The principal investigator will consider the question of why dissolved organic carbon (DOC) concentrations in seawater are nearly invariable worldwide. His recent studies indicate that DOC recovered by ultrafiltration is constituted by a well-defined set of acylated polysaccharides (sugar polymers), which appear to be of algal origin and to be ubiquitous in seawater. Now, the PI will continue a detailed study of the structure and composition of these polysaccharides in the >500 Dalton size fraction of seawater. Additionally, radiocarbon assays will be used to study their removal from the surface ocean by macroaggregates and their transport to the deep ocean. Major portions of the field work will be carried out through participation on funded cruises of other NSF investigators at the University of California at Irvine and the Virginia Institute of Marine Science who are currently studying DOC cycling in the deep ocean.
