears that the plume has spread throughout this vast area from Alaska to California,” the scientists wrote.

They estimated that the plume is moving toward the coast at roughly twice the speed of a garden snail. Radiation levels have not yet peaked.

“As the contamination plume progresses towards our coast we expect levels closer to shore to increase over the coming year,” Cullen said.

Even that peak won’t be a health concern, Buesseler said. But the models will help scientists model ocean currents in the future.

That could prove important if there is another disaster or accident at the Fukushima plant, which houses more than a thousand huge steel tanks of contaminated water and where hundreds of tons of molten fuel remain inside the reactors.

In a worst-case scenario, the fuel would melt through steel-reinforced concrete containment vessels into the ground, uncontrollably spreading radiation into the surrounding soil and groundwater and eventually into the sea.

“That’s the type of thing where people are still concerned, as am I, about what could happen,” Buesseler said.

Scientists now know it would take four to five years for any further contamination from the plant to reach the West Coast. ”

by Tracy Loew


960 Bq/kg of Cs-134/137 detected from wild boar in Fukushima — Fukushima Diary

” According to MHLW (Ministry of Health, Labour and Welfare), 960 Bq/Kg of Cesium-134/137 was measured from the meat of wild boar in Fukushima.

The sampling date was 6/11/2016. This reading is over 9 times much as food safety limit.

Cs-134 density was 154 Bq/Kg to prove it is contaminated from Fukushima accident.

From this report MHLW released on 7/19/2016, significant density of Cs-134/137 was detected from all of 33 wild boar samples and it exceeded the food safety limit (100 Bq/Kg) in 2/3 samples.

MHLW reports none of these wild boar meat was distributed for sale. ”

by Iori Mochizuki

source with French translation


Greenpeace reports jump in radioactive contamination in Fukushima waterways — The Japan Times

” Greenpeace Japan on Thursday said it has discovered radioactive contamination in Fukushima’s riverbanks, estuaries and coastal waters at a scale hundreds of times higher than pre-2011 levels.

One sample of sediment taken along the Niida River, less than 30 km northwest of the crippled Fukushima No. 1 power plant, revealed the presence of cesium-134 and cesium-137 at levels of 29,800 becquerels per kilogram.

That was just one of 19 samples of dried sediment and soil the environmental activist group took and analyzed from the banks of the Abukuma, Niida, and Ota rivers. The samples were collected by Greenpeace in February and March.

All of the samples but one exhibited more than 1,000 Bq/kg of radioactive material. The lowest level, 309 Bq/kg, was logged at a spot along the Abukuma River.

Cesium-134 has a half-life of about two years, but cesium-137 has a half-life of 30 years and is considered particularly hazardous. The standard limits set for radioactive cesium in Japan are 100 Bq/kg for general foods and 10 Bq/kg for drinking water.

“The radiological impacts of the Fukushima nuclear disaster on the marine environment, with consequences for both human and nonhuman health, are not only the first years. They are both ongoing and future threats, principally the continued releases from the Fukushima No. 1 plant itself and translocation of land-based contamination throughout Fukushima Prefecture, including upland forests, rivers, lakes and coastal estuaries,” the report said.

Greenpeace Japan also published the results of tests on dried marine sediment samples collected at 25 points off the Fukushima coastal area, including three river estuaries, during this same period, at depths of between 7.4 and 30.6 meters. The results showed that the highest level of cesium was 144 Bq/kg taken from a sample collected off the coast from the Fukushima power plant, while the lowest total cesium figure was 6.5 Bq/kg off Nakanosaku, well to the south of the plant.

In addition to Fukushima, Greenpeace Japan took dried sediment samples from Lake Biwa at three locations near the shore. The results showed cesium levels to be between 7.1 Bq/kg and 13 Bq/kg at two locations, and negligible at the other two.

