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标题: The Salinity of Ocean Waters [打印本页]

作者: 幽幽草    时间: 2007-4-18 17:14     标题: The Salinity of Ocean Waters

If the salinity of ocean waters is analyzed it is found to vary only slightly from place to place. Nevertheless some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation—— conversion of liquid water to water vapor. In this manner the salinity is increased since the salts stay behind. If this is carried to the extreme of course white crystals of salt would be left behind.

  The opposite of evaporation is precipitation such as rain by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by evaporation or decreased by the addition of fresh water by precipitation or runoff.

  Normally in tropical regions where the sun is very strong the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly in coastal regions where rivers dilute the sea salinity is somewhat lower than in other oceanic areas.

  A third process by which salinity may be altered is associated with the formation and melting of sea ice. When sea water is frozen the dissolved materials are left behind. In this manner sea water directly materials are left behind. In this manner sea water directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared. Of course when this ice melts it will tend to decrease the salinity of the surrounding water.

  In the Weddell Sea Antarctica the densest water in the oceans is formed as a result of this freezing process which increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world.

  NOTE

  salinity / sэ‘’linэti sэ`linэti/

  n [U] the high salinity of sea water海水的高含盐量。

  -à》saline / ‘’seilain US -lin `selin/

  1.adj [attrib作定语] fml文) containing salt salty含盐的;咸的:

  * a saline lake盐湖* saline springs盐泉

  * saline solution eg as used for gargling storing contact lenses etc盐溶液(如用于漱喉、存放隐形眼镜等)。

  2. n [U] medical医) solution of salt and water盐水




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