The ocean floor Copyrighted image Credit: photos.com

Carried in rivers and the sea are large amounts of sediment. Sediments may be organic carbon or carbonate carbon. In places like estuaries, the carbonate material includes sand, broken shells and silt.

Much of the organic material - like particles from plants and animals - may be scavenged by a web of consumers. In the sea itself there is a continual rain of debris sinking to the ocean floor.

In the deep ocean, core samples show that the ocean floor is sometimes coated with a thin green fluff. In winter and spring the floor appears uniformly greyish, but by the end of spring patches of green sediment start to appear.

The sediment contains chlorophyll, and could only have come from the surface. It appears fluffy - and contains high concentrations of organic carbon.

The amount of organic material accumulating on the ocean floor depends on the amount of photosynthetic activity in the sunlit waters above. If this is high, large aggregates of phytoplankton may sink to the seabed. By late summer the rain of sediment often reaches its peak.

Where do you find the carbon?

The organic sediments of the world's oceans and shallow seas, and associated decomposers

What form of carbon?

Organic carbon

How long will the carbon remain?

Most is consumed and returns to dissolved carbon within a few years, some remains for much, much longer. Average residence time about 2500 years

How much carbon is there?

About 1200 x 1012kg

What processes will free the carbon?

Respiration, lithification

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