title: The size-reactivity continuum of major bioelements in the ocean.
abstract: Most of the carbon fixed in primary production is rapidly cycled and remineralized, leaving behind various forms of organic carbon that contribute to a vast reservoir of nonliving organic matter in seawater. Most of this carbon resides in dissolved molecules of varying bioavailability and reactivity, and aspects of the cycling of this carbon remain an enigma. The size-reactivity continuum model provides a conceptual framework for understanding the mechanisms governing the formation and mineralization of this carbon. In the seawater bioassay experiments that served as the original basis for this model, investigators observed that larger size classes of organic matter were more bioavailable and more rapidly remineralized by microbes than were smaller size classes. Studies of the chemical composition and radiocarbon content of marine organic matter have further indicated that the complexity and age of organic matter increase with decreasing molecular size. Biodegradation processes appear to shape the size distribution of organic matter and the nature of the small dissolved molecules that persist in the ocean.
authors: Department of Biological Sciences and Marine Science Program, University of South Carolina, Columbia, South Carolina 29208; email: benner@mailbox.sc.edu.
authors: Ronald
authors: R
authors: Benner
authors: Rainer M W
authors: RM
authors: Amon
mesh_terms: D000818:Animals; D002244:Carbon / Q000032:analysis*; D057486:Carbon Cycle; D002250:Carbon Radioisotopes / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology; D008962:Models, Theoretical; D009792:Oceans and Seas; D009930:Organic Chemicals / Q000737:chemistry; D010316:Particle Size; D010839:Phytoplankton / Q000737:chemistry; D012623:Seawater / Q000737:chemistry / Q000382:microbiology; D012995:Solubility; D015048:Zooplankton / Q000737:chemistry
chemical_list: D002250:Carbon Radioisotopes; D009930:Organic Chemicals; D002244:Carbon
keywords: bioreactivity; chemical complexity; dissolved organic matter; molecular size; ocean carbon cycle; size-reactivity continuum