On its three-year anniversary, radiation from Japan’s nuclear power plant disaster at Fukushima has not shown up along the local coastline, according to radiation-monitoring scientists who released findings of their first sampling last week.
They expect to eventually detect small amounts of fall-out traveling on ocean currents by next year.
“We really don’t know when it’s going to get here,” said Steven Manley, professor of biological sciences at Cal State Long Beach, who started sampling kelp for radioactive chemicals to counter “wild claims” about fall-out from the Fukushima Daiichi nuclear plant meltdown reaching local shores.
Manley published a paper in April 2011, a month after the disaster, that radioactive iodine from Fukushima 250 times greater than normal was dropped on local kelp through rainfall. Since that initial exposure, he said, no other radioactive materials have come from Fukushima.
When the radioactive fall-out does arrive, he expects the contamination will be harmless and less than what kelp picks up from natural sources in the water.
“The ocean is full of natural radioactive materials,” said Manley. “These radioactive materials have been on earth ever since the earth was formed.” One such radioisotope, he said, is potassium 40, which is 1,000-fold more concentrated in kelp than the manmade cesium 137, a radioactive isotope found in fall-out from Fukushima. “And the kelp is doing fine,” he said. Local giant kelp is considered an indicator of ocean health and has flourished in recent years.
Cesium 134 and 137 are the major constituents of radioactive material that dropped into the ocean when the Japanese power plant was damaged by a tsunami bred by a 9.0 earthquake. Cesium 137, with a relatively long 30-year half-life compared to cesium 134’s two-year half-life, was detected in minute amounts in kelp during the initial sampling. That finding reflects residue from U.S. nuclear tests in the 1950s and ‘60s still in the marine environment today, Manley explained. Scientists did not detect the shorter-shelf-life cesium 134, which would more accurately indicate radioactivity coming from Japan, he added.
Manley along with scientist Kai Vetter from UC Berkeley and Lawrence Berkeley National Laboratory founded Kelp Watch 2014. The effort received grants from USC, the National Oceanic and Atmospheric Administration and California State University Council on Ocean Affairs, Science & Technology. The $10,000 in funds will help defray costs for collecting and processing the kelp.
With the help of other scientists who volunteered, kelp blades were collected from Alaska’s Kodiak Island to Baja California in February and March. Taken from 42 separate sites, including 31 in California, scientists analyzed 28 of 37 kelp samples. Samples were also taken from the related brown seaweed, sargassum, in Hawaii and Guam, Manley said.
Kelp is used for testing because it picks up and naturally filters contaminants in ocean water and concentrates them in its tissues, explained Manley. The contaminants do not affect the health of the kelp. “Kelp is very, very hardy,” he said. And since kelp is stationary, it serves as a constant barometer for collecting local data.
Manley and Vetter will determine the extent of water contamination rolling in on currents from Japan with two more samplings in mid-summer and late fall.
Local kelp samples were taken from the ocean off of San Clemente, Crystal Cove and Corona del Mar. Sampling off Laguna Beach is prohibited since it is a state-designated marine protected area.
Marine biologist Nancy Caruso, who assisted in collecting kelp off of Crystal Cove State Park, also helped process samplings at the Cal State Long Beach lab. “Interestingly enough, the Orange County kelp was the healthiest looking kelp,” she said. “It didn’t have any of the big holes in it, it didn’t have a lot of growth on it.” The colors of the various kelp samples also differed. The local kelp, she said, was a reddish color while other kelp was green and gray.
Processed kelp samples are sent to Vetter at UC Berkeley’s Lawrence Berkeley National Lab for detailed analysis.
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