Fig. 2. Oxidative remobilization of biogenic uraninite [UO_2(s)] in the dithionite–citrate–bicarbonate (DCB)-treated sediment suspensions with variable concentrations of Fe(II) addition at pH 4 or 5 (a), 7 (b), and 9 (c). The total UO_2(s) in the system was 16 µmol/L (3808 µg/L).