Higher levels of Fukushima cesium detected off west coast
Saturday, December 5, 2015, 4:42 PM - Heightened levels of radioactivity have been detected in water samples collected off the west coast of Canada and the U.S., which scientists say can be traced back to 2011's Fukushima nuclear disaster.
While the radiation levels have proven to be relatively harmless, with no threat to marine or human life, they need to be closely monitored, according to a statement released by Woods Hole Oceanographics Institution (WHOI) on Thursday.
More than 245 samples were taken along the west coast since 2011, which are helpful in determining the pattern of ocean currents around the globe.
Ever since the devastating earthquake that struck the Japan coastline in March 2011, and the resulting damage to the Fukushima Daiichi nuclear power plant, radioactive elements from the plant - specifically cesium-137 and cesium-134 - have been carried across the Pacific Ocean by currents.
The highest level of the isotope cesium-134 which the WHOI says is a "fingerprint" of Fukushima, was found from a sample collected about 2,500 km west of San Francisco, which contained a 50 per cent higher concentration of cesium than other samples collected along the coast. However, the levels still fall well below government safety standards for drinking water, swimming and other recreational activities, the release notes.
Cesium-134 can be distinguished from other radioactivity in the water including, cesium-137, mostly a result of nuclear weapon tests during the Cold War. Cesium-134 has a very short-half life of only a little over 2 years. This means that just two years after it is released into the environment, only half of it is in that radioactive form. In comparison, cesium-137 has a half-life of 30 years.
“Levels today off Japan are thousands of times lower than during the peak releases in 2011," said Ken Buesseler, marine radiochemist with WHOI. "That said, finding values that are still elevated off Fukushima confirms that there is continued release from the plant."
Source: WHOI news release
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