Abstract
Marine dissolved organic carbon (DOC) has important roles in the cycling of carbon in the global ocean that are still being illuminated and characterized. The pool has long been recognized for serving as one of Earth’s major carbon reservoirs and as a substrate supporting the metabolism of innumerable heterotrophic microbes. Here, the dynamics of carbon processed through oceanic DOC are considered at their broadest spatial scales. The chapter concludes with our sense of the system and priorities for research in large-scale DOC dynamics. The chapter presents advances in understanding and should be read in the context of prior editions of this book and the many papers cited.