PORT ANGELES — Radiation from the 2011 Fukushima Daiichi nuclear disaster appears to have peaked off the West Coast of North America and has been in such low amounts there is little human health or marine risk locally, according to a University of Victoria researcher.
“The maximum levels that we see both in sea water and also in living organisms are very low relative to levels that are known to cause health problems for humans or problems in the marine ecosystem,” said Jay Cullen, a professor at UVic’s School of Earth and Ocean Sciences.
The Integrated Fukushima Ocean Radionuclide Monitoring Network (InFORM) has been collecting seawater and fish samples from across the Pacific Northwest since October of 2014, searching for Fukushima radiation, Cullen said last Tuesday, during a talk that was part of Feiro Marine Life Center’s lecture series.
The Fukushima disaster was caused by a magnitude 9.0 earthquake off the coast of Japan and the 130-foot-tall tsunami the quake generated.
While measuring the radiation, scientists are mostly looking for Cesium-134 and Cesium-137 isotopes.
Because of its 2-year half-life, Cesium-134 is being used as a “fingerprint” to know if radiation is actually from Fukushima. Cesium-137, which sticks around much longer and has a half-life of 30 years, has been released during nuclear weapons testing, by reprocessing facilities and from the Chernobyl disaster in 1986.
Researchers have tested roughly 400 sockeye salmon and steelhead from rivers across the North American West Coast and only found one fish with the “fingerprint” isotope, Cullen said.
Those fish are being tested because they are the species known to travel the farthest west in the Pacific Ocean, he said.
So far, researchers had not seen any measurable increase in Cesium-137 in the vast majority of fish tested, he said.
Cesium-137 rates in the Strait of Juan De Fuca and Strait of Georgia are similar to what they were in 2008, before the Fukushima disaster, he said.
He said the straits appear to prevent the radiation from traveling to the inland waters.
Scientists already have seen contamination peak offshore and are now watching that apex move toward the coast, he said.
The contamination is being measured in becquerels, or the number of decay events per second.
The fish tested have on average 0.2 becquerels per kilogram. The Health Canada department says it is safe to eat fish with up to 1,000 becquerels per kilogram, Cullen said.
He said a person who lives in Victoria is naturally exposed to more than 2,000 times more radiation in a year than if a person ate 50 pounds of the only fish they found with Fukushima radiation.
The average radioactivity of seawater is roughly 14,000 becquerels per cubic meter, the vast majority of which is naturally occurring, Cullen said.
Offshore, scientists are measuring seawater with up to 10 becquerels of Cesium-137 per cubic meter, about five times more than before the Fukushima disaster, he said.
In the Strait of Juan de Fuca and the Strait of Georgia, scientists are detecting less than 2 becquerels of Cesium-137 per cubic meter.
As a comparison, Cullen said the Irish Sea currently sees about 61 becquerels of Cesium-137 per cubic meter.
The study is funded through 2019.
Reporter Jesse Major can be reached at 360-452-2345, ext. 56250, or at [email protected].