L1 /
9
CH3041
REDOX PROGRESSIONS
Siderite
CH4
H2
HCO3–
Methane
formation
Anoxic-
DO < 1 µM Methanic
DO < 1 µM Methanic
H2S < 1 µM
Lots
Silicates
NH3
N2
Fe2+
(some Fe3+)
Mn2+
NO3–
•Dissolved metal ions
Nitrate,
MnO2,
Fe (III) reduction
Postoxic
DO < 1 µM
H2S < 1 µM
H2S < 1 µM
Low/
Minor
Metal
sulphides, e.g.,
•Pyrite
HCO3–
HS–
H3PO4
H+
SO42–
•Dissolved metal ions
Sulphate
reduction
Anoxic
DO < 1 µM
-sulfidic
H2S > 1 µM
DO < 1 µM
-sulfidic
H2S > 1 µM
Present
Metal
oxides, e.g.,
•Hematite
•Goethite
HCO3–
NO3–
H3PO4
H+
O2
•Dissolved metal ions
Aerobic
respiration
Oxic
DO > 30 µM
SubOxic
DO < 30 µM
DO > 1 µM
DO < 30 µM
DO > 1 µM
None
(almost)
Solid Phases Added to Sediments
Components Added to Aqueous Phase
Main Components Removed from Aqueous Phase
Dominant Microbial Reaction
Oxygenation Status
Organics
FeCO3 siderite
hematite Fe2O3
goethite FeOOH
goethite FeOOH
pyrite
FeS2
