INTRODUCTION 



It has been postulated that ocean margins are significant sinks for carbon on a global 

 scale, however, there is little oceanographic data to support or refute this claim. Given this 

 uncertain role in the cycle of atmospheric carbon dioxide, and the potential impact of man's 

 activities in margin regions, it is important to obtain an improved understanding of the sources, 

 sinks and fate of carbon in ocean margins in general. The U.S. Department of Energy's 

 Ocean Margins Program is designing a field experiment in the vicinity of Cape Hatteras to 

 quantitatively test the question of whether this region is a net source or sink for carbon, and at 

 the same time develop a mechanistic understanding of the coastal carbon cycle which can be 

 applied to other margin regions throughout the globe. To meet these objectives, the principal 

 goals of the Ocean Margins Program are to: 



understand how the coastal ocean acts as a system, and as an interface between the 

 continental land mass and its estuaries, and the open ocean; 



understand the biogeochemical and physical processes which transport and transform 

 carbon within that system; and 



determine the net exchange of atmospheric CO2 with the ocean at the continental margin. 



To quantitatively constrain and understand the fate of carbon in ocean margin systems 

 will require a concerted approach consisting of observations in the water column and at the sea 

 floor. Processes in these two environments are governed and linked by physical processes. 

 Exchanges between the water column and the sea floor occur in the benthic boundary layer 

 (BBL). This implies the need for simultaneous observations of physical variables, e.g. 

 gradients in current velocity and direction, together with chemical and biological variables in 

 the water column and sea floor. 



Recent advances in moored oceanographic sensors as well as the development of new 

 biological and chemical techniques will permit use of novel approaches in studying the 

 biogeochemistry of the continental shelf and slope system. In addition, satellite data will 

 allow us to place our study off Cape Hatteras in a broader oceanographic context, as well as 

 assist us in planning and interpreting our site specific studies. In light of these new tools, we 

 have posed the following questions which can be answered within the context of the OMP 

 water column studies: 



What controls primary production on ocean margins? 



What are the rates and mechanisms of transformation of organic carbon between 



dissolved, colloidal and particulate pools, and of total carbon between organic and 



inorganic pools? 



What is the source of carbon in the Cape Hatteras region? 



What is the fate and magnitude of carbon exported off the Hatteras shelf? 



Are episodic events important in determining the net flux of carbon in ocean margins? 



