Table 1.

Solid phase characteristics for the four types of magnetite used in the experiments

Magnetite	Fe(II)/Fe(III)a	Size (nm)b	Size (nm)c	BET surface area (m2/g)d
Biogenic	0.40 ± 0.01	13.6 ± 2.1	11.4	53.7
13 nm	0.37 ± 0.01	13.2 ± 2.4	12.1	64.6
7 nm	0.21 ± 0.01	7.1 ± 1.2	6.6	156.3
500 nm	0.53 ± 0.03	524 ± 156	N/A	10.7

^aBased on ferrozine analysis of the solid phase equilibrated in bicarbonate buffer

^bBased on TEM analysis of bicarbonate buffered sample

^cBased on X-ray diffraction analysis of bicarbonate buffered sample

^dOn magnetite samples stored in anoxic MQ H₂O