As we ponder the natural pathways that could be perturbed to enhance ocean carbon uptake, it may be relevant to focus on existing reservoirs where carbon accumulates. One such reservoir, marine dissolved organic carbon (DOC), is particularly intriguing, because it stores carbon under relatively mild environmental conditions. The reduced carbon in this reservoir consists of diverse populations of molecules that are removed on different timescales, ranging from minutes to millennia. Short-lived DOC in the ocean appears to be primarily governed by well-understood and well-constrained production and removal pathways, whereas the processes that control the size and age of the long-lived reservoir remain mysterious. In this talk, I will discuss perspectives gained by examining the chemical composition of marine DOC and argue that intrinsic chemical features contribute to the long-term preservation of DOC in the marine environment. These findings provide chemical models for long-lived DOC that can be used in experiments to examine factors that control its stability. Such experiments may offer insights into the sensitivity of the current DOC reservoir to global change and its capacity for increased carbon storage.

marine dissolved organic carbon, long-term preservation, intrinsic stability