Table A1.

Mineral concentrations and surface properties

	Goethite	Ferrihydrite	Gibbsite	Kaolinite	Illite
ρ (concentration in g l−1)	6·174	0·324	1	35·12	39·94
A (specific surface area in m2 g−1)	105a,*	750c	54d	23·6e	25·19h
Ns (site density in site nm−2)	6·15a	4c	4c	0·82e	2·5h
≡ X- (basal site density in mmol kg−1)	−	−	−	4·5f	5·15g
C1 (innersphere capacitance in F m−2)	0·9b	0·9†	1·1c	1·5g	1·5g
C2 (outersphere capacitance in F m−2)	0·74b	0·74†	0·74‡	5g	5g

* Values taken from: ^a Hiemstra and Van Riemsdijk (1996), ^b Hiemstra and Van Riemsdijk (2006), ^c Gustafsson (2001), ^e Manning and Goldberg (1996), ^g He et al. (1997), ^h Gu and Evans (2008).

^† Assumed to be equal to those of goethite; ^‡ assumed to be equal to those of Fe-oxides.