The organic carbon generated biologically and distributed in the world ocean is intimately related to the functioning of the entire global carbon cycle as well to the ecology of the seas. The investigators on this project, who are established leaders in the study of the marine carbon cycle, will continue their research into the cycling of organic carbon in both its dissolved and particulate forms. The overall objective is to use the natural and anthropogenic radiocarbon (14C) in dissolved and particulate organic matter to estimate turnover times and reservoir sizes in the ocean. They will examine changes in the carbon reservoirs and turnover since the last measurements were made one decade ago in the North Atlantic and North Pacific basins. They will also attempt to constrain the residence time of upper ocean refractory dissolved organic carbon by surveying the 14C composition of dissolved and particulate organic matter in specific organic classes such as protein, carbohydrate, and lipids. Finally, they propose to measure 14C in bacterial nucleic acids to investigate bacterial utilization of old dissolved organic matter. The investigators anticipate that this work would lead to major new insights into the biogeochemical role played by these non-living forms of carbon in the world ocean.
