As the radioactive cloud dispersed radioactive minerals across the Pacific (mostly moving away from Tokyo), some caesium and iodine were found in Japanese fish.
Both the U.S. FDA and Department of Homeland Security radiation detectors have been involved in screening cargo originating from Japan. In March some passengers arriving from Japan at O'Hare Airport in Chicago and also in Korea had above-normal radiaton levels, according to Robert Neff's March 18 blog at "The Marmot's Hole."
Helicopter drones sent by France and the U.S. also helped to monitor Japan's radiation levels, according to "NEI Notes" at Twitter. Technological innovation in the disaster came from Japan as well, in the form of the "Twitter Animal" or "Twimal" from the Japanese firm Takara TOMY (described at Singularity Hub). Twimal can read Twitter aloud in Japanese.
TEPCO Still Cooling Plants
Japan's TEPCO pumped inert nitrogen into reactor No 1 to help prevent a hydrogen explosion, which had caused some buildup in pressure inside of reactor one. Hydrogen caused explosions in the forty-year-old Fukushima-Daichi reactors (normally cooled by water) when zirconium (a metal) in the reactors was oxidized. It can take twenty years to recoup the cost of building a plant according to nuclear power opponent Dr. Helen Caldecott; apparently it is for this reason most reactors worldwide are aged between twenty and forty years. TEPCO continues to flood the reactors with water.
TEPCO ordered storage tanks for the radioactive water. TEPCO says it has released water with low radioactivity into the sea in order to store highly radioactive water.
Radioactivity in Sea and Soil Near the Power Plants
According to information provided KYODO News Service (cited by the NEI), first using concrete, later polymers, then sodium silicate, TEPCO repaired a breach in the No 2 reactor area. According to the BBC (April 6, 2011), "[t]he plant's operator, Tepco (Tokyo Electric Power Co), said it had injected chemical agents to solidify soil near a cracked pit of the No 2 reactor that was the source of the leak."
Except for brief spikes in radiation at reactor No. 1 due to the early April 7.1 magnitude aftershock, radiation levels at all Fukushima's reactors continue to decline. According to the information at NEI, TEPCO is now constructing barriers from steel sheets, and is taking steps to protect backup power generatiors for cooling systems. A number of aftershocks occurred including a 7.1 aftershock on April 7 and an additional 6.1 magnitude earthquake occurred April 11.
Reports on the amount of radioactivity actually released from the plant have fluctuated. Levels of radioactive iodine in sea water near the plant spiked to several thousand times the normal amount in March, remaining above allowed limits into the end of April. At one site, on May 2nd, radioactive iodine again spiked to double allowed levels, as some water used to cool reactors continues to flow into the sea.
Radioactive particles likewise entered the soil when the reactor exploded and spewed forth contents. Low levels of plutonium found in the soil suggest a breach in the containment mechanism for one of the reactors with possible damage to the fuel rods (partial core meltdown), according to Denis Flory of the International Atomic Energy Agency (IAEA). The presence of plutonium suggests "degradation of the fuel in at least one of the six reactors," although some of the plutonium may have come from spent fuel rods in the cooling pools (March 27, 2011; reported March 28 by Tomoko Yamazaki, "Tokyo Electric Finds Plutonium in Soil Near Fukushima Plant"). The pools, like the reactors, lost their cooling systems.
The presence of tellurium 129 and 129m isotopes suggest that some fission occurred at some point in the past, but does not suggest that fission is presently occurring, according to information at Nucleartownhall. Currently TEPCO is removing some of the radioactive materials in the soil using remote-control bulldozers.
Radioactive Clouds and Ocean Currents
Radioactive clouds continue to disperse from Fukushima. Weatheronline.co data shows the clouds drifting currently Eastward toward Alaska, with a small bit of cloud circling back across Siberia apparently. Lesser concentrations of the cloud may touch other areas of the Pacific coastline in the U.S. and Canada. Much of the cloud remains north of Tokyo, although apparently Tokyo's radiation levels spiked in late March acccording to data at chottomatte.net. Upper ocean currents (the top 400 meters) tend to move in the same direction as winds and clouds.
Radiation Dispersal, Ocean Currents, and Fish
Radioactive iodine has been found in sand-lance fish off Fukushima at double the newly-set legal limits (radioactive iodine in Japanese fish was previously not monitored), while radiactive caesium has been found just above the legal limit at 525 becquerals/kilogram. Right after Chernobyl, plankton-feeding fish in the area reached caesium levels of around 1000 becquerals/kg, while predator fish such as pike spiked to almost double that a year later in 1987, according to Igor Ryabov at the A.N. Severtsov Institute of Ecology and Evolution in Moscow.
Radiation levels gradually decreased in the Chernobyl fish but persisted for at least fifteen years. However the fish in the lakes and cooling pond around Chernobyl may have absorbed more caesium due to the lakes' low potassium content, according to Ryabov. Lakes near Chernobyl are fairly stagnant as well, unlike the sea. In any case, the area around Fukushima at least is not being fished much due to damage caused by the tsunami.
Alaska's Fisheries
The range of red and pink salmon extends from the Japanese and Siberian coast to the North American Pacific Coast. The season for sockeye and other salmon on the North American Pacific Coast is in the summer and early fall according to Philip Gantt's (December, 2007) description of fishing at Seward, Alaska. Salmon fry are currently hatching in fresh water streams according to "The Life Cycle of Pacific Salmon."
