Biological processes in oceans

The CO2 system in seawater is an important and complicated balance system in oceans it is composed of some sub-balance systems and is influenced by atmospheric, biological, geologic and other processes. The Pco2 in seawater is an important parameter of the sea s CO2 system and is very sensitive to physicochemical and biological processes in oceans. Its distribution and change are closely related to factors such as water mass and biological activity. 

Carbon dioxide plays a key role in climate, in biological processes, in weathering reactions, and in marine chemistry. I shall next describe how the partial pressure of this gas in the atmosphere may be calculated. Because there is a rapid exchange of carbon dioxide between ocean and atmosphere, we must consider the fate of dissolved carbon. 

Natural sources of CO include CO from biomass burning and the oxidation of organics such as methane and isoprene, CO from biological processes in soils, CO from vegetation and termites, and CO from the ocean. 

However, what remains unknown is the source of the original bromine that initiates the chemistry. There have been a number of hypotheses, including the photolysis of bromoform which is generated by biological processes in the ocean (Barrie et al., 1988) or reactions of sea salt, either suspended in the air or deposited on, or associated with, the snowpack. These include photolysis of BrN02 formed from the reaction of sea salt particles with N2Os (Finlayson-Pitts et al., 1990), the... 

To increase the reliability of assessing the role of the World Ocean in the global carbon cycle, a more detailed description is needed of the production processes in ocean ecosystems. Along with the physical and chemical processes of transformation and motion of carbon in the ocean medium, the biological processes play an important role. In particular, phytoplankton, just like the nutrient elements, assimilates dissolved C02 from saltwater. As a result, an organic substance is formed that partially goes to the nutrient chains of the trophic pyramid of a given basin of the World Ocean and partially descends to bottom sediments. The totality of all the... 

Figure 12.1 Elements up to atomic number 103 are shown in a context of their involvement in biological processes in the ocean.

There are very few measurements of the DMS concentration in the sea surface microlayer. The first report (44) indicated an enrichment of 5 times relative to underlying water samples. Other reports indicate that no enrichment was observed in tne microlayer DMS concentration (23.47.511. These differences may be related to the sampling techniques used. It is possible that chemical and biological processes in tne sea surface microlayer may affect the transfer of DMS from the bulk ocean to the atmosphere. However, at present, very little is known about the processes affecting the chemistry of DMS in the microlayer. 

Devol, A. H. (1978). Bacterial oxygen uptake kinetics as related to biological processes in oxyged deficient zones of the oceans. Deep Sea R S. 25, 137-146. 

Goldman, J. (1988). Spatial and temporal discontinuities of biological processes in surface waters. In Towards Theory on Biological—Physical Interactions in the World Ocean (Rothschild, B., ed.). Kluwer, pp. 273—296. 

Patterns of chemical distributions within the ocean are primarily controlled by biological processes and ocean circulation. Major features of this biogeochemical mosaic include removal of nutrients from warm surface ocean waters, concentration of these same nutrients in deep-ocean waters, and depletion of dissolved oxygen at intermediate water depths. These patterns are imprinted as mixing and advection carry nutrient-laden water from ocean depths into the sunlit upper water. These nutrients are used during photosynthesis to generate particulate and dissolved products that sink or are mixed into the interior ocean, where they are respired back into dissolved metabolites. Interactions of these physical and biological processes occur on time scales of days to hundreds of years and are expressed by the vertical concentration profiles of a variety of dissolved chemical... 

The main removal process for oceanic components is via sedimentation and burial thus, the interaction of dissolved metals with particles in sea water is a major indication of their concentration and distribution in the world s oceans. In open ocean areas the particle cycle is driven by the biological production of particles in the surface layers, which after processes of mineralization and packaging reach the necessary size and density to fall to the ocean bottom. On the basis of this consideration, one can say that in the open ocean area the biogeochem-ical cycle of trace metals determining their distribution and speciation is frequently dominated by biological processes. In eoastal areas or particular geographical zones, other phenomena, e.g., inorganic precipitation, can take place. 

The balance between P and R is responsible for regulating the concentration of 02 in the oceans and the atmosphere (27). Thus, biological processes in the sea (probably more than half of the total global photosynthesis takes place in the sea) regulate po2 and in turn the redox intensity of the interface between atmosphere and hydrosphere. 

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 first strand of evidence for the global ocean uptake comes from models of the ocean carbon cycle. These generally combine descriptions of the relevant carbonate chemistry with some representation of tracer transport in the ocean. As well they need a model (usually highly simplified) of the biological processes in the ocean and finally some parameterization of the surface fluxes of... 

Methyl chloride supplies about 0.5 ppb of chlorine to the stratosphere. Prior to 1996, the atmospheric input of CH3CI was assumed to be a result of biological processes in the ocean. Tropical terrestrial sources, biomass burning and tropical plants, are now believed to be important. The dominant sink of CH3CI is reaction with the OH radical in the... 

---