April 2016 MAINE COASTAL NEWS Page 9. Waterfront News Five years after the Fukushima nuclear


Fukushima Site Still Leaking After Five Years The highest level of cesium Buesseler’s


accident, there is still no U.S. federal agency responsible for studies of radioactive con- taminants in the ocean. But scientifi c data about the levels of radioactivity in the ocean off our shores are available publicly thanks to ongoing eff orts of independent research- ers, including Ken Buesseler, a radiochemist with Woods Hole Oceanographic Institution (WHOI), who has led the eff ort to create and maintain an ocean monitoring network along the U.S. West Coast. Since 2011, Buesseler has received con-


tributions from citizens, small businesses, foundations and large companies to enable the sampling of nearly 1000 seawater sam- ples for Fukushima radionuclides. Buesseler has been involved in seven cruises off Japan, sampling off Fukushima at least once every year, most recently in October 2015, and has published 19 peer-reviewed papers based on his analysis of seawater and sediments from the Pacifi c.


Buesseler’s work reveals that levels of


radioactive forms of cesium in the ocean off Japan are thousands of times lower than during the peak releases in 2011, however, his analysis of cesium and strontium indicate releases from the plant are not yet “under control,” a statement used by the Japanese government to describe the situation when levels are below regulatory limits. “To date, we have focused our eff orts on


testing for the two isotopes of cesium (137 and 134) and strontium,” says Buesseler. “The cesium isotopes were the most abun- dant after the accident and provide the fi rst indication of whether contamination from Fukushima is present in a seawater sample.” Because cesium-134 has a half-life of just two years, researchers know, when detected, that it comes from Fukushima. Cesium was 40 times more abundant in the water after the accident than strontium – a ratio that the scientists discover is changing. The changing concentrations of both


these elements in the waters off Japan tell a story of continued small leaks and raise concerns about the materials still stored at the reactor site.


Cesium off Japan Cesium levels in the water off Japan


spiked after the accident, then fell dramati- cally in the following year. Since then, how- ever, rather than a steady decline, the cesium levels have remained relatively constant. “Levels today off Japan are thousands


of times lower than during the peak releas- es in 2011,” says Buesseler. “But we are not seeing the steady decrease we would expect to see off Fukushima if all sources had stopped; rather, we are fi nding values are still elevated, which confi rms that there is continued release from the plant.”


team found in a sample taken off Japan in October 2015 measured 200 Becquerels per cubic meter (about 264 gallons) of seawa- ter. (A Becquerel equals one decay event per second.) The samples were collected following a typhoon in September that delivered unusually heavy rains, which the researchers suspect may have caused elevat- ed cesium levels in the ocean. These levels are still higher than prior to the accident but much lower than at the peak of the releases in 2011 when there were 50 million Bq/ m3


in the ocean immediately off the dock at Fukushima. While not declining as quickly as re-


searchers had expected, the levels detected near Japan are still more than 40 times lower than US government safety limits for drinking water, and well below limits of con- cern for direct exposure while swimming, boating, or other recreational activities. At these lower levels, the concern remains for seafood safety and internal consumption of radioactive contaminants in fi sh. Strontium off Japan


The scientists have learned that cesium


is just part of the story: Strontium, too, is not falling as expected. Strontium-90 has nearly the same half-life of cesium-137, and the researchers expected its levels would drop in step with cesium. Yet Buesseler and colleagues led by Universitat Autònoma of Barcelona, Spain have found that strontium is not decreasing as fast as cesium. Whereas there was approximately 40 times more ce- sium than strontium in the waters off Japan in 2011, by 2013, there was approximately 10 times more cesium than strontium. The concern lies in the thousands of tons of strontium still stored in tanks at the nuclear power plant and accumulated in buildings and soils, some of it still leaking into the ocean. “We think that when there is heavy rain,


more cesium, strontium, and other isotopes from the nuclear power plant are carried into the ocean,” says Buesseler. “We are still investigating how that occurs –whether carried in the groundwater or from the run off of sediment – but clearly it is highest near the contaminated site of the Fukushima nuclear power plants.” Because strontium-90 mimics calcium


in humans and animals, it is taken up by and concentrated in bones, where it remains for long periods of time, making it a greater health concern than cesium. Cesium, on the other hand, fl ushes out of the body much faster.


