The MBARI Chemical Sensor Program
The Ocean Conveyor


The Ocean Conveyor:  The flow of water through the deep sea has been determined primarily with chemical tracers.  For example, dissolved silicate concentrations increase with time as diatoms (phytoplankton with silica shells) fall into the deep sea and dissolve.  Older waters have more silicate, therefore.  The movie loop shows the location of waters at 3000 m depth with progressively higher Si concentrations.  The lowest values are found in the North Atlantic, where cold, low Si waters sink into the deep sea.  These are the youngest deep waters.  Increasing Si concentrations are found through the South Atlantic, around Antarctica and up into the Indian and South Pacific Oceans.  Waters with the highest Si are found in the North Pacific.  These are the oldest deep waters in the ocean.  Deep water forms primarily in the North Atlantic because surface salinities are greatest in the Atlantic and the saltier water becomes more dense than Pacific surface water when cooled in the winter.