Phytoplankton biological cycling

Inputs of agricultural fertilizers are having more than one impact on the biological pump. A shift in the NO PO4 Si(OH)4 of natural waters is causing a shift in the phytoplankton community structure that should impact the biological cycling of carbon in aquatic systems (Conley et al, 1993). Additionally, a recent shift in the C N P ratios of deeper waters and an increase in export production have been observed for the northern hemisphere oceans (Pahlow and Riebesell, 2000). 

Biological cycling not only removes some ions from surface waters, it also transforms them. The stable form of iodine (I) in seawater is iodate (IOf), but biological cycling results in the formation of iodide (F) in surface waters, because the production rate of the reduced species is faster than the rate of its oxidation. Biological uptake of IOf in surface water results in a nutrient-like profile, contrasting with the conservative behaviour of most halide ions, for example CP and Br . The biological demand for NCp also involves transformation. Phytoplankton take up NO3 and reduce it to the -3 oxidation state (see Box 4.3 Fig. 5.12) for... 

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... 

The dynamics of marine organic carbon can be described as a set of three nested cycles in which the biological pump is the cycle with flux and reservoir of intermediate magnitude (Figure 3). The cycle with the shortest timescale, which operates within the surface ocean, is composed of net primary production by phytoplankton... 

---