Radiation from damaged Fukushima reactor barely detectable off west coast #uranium
Radiation from damaged Fukushima reactor barely detectable off west coast
Concentration levels are thousands of times below drinking water standards, scientists say
By Kevin Griffin
November 11, 2014
Radiation from Fukushima in Japan has been detected off the coast of North America but at amounts thousands of times lower than acceptable levels in drinking water.
The small amounts of Cesium 134 were measured about 150 km due west of Eureka, Calif., by scientists at Woods Hole Oceanographic Institution as part of the U.S. organization’s regular monitoring of radioactivity in the ocean.
Ken Buesseler, a research scientist at Woods Hole, said the samples measured less than two becquerels of Cesium 134 from the radioactive plume sent into the Pacific Ocean from the Fukushima Dai-Ichi nuclear power plant after damage from the 2011 earthquake and series of tsunamis released radiation into the atmosphere and ocean.
Scientific models of the amounts of radioactivity from Fukushima arriving via ocean currents along the west coast of North America predicted anywhere from one extra becquerel to as many as 30 becquerels (a becquerel measures the rate at which radioactive material emits radiation and decays.)
“Part of this is a good-news story,” he said from Woods Hole, Mass.
“We’re confirming the lower estimates and these are several thousand times below drinking water standards. Yet the public will be concerned because they’ll hear it is out there.”
Buesseler is officially presenting the results Thursday at conference of the Society of Environmental Toxicology and Chemistry in Vancouver.
Buesseler and Woods Hole have also recruited about 50 local organizations and individuals in a citizen scientist program to take samples of sea water along the coast of North and Central America and Hawaii to send to Woods Hole for testing. More than six locations in B.C. are part of the program, including Vancouver, Bamfield and Haida Gwaii.
None of those samples taken much closer to shore and along beaches since January have shown the presence of Cesium 134.
In the U.S., the safe drinking water standard is 7,400 becquerels of cesium per cubic metre of water; in Canada, the standard is 10,000.
“We have 20 samples,” Buesseler said, “and 10 showed a detectable amount of 134.”
Scientists are measuring for Cesium 134 because it has a half-life of two years, so any amount of the isotope would mark it as coming from Fukushima. Samples measured by Woods Hole scientists do show six becquerels of Cesium 137. That isotope has a half-life of 30 years and is considered the remnant of atmospheric weapons testing of atomic bombs in the 1950s and 1960s.
“I’m concerned enough to want to keep monitoring but not concerned for my health from swimming in water with those levels,” he said.
What remains an unknown for Buesseler is the mixing that takes place between coastal water and deeper and colder ocean water. Samples taken this winter, he said, when there is usually less upwelling of colder water, may show different results.
The offshore radioactivity results came from samples collected in August by a group of volunteers on the research vessel Point Sur. They were taken between Dutch Harbor, Alaska and Eureka. They confirm earlier data by John Smith, a scientist at Fisheries and Oceans Canada in Dartmouth, N.S..
Buesseler will take part in an Ask Me Anything forum on Reddit at 10 p.m. PST today, at http://reddit.com/r/science.