Organic carbon burial with reactive iron across global environments

Abstract

The burial of carbon in the marine realm exerts a controlling influence on the global carbon cycle (Falkowski et al., 2000). In particular, the burial of organic carbon (OC) in marine sediments is the largest long-term net sink for carbon on Earth (Burdige, 2007), with 200 megatonnes of carbon buried in this manner per year (Mt C yr −1 , Canadell et al., 2021). Thus, OC burial in marine sediments plays a key role in controlling atmospheric CO 2 on geological timescales. Therefore, knowing the factors controlling the size, efficacy, and longevity of this sink is vital for understanding long-term carbon cycling (Burdige, 2007;Hedges & Keil, 1995).The vast majority of OC reaching the seafloor is remineralized before burial within the sediment (on average 87% of OC is remineralized at the sediment water interface; Burdige, 2007), meaning it returns to the equilibrating ocean-atmosphere CO 2 system. Burial of the OC fraction which does not get remineralized is highly dependent on