The safety of Lake Biwa, which provides drinking water for about 14 million people in the Kansai region, has become a major bone of contention between Kansai Electric Power Co., which wants to restart reactors in neighboring Fukui Prefecture, and residents in and around Lake Biwa who are fighting to keep them shut down. ”

by Eric Johnston


Most radioactive caesium fallout on Tokyo from Fukushima accident was concentrated in glass microparticles — EurekAlert!; Simply Info

” New research shows that most of the radioactive fallout which landed on downtown Tokyo a few days after the Fukushima accident was concentrated and deposited in non-soluble glass microparticles, as a type of ‘glassy soot’. This meant that most of the radioactive material was not dissolved in rain and running water, and probably stayed in the environment until removed by direct washing or physical removal. The particles also concentrated the radioactive caesium (Cs), meaning that in some cases dose effects of the fallout are still unclear. These results are announced at the Goldschmidt geochemistry conference in Yokohama, Japan.

The flooding of the Fukushima Daiichi Nuclear Power Plant (FDNPP) after the disastrous earthquake on March 11 2011 caused the release of significant amounts of radioactive material, including caesium (Cs) isotopes 134Cs (half-life, 2 years) and 137Cs (half-life, 30 years).

Japanese geochemists, headed by Dr Satoshi Utsunomiya (Kyushu University, Japan), analysed samples collected from within an area up to 230 km from the FDNPP. As caesium is water-soluble, it had been anticipated that most of the radioactive fallout would have been flushed from the environment by rainwater. However, analysis with state-of-the-art electron microscopy in conjunction with autoradiography techniques showed that most of the radioactive caesium in fact fell to the ground enclosed in glassy microparticles, formed at the time of the reactor meltdown.

The analysis shows that these particles mainly consist of Fe-Zn-oxides nanoparticles, which, along with the caesium were embedded in Si oxide glass that formed during the molten core-concrete interaction inside the primary containment vessel in the Fukushima reactor units 1 and/or 3. Because of the high Cs content in the microparticles, the radioactivity per unit mass was as high as ~4.4×1011 Bq/g, which is between 107 and 108 times higher than the background Cs radioactivity per unit mass of the typical soils in Fukushima.

Closer microparticle structural and geochemical analysis also revealed what happened during the accident at FDNPP. Radioactive Cs was released and formed airborne Cs nanoparticles. Nuclear fuel, at temperatures of above 2200 K (about as hot as a blowtorch), melted the reactor pressure vessel resulting in failure of the vessel. The airborne Cs nanoparticles were condensed along with the Fe-Zn nanoparticles and the gas from the molten concrete, to form the SiO2 glass nanoparticles, which were then dispersed.

Analysis from several air filters collected in Tokyo on 15 March 2011 showed that 89% of the total radioactivity was present as a result of these caesium-rich microparticles, rather than the soluble Cs, as had originally been supposed.

According to Dr Satoshi Utsunomiya;

“This work changes some of our assumptions about the Fukushima fallout. It looks like the clean-up procedure, which consisted of washing and removal of top soils, was the correct thing to do. However, the concentration of radioactive caesium in microparticles means that, at an extremely localized and focused level, the radioactive fallout may have been more (or less) concentrated than anticipated. This may mean that our ideas of the health implications should be modified”.

Commenting, Prof. Bernd Grambow, Director of SUBATECH laboratory, Nantes, France and leader of the research group on interfacial reaction field chemistry of the ASRC/JAEA, Tokai, Japan, said:

“The leading edge observations by nano-science facilities presented here are extremely important. They may change our understanding of the mechanism of long range atmospheric mass transfer of radioactive caesium from the reactor accident at Fukushima to Tokyo, but they may also change the way we assess inhalation doses from the caesium microparticles inhaled by humans. Indeed, biological half- lives of insoluble caesium particles might be much larger than that of soluble caesium”. ”

Goldschmidt Geochemistry Conference


* * *

Read a similar article by SimplyInfo that sheds more light on the radioactive fallout from Fukushima Daiichi.

Over double density of cesium-134/137 as safety limit detected from served school lunch in Utsunomiya city — Fukushima Diary

” According to Utsunomiya city government, they detected over double density of Cs-134/137 as safety level from school lunch after serving it to the students this May.

It was bamboo shoot contained in the school lunch of 5/10/2016 as an ingredient.

It was already served and consumed by 560 students and teachers at an elementary school when they obtained the analysis result.

