EPA method 908.0 for total Uranium. Also EPA method 908.1, fluorometric.
Secondary enrichment can occur when reducing conditions cause the uranium to precipitate out.
This leads to elevated 226 Ra. Thorium may be more soluble in the presence of high concentrations of organic material. May end up in solution via alpha recoil. EPA method 908.0 for total Uranium. Also EPA method 908.1, fluorometric.