Biological productivity in the ocean

The seawater data show the presence of a number of bromine compounds. These compounds were not measurable in the atmospheric samples, so biological production in the oceans is the probable source. The elevated CCI2F2 and the higher values in the CCI4 data indicate that these samples may be slightly contaminated CCI2F2 was used extensively in the laboratory on the ship. 

Other tracers (like the macronutrients phosphate, nitrate, and silicate, or the micronutrients Fe and Zn) are chemically and biologically active and are a prerequisite for biological production in the ocean s surface layer. Surface nutrient concentrations are very low in most regions of the world ocean due to... 

Most natural atmospheric ice nuclei appear to originate at the earth s surface, over both continents and regions of high biological productivity in the oceans [6, 8, 12, 13, 14], where the primary source is gas-to-particle conversion from the gases emitted into the atmosphere by the ocean surface. There are typically 10 to 5 X 10 m IN active at T -15 to —40°C [15] their concentrations increase rapidly with supercooling and with supersaturation with respect to ice. 

It is hard to see how the observed differences in atmospheric CO2 between late glacial and post-glacial times, let alone the likely variations over a few hundred years, could occur without the existence of some kind of feedback process between the ocean and the atmosphere. One such process could be changes in the level or character of biological productivity in the upper ocean waters. 

Nitrate is the largest pool of combined nitrogen in the ocean, with deep water concentrations around 20 to 30 pmol L in the Atlantic and up to 45 pmol in the Pacific. The isotopic composition of the NOs" pool is affected by a variety of processes that move N in and out of the ocean or its biota (Fig. 29.3), and subsurface N03 acts as a critical isotopic end member for biological production in the upper water column. Of the processes shown in Fig. 29.3, pelagic denitrification and N2-fixation are generally viewed as the major, long-term controls on the size and isotopic composition of the oceanic pool of NOs" (Brandes and Devol, 2002). 

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. 

From the above comments, it will be seen that the principal factor driving the diagenetic milieu in the sediments is the biological productivity of the oceanic surface waters. A map of biological productivity of Pacific ocean surface waters shows that the productivity of the northern sector of the Southwestern Pacific Basin is 50-100 gC m yr, in the C-C F.Z. is in the range 100-150 gC m yr and in the Peru Basin is... 

Biotuibation is an essential requirement for benthic lifting of manganese nodules and maintaining the nodules at the sediment surface. In both the C-C F.Z. and the Pern Basin, the biological productivity of the oceanic surface waters is high enough that the amount... 

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