Ocean+Notes

= WTBW 04/07/08 =

=//__ Salinity __//= ==  •     Most of the salt in the oceans came from land. Over millions of years, rain, rivers, and streams have washed over rocks containing the compound sodium chloride (NaCl), and carried it into the sea. ==

•    Some of the salt in the oceans comes from undersea volcanoes and  [|hydrothermal vents].
= = = = =//__ Hypersaline vs. Hyposaline __//=

•   The average ocean salinity is 35 ppt. This number varies between about 32 and 37 ppt.
==  •     Rainfall, evaporation, river runoff, and ice formation cause the variations. For example, the Black Sea is so diluted by river runoff, its average salinity is only 16 ppt. Freshwater salinity is usually less than 0.5 ppt. == =//__ Aquatic Wildlife __//= ==  •     Water between 0.5 ppt and 17 ppt is called brackish. [|Estuaries] (where fresh river water meets salty ocean water) are examples of brackish waters. ==

•   Most marine (ocean dwelling) creatures keep the salinity inside their bodies at about the same concentration as the water outside their bodies because water likes a balance.
==  •     If an animal that usually lives in salt water were placed in fresh water, the fresh water would flow into the animal through its skin. If a fresh water animal found itself in the salty ocean, the water inside of it would rush out. == =//__ The movement of Water in Cells __//= ==  •     The process by which water flows through a semi-permeable membrane (a material that lets only some things pass through it) such as the animal's skin from an area of high concentration (lots of water, little salt) to an area of low concentration (little water, lots of salt) is called osmosis. ==

•   This is also why humans (and nearly all mammals) cannot drink salt water. When you take in those extra salts, your body will need to expel them as quickly as possible.
==  •     Your kidneys will try to flush the salts out of your body in urine, and in the process pump out more water than you are taking in. Soon you'll be dehydrated and your cells and organs will not be able to function properly. ==

=__ The Essential Principles of Oceans  __=

•  The Oceans makes the Earth habitable.
=__ The Essential Principles of Oceans  __=

7) The ocean is largely unexplored.
=//__ Ocean Water: Pressure  __//=

•   To travel into this high-pressure environment we have to make some adjustments. Humans can travel three or four atmospheres and be OK. To go farther, submarines are needed.
= Pause and Reflect =

=__ Ocean Water: Temperature __=

•   As seawater increases 5 ppt in salinity, the freezing point decreases by 0.5°F.
=__ Climatic change and salinity  __   =

•   No glaciers existed, and sea levels were much higher than they are today, worldwide.
==  •     In fact, the interior of North America was flooded, all across the Great Plains, from the Gulf of Mexico northward through Canada. Sea level was several hundred feet higher than it is today. == = Ocean Influence on Weather = == •     During the Ice Ages which reocurred periodically through out the Late Cenozoic, particularly in the Pleistocene Epoch (10,000 years to about 2 million years ago), much of the world's water was tied up in continental ice sheets. ==

• Glaciers  covered almost one-third of the land. Consequently, sea level was about 400 feet lower than it is today, and the continental shelves were exposed as dry land.
== •     We are currently in an interglacial period, but we still have glaciers on the Earth. ==

= = = = =__ Marine Animals __=

=__ Life in the sea affects composition of sea water  __=

==  •     The dissolved chemicals in sea water and freshwater are very different from each other. Part of the explanation is the role played by marine organisms (plants, animals, and single-celled organisms). ==

•   Other marine organisms require silica to construct their shells (diatoms, radiolarians, some sponges).
=__ Zones of the Ocean __= ==  •     The ocean can be divided into three vertical zones, depending on temperature. The top layer is the surface layer, or mixed layer. This layer is the most easily influenced with solar energy (the sun's heat), wind and rain. ==

= __Ocean Temperature Profile__ =