LOAC-OCB v1.0: A model to explore terrestrial organic carbon burial along the land-to-ocean aquatic continuum

Abstract. Various aquatic environments along the land-to-ocean aquatic continuum (LOAC) retain and potentially bury significant amounts of organic carbon (OC). However, the total amount of buried OC, the relative importance of different ecosystems in this process, and the hierarchical influence of upstream systems on downstream burial dynamics remain uncertain. A major limitation in quantifying these processes is the absence of an integrative, process-based modeling framework operating at Earth system scales. Here, we present the LOAC-OCB model, the first global tool for simulating the transport and burial of particulate terrestrial OC along the LOAC. Using openly available data products, this steady-state model provides spatially explicit organic carbon burial (OCB) estimates at 0.0625 x 0.0625° spatial scale, incorporating 170,997 lakes, 6,000 reservoirs, 3,515 floodplains, and 377 coastal ecosystems worldwide. The model was evaluated through a multi-faceted validation using independent global datasets and previously published estimates. Our results indicate that the LOAC buries approximately 52.1 % of the particulate OC imported from terrestrial ecosystems, with reservoirs and coastal ecosystems showing the highest median OCB rates (94.3 ± 3.8 and 53.1 ± 14.1 g C m-2 y-1, respectively). Additionally, floodplains and reservoirs exert the greatest influence on global OCB fluxes, contributing 0.97 and 0.72 Pg C y-1, respectively. LOAC-OCB also enables further exploration of the interactions among aquatic ecosystems, shedding light on their interconnected roles in the global distribution of OCB and the relevance of burial processes in modulating terrestrial-to-ocean OC fluxes.