Removal of organic particles

As far as the organic content of sediments is concerned, it should be noted that the greater part of organic material undergoes recycling before it settles out. In the Baltic sea, Pustel nikov (1976) estimated that the organic content in the last meter of the water column above the sediment represents about 12% of the surface water content and about 1.5% of the total primary production. 

Banoub and Williams (1972) measured the eutrophic activity in the Mediterranean Sea. Surprisingly they found no difference between this area and the English Channel, which is ten times more productive. This might be connected to the turnover rate of sugars 2ind amino acids which is about 1—5% day . While it is important in surface waters (20—40% day ), it decreases rapidly with depth (less than 1% day below 300 m) with a much lower consumption of oxygen (1 jul yr ). 

Apparently, the particulate organic matter is oxidized, even in deep waters, but at a very slow rate. This modification of organic matter tends to the formation of very inert substances, more aliphatic molecules, refractory to further decomposition. The organic matter first loses nitrogen, phosphorus and oxygen since the activation energies for cleav e of the C—C and C—H bonds are several kcal mole higher than those of the C—N, C—P or C—O bonds (Toth and Lerman, 1977). 

Only the large particles such as faecal pellets sink at a sufficient rate to reach the sediment in a more or less unmodified state. In fact, exceptionally 

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