Organic matter in the water column: future research challenges

Recent research has greatly changed our knowledge of processes affecting organic matter in the water column. Here we review some of this recent research and suggest several areas which are particularly challenging for future studies. Major areas discussed are newly developed methods of dissolved organic carbon (DOC) analysis and the implications of the results, and the potential significance of organic colloids in seawater. Recent advances in techniques for the analysis of small, labile organic molecules and in radiotracer techniques used to follow rates and mechanisms of biological consumption are also discussed. Ocean-atmosphere transport and photochemical processes can act as both sources and sinks of organic matter in the sea. This is an area where significant progress has been made recently. Finally, we discuss current knowledge of river transport to the oceans and particle sedimentation in the sea as well as some of the limitations on this knowledge.