D'après une recherche effectuée par Lucas Whitefield, des traces de plutonium et de strontium auraient été décelées sur toute la côte ouest de l'Amérique du Nord.
Il aurait fait cette découverte en consultant la base de donnée gouvernementale états-unienne EPA-Radnet.
Il a consigné ses observations (en anglais) sur cette page :
https://docs.google.com/document/pub?id=1e0VxH-YSMw7dRlrVpmi69jpCWrwn8k1f0T2gZWWG73Q
Son étonnement provient du fait que cette information ne semble pas être diffusée dans les rapports publics.
Alexander Higgings reprend cette information en publiant sur son blog les résultats de la recherche de plutonium et de strontium :
Mais cette information semble difficile à confirmer aujourd'hui, quand on consulte la même base de donnée.
Lien vers la base de données d'EPA :
http://www.epa.gov/radiation/rert/radnet-sampling-data.html#all
Les traces de plutonium pourraient en fait être des restes des essais atomiques dans l'atmosphère. Ce commentaire de Semile, sur le site de A. Higgings développe cette idée :
lien :
Plutonium-239 background level
Atmosphere nuclear weapons testing, which ended in 1980, is the major source of plutonium contamination. Since this time, essentially all fallout 239Pu has been removed from the atmosphere,
allowing for measurement of baseline measurement of plutonium in air.
Air concentrations of 239Pu at the Pacific Northwest National Laboratory near Richland, Washington averaged 1.3×10-7 Bq/m3 (3.5×10-6 pCi/m3).
http://www.atsdr.cdc.gov/ToxProfiles/tp143-c6.pdf
3.5×10-6= 0.0000035pCi/m3 Plutonium-239
N.B RadNet Readings:
‘Description: The amount, activity, or concentration measured. Amounts can be zero, non-detect (ND), positive or negative. A negative result occurs when random effects and limitations in
themeasurement process cause the measured value for the sample to be less than that of the laboratory blank or background, which is subtracted from the sample measurement. Although negative
radioactivity is physically impossible, the inclusion of negative results allows better statistical analysis of the data.’
:.
This means the background level has been subtracted from the results i.e. the given levels are lower than actual amount present by ~0.0000035. If this is ~figure:
South of Japan:
Guam level = 4.4x than background [0.000012+0.00000350=1.55e-5 :. 1.55e-5/ 3.5e-6]
Saipan on 21st = 3.6x higher by 24th back to normal level
Mainland US figures that caught my attention (again plutonium-239 only):
3/15/2011
ANAHEIM CA -0.0000015
RIVERSIDE CA 0.0000013
3/18/2011
SAN FRANCISCO CA 0.0000065
SEATTLE WA -0.0000013
Between thee dates of 15-18th the levels rose in California ~3x higher than background level though was at ~background level in Washington on 18th.
The data is really small & this summary is to provoke more info to be released
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