Pathways Of Microbial Respiration Of Organic Carbon Flashcards
Fermentation of POC & DOC into simpler compounds: (2)
Anaerobic zone of soil.
POC anaerobically decomposed to DOC through fermentation.
Aerobic respiration of POC & DOC: (5)
Aerobic conditions, above water table.
Various decomposer organisms decay plant material through aerobic respiration - The energy released powers their metabolism.
Typically more than half the NPP in wetlands is decomposed aerobically.
DOC is reduced to DIC or to CO2.
POC is reduced to CO2.
POC & DOC oxidation through reduction of NO3- (4)
NO3- is used to oxidise organic carbon to CO2 by denitrification.
Only if there is a high enough concentration of NO3- in the soil.
Usually not a key pathway of carbon breakdown, unless receiving runoff high in NO3-, such as from agriculture.
In other wetlands, there is usually insufficient NO3- for denitrification to occur.
DOC oxidation through reduction of SO4 2- (5)
DOC can be oxidised to DIC by a sulfate reduction.
Occurs if there is little or no O2 or NO3- available.
Anaerobic process carried out by specialist bacteria.
Often dominates in estuaries, salt marshes and mangrove swamps as seawater has a constant supply of sulfate SO4 2-.
Less common in freshwater, as there are low levels of sulfate.
DOC oxidation by reduction of CO2: (2)
Carbon metabolism can occur through methangenesis, a chemical reaction creating methane, if oxygen, nitrogen or sulfate aren’t present.
Two types of reaction - The reduction of ethanoic acid and a reduction of CO2 using hydrogen.
The five major pathways in microbial respiration of organic carbon in wetland soils:
Aerobic respiration of POC and DOC,
Fermentation of POC and DOC into simpler compounds,
POC and DOC oxidation through reduction of NO3-,
DOC oxidation through reduction of sulfate SO4 2-,
DOC oxidation through reduction of CO2.
