[cs_content][cs_section parallax=”false” separator_top_type=”none” separator_top_height=”50px” separator_top_angle_point=”50″ separator_bottom_type=”none” separator_bottom_height=”50px” separator_bottom_angle_point=”50″ style=”margin: 0px;padding: 45px 0px;”][cs_row inner_container=”true” marginless_columns=”false” style=”margin: 0px auto;padding: 0px;”][cs_column fade=”false” fade_animation=”in” fade_animation_offset=”45px” fade_duration=”750″ type=”1/1″ style=”padding: 0px;”][cs_text]Shipwrecks and Salvage > 6. Corrosion at Depths >
Describe the action of sulfate reducing bacteria around deep wrecks[/cs_text][/cs_column][/cs_row][/cs_section][cs_section parallax=”false” separator_top_type=”none” separator_top_height=”50px” separator_top_angle_point=”50″ separator_bottom_type=”none” separator_bottom_height=”50px” separator_bottom_angle_point=”50″ style=”margin: 0px;padding: 45px 0px;”][cs_row inner_container=”true” marginless_columns=”false” style=”margin: 0px auto;padding: 0px;”][cs_column fade=”false” fade_animation=”in” fade_animation_offset=”45px” fade_duration=”750″ type=”1/1″ style=”padding: 0px;”][cs_text]
- Seawater contains approximately 840 ppm of sulfates.
- Much corrosion of metals in deep water is caused by anaerobic bacteria that reduce sulfate to sulfide:
SO42- + 5H2O + 8e– → HS– + 9OH–
- This reduction half-equation is accompanied by the oxidation half-equation of the metal involved, such as iron:
Fe → Fe2+ + 2e–
- Combining the above two equations:
4Fe + SO42– + 5H2O → 4Fe2+ + HS– + 9OH–
- The products react to form the insoluble compounds of iron sulfide and iron hydroxide:
4Fe2+ + HS– + 7OH– → FeS(s) +3Fe(OH)2(s) + H2O(l)
- The main sulfate-reducing bacterium is Sporovibrio desulfuricans, which obtains energy from the reduction process.
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