English: Environmental processes controlling the apparent recalcitrance of oceanic DOC. The dots represent DOC molecules and arrows represent physicochemical and biological processes that impact DOC concentration and molecular composition. In the surface ocean, DOC derived from primary production is rapidly remineralized or transformed through microbial degradation (black arrow), photochemical degradation (yellow arrow), or particle exchange (green arrow). Labile components are removed down the water column and DOC becomes diluted by processes, such as particle exchange (brown arrow), sediment dissolution (gray arrow), and microbial reworking (white arrow), which continue to alter, add, and/or remove molecules from the bulk DOC pool. Thus, the apparent recalcitrance of DOC in the ocean’s interior is an emergent property that is largely controlled by environmental context.