Oceanic biogeochemical cycles

Pasquer B, Laruelle G, Becquevort S, Schoemann V, Go-osse H, Lancelot C (2005) Linking ocean biogeochemical cycles and ecosystem structure and function results of the complex Swamco-4 model. J Sea Res 53 93-108... 

Chemical and biological processes in the sediments and benthic boundary layer (BBL) are important contributors to oceanic biogeochemical cycles, especially in the Arabian Sea due to its uncommon geographical setting. The oceanographic conditions experienced by various margins (e.g. Somalia/Oman versus India/Pakistan) are widely different, which in conjunction with the extensive mid-depth 02 deficiency produce a variety of BBL and sedimentary environments with respect to, among other factors, food supply, redox status and the nature and activity of benthic communities (Cowie, 2002). 

The majority of published °Pb reports address the utility of °Pb as a geochronological tool rather than as an element that is involved in complex biogeochemical cycles. Nonetheless, some of these studies do provide insight into the geochemical behavior of °Pb and °Po. Nearly all of the lead in the world s surface oceans is believed to be of anthropogenic origin—derived from combustion... 

Biogeochemical cycle. As discussed early in the chapter, this term describes the global or regional cycles of the "life elements" C, N, S, and P with reservoirs including the whole or part of the atmosphere, the ocean, the sediments, and the living organisms. The term can be applied to the corresponding cycles of other elements or compounds. 

This chapter focuses on types of models used to describe the functioning of biogeochemical cycles, i.e., reservoir or box models. Certain fundamental concepts are introduced and some examples are given of applications to biogeochemical cycles. Further examples can be found in the chapters devoted to the various cycles. The chapter also contains a brief discussion of the nature and mathematical description of exchange and transport processes that occur in the oceans and in the atmosphere. This chapter assumes familiarity with the definitions and basic concepts listed in Section 1.5 of the introduction such as reservoir, flux, cycle, etc. 

An important example of non-linearity in a biogeochemical cycle is the exchange of carbon dioxide between the ocean surface water and the atmosphere and between the atmosphere and the terrestrial system. To illustrate some effects of these non-linearities, let us consider the simplified model of the carbon cycle shown in Fig. 4-12. Ms represents the sum of all forms of dissolved carbon (CO2, H2CO3, HCOi" and... 

Although it is one of the smallest reservoirs in terms of water storage, the atmosphere is probably the second most important reservoir in the hydrosphere (after the oceans). The atmosphere has direct connections with all other reservoirs and the largest overall volume of fluxes. Water is present in the atmosphere in solid, liquid, and vapor forms, all of which are important components of the Earth s natural greenhouse effect. Cycling of water within the atmosphere, both physically (e.g. cloud formation) and chemically, is also integral to other biogeochemical cycles and climate. Consult Chapter 17 for more details. 

In addition to biogeochemical cycles (discussed in Section 6.5), the hydrosphere is a major component of many physical cycles, with climate among the most prominent. Water affects the solar radiation budget through albedo (primarily clouds and ice/snow), the terrestrial radiation budget as a strong absorber of terrestrial emissions, and global temperature distribution as the primary transporter of heat in the ocean and atmosphere. 

Buesseler, K. O. (1998). The decoupling of production and particulate export in the surface ocean. Glob. Biogeochem. Cycles 12,297-310. 

Christensen J. P., Murray, J. W., Devol, A. H. and Codispoti, L. A. (1987). Denitrification in continental shelf sediments has major impact on oceanic nitrogen cycle. Glob. Biogeochem. Cycles 1,97-116. 

Karl, D., Letelier, R., Tupas, L. et al. (1997). The role of nitrogen fixation in biogeochemical cycling in the subtropical North Pacific Ocean. Nature 388, 533-538. 

Van Cappellen, P. and Ingall, E. D. (1994). Benthic phosphorus regeneration, net primary production, and ocean anoxia A model of the coupled marine biogeochemical cycles of carbon and phosphoms. Paleoceanography 9,677-692. 

Antoine, D., Andre, J.-M., and Morel, A. (1996). Oceanic primary production, 2. Estimation at global scale from satellite (coastal zone color scanner) chlorophyll. Global Biogeochem. Cycles 10, 57-70. 

We assume that our readers have a background in science attainable by completing a university level course in introductory chemistry. We also expect our readers to be involved in one of the disciplines integral to the study of biogeochemical cycles. This includes appropriate subdisciplines of chemistry, biology, and geology, and the sciences that deal with soils, atmospheres, and oceans. 

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