Carbon in the Oceanic Coastal Margin

Abstract

In this chapter we address the behavior of inorganic and organic carbon in the shallow coastal ocean where a large part of the biological production and sediment accumulation occur. At present, the coastal zone is more or less synonymous with the continental shelf that is covered by ocean water as a result of ice melting and sea level rise of 120 meters since the end of the Last Glacial Maximum about 18,000 years ago. In some intervals of the geologic past, shallow epicontinental seas were much more widespread during the periods of marine transgressions when the land was covered by seawater due to a rising sea level, caused by such factors as change in the relative elevation of land and(or) displacement of the ocean-water volume by the growth of spreading ridges on the ocean floor. In fact, a large part of marine sediments preserved on the continents was formed in shallow seas of the past that covered parts of the cratons of what are now different continents. The importance of the coastal ocean in the regulation of the global carbon cycle is primarily related to its position at the junction of the land, atmosphere, and open ocean, with all of which it interacts differently and modifies the transport fluxes of carbon. We emphasize in this chapter the inorganic and organic carbon cycles in the coastal ocean at the time scale of the Industrial Era, the last approximately 300 years, and up to three centuries into the future that are the time of increasing perturbations of the global carbon cycle by human activities.