Organic matter burial flux

Using the simplihcation that AM JAt = 0, Equation (18) reduces to an equation relating the organic matter burial flux Fbg in terms of other known entities ... 

Organic burial efficiency the accumulation rate of organic matter below the active zone of diagenesis divided by the organic matter flux to surface sediments. 

Although photosynthesis is the ultimate source of O2 to the atmosphere, in reality photosynthesis and aerobic respiration rates are very closely coupled. If they were not, major imbalances in atmospheric CO2, O2, and carbon isotopes would result. Only a small fraction of primary production (from photosynthesis) escapes respiration in the water column or sediment to become buried in deep sediments and ultimately sedimentary rocks. This flux of buried organic matter is in elfect net photosynthesis , or total photosynthesis minus respiration. Thus, while over timescales of days to months, dissolved and atmospheric O2 may respond to relative rates of photosynthesis or respiration, on longer timescales it is burial of organic matter in sediments (the net photosynthesis ) that matters. Averaged over hundreds of years or longer, burial of organic matter equates to release of O2 into the atmosphere - - ocean system ... 

If for every 1,000 rounds of photosynthesis there are 999 rounds of respiration, the net result is one round of organic matter produced by photosynthesis that is not consumed by aerobic respiration. The burial flux of organic matter in sediments represents this lack of respiration, and as such is a net flux of O2 to the atmosphere. In geochemists shorthand, we represent this by the reaction... 

Figure 14 The simplified geochemical cycles of carbon and sulfur, including burial and weathering of sedimentary carbonates, organic matter, evaporites, and sulfides. The relative fluxes of burial and weathering of organic matter and sulfide minerals plays a strong role in controlling the concentration of atmospheric O2.

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