Fig. 3. X-ray diffraction patterns of the (a) <53 µm and (b) >53 µm fractions of the untreated and treated sediments with 4 mol L^-1 NaOH, 1 mol L^-1 NaNO₃, and 0.88 mol L^-1 Al(NO₃)₃ solution at 7 d. The horizontal lines are the characteristic peaks of nitrate–cancrinite (Buhl et al., 2000).