Formation and protection of geopolymerized organic carbon in marine sediments by iron and manganese

Thursday 27 February 2020 - 14:00 to 15:00
NOC Southampton - Node Room (074/02) (Waterfront Campus).
Other Venue: 
NOC Southampton - Node room (064/03) Waterfront Campus)
Dr Oliver Moore (University of Leeds)

The preservation of organic carbon (OC) is fundamental to the Earth system.  In the marine environment, the balance between the degradation and preservation of OC in seawater exerts an important control on air-sea gas exchange, and thus short term climate, whilst in marine sediments, the burial of OC helps regulate atmospheric CO2 and O2, and thus planetary homeostasis, over geological time. On the other hand, it is well known that OC preservation is enhanced under a euxinic/reducing water column, however this does not explain why ~94% of OC burial occurs under an oxic water column on continental margins. The biogeochemical cycling of OC within marine systems and terrestrial systems has been linked to the cycling of Fe and Mn (hydr)oxide minerals. In fact, OC may be protected from microbial degradation by these minerals and ultimately buried with them. Yet despite decades of research, the fundamental mechanisms by which OC is associated with reactive Fe and Mn minerals remains elusive. Here, for the first time we show that under conditions approximating continental shelf marine porewater environments, reactive Fe and Mn catalyze condensation reactions of labile OC, which results in the production of recalcitrant geopolymerized substances (GPS) that display a similar structure to refractory OC found in marine systems.

Seminar category: 
POETS Corner