Biological carbon pump

From a geochemical perspective, sinking POM is an important mechanism by which carbon and other elements are transferred from the sea surfece into the deep sea and onto the sediments. This transport is termed the biological pump and includes the sinking of inorganic particles that are of biogenic origin, namely calcium carbonate and silicate shells. 

The export of DOC into the middle and bottom waters of the ocean represents 20% of the total annual export of carbon from the surfece waters. Thus, DOC export represents a significant part of the biological pump contributing to the ocean s ability to extract and store atmospheric carbon. This export also has ramifications on nutrient... 

The future response of the ocean to increasing injection of anthropogenic carbon into the atmosphere can be predicted by considering how the physical and biological pumps are most likely to respond. Initially, the physical fectors will lead to a decrease in the ocean s uptake rate. This is a result of four fectors. First, as discussed in Chapter 25.3.1,... 

Priority 1 — Quantifying the Anthropogenic Carbon Input Priority 2a — Understanding the Biological Pump Priority 2b — Tracing Water Masses Priority 3 — Other Analytes of Interest... 

Atmosphere-ocean carbon exchange is much controlled by physical processes, including mixing of the surface and deep layers of the ocean across the thermo-cline. Biological processes favor the movement of carbon from the surface layer to deep layers and down to bottom sediments. The biological pump functions as a result of phytoplankton photosynthesis. 

Carbon Sequestration via Ocean Fertilization and the Biological Pump ACKNOWLEDGMENTS... 

Not all of the primary production in the ocean feeds carbon into the biological pump. The vast portion of carbon fixed globally each year in the euphotic zone is remineralized by zooplankton and bacteria in the euphotic zone and converted straight back to CO2 and dissolved nutrients. These recycled nutrients may then be used to fuel further carbon fixation. 

The influence of the biological pump on the distribution of DlC carbon in the ocean may serve as a rough model for the influence it has on the distribution of a score of other elements. Low concentrations of DlC are observed in surface waters (Figure 1) due to the uptake of dissolved CO2 (and perhaps HCO/ Raven, 1997) by phytoplankton. Concentrations of... 

The biological pump influences, to varying degrees, the distribution of many elements in seawater besides carbon, nitrogen, phosphorus, and silicon. Barium, cadmium, germanium, zinc, nickel, iron, selenium, yttrium, and many of the REEs show depth distributions that very closely resemble profiles of the major nutrients. Additionally, beryllium, scandium, titanium, copper, zirconium, and radium have profiles where concentrations increase with depth, although the correspondence of these profiles with nutrient profiles is not as tight (Nozaki, 1997). 

Because zinc is required for the growth of phytoplankton, its availability affects the biological pump. Although zinc limitation of an entire phytoplankton community has never been demonstrated, levels of dissolved zinc are often low enough to limit many taxa (Morel et al, 1994 Sunda and Huntsman, 1995b Timmermans et al, 2001). Zinc is an integral part of the enzyme, carbonic anhydrase (Morel et al, 1994), which helps maintain an efficient supply of CO2 to Rubisco. 

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