
Florida sinkhole causes radioactive water to leak into aquifer - jburgess777
http://www.bbc.co.uk/news/world-us-canada-37390562
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HillaryBriss
> _The water contained phosphogypsum, a slightly radioactive by-product from
> the production of fertilizer._

The wikipedia article on phosphogypsum is not particularly reassuring:

 _...the marine-deposited phosphate ore from central Florida is weakly
radioactive, and as such, the phosphogypsum by-product (in which the
radionuclides are somewhat concentrated) is too radioactive to be used for
most applications. As a result, there are about 1 billion tons of
phosphogypsum stacked in 25 stacks in Florida (22 are in central Florida) and
about 30 million new tons are generated each year._

[https://en.wikipedia.org/wiki/Phosphogypsum](https://en.wikipedia.org/wiki/Phosphogypsum)

How long does phosphogypsum stay radioactive?

~~~
m0rphling
From that wiki page:

 _Phosphogypsum is radioactive due to the presence of naturally occurring
uranium and thorium_

 _The United States Environmental Protection Agency has banned most
applications of phosphogypsum with a radium-226 concentration of greater than
10 picocurie /gram (0.4 Bq/g)._

[https://en.wikipedia.org/wiki/Isotopes_of_radium#Radium-226](https://en.wikipedia.org/wiki/Isotopes_of_radium#Radium-226)

 _The longest lived, and most common, isotope of radium is 226Ra with a half-
life of 1,600 years. 226Ra occurs in the decay chain of 238U (often referred
to as the radium series.)_

With a half-life of 1600 years for Radium-226, quite a long time.

