Seaborne radiation from Japan’s Fukushima nuclear disaster has reached North America.
Scientists at the Woods Hole Oceanographic Institution detected small amounts of cesium-134 and cesium-137 in a sample of seawater taken in February from a dock on Vancouver Island, British Columbia.
It’s the first time radioactivity from the March 2011 triple meltdown has been identified on West Coast shores.
Woods Hole chemical oceanographer Ken Buesseler emphasized that the radiation is at very low levels that aren’t expected to harm human health or the environment.
“Even if the levels were twice as high, you could still swim in the ocean for six hours every day for a year and receive a dose more than a thousand times less than a single dental X-ray,” Buesseler said. “While that’s not zero, that’s a very low risk.”
Massive amounts of contaminated water were released from the crippled nuclear plant following a 9.0 magnitude earthquake and tsunami. More radiation was released to the air, then fell to the sea.
Frustrated by the absence of monitoring by U.S. federal agencies, Buesseler last year launched a crowd-funded, citizen-science seawater sampling project.
He’s tracked the radiation plume across 5,000 miles of the Pacific Ocean, using highly sensitive, expensive equipment at his Cape Cod, Massachusetts, laboratory. There, he analyzes samples sent to him by West Coast volunteers and scientists aboard research cruises.
In October, he reported that a sample taken about 745 miles west of Vancouver, British Columbia, tested positive for cesium-134, the so-called fingerprint of Fukushima because it can only have come from that plant.
It also showed higher-than-background levels of cesium-137, another Fukushima isotope that already is present in the world’s oceans because of nuclear testing in the 1950s and 1960s.
In November, Buesseler reported that Fukushima radiation had been identified in 10 offshore samples, including one 100 miles off the coast of Eureka, California.
The Vancouver Island sample was taken Feb. 19 from a dock in Ucluelet, a working harbor community in Pacific Rim National Park Reserve.
It contained 1.5 becquerels per cubic meter (Bq/m3) of cesium-134, the Fukushima fingerprint, and 5 Bq/m3 of cesium-137. A becquerel is a basic unit of radioactivity.
That compares to 50 million Bq/m3 of the isotopes near Japan just after the meltdown and about 1,000 Bq/m3 near Japan now, Buesseler said.
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