An ocean current called the North Pacific Gyre is bringing Japanese radiation to the West Coast of North America:
While
many people assume that the ocean will dilute the Fukushima radiation, a
previously-secret 1955 U.S. government report concluded that the ocean
may not adequately dilute radiation from nuclear accidents, and there
could be “pockets” and “streams” of highly-concentrated radiation. The University of Hawaii’s International Pacific Research Center created a graphic showing the projected dispersion of debris from Japan: Last
year, scientists from the National Oceanic and Atmospheric
Administration's (NOAA) Pacific Marine Environmental Laboratory and 3
scientists from the GEOMAR Research Center for Marine Geosciences showed
that radiation on the West Coast of North America could end up being 10 times higher than in Japan:
After
10 years the concentrations become nearly homogeneous over the whole
Pacific, with higher values in the east, extending along the North
American coast with a maximum (~1 × 10?4) off Baja California.
***
With
caution given to the various idealizations (unknown actual oceanic
state during release, unknown release area, no biological effects
included, see section 3.4), the following conclusions may be drawn. (i)
Dilution due to swift horizontal and vertical dispersion in the vicinity
of the energetic Kuroshio regime leads to a rapid decrease of
radioactivity levels during the first 2 years, with a decline of
near-surface peak concentrations to values around 10 Bq m?3 (based on a
total input of 10 PBq). The strong lateral dispersion, related to the
vigorous eddy fields in the mid-latitude western Pacific, appears
significantly under-estimated in the non-eddying (0.5°) model version.
(ii) The subsequent
pace of dilution is strongly reduced, owing to the eastward advection of
the main tracer cloud towards the much less energetic areas of the
central and eastern North Pacific. (iii) The magnitude of
additional peak radioactivity should drop to values comparable to the
pre-Fukushima levels after 6–9 years (i.e. total peak concentrations
would then have declined below twice pre-Fukushima levels). (iv) By then
the tracer cloud will span almost the entire North Pacific, with peak concentrations off the North American coast an order-of-magnitude higher than in the western Pacific.
***
And
a team of top Chinese scientists has just published a study in the
Science China Earth Sciences journal showing that Fukushima nuclear
pollution is becominghttp://link.springer.com/article/10.1007/s11430-012-4520-2">more concentrated as
it approaches the West Coast of the United States, that the plume
crosses the ocean in a nearly straight line toward North America, and
that it appears to stay together with little dispersion:
On
March 30, 2011, the Japan Central News Agency reported the monitored
radioactive pollutions that were 4000 times higher than the standard
level. Whether or not these nuclear pollutants will be transported to
the Pacific-neighboring countries through oceanic circulations becomes a
world-wide concern.
***
The
time scale of the nuclear pollutants reaching the west coast of America
is 3.2 years if it is estimated using the surface drifting buoys and
3.9 years if it is estimated using the nuclear pollutant particulate
tracers.
***
The
half life of cesium-137 is so long that it produces more damage to
human. Figure 4 gives the examples of the distribution of the impact
strength of Cesium-137 at year 1.5 (panel (a)), year 3.5 (panel (b)),
and year 4 (panel (c)).
***
It
is worth noting that due to the current near the shore cannot be well
reconstructed by the global ocean reanalysis, some nuclear pollutant
particulate tracers may come to rest in near shore area, which may
result in additional uncertainty in the estimation of the impact
strength.
***
Since
the major transport mechanism of nuclear pollutants for the west coast
of America is the Kuroshio-extension currents, after four years, the
impact strength of
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