Benthic cycling of oxygen, nitrogen and phosphorus

Abstract

6.6 Summary: In this chapter we have summarized the general availability of oxygen, nitrate and phosphate in the oceans and aspects of their significance in the biogeochemical cycles of marine sediments. Oxic respiration is by far the most important pathway of organic carbon in deep-sea sediments and significantly determines the recycling of organic matter introduced onto the sediment surface. Even if some uncertainty remains, benthic oxygen fluxes reveal probably a reasonable approximation to the total carbon oxidation rate under deep-marine conditions. However, benthic fluxes vary considerably in the various ocean basins and the interactions between all parameters controlling benthic biogeochemical activities are not yet completely understood. Above, we showed some examples in which benthic activity deviates from the generally expected situation as suggested by export fluxes from the surface waters. We further elaborate these concepts in Chapter 12 where we summarize existent approaches for the regionalization of benthic fluxes and present methods how to access mineralization processes in surface sediments of the deep-sea globally and arrive at a definition of benthic biogeochemical provinces. © 2006 Springer-Verlag Berlin Heidelberg.