Radiation in the ocean from the Fukushima nuclear power plant accident in 2011 in Japan has yet to reach the California coast, scientists said Monday.
Researchers have detected miniscule amounts of the radioactive isotope cesium-134 in the ocean off Vancouver, Canada, as John Norton Smith, a senior research scientist at Canada's Bedford Institute of Oceanography, said at a meeting of the American Geophysical Union in Hawaii. It's at levels lower than naturally occurring radiation, like polonium-210, which is already in the ocean, he said.
Scientists are testing samples and using models to try to zero in on when it will reach the California coast -- they say they expect it this spring -- and how much there will be when it does, said Ken Buesseler, a scientist at the Woods Hole Oceanographic Institution in Massachusetts.
Researchers have also detected radioactive cesium-137 in the ocean. This is not a surprise, said Buesseler. It's been around since the nuclear weapons tests in the 1950s and 1960s. With a half-life of 30 years, it's going away, but still around in trace amounts.
One of the outstanding questions now is, how much cesium-134 -- the stuff from Fukushima -- will eventually make it to our coast?
The data collected by scientists at the Bedford Institute fits into two different models -- one predicting that it could reach levels comparable to the levels of cesium-137 when weapons testing was still going on, the other that it would be closer to cesium-137 levels in the 1990s.
"It's really a little hard to predict at this moment which model is correct, said Smith. Either outcome, he emphasizes, is not dangerous to humans because the levels are so low.
"It's clearly not an environmental or human health radiological threat," he said Monday.
Once it does start arriving researchers will know, said Buesseler. He's organizing a citizen science project, in which volunteers all over the West Coast collect ocean water samples to test for radioactivity. Collection points in California include Point Reyes, Pacifica and Santa Cruz.
"It's not here yet," Buesseler said. "When we're talking about the arrival of the plume -- and, you know, I'm the first person to say radioactivity can be quite dangerous, we should be concerned -- but maybe not at the levels we're going to expect coming across from Japan."
Another radiation-detecting project underway in California is Kelp Watch 2014, a program to monitor kelp forests on the coast for cesium-134.