|Reburial of fossil organic carbon in marine sediments|
Dickens, A.F.; Gélinas, Y.; Masiello, C.A.; Wakeham, S.; Hedges, J.I. (2004). Reburial of fossil organic carbon in marine sediments. Nature (Lond.) 427(6972): 336-339
In: Nature: International Weekly Journal of Science. Nature Publishing Group: London. ISSN 0028-0836, more
Burying; Fossils; Organic carbon; Sedimentation; Marine
|Authors|| || Top |
- Dickens, A.F.
- Gélinas, Y.
- Masiello, C.A.
Marine sediments act as the ultimate sink for organic carbon,sequestering otherwise rapidly cycling carbon for geologic timescales.Sedimentary organic carbon burial appears to be controlledby oxygen exposure time in situ, and much research hasfocused on understanding the mechanisms of preservation oforganic carbon. In this context, combustion-derived blackcarbon has received attention as a form of refractory organiccarbon that may be preferentially preserved in soils andsediments. However, little is understood about the environmentalroles, transport and distribution of black carbon.Here weapply isotopic analyses to graphitic black carbon samples isolatedfrom pre-industrial marine and terrestrial sediments. Wefind that this material is terrestrially derived and almost entirelydepleted of radiocarbon, suggesting that it is graphite weatheredfrom rocks, rather than a combustion product. The widespreadpresence of fossil graphitic black carbon in sediments has thereforeprobably led to significant overestimates of burial of combustion-derived black carbon in marine sediments. It could beresponsible for biasing radiocarbon dating of sedimentaryorganic carbon, and also reveals a closed loop in the carboncycle. Depending on its susceptibility to oxidation, this recycledcarbon may be locked away from the biologically mediatedcarbon cycle for many geologic cycles.