Since the Tohoku earthquake and tsunami crippled Japan's Fukushima Daiichi nuclear power plant in 2011, concerns have spread among the public that water with traces of radioactive material might be traveling in a plume across the Pacific Ocean toward the west coast of North America.
Experts say the radiation levels reaching the U.S. coast and Hawaiian Islands will be too low to threaten human health or marine life, but no U.S. government or international agency is actually monitoring radiation in these places.
Now, a scientist at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts is launching a new citizen science project to measure levels of radioactive cesium in water washing up along the West Coast. [Fukushima Radiation Leak: 5 Things You Should Know]
"The levels of cesium in the ocean we expect of the west coast of North America are not of concern for our own exposure or fisheries," said WHOI marine chemist Ken Buesseler, who is leading the project. But whether people agree with these predictions or not, radiation levels should be monitored to confirm them, Buesseler told LiveScience.
A recent study suggests the radioactive plume from Fukushima will reach U.S. coastal waters this year, peaking in 2016. But ocean currents off Japan's eastern coast have most likely diluted the radioactivity to well within safe levels set by the World Health Organization, said study leader Vincent Rossi, an oceanographer and postdoctoral research fellow at the Institute for Cross-Disciplinary Physics and Complex Systems in Spain.
Buesseler started sampling the seawater around the Fukushima plant — sometimes from as close as a half mile away — three months after the disaster. His team has dozens of water samples from the coast of Japan to the middle of the Pacific, but needs samples spanning the rest of the Pacific to the West Coast.
He launched a website Jan. 14 called "How Radioactive is Our Ocean?", where the public can make tax-deductible donations to support the analysis of existing samples or propose and fund new sampling locations along the West Coast.
Collection and analysis of a seawater sample costs $550 to $600, depending on the site's location. The scientists are asking individuals or communities to donate a minimum of $100 in seed funding, and WHOI will create a fundraising website for each location that is selected for sampling.
When a person or group raises enough money, WHOI will send a sampling kit so volunteers can collect about 5 gallons (19 liters) of seawater and ship it back to WHOI for analysis.
The scientists will use a $75,000 instrument to detect levels of biologically hazardous gamma-rays, produced by the decay of radioactive cesium in the samples. The results of the analysis will be posted on an online map, showing cesium concentrations and the names of sponsors.
The oceans already contain naturally occurring radioactive chemical elements, as well as remnant radiation from nuclear-weapons testing during the 1950s and '60s. Scientists can take a fingerprint of the Fukushima radiation by precisely measuring the ratio of the chemical variant cesium-137 left by weapons testing, which has a 30-year half-life, to the chemical form cesium-134 from Fukushima, which has a two-year half-life. (Half-life is the time it takes for half of the material to radioactively decay.)
The U.S. safety limit for cesium levels in drinking water is about 28 Becquerels (Bq), the number of radioactive decay events per second, per gallon (7,400 Bq/cubic meter). For comparison, uncontaminated seawater contains only a few Bq/cubic m of cesium, and much higher levels of other, naturally occurring radioactive elements.
In a separate project, known as Kelp Watch 2014, researchers plan to monitor radiation in California's kelp forests.
"Part of the reason for doing this is because the public is very freaked out by all this talk of radioactivity,” the study's leader, biologist Steven Manley of California State University, Long Beach, told KQED Science. “If they can actually see the numbers and a commentary as to what they mean, hopefully that’ll put them at ease."
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