It was 234 Bq/Kg in total of Cs-134/137 (food safety limit is 100 Bq/Kg). The city government comments no health problem was reported related to the contaminated bamboo shoot. ”

by Iori Mochizuki


Geology graduates investigate Fukushima-derived radioactivity in Hawaiʻi — University of Hawai’i

” On March 11, 2011, following the Tohoku earthquake and tsunami, several reactors at the Fukushima Dai-ichi Nuclear Power Plant suffered damage and released radioactive chemicals into the atmosphere and contaminated wastewater into the nearby Pacific Ocean. Hannah Azouz and Trista McKenzie, two recent graduates from the University of Hawaiʻi at Mānoa School of Ocean and Earth Science and Technology (SOEST) bachelor of science in geology program, assessed the extent to which the soil of Hawaiʻi and locally purchased fish have been impacted by radioactivity from this event.

The students’ mentor, Henrietta Dulai, associate professor of geology, explained the motivation for this work, “My research team has been monitoring Fukushima-derived cesium in the Pacific Ocean since 2011 and we concluded that the Hawaiian Islands were spared from a direct hit of radionuclide plume spread by ocean currents. Yet, fish migrate and so even fish caught locally may accumulate some cesium in waters north of Hawaiʻi. Further, only one week after the disaster, the Department of Health identified Fukushima-derived radionuclides in the air, milk and precipitation over Hawaiʻi Island. We wanted to determine how much cesium was deposited from the atmosphere to the islands.”

Locally-purchased fish

To investigate the impact on locally-purchased fish, Azouz measured Fukushima-derived cesium isotopes in thirteen types of fish that are most commonly consumed in Hawaiʻi.

The FDA-accepted intervention limit for cesium isotope intake is 300 Bq/kg for fish. All fish tested were significantly below intervention limits—the highest cesium concentration in the examined species was in the Ahi tuna, carrying less than 1 Bq/kg.

“These data are informative to the community and they reassure me about the safety of the food we consume,” said Azouz. “The activities of the radionuclides were gratefully low—a person consuming the annual average amount of fish would receive the same dose of radioactivity as if they consumed one banana.”

“I did not know how passionate I would become about earth sciences,” said Azouz, who grew up in California but now calls Kailua home. “The most rewarding thing about this project is providing honest relief and real answers to the public. I can’t wait to publish this study and get it out onto the internet for the rest of the community to see!”

Azouz’s work was funded by the Undergraduate Research Opportunities Program (UROP) at UH Mānoa, with support from the Honors Program and SOEST.

“I recommend the University’s Honors Program as a great way to jump start a future career in your favored field. The research opportunities are endless,” said Azouz.

Soil and mushrooms

To estimate the atmospheric fallout of Fukushima-derived cesium and iodine onto Hawaiʻi, McKenzie analyzed mushroom and soil samples from Oʻahu and Hawaiʻi Island from areas with various average rainfall.

McKenzie’s research confirmed and quantified the presence of Fukushima-derived fallout in Hawaiʻi—the radioactive elements were present in both mushrooms and soil. However, the activities detected were much lower than fallout associated with the nuclear weapons testing in the Pacific. Additionally, they found that Fukushima-derived cesium in soils was correlated with precipitation—the more rainfall, the more cesium.

The levels of cesium activity (factoring both historical and Fukushima-derived fallout) in mushrooms were more than 12 times under the Derived Intervention Limit. For soils, there is no specific safety limit for radiocesium, but McKenzie found cesium inventories were not high—up to 1,200 Bq/m2cesium in Hawaiʻi soils compared to 200,000 Bq/m2 in forest soils found near the Fukushima Power Plant.

McKenzie’s fieldwork was funded by UROP at UH Mānoa, as was a trip to Vienna, Austria, to present her research at the European Geosciences Union (EGU) General Assembly. Subsequent to her presentation in Vienna, McKenzie also won the American Geophysical Union Multi-Society Undergraduate Spring 2016 Virtual Poster Showcase.

“I chose this project for my undergraduate research because it offered me a chance to investigate a really important question,” said McKenzie. “I’ve enjoyed both the field and lab work, and as a result of attending the EGU, I was able to meet geologists from all over the world and gain valuable presentation experience,” said McKenzie.

Both Azouz and McKenzie will continue working with Dulai in the fall—this time as graduate students. ”

by Marcie Grabowski