Since many radioactive iodine isotopes have a short half life (the exception is iodine-129 which can occur in small quantities as the result of fission), there will hopefully be little or none in sea water and plankton ingested by Alaska's salmon. (Salmon also eat some fish.) However, some radioactive minerals such as caesium have longer half lives than iodine. In the sea at least, heavier radioactive particles should eventually sink and perhaps be covered in silt according to the U.S. National Research Council's Radioactivity in the Marine Environment. If silt does absorb the radioactive matter, salmon feeding off Alaska's upwelling coastal currents may remain safe.
There is cause to monitor salmon however, according to Rutgers marine sciences and geology professor Paul Falkowski (quoted at fanaticcook): "In a worst-case scenario, said . . . Falkowski, . . . a major ocean current that travels up the coast of Japan, across the Pacific and into the Gulf of Alaska could carry radiation to Alaska fisheries months from now, . . . although he and other experts considered it highly unlikely that the current would take the radiation to Alaska unless the leak became far worse." Predator fish are the most likely to suffer from radiation, since it builds up when fish eat other fish.
According to EPA's "air filter and air cartridge data," Alaska has reported the highest measurements of radiation (caesium 134, caesium 136, caesium 137; iodine 131; tellurium 129 and tellurium 129m) in the air for the U.S. Although the U.S. imports 80% of its fish, Alaska and the Pacific Northwest remain among the most important sources for domestic fish. Other important sources include the Gulf of Mexico, which was the scene of last year's oil spill, and coastal South Carolina.
Fish from northern oceans, particularly from New Foundland and Greenland, also may contain high amounts of mercury. Mercury is likewise a problem in North America's streams and lakes.
Fallout
The EPA data shows spikes in North America's atmospheric radiation with trace amounts of caesium 134, 136, and 137 (mostly 137), also spikes of iodine 131, tellurium 129, and 129m, with highest spikes so far in Alaska. Moderate radiation has been reported in California, Hawaii, Arizona, Florida, and other states. Radioactive caesium isotopes are the main radioactive ingredients reported in rain water according to the EPA data, with the highest amounts observed in rain along the Pacific coast.
Fallout affects all food, particularly milk, as iodine can build up in milk although it has short half life. Caesium however has a half life of 30 years and may stay around in the food chain. Traces of both radioactive caesium and iodine have been found in milk as well as in North America's air and rain.
Pacific Ocean Radiation: A Site of Previous Dumping, Tests
The Pacific is no stranger to radiation. Most nuclear test sites have been in the Pacific (see the Atomicarchive.com's map), and for this reason New Zealand, which does not currently operate a nuclear reactor (although it does not ban reactors either) has, since the mid 1980's, banned ships carrying nuclear weapons or powered by nuclear fuel.
Beginning in 1946, "low-level nuclear waste" from research, medicine, and the nuclear industry has also been dumped in closed containers into the world's oceans, according to the International Atomic Energy Agency. Occasionally higher levels of caesium and plutonium have been detected near the dumping sites, The dumping of waste was banned in 1994.
Testing has been banned by some nations. It's argued by some however that the sea's mineral sediment may cover nuclear isotopes. In any case, since the sea and sea life is mineral rich, sea life is less susceptible to contamination by radioactive minerals than life on land, although there is evidence that radioactivity can build up in both seaweed and fish. UCB Comedy's " BP Spills Coffee " video said of the oil in the Gulf, "It's a little coffee on a big table." Perhaps the same can be said of the Pacific's radiation.
Sources
- "Are Alaska Fisheries at Risk?" Fanatic Cook. (2011/03/26; accessed 2011.)
- Atomicarchive.com. " Nuclear Test Sites." Map. (Accessed 2011.)
- Caldicott, Helen. "Nuclear Power Isn't Clean; It's Dangerous." (2001/09/03; accessed 2011.)
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- Conley and Francis. "High Radiation in Japanese Fish Raises Concerns." ABC News. (2011/04/06; accessed 2011.)
- Environmental Protection Agency. "Japanese Nuclear Emergency: Radiation Monitoring." RadNet Data. (Accessed 2011.)
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- Gantt, Philip. "Alaska Fishing, the Beaches in Seward." Suite 101. (2007/12/21; accessed 2011.)
- International Atomic Energy Agency. "Fukushima Nuclear Accident Update Log." (2011/04/11; accessed 2011.)
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- Neff, Robert. Blog. The Marmot's Hole. (2011/03/8; accessed 2011.)
- Nishikawa, Yoko. "Plutonium found in soil near Fukushima plant." Reuters. Rpt. in The Christian Science Monitor. (2011/03/29; accessed 2011.)
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- Nuclear Energy Institute. "Information on the Japan Earthquake and Reactors in That Region." Updated daily. (2011/04/11; accessed 2011.)
- Nucleartownhall.com (Accessed 2011.)
- Ryabov, Ivor. "Long-term Observation of Radioactivity Contamination of Fish Around Chernobyl." Moscow: Russian Academy of Sciences. (Accessed 2011.)
- U.S. National Research Council. Radioactivity in the Marine Environment . (Accessed 2011.)
- Weatheronline.co. Cloud Spread - Fukushima. (Accessed 2011.)
- Yamazaki, Tomoko. "Tokyo Electric Finds Plutonium in Soil Near Fukushima Plant." (2011/03/28; accessed 2011.) Bloomberg. Business Week.
Catherine E Whitehead - C. E. Whitehead holds degrees in education and linguistics. She likes languages, computers, and cooking.
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