Figure 2 Sed Geo 94
Figure 2.
pH-pE(Eh)
diagram for Fe species in seawater (1 atm, 25 °C, 35 ppt. salinity, total dissolved sulfur species: 28 mM (activity coefficient, 0.12; Garrels and Christ, 1965, p.l03). The area of interest is within the stability field of water-- below the oxidation of H
2
O to O
2
, and above reduction of H
2
O to H
2
.
Shaded areas
show mineral phase stable at designated concentrations of dissolved Fe.
Lightly shaded areas
indicate region in which mineral dissolves until concentrations observed under some anoxic conditions are reached.
Reduction of SO
4
2-
to H
2
S and HS
-
(concentration independent) is shown by the
long dashes;
reduction of NO
3
to N
2
is indicated by the
line of short dashes
(concentration independent ).
Solubility of Fe species is calculated at approximate oxic (10-9 M; Gordon et al., 1982) and anoxic ( 10-6 M; Jacobs et al., 1987) concentrations.
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Pe
pH
[H
+
] in ppm
Log PO
2
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