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 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.

海水鹽度

如果我們分析海水的鹽度，會發現地區間只有輕微的變化，然而有些小的變化是重要的。

 導致海洋的鹽度變化的基本過程有三個，其中之一是通過蒸發的方式即把液態水轉化為水蒸 氣來減少海洋中的水分。  這樣由于鹽留了下來，所以鹽度增大。

 當然，如果這種方式走向 極端，將會余下白色的鹽晶體。  與蒸發相反的是降水，如降雨，由此水被加入海中，海水 被稀釋，從而鹽度降低。

 這種情形會發生在大量降雨的地區，或江河入海岸處。  因此，鹽 度通過蒸發減少水分而上升或通過降水或徑流增加淡水成分而下降。  一般來說，在陽光很

 強烈的熱帶地區，海水的鹽度略高于世界上其它沒有熱帶那樣多的蒸發的地區。  同理，在 江河稀釋海水的海岸地帶，海水鹽度略低于其它海區。

 第三個可以變更鹽度的過程與海洋 中冰的形成和融化有關。  海水凍結時，溶于其中的物質被留了下來。  這樣，在新形成的海

 水冰面的正下方的海水比在冰形成之前有更高的鹽度。  當然，當冰融化的時候，會降低周 圍水中的鹽度。

 在南極洲邊緣的威德爾海中，結冰過程增加低溫海水的鹽度，從而形成了 濃度最大的海水。  這些大密度的海水下沉，可以在世界海洋的深水域發現。

譯路通武漢漢口翻譯公司

2012.8.8