Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers assess radioactivity released to the ocean from the Fukushima nuclear facility

07.12.2011
With news this week of additional radioactive leaks from Fukushima nuclear power plants, the impact on the ocean of releases of radioactivity from the plants remains unclear. But a new study by U.S. and Japanese researchers analyzes the levels of radioactivity discharged from the facility in the first four months after the accident and draws some basic conclusions about the history of contaminant releases to the ocean.

The study, conducted by Woods Hole Oceanographic Institution chemist Ken Buesseler and two Japanese colleagues, Michio Aoyama of the Meteorological Research Institute and Masao Fukasawa of the Japan Agency for Marine-Earth Science and Technology, reports that discharges from the Fukushima Dai-Ichi nuclear power plants peaked one month after the March 11 earthquake and tsunami that precipitated the nuclear accident, and continue through at least July. Their study finds the levels of radioactivity, while quite elevated, are not a direct exposure threat to humans or marine life, but cautions that the impact of accumulated radionuclides in marine sediments is poorly known.

The release of radioactivity from Fukushima—both as atmospheric fallout and direct discharges to the ocean—represent the largest accidental release of radiation to the ocean in history. Concentrations of cesium-137, an isotope with a 30-year half life, at the plants's discharge point to the ocean, peaked at over 50 million times normal/previous levels, and concentrations 18 miles off shore were much higher than those measured in the ocean after the Chernobyl accident 25 years ago. This is largely due to the fact that the Fukushima nuclear power plants are located along the coast, whereas Chernobyl was several hundred miles from the nearest salt water basins, the Baltic and Black Seas. However, due to ocean mixing processes, the levels are rapidly diluted off the Northwest coast of Japan.

The study used publically available data on the concentrations of cesium-137, cesium-134, and iodine-131 as a basis to compare the levels of radionuclides released into the ocean with known levels in the sea surrounding Japan prior to the accident. Impacts of the Fukushima Nuclear Power Plants on Marine Radioactivity is published in the latest issue of Environmental Science & Technology and is available on the journal's website. Buesseler received funding support for this work from the Gordon and Betty Moore Foundation and the National Science Foundation’s Chemical Oceanography program.

The investigators compiled and analyzed data on concentrations of cesium and iodine in ocean water near the plants’s discharge point made public by TEPCO, the electric utility that owns the plants, and the Japanese Ministry of Culture, Sports, Science and Technology (MEXT). The team found that releases to the ocean peaked in April, a fact they attribute to “the complicated pattern of discharge of seawater and fresh water used to cool the reactors and spent fuel rods, interactions with groundwater, and intentional and unintentional releases of mixed radioactive material from the reactor facility.” They also found that the releases decreased in May by a factor of 1000, “a consequence of ocean mixing and a primary radionuclide source that has dramatically abated,” they report.

While concentrations of some radionuclides continued to decrease, by July they were still 10,000 times higher than levels measured in 2010 off the coast of Japan. This indicates the plants “remain a significant source of contamination to the coastal waters off Japan,” they report. “There is currently no data that allow us to distinguish between several possible sources of continued releases, but these most likely include some combination of direct releases from the reactors or storage tanks, or indirect releases from groundwater beneath the reactors or coastal sediments, both of which are likely contaminated from the period of maximum releases.”

Buesseler says that at levels indicated by these data the releases are not likely to be a direct threat to humans or marine biota in the surrounding ocean waters, but says there could be concern if the source remains high and radiation accumulates in marine sediments. “We don’t know how this might impact benthic marine life, and with a half-life of 30 years, any cesium-137 accumulating in sediments or groundwater could be a concern for decades to come,” he said.

In June, Buesseler led the first international, multidisciplinary assessment of the levels and dispersion of radioactive substances in the Pacific Ocean off the Fukushima Dai-Ichi nuclear power plants—a major research effort also funded by the Gordon and Betty Moore Foundation. During the research expedition, a group of 17 researchers and technicians spent two weeks aboard the University of Hawaii research vessel R/V Kaimikai-O-Kanaloa examining many of the physical, chemical, and biological characteristics of the ocean that determine the fate of radioactivity in the water and potential impact on marine biota. The results of their initial assessments will be presented in Salt Lake City in February 2012 at the Ocean Sciences Meeting, an international gathering of more than 4,000 researchers sponsored by The Oceanography Society, the American Society of Limnology and Oceanography, and the American Geophysical Union.

While international collaborations for comprehensive field measurements to determine the full range of isotopes released are underway, it will take some time before results are available to fully evaluate the impacts of this accident on the ocean.

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. 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.

WHOI Media Relations | EurekAlert!
Further information:
http://www.whoi.edu

More articles from Ecology, The Environment and Conservation:

nachricht Emissions from road construction could be halved using today’s technology
18.05.2020 | Schwedischer Forschungsrat - The Swedish Research Council

nachricht When every particle counts: IOW develops comprehensive guidelines for microplastic extraction from environmental samples
11.05.2020 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

Im Focus: New double-contrast technique picks up small tumors on MRI

Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.

researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...

Im Focus: I-call - When microimplants communicate with each other / Innovation driver digitization - "Smart Health“

Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.

When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...

Im Focus: When predictions of theoretical chemists become reality

Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.

Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...

Im Focus: Rolling into the deep

Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.

A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

Black nitrogen: Bayreuth researchers discover new high-pressure material and solve a puzzle of the periodic table

29.05.2020 | Materials Sciences

Argonne researchers create active material out of microscopic spinning particles

29.05.2020 | Materials Sciences

Smart windows that self-illuminate on rainy days

29.05.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>