A European research project is studying and quantifying the exchange processes of carbon and associated elements between the continental shelf of western Europe and the open Atlantic Ocean. Research is conducted to develop hydrodynamical, biogeochemical and ecological models that characterise cross-shelf and pelagic-benthic exchange processes.

The aim of the Ocean Margin EXchange (OMEX) project, supported by the European Commission in the framework of its MArine Science and Technology Programme (MAST), is to gain a better understanding of the physical, chemical and biological processes occurring at the ocean margins in order to quantify fluxes of energy and matter across this boundary.   Recognising the environmental significance of shelf-edge exchange and its role in global biogeochemical cycling, this MAST initiative aims to characterise the flux of carbon, nutrients and other trace elements between the open ocean and the coastal seas.

During OMEX I (1993-1996) investigations concentrated in the Northeastern Atlantic Ocean on the Celtic Sea shelf edge which links a relatively broad continental shelf with the deep sea. OMEX II (1997-2000) is designed to look at a contrasting system, the relatively narrow Iberian margin off the northwestern Spanish and Portuguese coasts.  Designed to meet the priority goals of the International Geosphere-Biosphere Programme (IGBP), OMEX takes into account the specific features of the European marine environments and settings, and capitalises on the expertise of the European oceanographic community within the MAST framework.

Through the co-operation of 40 principal investigators, more than 100 scientists from 10 European countries are working together.

The main objective of the OMEX project is to quantify exchange processes at the ocean margin as a basis for developing global models to predict the impact of environmental changes on the oceanic system and, more specifically, on the coastal zone.  Given the complexity of the processes occurring along the ocean margin, efforts have been made to provide data concerning the local factors affecting horizontal and vertical transport of material in relation to general circulation, and emphasis is being given to evaluating the role of filaments and eddies in the exchange between coastal zones and the open ocean. 

The central focus of this work is directed at understanding of the various components of the carbon cycle and associated elements (especially, nutrients and oligo-elements).  Ecological models have been developed to assess the population dynamics in relation to food supply. In particular, the mechanism of nutrient transfer from deep water to surface water, occurring at the northern margin of the Gulf of Biscay and at the Iberian Margin, and the resulting enhanced productivity in these areas has been investigated carefully.

The physical, chemical, biological and sedimentological aspects of the use or burial of carbon (organic and inorganic) have been investigated by examining the vertical distribution of dissolved and particulate matter. The transport and rate of accumulation of sediments have been determined with particular consideration for the role of the nepheloid layer. All this information is integrated to quantify the fluxes across the ocean margin, thereby providing fundamental data for the evaluation of the budgets of carbon, nutrients and trace elements between the continents, the coastal zone and the open ocean.