Marine scientists say they are concerned about radiation spewing from the crippled Japanese nuclear plant even though they expect it will take at least two years for radioactive material to reach Hawaii, perhaps three to hit the West Coast.
They want to drop a fleet of 60 ocean-going drifters into the debris field as a kind of early-warning system to get a better idea of how much radiation has entered the Pacific Ocean and where it's going.
"Currently, we are blind," said Nikolai Maximenko, a physical oceanographer at the University of Hawaii's International Pacific Research Center. "We do not even know where the main plume of floating debris and all those houses (from the Japanese coast) are. We are pulling together an emergency project to put drifters into those patches of floating debris to know where they are."
Maximenko and colleagues at several U.S. institutions say they need to act quickly and are proposing to drop the drifters next month from C-130 aircraft operated by the U.S. Coast Guard and Japanese research ship later this summer. The researchers say that satellite tracking won't work because the pieces of debris on the surface are too small, and that using existing models of Pacific Ocean circulation won't give an accurate enough picture of where the plume is headed.
In addition to warning communities across the Pacific, the project would help make better short-term predictions for people living along the Japanese coast, according to Luca Centurioni, physical oceanographer at the Scripps Institution of Oceanography in La Jolla, Calif., and co-principal investigator on the project.
"The general ocean circulation generally well understood, but if you want to make a shorter prediction, you need models to help you out," Centurioni said.
The proposal would extend the reach of the Global Drifter Program, which has some 900 instruments taking a variety of measurements across the world's oceans.
Japanese scientists are sampling the coastal waters for radioactive nucleides that could pose a danger to humans and the marine ecosystem. Even though the plant isn't discharging cooling water from the plant's damaged reactors, radiation is still entering the ocean, says Ken Buesseler, a marine chemist at the Woods Hole Oceanographic Institute.
"We know there are still discharges there may be a delayed release even if they plug every hole," Buesseler told Discovery News from his office at Woods Hole, Mass. "I see no evidence from the Japanese data that releases have decreased."
A quarter-century ago, Buesseler studied radioactive releases from the Chernobyl nuclear plant in Ukraine, and found that radiation was carried by winds and rain into the Black Sea, several hundred miles away. The levels of radiation along the Japanese coast are much higher, he said.
Buesseler says there are still many unanswered questions about radiation levels in the ocean.
"What we don't know is if that's the main source or there were explosions or releases to the atmosphere," Buesseler said. "They also don't know how far north and south and further into the ocean or how much has gone up."
Buesseler said Japanese officials are providing data for three radioactive particles: iodine 131 (which decays rapidly has an eight-day half-life) cesium 134 (two-year half-life) and cesium 137 (30 year half-life). Buesseler notes that there are other kinds of radioactive particles produced by nuclear plants that are not being monitored.
"We don't know about plutonium," he said. "No one has taken that on in Japan."
Debris from the nuclear plant is expected to contain long-living radioactive objects, as well as industrial toxins, researchers say. Still, most of the radioactive particles from the plant that make their way directly into the ocean will become less concentrated over time -- like a drop of colored dye in a bathtub.
"If you take a volume of water across the Pacific Ocean, with the vertical and horizontal dispersion it's going to be mixed up and diluted so by the time it travels across the pacific you don't expect high concentrations," Centurioni explained.
Less well-known, however, is the fate of contaminated debris, he added.
The U.S. Environmental Protection Agency says the amount of radiation reaching U.S. shores through the air currents, rain or ocean water will be so small that it will be tough to detect, and less than the amount that people receive from the sun's cosmic rays or other natural background sources.
The National Oceanic and Atmospheric Administration does have a marine debris tracking program and will be coordinating sightings of the debris patch from ships crossing the Pacific.
After hitting the West Coast in three years or so, oceanographers say the debris from Japan is expected to enter a swirling gyre of water known as the "Great Pacific Garbage Patch." The patch has been known about for several years, and occasionally dumps plastic, running shoes and other flotsam onto beaches in Hawaii and the Northwest coast.