How much of the Cesium found in vegetables is simply leftover from Chernobyl?
Berkeley nuclear engineering team:
I was wondering if you had an estimate about how much of the Cesium-137 you have detected in leafy greens, mushrooms, grass, etc might be left-over from Chernobyl?
Also, does anybody have an estimate of the Cesium fallout over California from Chernobyl?
This site:
http://www.davistownmuseum.org/cbm/Rad7c.html#USA
claims that the amount of Cs-137 fallout over Washington state from Chernobyl was significantly higher (at 300 Bq/m2) than what can be inferred from the data published here (50 Bq/m2).
Can anybody comment on this?
Can anybody comment on this? Thanks!
Cesium found in vegetables
My experience says the local deposition of radionuclides may be strongly dependent on the local wheather conditions during the plume spreading, mainly rain/snow affect the plume washout to the ground. Infact local conditions may cause relevant differences in depositions in not-too-far from each other locations. So it could happen you may measure radioactivity in "wide ranges", for example a valid range could be 10-1000 Bq/m^2 or 5-500 Bq/m^2.
At the time of Chernobyl we measured roughly 1000-10000 Bq/m^2 of 137Cs and 10-100 Bq/m^2 just a few km away.
Most important thing regarding deposition, you can remove about 90% of the deposited radioactivity (namely I-131 and Cs-134/137) just washing the vegetables before consumption with fresh water.
On the contrary, when radioactivity (mainly Cs-137) moves to the ground and vegetables grow in that place, you can't remove it washing because the vegetable capted the radioactivity while growing (Cesium behaves like Potassium that is uptaken by vegetable's roots).
The FAO consumption limit for Cs-137 for food "on international trade routs" is 1000 Bq/kg and it does mean you receive a committed dose of 1 mSv eating that kind of food for a whole year without any precautions.
Conclusion: food concern for far-away nuclear accidents is not a forced countermeasure (like the ones in Fukushima prefecture now) but a way show to the public that there isn't a risk situation.
It's a real concern for near-to-accident regions.
/regards
Sergio Manera (radioprotection and environmental measurements head LENA - University of Pavia)
Hi Sergio, Thank you for
Hi Sergio, Thank you for your explanation. It is so awesome for me to find an italian scientist here on this website. I am italian as well, at the moment living in the States, and I was wondering if you could give me an email address that I can use to ask you a few questions. I would really appreciate it. Thanks so much again. Buona giornata.
Thank you (from the original
Thank you (from the original question poster). I still wonder if the deposition from Fukushima we experienced on the US west coast is small compared to the deposition we had after chernobyl. I wonder in particular if the Cs-137 that has been measured in vegetables and mushrooms here recently is leftover from Chernobyl, as opposed to fallout from Fukushima. The Chernobyl leftover should still be at 50% of the original deposition (since we've only been through one half-life of Cs-137).
Some of the cesium-137 they
Some of the cesium-137 they are finding could also be attributed to the nuclear reactors in the california area releasing their effluents into the air and water on a yearly basis. Some of these radioisotopes would raise the background levels I would think.
Ty
Thanks so much for this info.
Now that Dr. Chivers is
Now that Dr. Chivers is posting again, I'll bump up this question which seems very relevant.
Interesting question...
Answers?
Hello, anybody reading this?
Just wondering...
bump
bump
how do you even read these results?
i get for milk for example
best by date of
4/16/2011
a reading of
0.22 ± 0.04 (12,200)
does that mean on 4/16 the measurement should be .22?
does that mean when it was bottled the measurement should have been .22?
does that mean when the test was run which there isn't a date on which
the measurement was taken. If milk was bottled 20 days prior,
and these are the measurement when the sample was tested , doesnt that mean
the initial concentration on the day it was bottled is extremely higher?
without a date that tells you when it this .22 was measured the values
are misleading
Not sure what numbers you're
Not sure what numbers you're referring to since you're not providing a source, and so I'm not sure how it relates to my original post. Anyway, looking forward to comments by Dr. Chvers et al.
sorry
meant the UC Berkeley milk readings on this website.