G02_P08

Organic carbon cycling in the deep ocean: Implications from radiocarbon

Kim M^1,2,3,  Hwang J², Haghipour N^3,4, Eglinton T³

¹Kyungpook National University, Daegu, South Korea, ²School of Earth and Environmental Sciences/Research Institute of Oceanography, Seoul National University, Seoul, South Korea, ³Geological Institute, Swiss Federal Institute of Technology in Zürich (ETHZ), Zurich, Switzerland, ⁴Laboratory of Ion Beam Physics, ETH Zürich, Zurich, Switzerland

The transport of carbon from surface waters to the deep ocean via primary production and subsequent export of POC, known as the biological carbon pump, is a crucial process for sequestration of atmospheric CO₂. Large-scale sediment trap studies have advanced our understanding of material fluxes during vertical transit from surface to deep waters. However, despite the potential importance in the oceanic carbon cycle, the global feature of lateral supply of aged organic matter hosted on lithogenic particles derived from sediment resuspension has not been systematically examined.

Here I summarize the results of previous studies that have insights on the lateral transport of aged organic matter: Amundsen Sea, East/Japan Sea, deep abyssal Pacific, and the Northwest Atlantic. Especially in Kim et al. (2020), we compiled concentrations and fluxes of lithogenic material in the ocean on a global-scale by using literature data of sediment trap studies to understand the contribution of resuspended sediment to sinking particulate matter. Examination of Δ¹⁴C values of sinking POC revealed strong relationships with parameters that represent contribution of resuspended sediment. We then derive estimates for the contribution of aged POC from sediment resuspension to sinking POC based on these relationships and global lithogenic material flux data. Based on this relationship, and the global mean of lithogenic content of sinking particulate matter, we calculate that aged POC from sediment resuspension comprises 3~5 % of sinking POC intercepted by sediment traps.