Fukushima’s Contamination
Produces Some
Surprises at Sea
Japanese Nuclear Meltdown
EMF Radiation Protection
Magnetic Field Meters
September 28,
2011 | By DAVID
JOLLY
Six months after the accident at Fukushima Daiichi, the news
flow from the stricken nuclear power plant has slowed, but
scientific studies of radioactive material in the ocean are
just beginning to bear fruit.
The word from the land is bad enough. As my colleague Hiroko
Tabuchireported
on Saturday, Japanese officials have detected
elevated radiation levels in rice near the crippled
reactors. Worrying radiation levels had already been
detected in beef, milk, spinach and tea leaves, leading to
recalls and bans on shipments.
Off the coast, the early results indicate that very large
amounts of radioactive materials were released, and may
still be leaking, and that rather than being spread through
the whole ocean, currents are keeping a lot of the material
concentrated.
http://www.bloomberg.com/news/2011-08-02/tepco-reports-second-deadly-radiation-reading-at-fukushima-plant.html
Most of that contamination came from attempts to cool the
reactors and spent fuel pools, which flushed material from
the plant into the ocean, and from direct leaks from the
damaged facilities.
Japanese government and utility industry scientists estimated this
month that 3,500 terabecquerels of cesium 137 was released
directly into the sea from March 11, the date of the
earthquake and tsunami, to late May. Another 10,000
terabecquerels of cesium 137 made it into the ocean after
escaping from the plant as steam.
The leakage very likely isn’t over, either. The Tokyo
Electric Power Company, the operator of the plant, said
Sept. 20 that it believed that something on the order of 200
to 500 tons a day of groundwater might still be pouring into
the damaged reactor and turbine buildings.
Ken Buesseler, a
scientist at the Woods Hole Oceanographic Institution, who
in 1986 studied the effects of the Chernobyl disaster on the
Black Sea, said the Fukushima disaster appeared to be by far
the largest accidental release of radioactive material into
the sea.
Chernobyl-induced radiation in the Black Sea peaked in 1986
at about 1,000 becquerels per cubic meter, he said in an
interview at his office in Woods Hole, Mass. By contrast,
the radiation level off the coast near the Fukushima Daiichi
plant peaked at more than 100,000 becquerels per cubic meter
in early April.
Before Fukushima, in 2010, the Japanese coast measured about
1.5 becquerel per cubic meter, he said.
‘‘Chernobyl might have been five times bigger, over all, but
the ocean impact was much smaller,’’ Mr. Buesseler said.
Working with a team of scientists from other institutions,
including the University of Tokyo and Columbia University,
Mr. Buesseler’s Woods Hole group in June spent 15 days in
the waters off northeast Japan, studying the levels and
dispersion of radioactive substances there and the effect on
marine life.
The project, financed primarily by the Moore Foundation
after governments declined to participate, continued to
receive samples from Japanese cruises into July.
While Mr. Buesseler declined to provide details of the
findings before analysis is complete and published, he said
the broad results were sobering.
“When we saw the numbers — hundreds of millions of
becquerels — we knew this was the largest delivery of
radiation into the ocean ever seen,’’ he said. ‘‘We still
don’t know how much was released.’’
Mr. Buesseler took samples of about five gallons, filtered
out the naturally occurring materials and the materials from
nuclear weapon explosions, and measured what was left.
The scientists had expected to find ocean radiation levels
falling off sharply after a few months, as radioactive
substances were dispersed by the currents, because, he said,
“The ocean’s solution to pollution is dilution.’’
The good news is that researchers found the entire region 20
to 400 miles offshore had radiation levels too low to be an
immediate threat to humans.
But there was also an unpleasant surprise. “Rather than
leveling off toward zero, it remained elevated in late
July,’’ he said, up to about 10,000 becquerel per cubic
meter. ‘‘That suggests the release problem has not been
solved yet.”
The working hypothesis is that contaminated sediments and
groundwater near the coast are continuing to contaminate the
seas, he said.
The international team also collected plankton samples and
small fish for study. Mr. Buesseler said there were grounds
for concern about bioaccumulation of radioactive isotopes in
the food chain, particularly in seaweed and some shellfish
close to the plants. A fuller understanding of the effect on
fish that are commercially harvested will probably take
several years of data following several feeding cycles, he
said.
‘‘We also don’t know concentrations in sediments, so benthic
biota may be getting higher doses and if consumed
(shellfish), could be of concern,’’ he wrote later in an
e-mail, referring to organisms that dwell on the sea floor.
The study also found that the highest cesium values were not
necessarily from the samples collected closest to Fukushima,
he said, because eddies in the ocean currents keep the
material from being diluted in some spots farther offshore.
The overall results were consistent with those previously
found by Japanese scientists, Mr. Buesseler said.
He said more research was urgently needed to answer several
questions, including why the level of contamination offshore
near the plant was so high.
“Japan is leading the studies, but more work is needed than
any one country, or any one lab, can possibly carry out,” he
said.
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