The Fukushima Daiichi Nuclear Plant, damaged by an earthquake and tsunami on March 11, 2011 released large amounts of radioactive iodine into the atmosphere. In a report by the Environmental Health News, it has been confirmed that radioactive iodine from the Fukushima nuclear disaster was detected in kelp collected in California’s urban coastline, up to 2.5 becquerel per gram of dry weight – 250-times higher than levels found in kelp before the accident.
Projected paths of the radioactive atmospheric plume emanating from the Fukushima reactors, best described as airborne particles or aerosols for I-131, Cs-137, and S-35S, and subsequent atmospheric monitoring showed it coming in contact with the North American continent at California, with greatest exposure in central and southern California.
Government monitoring sites in Anaheim (southern California) recorded peak airborne concentrations of I-131 at 1.9 pCi m−3 from a baseline of zero.
Once Scientists from California State University, Long Beach became aware of the magnitude of the disaster and the composition of the radioactive plue, they tested giant kelp collected in the ocean off Orange County and other locations, and detected radioactive iodine, which was released from the damaged nuclear reactor.
“Basically we saw it in all the California kelp blades we sampled,” said Steven Manley, a Cal State Long Beach biology professor who specializes in kelp. Manley said that natural radiation in the ocean water is around 15 becquerel per liter.
If scientists calculated the levels in the water squeezed out of the kelp, “it would be 400 Bq per liter, which is well above the ocean average for natural radiation,” he said.
In the kelp itself, the amounts of Fukushima radioactivity were about the same as natural radioactive potassium found in other research.
Kelp was collected at three sites off Orange County, as well as Palos Verdes Peninsula in Los Angeles County, Santa Barbara, Pacific Grove and Santa Cruz. The highest concentration of iodine 131 was found in the kelp off Corona del Mar, which receives runoff from a large portion of Orange County. Its kelp was collected on April 15 of last year and tested five days later.
Some radioactive material probably accumulated in fish that eat the kelp – opaleye, halfmoon and senorita.
“If they were feeding on it, they definitely got dosed. We just don’t know if it was harmful. It’s probably not good for them. But no one knows,” Manley said. “In the marine environment it was significant, but probably not harmful at the levels we detected it, except it may have affected certain fish’s thyroid systems, the ones that fed on the kelp.”
One toxicologist who works with fish said fish thyroids are sensitive to radioactive iodine but there is no data on its effects. High levels might cause thyroid tumors in the exposed fish or alter their cells’ genetic material.
U.S. Environmental Protection Agency officials in San Francisco and Washington, D.C. declined to comment on the report or whether they will consider monitoring kelp. The EPA measured air and milk on the West Coast after Fukushima and concluded that “radiation levels remained well below any level of public health concern.”