Ocean biological processes, effect

The advent of new techniques to collect undisturbed sediment cores, with well preserved sediment - water interface has brought into sharper focus the various deep sea sedimentary processes, their rates and their effects on the preserved records. As mentioned earlier, recent studies have shown that the record contained in sediments is not a direct reflection of the delivery pattern of a substance to the ocean floor as has so far been assumed the record is modified as a result of several complex physical, chemical and biological processes. Therefore, information on the temporal variations in the tracer input to oceans, if sought, has to be deciphered from the sediment-residuum. In the following we consider one specific example of retrieval of information from the sediment pile the application of deep sea sediments to obtain historical records of cosmic ray intensity variations. 

The feature of chemotropicity of the Black Sea redox layer is well known, and this Sea is successfully used as a natural laboratory making the chemical species and the sequence of microbes easy to study on repeated cruises. The Black Sea is also an ideal site to study the effect of climate on the ocean structure. It is of small enough scale that variability in climate can vary physical forcing and thus chemical fluxes and biological processes. 

An especially important gap in the present knowledge of processes changing the characteristics of water masses within the Southern Ocean centers on the effect of the seasonal cycle, the formation and dissolution of pack ice and its associated biological processes. One aim must be to explain the paradox of the mismatch of dissolved nutrient concentration and the primary production in the pelagic ecosystems (9). One important hypothesis that needs further testing is the possibility of Fe limitation of nutrient uptake (10). 

A.E. Gargett, J. Marra (2001). Effects of upper ocean physical processes - turbulence, advection, and air-sea interaction - on oceanic primary production. In A.R. Robinson, J.J. McCarthy, B.J. Rothschild (Eds), The Sea Biological-Physical Interactions in the Ocean (pp. 19-49). Wiley, New York. 

In the short term, the most significant temporary sink for dissolved nutrients is uptake by phytoplankton. This is followed by remineralisation, which returns nutrients to solution or loss from the system by burial in sediments or export to ocean waters. These processes effectively separate N, P and Si because reminer-alisation returns them to solution at different rates (Officer Ryther, 1980). In particular, Si dissolves slowly from shell material, and denitrification leads to the loss of biologically available nitrogen from the system as nitrogen gas. 

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