Cesium137 and a fresh water pond

Submitted by Anonymous on Tue, 2011-04-05 17:12

Thanks for fielding these questions.

The pond: about 756 L; water is not in contact with the ground as the pond is an above ground vinyl enclosure; passive filtration via external (approx. 75 L.) tank; water volume circulates about once per hour. Three aquatic turtles; two carp; a seemingly uncountable number of mosquito fish and a rooted aquatic plant reside in the pond.

A general question:
What might be the behavior of Cesium-137 after it enters the fresh water pond from rainfall?

Specific questions:
1) Will the isotope evaporate? (sea level)
2) Does it sink into the ooze at the pond bottom?
3) Do microbial organisms mitigate the radioactive rate of decay?
4) Is there a simple calculation for determining the dilution?

Related question:
Does the unit measure of Becquerel relate to a specific amount of mass present in the water?

Thanks so much for the education!

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1) Cs is not very volatile,

Submitted by Brian (not verified) on Tue, 2011-04-05 17:34.

1) Cs is not very volatile, so it probably will not evaporate.
2) It might sink into the ooze, or stay dissolved in the water.
3) Microbial organisms do not affect the radioactive rate of decay. The decay rate is a purely nuclear process, so chemistry, etc. have no effect on it (except in a few rare cases which do not apply here - electron capture decay of ionized atoms).
4) Yes. If you know how many inches of rain have fallen, multiply by surface area of the pond in inches, and by 0.016387064 liters per cubic inch to get the liters of rain deposited into the pond. The dilution factor is (liters of rain) / (liters of rain + 756 L).

The unit of Bq measures the number of decays per second. For a specific isotope, this is equivalent to a certain mass of the radioactive isotope.

Brian [BRAWM team member]

FW pond

Submitted by Jonathan (not verified) on Tue, 2011-04-05 17:57.

Thanks, Brian.

Celsium 137 and grass/soil?

Submitted by Anonymous (not verified) on Tue, 2011-04-05 18:18.

After all the rain we had a few days back, I was wondering what happens to Celsium 137 when it lands on grass/gardens etc. Does it go into the ground and deposit? I know they have long half-lives and am wondering if our land will continue to stay contaminated long term.
Thanks for providing such a great to the public.