“Whereas it takes approximately two


months for half of the radioactive cesium to fl ush out of fi sh, it takes more like two years for strontium to fl ush out of fi sh because


B R B Continued from Page 6.


all I had was an engine payment. I bought a bunch of wood and I assembled that and when that ran out I quit. Then the next year I gathered up some more stuff and kept going. The one I have got now is 43½ by 15. I just took the molds and spread them. I put that one over on October 26, 2008, 25 years and a day between them. It took me fi ve years to build that one. For an engine I bought a takeout, an 892, which had 7500 hours on it. I’m going to haul that out next month and change it. She has got 23,000 now and she is pretty well worn out. I have got two 892s coming from Florida right now.” Benny built at Prospect, Winter Harbor


and Beals Island. He is the one that built the plug for the 37 Repco, which was designed by Ernest Brierly. Dan added, “He built the


plug upside down. He wanted them to widen the stern but they wouldn’t. He worked for Repco for a while and then he moved to Jonesport and worked with Junior for a while building boats. Then he built one for himself, 30 by 10, named LITTLE BEN and wouldn’t that haul ass too. Then his appendix burst, and that did him as far as physical work went.”


The Young Brothers, Colby, Arvid and


Arvin, are related to the Backmans. Elrica was the oldest daughter of Herman and Elrica’s daughter was Sarah who married a Young.


Dan would not say this 1943 Otto Back-


man built boat would be done next year. As soon as the lobster season is done you can bet he will be back in the shop and with any luck she will see the water in 1917 for her 74th


birthday!


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it’s in their bones,” says Buesseler. “So if the supply of strontium to the ocean gets worse, it would take longer for the levels to decrease in seafood. So far, strontium levels are more than a hundred times lower than cesium when measured in fi sh, so it has not been a concern, but we have to monitor it.” Monitoring the North American West Coast


In addition to studying the waters off Ja-


pan, Buesseler and his colleagues have been actively monitoring the Pacifi c waters off the North American West Coast, primarily for cesium, the most abundant element after the accident. So far, they have detected only minute quantities of Fukushima cesium. Fukushima-derived cesium fi rst arrived


along the west coast of North America in February 2015, measuring 6 Bq/m3 in Ucluelet, British Columbia. The highest numbers the researchers have seen in the eastern Pacifi c are almost 10 Bq/m3


, found


some 1,500 miles north of Hawaii. “If you were to swim in waters at this


level the health eff ects, or dose, would be 1000 times less than a single dental x-ray. This is not zero, but a very small risk that would not stop me from swimming or eating seafood from our side of the Pacifi c,” said Buesseler.


Because cesium levels have been so


small and the cost of analyzing samples for strontium is so great, the researchers have not been analyzing samples off North America for strontium, until recently. The researchers receive enough ques- tions about strontium that they re-analyzed


some of the West Coast samples that con- tained Fukushima cesium-134 looking for strontium, and have not detected any above the background levels that were there before Fukushima. “So little strontium was released rel-


ative to cesium from Fukushima in 2011, that even though Fukushima cesium is detectable, the strontium-90 signal is not detectable in these samples, at least in the eastern Pacifi c,” says Buesseler. The researchers continue to collect and


analyze samples both from citizen scientists and, when possible, from ships and research cruises on the eastern side of the Pacifi c. The data are made publically available through the Our Radioactive Ocean, the crowd-funding website Buesseler created for this purpose. The site’s map interface allows the public to see where samples were collected and the cesium values measured in each sample. Levels in the ocean are expected to peak


along the West Coast of the U.S. some time in 2015 or 2016. The Woods Hole Oceanographic Insti- tution is a private, non-profi t organization on Cape Cod, Mass., dedicated to marine re- search, engineering, and higher educat ion. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit www.whoi.edu.


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