Oceans nutrient status

Die and the nutrient concentration in surface waters (Broecker and Maier-Reimer, 1992), such that even a perfect reconstruction of surface water 13c/12c Yould not provide direct information of surface-ocean nutrient status. In addition, the 13c/12c qP planktonic foraminiferal fossils found in surface sediments appears to be an imperfect recorder of the of DIC in modem surface... 

Within the polar oceans involved in deep water formation, certain regions are more important than others. The Antarctic Zone, the most polar region in the Southern Ocean, is involved in the formation of both deep and intermediate-depth waters, making this region important to the atmosphere/ocean CO2 balance. The quantitative effect of the Subantarctic Zone on atmospheric CO2 is less certain, depending on the degree to which the nutrient status of the Subantarctic surface influences the preformed nutrient concentration of newly formed subsurface water (Antarctic Intermediate Water and Subantarctic mode water), but its significance is probably much less than that of the Antarctic. 

In the polar ocean, both export production and nutrient status must be known to determine the impact on atmospheric CO2, because both of these terms are needed to determine the ratio of CO2 supply from deep water to CO2 sequestration by export production (Figure 7). For instance, a decrease in export production associated with an increase in surface nutrients would imply an increased leak in the biological pump, whereas a decrease in export production associated with reduced nutrient availability would imply a smaller leak in the pump. In low-latitude regions of upwelling, nutrient status is less important from the perspective of the global biological pump. Nevertheless, since nutrient status is potentially variable in these environments, it must be constrained to develop a tractable list of explanations for an observed change in productivity. 

The oceanic N2O distribution is determined primarily by the oxygen and nutrient status of the water... 

The concentration of dissolved nutrients in the deep waters of the Eastern Mediterranean is much lower than those in other oceans of the world, and when these are mixed into the surface waters they support very low primary productivity. The basic reason for this ultra-oligotrophic status is that the Mediterranean has an anti-estuarine (reverse thermohaline) circulation in which nutrient-depleted surface waters flow into the western basin at the Straits of Gibraltar and then on into the eastern basin at the Straits of Sicily. The deeper counter current consists of Levantine Intermediate Water (LIW) which contains a significant amount of dissolved nutrients. 

---