Fig. 3. Effect of various single reagent-grade amendments (hydroxyapatite, illite, zeolite) on U concentration (A) and pH (B) after equilibrating for 30 d in 1.0 mM CaCl₂. Figure C is the subsequent 1.0 mol L^-1 NH₄Cl-extractable U after equilibration. Error bars indicate the standard deviation of the means.