Redox iron sulfur silica
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REDOX: IRON, SULFUR, & SILICA. Redox Potential. pE = -log free electrons When corrected to pH 7 (H + = OH - ), called E h When E h positive – oxidizing environment When E h negative – reducing environment. Redox vs. pH. Redox ( mv ) of common liquids. Example of Redox data.

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Redox iron sulfur silica


Redox potential
Redox Potential

  • pE = -log free electrons

  • When corrected to pH 7 (H+ = OH-), called Eh

  • When Eh positive – oxidizing environment

  • When Eh negative – reducing environment

Redox vs ph
Redox vs. pH

Redox mv of common liquids
Redox (mv) of common liquids

Example of redox data
Example of Redox data

Ph and orp in lake skiennungen
pH and ORP in Lake Skiennungen

Fe mn in oligotrophic and eutrophic lakes
Fe & Mn in oligotrophic and eutrophic lakes

Redox sulfur and iron
Redox: Sulfur and Iron

Fe mn in crooked lake mesotrophic
Fe & Mn in Crooked lake(mesotrophic)

Fe mn in little crooked lake eutrophic
Fe & Mn in Little Crooked lake(eutrophic)

Iron oxidizing bacteria
Iron Oxidizing Bacteria

  • Gallionella (an iron-oxidizing bacterium)

  • 4Fe (HCO3)2 + O2 + 6H2O 4Fe (OH)3 + 4H2CO3 + 4CO2 + 58 kcal

Ferrobacillus iron bacteria
Ferrobacillus iron bacteria

  • 4FeCO3 + O2+ 6H2O Fe(OH)3 + 4CO2

Mn cycling relative to o 2
Mn cycling relative to O2

Redox and sulfur
REDOX and Sulfur

S in oligotrophic and eutrophic lakes
S in oligotrophic and eutrophic lakes

So 4 in a mesotrophic hardwater lake
SO4 in a mesotrophichardwater lake

So 4 budget for linsley pond
SO4 budget for Linsley Pond

Orp ph and sulfur bacteria
ORP, pH, and Sulfur bacteria

Autotrophic sulfur oxidizing bacteria and iron transformations
Autotrophic Sulfur-Oxidizing Bacteria and Iron Transformations

  • Thiobacillus

  • Some of the reactions that it can mediate

  • FeS2 + 3½O2+H2O FeSO4 + H2SO4

  • 2FeSO4 + ½O2+ H2SO4 Fe2(SO4)3 + H2O

Bacterial transformations of sulfur
Bacterial Transformations of Sulfur Transformations

  • Sulfate-Reducing Bacteria (heterotrophic and anaerobic)

  • Sulfur-Oxidizing Bacteria

    • Chemosynthetic

    • Pigmented Autotrophic

Sulfate reducing bacteria
Sulfate-Reducing Bacteria Transformations

  • Ex: Desulfovibrio

  • Heterotrophic and anaerobic

  • H2SO4 + 2(CH2O) 2CO2 2H2O + H2S

  • H2SO4 + 4H2 H2S + 4H2O

Chemosynthetic sulfur oxidizing bacteria
Chemosynthetic Sulfur-Oxidizing Bacteria Transformations

  • Ex: Beggiatoa

  • Deposit elemental S inside cell

  • H2S + ½O2 S + H2O

  • S + 1½O2 + H2O H2SO4

  • Ex: Thiobacillus

  • Deposit elemental S outside

  • 2Na2S2O3 + O2 2S + 2Na2SO4

Green sulfur bacteria
Green Sulfur Bacteria Transformations

  • Ex: Chlorobium

  • Uses a pigment similar to chlorophyll

  • CO2 + 2H2SLIGHT Food + H2O + 2S

  • 2CO2 + 2 H2O + H2S LIGHT Food + H2SO4

Purple sulfur bacteria
Purple Sulfur Bacteria Transformations

  • Ex: Chromatium

  • They deposit sulfur intracellularly

  • Same reactions as Chlorobium

Purple non sulfur bacteria
Purple Non-Sulfur Bacteria Transformations

  • Ex: Rhodobacter

  • Na2S2O3+2CO2 +3H2O LIGHT Food + Na2SO4 +H2SO4

Sulfate reduction in lake gek gel and the black sea
Sulfate reduction in Lake TransformationsGek Gel and the Black Sea

Distribution of sulfur in meromictic lake belovod
Distribution of sulfur in Transformationsmeromictic Lake Belovod

Abandoned mine drainage
Abandoned Mine Drainage Transformations

Amd discharges
AMD Discharges Transformations

Acid precipitation
Acid Precipitation Transformations

Si in lakes
Si in lakes Transformations

Some common diatoms
Some Common Diatoms Transformations

Si in oligotrophic lawrence lake
Si in Transformationsoligotrophic Lawrence Lake

Dynamics of diatom periphyton and plankton
Dynamics of diatom Transformationsperiphyton and plankton

Green algae and diatoms
Green Algae and Diatoms Transformations