From: Quarterdeck Volume 5, Number 1, Spring 1997

Particles in the water column

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1. Phytoplankton are microscopic marineplants. They use chlorophyll to absorb light, which supplies the energythey need to create living tissue out of carbon (C) and raw nutrients suchas nitrogen (N) and phosphorus (P). Phytoplankton are abundant near theocean surface, where there is plenty of sun. In these upper layers of thewater column phytoplankton are responsible for most of the light absorptionand scattering. When plankton die, their skeletons sink very slowly.

2. Tiny, slowly sinking particles sometimes stick together toform aggregates, and these larger clumps sink through the water more quickly.

3. When marine creatures feed on phytoplankton, they remove thetiny living particles from the water. In return they excrete waste products,including fecal pellets that sink quickly. The waste contains some of thesame nutrients that the plankton initially incorporated. Waste particlessink to seafloor where the nutrients from suface waters are released inocean sediments.

4. Instead of using photosynthesis to survive zooplankton eatphytoplankton near the sea surface. They repackage material into fecal pelletsor transport it to deeper waters as they migrate throughout the water column.

5. Turbulence caused by currents and storms stirs up sedimentfrom the ocean floor making the water cloudy. In this way buried nutrientsre-enter the deepest layer of the water column. Resuspended sediments causemost of the light scattering in the deep ocean.

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