In article ,
Bill who putters wrote:

Strange thought entered my mind concerning the tragedy in Japan. With
the higher levers do radiation entering the ocean. With this make the
fish unsuitable for harvesting and will this enable the fish populations
to have a long respite ?
Anyone know about the ramifications ?

Woods Hole Chimes in.

http://www.sciencenewsline.com/natur...910240000.html


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Impact of radiation from Japan: Woods Hole expert answers your questions

March 29, 2011 " Woods Hole Oceanographic Institution

On March 11, 2011 a magnitude 9.0 earthquake one of the largest ever
recorded, occurred 80 miles off the coast of Japan. The earthquake
created a series of tsunamis, the largest estimated to be over 30-feet,
that swept ashore along the northeast coast of the main island, Honshu.
In addition to killing more than 9,000 people, the earthquake and
tsunamis badly damaged the Fukushima Daiichi nuclear power plant,
eventually causing four of the six reactors there to release radiation
into the atmosphere and ocean.

What is being released from the Fukushima reactors and how dangerous is
it?
So far, we know that releases from the Fukushima reactors have been
primarily composed of two radioactive substances: iodine-131 and
cesium-137. In large doses, both of these isotopes or radionuclides, as
they are called, can cause long-term health problems. So far, however,
only those working at the plant face the most serious exposure.

More about iodine-131 and cesium-137

Are there different types of radiation?
In general, there are two types of radiation, ionizing and non-ionizing.
Non-ionizing radiation includes visible light and radio waves things
that, as the name implies, do not have the ability to form charged ions
in other materials. Ionizing radiation, however, can and as a result
presents a serious health threat because it can alter the atomic
structure of living tissue. Ionizing radiation also comes in several
different types, including alpha, beta, and gamma radiation, all with
different degrees of concern and health impacts.

More about types of radiation

How long is the radiation from these substances a risk to humans and the
environment?
Radioactive materials are, by their very nature, unstable and decline in
strength over time. This change is measured in half-lives the length
of time it takes for the radiation to decrease by one-half. Every
radioactive substance has a different half-life, ranging from fractions
of a second to billions of years. Those with longer half-lives are
potentially more difficult to deal with because they remain radioactive
for longer periods of time. Cesium-137, for example, has a half-life of
30 years and so is a potentially serious health threat for decades or
centuries. Iodine-131, on the other hand, has a half-life of just 8 days
and so loses much of its potency after just days and effectively
disappears after one to two months.

More about half-lives

How far can radiation travel?
Ionizing radiation itself cannot travel very far through the air.
Typically, dust and other particles, seawater and other liquids, or even
gases become radioactive due to exposure to radionuclides and are then
transported great distances. In the months and years after the explosion
at the Chernobyl nuclear power plant in Ukraine scientists were able to
track the spread of radioactive material in the atmosphere and the ocean
around the globe. Within a week after the explosions at the Fukushima
plant, there were reports of very small increases in the continental U.S.

More about mapping and monitoring radiation from Japan

What is the normal background level of radiation?
The normal background level of radiation is different for different
places on the planet. Radiation in some places is higher because these
receive less of the natural protection offered by Earth s atmosphere or
because they are in places where the surrounding rocks contain more
radioactive substances, such as radon. In the ocean, the largest source
of radiation comes from naturally occurring substances such as
potassium-40 and uranium-238, which are found at levels 1,000 to 10,000
times higher than any human sources of radiation (see illustration). The
largest human release of radionuclides was the result of atmospheric
nuclear weapons tests carried out by the U.S., French and British during
the 1950s and 60s. Despite even the high concentration of nuclear
fallout in the Pacific caused by U.S. tests on the Marshall Islands,
there is no known adverse health effect associated with eating seafood
from the Pacific.

More about natural background radiation

If there are warnings in Japan about eating certain products
contaminated by radiation, why is it safe to eat the seafood?
Except for the vicinity of the reactors, seafood and other products
taken from the sea should be safe for human consumption. Radiation
levels in seafood should continue to be monitored, of course, but
radiation in the ocean will very quickly become diluted and should not
be a problem beyond the coast of Japan. The same is true of radiation
carried by winds around the globe. However, crops and other vegetation
near the reactor site (including grass that cows eat to produce milk)
that receive fallout from the atmosphere build up radioactivity can
remain contaminated even if washed. When these foods are consumed, a
person receives much of this dose internally, often a more severe
pathway to receive radiation than by external exposure.

More about radiation and food safety

How does radiation released from the Japanese reactors compare to the
accident at Chernobyl?
We still don t know exactly how much radiation was released at Fukushima
or how much will ultimately be released before the reactors are fully
contained. The Chernobyl accident was much more violent and resulted in
a complete breach of the reactor vessel. The event also started a very
hot graphite fire that released large amounts of radioactive material
into the atmosphere equivalent to between 3 and 5 percent of the total
reactor inventory. Winds carried the radioactive fallout first to the
north and eventually into the Black Sea to the south. Radiation in the
Black Sea and Baltic Sea, though elevated, remained well below EPA
guidelines for radiation in drinking water.

More about the after-effects of Chernobyl

How will the radioactive material released in Japan affect humans?
It s still too early to tell, but unless we learn that the type or
amount of material released is larger than reported or changes
dramatically it will likely have significant long-term impacts only
within a few miles or tens of miles from the plant. This is because the
further the radioactive material travels, the more dispersed (and the
less harmful) it becomes. The effects of Chernobyl were felt well beyond
Ukraine in part because the amount of radioactive material released was
large and because it also included substances such as plutonium that
have very long half-lives. That being said, people who live near the
plants would be wise to follow the minimum safe distance restrictions
and other precautions recommended by the Japanese government and at-risk
individuals should take suggested extra precautions such as taking
potassium iodide to avoid thyroid problems.

More about radiation in the environment

Is there any danger to people in other parts of the world?
Prevailing winds over from Japan blow east towards North America; ocean
currents in the region also flow generally east into the North Pacific,
though much slower than winds. However, radioactive materials carried by
winds or currents will be quickly diluted until the radiation falls
below background levels. Unless radioactivity from Fukushima finds its
way directly to another part of the world through food or other
commercial products, it should become sufficiently dispersed over time
that it will not prove to be a serious health threat elsewhere. Over
time, the radioactivity associated with the Fukushima plant should
continue to decline even further. In particular, radiation from
iodine-131 will decay very quickly, but even the effects of the much
longer-lived cesium-137 will decline in strength. Today, people who eat
seafood from the Black Sea, which received a considerable amount of
fallout from Chernobyl (see map), consume a dose of cesium-137 that is
100 times below the one provided by a naturally occurring radionuclide,
polonium-210, that is not considered harmful to animals or humans.

More about the environmental health effects of radiation

Why is this event of interest to oceanographers?
Oceanographers use substances called tracers to study the path and rate
of ocean currents and of processes such as mixing that are important
parts of the global ocean and climate systems. There are many different
radionuclides that scientists use as "clocks" to measure how fast the
ocean mixes and sediment accumulates on the seafloor. Some of these
substances are natural, but many are the result of human activity, such
as the Chernobyl accident or nuclear weapons testing, and now releases
at Fukushima.

More about radioactive tracers in the ocean

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Bill S. Jersey USA zone 5 shade garden

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