Coastal regions are only a small fraction of the total volume of the ocean, but they exert a 

 disproportionate influence upon it. Human activities have the greatest impact in this zone. But 

 the interaction goes both ways - conditions in the coastal zone can also have great influence on 

 human activities. Most rivers enter the sea through estuarine zones, complex, highly variable 

 regions that often show immense biological productivity. Each is distinct, and each modifies the 

 material passing through it in its particular fashion. Many coastal zone organisms range far 

 and influence open-ocean communities. Natural and man-made materials washed or blown 

 from the continent either settle and interact with the biota or move out to sea. The resultant 

 fluxes of chemicals, particles, and biota represent boundary conditions that must be defined if 

 we are to understand the ocean system. 



In the surface layer, plankton convert dissolved materials into a vertical flux of particulate 

 matter. As particles sink, consumption, decomposition, and chemical exchanges (dissolution 

 and adsorption) modify their original composition. Much of the particulate matter returns to 

 solution at various depths as it falls or is eaten, digested, and excreted. Some fraction of the 

 particulate mass, still reactive, reaches the bottom. Chemical and biological modifications 

 occur within the sediments. To a large extent, the sediment particles themselves consist of the 

 remains of planktonic organisms. Their organic components are progressively degraded as 

 bottom dwellers consume them, but a small fraction of the organics may persist and eventually 

 become petroleum. The skeletal remains mostly redissolve, but some endure and survive 

 burial to become a part of the sediment where they record the ocean's history over millions of 

 years. 



The thick sediment deposits along the continental margins form a significant repository for 

 products of ocean-continent interaction. Understanding the distribution and history of these 

 deposits provides temporal constraints on chemical, biological, and particulate fluxes, as well 

 as a guide to the evolution of biota, climate, and oceanographic conditions during their 

 formation. The deepest sediments along passive continental margins record the earliest history 

 of new ocean basins created by continental rifting and seafloor spreading. Ocean drilling 

 provides access to the deep sedimentary layers in the margins and ocean basins and the crustal 

 rocks beneath them. 



Deep-ocean ridge crest processes are responsible for the chemical and thermal properties of 

 hydrothermal vent systems. These systems are important as sources and sinks for chemical 

 elements in the oceans and are responsible for extensive sulfide mineralization. They provide 

 unique habitats fervent communities. Through seafloor spreading, ocean ridge systems create 

 and modify 70% of the earth's crust. A comprehensive understanding of the processes that 

 control the dynamics, structure, composition and variability of these systems is required. 



The Geosciences: A New Global Initiative 



The scientific issues and global perspectives of the ocean sciences are critical components of the 

 tightly connected ocean-atmosphere-geosphere-biosphere system. Taken together, they form a 

 major new initiative within the National Science Foundation known as the Global Geosciences 

 Program, begun in FY 1 987. This effort, in which ocean sciences play an integral part, 

 consists of separate but related research efforts and treats the earth as an integrated system of 

 physical processes. It encompasses the full range of earth sciences and includes global 

 tropospheric chemistry, properties of the solid earth, dynamics of global ecosystems, and 

 features of global ocean and atmospheric circulation and biogeochemical fluxes as well as their 

 relationship to climate variability. 



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