Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 19

Because water evaporates faster from some parts of the ocean than others and rainfall and river discharge to the ocean isn’t uniform around the globe, certain parts of the ocean are saltier than others. For example, salinity in the Red Sea ranges from 36 ppt (parts per thousand) to 41 ppt (about 3.6 to 4.1 percent). In the Mediterranean Sea, surface waters average 38 ppt but can approach 40 ppt in the extreme western parts. Saltwater taffy, anyone?

Salinity also fluctuates in certain areas of the ocean. For example, in polar regions, the salinity of water near the surface increases as ice forms, leaving much of the salt behind. As the ice melts, salinity decreases due to the influx of fresh water. Likewise, in coastal areas, salinity is lower in areas where freshwater from rivers and streams enters the ocean. When the salinity dips below about 30 ppt, the water is often called brackish.