Patterns and drivers of sedimentary carbon in global aquatic ecosystems during the Anthropocene.

Aquatic ecosystems serve as critical carbon sinks, with sediments playing a key role in long-term organic carbon sequestration. However, the global patterns and trajectories of sedimentary total organic carbon concentration (TOC) and organic carbon burial rates (OC-BR) during the Anthropocene remain poorly constrained. Here, we present a comprehensive global synthesis of sediment core records from lakes, reservoirs, inland wetlands, and coastal systems, integrating over 18,000 rows data from 585 sites across diverse climatic and geographic settings. Generally, our results show that both TOC and OC-BR increased since the 1950s-1960s, coinciding with the onset of the Great Acceleration. These trends are primarily attributable to anthropogenic-driven changes in temperature, atmospheric CO₂, and nitrogen deposition. Spatially, TOC and OC‑BR exhibit higher values in shallow, anthropogenically influenced, low‑latitude regions, though carbon sequestration efficiency varies considerably across ecosystem types. Projections under future socio-economic scenarios suggest that sedimentary carbon sequestration may approach a ceiling (e.g. sedimentary carbon-store capacity could not increase without limitation), limiting the future capacity of aquatic systems as carbon sinks. These findings highlight the influence of climate change on sedimentary systems during the Anthropocene epoch.