531
Glossary of Chemical Oceanography Terms
anoxic Waters
Aerobic Respiration: Bacterial oxidation of organic matter using oxygen.
Anaerobic Respiration: Bacterial oxidation that occurs without oxygen. Other sources of
electron acceptors are used, such as NO 3
– , MnO 2 , and SO 4
2– .
Anoxic: Devoid of oxygen.
Anoxic Interface: The interface between waters with and without oxygen. It is normally
controlled by the advection of oxygen into deep waters. This advection is limited by
a salinity gradient or a sill that separates the deep waters from outside deep waters
with oxygen.
Black Sea: The largest anoxic basin in the world. The waters below a depth of 200 m have
no oxygen, while the levels of hydrogen sulfide can be as high as 400 μM.
Cariaco Trench: An anoxic basin off the coast of Venezuela. The waters below a depth of
250 m are devoid of oxygen and have levels of hydrogen sulfide of 60 μM.
Electron Acceptor: A molecule or atom that can accept electrons.
Framvaren Fjord: An anoxic fjord in the south of Norway. The waters below 20 m are
devoid of oxygen and have hydrogen sulfide levels as high as 6 mM (the highest
recorded levels).
Goteland Deep: A deep basin in the Baltic Sea that has become anoxic over the years.
Hydrogen Sulfide: The common form of reduced sulfur present in waters devoid of oxygen. It is formed by the reduction of sulfate by bacteria.
Iron Reduction: The formation of Fe(II) from the reduction of the oxides of Fe(III) by photochemical reactions or by bacteria.
Manganese Reduction: The formation of Mn(II) from the reduction of the oxides of
Mn(IV) by bacteria.
Saanich Inlet: A fjord near Seattle, Washington, that becomes anoxic from time to time.
Sulfate Reduction: The formation of H 2 S from the reduction of SO 4
2– , normally by bacteria in waters that are devoid of oxygen.
Sulfur Oxidation: The oxidation of H 2 S with oxygen yields products such as polysulfides,
SO 4
2– , SO 3
2– , and S 2 O 3
2– .
Glossary of Chemical Oceanography Terms
anoxic Waters
Aerobic Respiration: Bacterial oxidation of organic matter using oxygen.
Anaerobic Respiration: Bacterial oxidation that occurs without oxygen. Other sources of
electron acceptors are used, such as NO 3
– , MnO 2 , and SO 4
2– .
Anoxic: Devoid of oxygen.
Anoxic Interface: The interface between waters with and without oxygen. It is normally
controlled by the advection of oxygen into deep waters. This advection is limited by
a salinity gradient or a sill that separates the deep waters from outside deep waters
with oxygen.
Black Sea: The largest anoxic basin in the world. The waters below a depth of 200 m have
no oxygen, while the levels of hydrogen sulfide can be as high as 400 μM.
Cariaco Trench: An anoxic basin off the coast of Venezuela. The waters below a depth of
250 m are devoid of oxygen and have levels of hydrogen sulfide of 60 μM.
Electron Acceptor: A molecule or atom that can accept electrons.
Framvaren Fjord: An anoxic fjord in the south of Norway. The waters below 20 m are
devoid of oxygen and have hydrogen sulfide levels as high as 6 mM (the highest
recorded levels).
Goteland Deep: A deep basin in the Baltic Sea that has become anoxic over the years.
Hydrogen Sulfide: The common form of reduced sulfur present in waters devoid of oxygen. It is formed by the reduction of sulfate by bacteria.
Iron Reduction: The formation of Fe(II) from the reduction of the oxides of Fe(III) by photochemical reactions or by bacteria.
Manganese Reduction: The formation of Mn(II) from the reduction of the oxides of
Mn(IV) by bacteria.
Saanich Inlet: A fjord near Seattle, Washington, that becomes anoxic from time to time.
Sulfate Reduction: The formation of H 2 S from the reduction of SO 4
2– , normally by bacteria in waters that are devoid of oxygen.
Sulfur Oxidation: The oxidation of H 2 S with oxygen yields products such as polysulfides,
SO 4
2– , SO 3
2– , and S 2 O 3
2– .