Re:Florida sinkhole causes radioactive water to leak into aq...
by m0rphling on Saturday September 17, 2016 @04:41AM
(#12519711)
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
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.
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
How long does phosphogypsum stay radioactive?