One year after the nuclear meltdown at Japan’s Fukushima Daiichi nuclear power plant, scientists are beginning to understand exactly what happened. Concerns about nuclear fallout have dissipated, and safe parts of the area around the plant have slowly begun to be repopulated by people and wildlife.
Yet as one problem subsides, another arises. The pile of garbage carried back to sea after the tsunami, officially known as the storm’s debris field, has been kept in motion by ocean currents over the past 12 months. Now it’s a line of trash thousands of miles long, migrating quickly toward Guam, Hawaii, and the West Coast of the U.S. Junk is one concern, but health officials are wondering how much water that came in contact with the nuclear plant’s radioactive core has been washed out to sea, potentially making its way through the ocean’s food chain and remaining toxic for hundreds of years.
Debris is what you might expect from the 3 million tons of Pacific Ocean water that flooded Japan's east coast, then slowly receded: boats, car parts, lumber, scrap metal. The heavier objects are believed to have sunk not far from there—although a Russian fishing crew spotted a refrigerator last fall. Much of the remaining material won’t easily break down in the water column, nor from the complex friction created by ocean currents. It also won’t stay together. Modeling teams at the International Pacific Research Center in Hawaii have mapped the spread of the plume, noting that it has traveled 2,000 miles since the tsunami struck land in March 2011. An animation shows how it might soon engulf Midway Island, a U.S. military hub.
Follow the path as the plume spreads and the ultimate destination becomes clear. As ocean currents head eastward across the Pacific, the plume is expected eventually to hit the West Coast of the United States. The National Oceanic and Atmospheric Administration has led surveying missions over the western Pacific to chart the path of the debris, using advanced computer models to track ocean currents, wind variabilities, and other geographic metrics. “We’re preparing for the best- and worst-case scenarios—and everything in between,” Nancy Wallace, director of NOAA’s Marine Debris Program, said in a statement.
The models show that the sludge may touch the north shore of the Hawaiian archipelago as soon as next month, then continue its meander to the northwest U.S. in early 2013. Circular momentum caused by both ocean currents and the wind-based Coriolis force fueled by the Earth’s rotation will then lead the debris back toward the central Pacific in 2014.
In the days after the meltdown, thousands of gallons of radioactive water flowed into the ocean.
There are certainly limits to computer models, and scientists have difficulty forecasting weather more than a few weeks in advance, let alone ocean movements years from now. While stray objects may wash up on beaches, there’s reason to believe the broader collection of floating junk will end up in an area of ocean about 1,000 miles north of Hawaii known as the Great Pacific Garbage Patch. Since it was discovered in 1997, the area, hundreds of miles across and at the very center of rotating currents, has long been considered a dead zone for marine wildlife, a virtual landfill of millions of tons the world’s trash, washed up over decades and kept in slow, perpetual rotation.
When Newsweek reported on the GPGP in 2009, ocean conservationists with the Ocean Voyages Institute in Sausalito, Calif., were trying to imagine ways to clean it up, ideally through recycling the material into usable oil (much of it is floating plastic), . Yet with the tsunami debris joining the gyre, the problem is compounding more quickly than anyone can measure. Charles Moore, a ship captain who discovered the gyre in 1997, gave up long ago, saying that the effort to clean it up would bankrupt any nation.
Once ocean advocates accept the degrading impact of aging garbage infesting the waters, questions remain about a longer-lasting threat: radiation. Much of the tsunami water refilled the Pacific days before the meltdown of nuclear reactors at the Fukushima plant. But in the days after the meltdown, thousands of gallons of radioactive water flowed into the ocean as well, according to several on-site incident reports. Plant officials at Fukushima even dumped highly radioactive water into the Pacific to make room for even more radioactive water needed to cool storage containers. According to the Union of Concerned Scientists, in April 2011, levels of radioactive iodine-131 and cesium-137 in seawater off the Japan coast were measured at 5 million and 1 million times what most governments consider an acceptable level of exposure. Different compounds have different radioactive half-lives, but the most potent will stay toxic for several centuries.
Nuclear scientists have been deluged with government and industry reports marking the one-year anniversary of the Fukushima meltdown. But among the most respected is one from the American Nuclear Society, the leading group of nuclear professionals. ANS researchers found that all off-site health consequences of the Fukushima Daiichi accident may ultimately be negligible. “From what we know now, there will be no major measurable health impacts,” says Dale Klein, former chairman of the Nuclear Regulatory Commission, who helped write the ANS report. NOAA and nuclear scientists have also dismissed concerns of health impacts on contaminated water that came in contact with the reactor.
Wildlife biologists and environmentalists, however, aren’t as quick to dismiss the impending risks. “It’s one thing to have radioactivity to humans, it’s another thing to have little teeny amounts that bioaccumulate in the food chain,” says Miyoko Sakashita, oceans director with the Center for Biological Diversity. (That process occurs when small amounts of radiation make their way into bigger and bigger organisms, eventually ingested by humans.) The environmental group Greenpeace has questioned government surveying of radiation, at times conducting toxicity tests of its own. “It’s a concern that you’ve done some serious damage to the marine field around Japan,” says Jim Riccio, a nuclear policy analyst with the group.
Japan, largely powerless to stop the spread of its debris, has with limited success monitored the threat of radiation it may export. Demand for seafood from Japan dropped by 47 percent in South Korea, Japan’s closest trading partner. Inspectors with the U.S. Food and Drug Administration, meanwhile, have kept watch on seafood caught in the west Pacific that is sold within America's borders. As of December, the regulatory agency said it had detected no radionuclides in any fish imported from Japan.