Searching for signs of Fukushima radiation on North Coast
Published: Thursday, February 6, 2014 at 7:55 a.m.
Last Modified: Thursday, February 6, 2014 at 7:55 a.m.
Two divers hauled a mesh bag full of common brown kelp out of a Mendocino County cove Tuesday, kicking off a scientific search for evidence that radiation from the crippled Fukushima nuclear reactors has traveled 5,000 miles across the Pacific Ocean to California.
If cesium isotopes from the reactors ravaged by an earthquake and tsunami nearly three years ago in Japan have reached the state, they will be concentrated in kelp that flourishes along the West Coast, experts say.
Initial results from the search, called Kelp Watch 2014 and stretching from Alaska to Mexico, will be posted online by the end of April by marine biologist Steven Manley's lab at CSU Long Beach.
The year-long project, Manley said, intends to answer questions on the minds of many Californians who wonder if the state's coastal waters — and the food from them — are as safe as they used to be.
“The public wants to know,” Manley said. “Whenever you deal with radioactivity there's a real sensitivity. People get scared.”
“It is a huge question,” said Laura Rogers-Bennett, a California Department of Fish and Wildlife environmental scientist based Bodega Marine Laboratory.
Rogers-Bennett and her colleague, Cynthia Catton, collected Tuesday's sample — the first for Kelp Watch 2014 — close to shore at Van Damme Beach, nearly 100 miles north of Santa Rosa.
Biologists say kelp, which grows in abundance along the coast, acts like a sponge in soaking up elements contained in seawater, including, possibly, radiation.
Fourteen pounds of raw kelp, dried and ground to one liter of powder at the Bodega facility,will be shipped to Lawrence Berkeley National Laboratory in Berkeley, where $80,000 gamma-ray spectrometers will determine if the kelp absorbed cesium isotopes that match Fukushima's radioactive fingerprint.
The Bodega lab, run by UC Davis, is among the nearly two dozen organizations voluntarily participating in Kelp Watch 2014, aiming to collect kelp this year from more than 45 sites ranging from Alaska to Baja California.
A radioactive plume reaching across the Pacific from Japan is expected to reach California this year, and public interest has spiked.
Google searches for the term “Fukushima California” peaked in January at nearly double the level in March 2011, when the Fukushima plant sustained a meltdown.
“There's a lot of misinformation out there,” said Pete Kalvass, a Department of Fish and Wildlife marine biologist in Fort Bragg. “It'll be good to get some results.”
The California Department of Public Health, which periodically tests seawater and sea life for radioactivity, reported last month that all results from 2011 through 2013 were below “laboratory minimum detectable limits.”
Based on information from federal agencies and its own testing, the agency said “there are no health and safety concerns to California residents.”
The state public health agency “has not seen nor heard of any data that suggests any abnormal radiation levels in sea kelp off the California coast,” according to Wendy Hopkins, a department spokeswoman.
Kai Vetter, head of the Applied Nuclear Physics Program at the Lawrence Berkeley lab and a collaborator in Kelp Watch 2014, expects to reach a similar conclusion.
His lab's website — radwatch.berkeley.edu — notes that research is ongoing but “the basic answer” is that Fukushima's radiation will turn out to be minimal, with “no harmful effects on the ocean or people in our state.”
Radiation from Fukushima carries a specific ratio of cesium 134 and cesium 137 isotopes, which his equipment can readily identify, Vetter said.
Scientists must also sort out reactor-bred radiation from naturally occurring radiation emanating from soil, minerals, concrete, food and human bodies.
Conventional Geiger counters can't make that distinction, nor identify the source of any radiation they detect, Vetter said.
“We live be in a world of radiation,” he said. “For many people that's a big surprise.”
A relatively small amount of background radiation in the Pacific Ocean is left over from nuclear bomb testing during the Cold War, he said.
On the beach at Van Damme, Rogers-Bennett displayed her haul of giant kelp. “See how beautiful they are,” she said, pointing out the textured fronds attached to a stem.
Kelp, a type of marine algae, is a “really good sentinel” because it absorbs and concentrates whatever is in the water column and passes it up the food chain, she said.
Kelp Watch 2014 intends to sample both giant kelp and bull kelp, but divers found none of the latter on Tuesday.
Bull kelp, which grows from a spore to as tall as 50 feet each year along the Sonoma coast, forms a long thin whip capped by a floating ball and an array slender fronds.
Rogers-Bennett said she plans to sample kelp later this year in the county, where there are also pockets of giant kelp.
“This is where I would look first,” said Susan Williams, a professor of ecology at the Bodega lab, referring to the project's target. “If it's not in the kelp I would be reassured that not a lot of radiation is getting into the food web.”
Fukushima's crippled reactors are still leaking tainted water, at a rate of 300 tons — nearly 72,000 gallons — a day, according to a National Geographic report last year.
The Pacific Ocean, with 187 quintillion gallons (187 with 18 zeroes) of water, dilutes Fukushima's discharge, and models of the radioactive plume indicate that much of it will wind up in the North Pacific Gyre, the circular flow that traps the Great Pacific garbage patch.
But there is “no U.S. government or international plan to monitor” the plume, according to a Woods Hole Oceanographic Institution report last week.
Ken Buesseler, a Woods Hole marine chemist who led the first assessment of Fukushima's ocean contamination in 2011, is now conducting a sampling of West Coast seawater.
His first report, posted online last week, said that four samples — from Point Reyes, La Jolla and two sites in Washington state — showed “no detectable Fukushima cesium.”
Buesseler and Manley both say sampling done early this year will precede the plume's arrival on the West Coast, thereby establishing baseline level of seawater radiation.
Kelp Watch 2014's first sampling period runs through March 5, with subsequent samplings in July and October.
“If we don't see anything (in the first sampling), we'll just keep on going, Manley said.
Lack of information about Fukushima radiation breeds suspicion, he noted. “People think there's a conspiracy,” he said. “We want to alleviate some of that.”
(You can reach Staff Writer Guy Kovner at 521-5457 or email@example.com.)
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