4 Salinity is a measure of the amount of dissolved salts in seawater Parts Per Thousand (ppt).The total salt content of seawater is, on average, 35 ppt, or 3.5 %
5 Variations in Salinity 37 ppt in subtropical regionSalinities are lower in equatorial regions where precipitation is abundant.Salinities of 32 or 33 ppt occur in polar regionsThe lowest salinities often occur where large rivers empty into the oceans.
7 Sources of Sea Salt Minerals flushed in by Rivers SeawaterMinerals flushed in by RiversWeathering of crustal rocksChlorine and sulfur dioxide dissolve in water from Volcano Eruptions
8 Removal of Sea Salts Salts are removed and added at the same rate. SeawaterSalts are removed and added at the same rate.Some sea salts precipitate from seawater near arid, coastal regions.Salty spray droplets from breaking waves are picked up by winds and deposited inland.Marine organisms remove ions from seawater to build their shells, bones, and teeth.
11 _ Cold water (sinks) is more dense than warm water (rises) SeawaterFreshwater has a maximum density of 1.00 g/cm3 - density of seawater 1.02 g/cm g/cm3_ Cold water (sinks) is more dense than warm water (rises)Freezing point: Sea= -2 C Fresh = 0 C
12 Absorption of LightSeawaterWater absorbs light, which gives rise to another physical property of oceans—they are dark.In general, light penetrates only the upper 100 m of seawater.
13 Ocean Layering Ocean surface temperatures range from –2°C in polar SeawaterOcean LayeringOcean surface temperatures range from–2°C in polar30°C in equatorialaverage surface temperature being 15°C.Ocean water temperatures decrease significantly with depth.
14 SeawaterOcean LayeringA typical ocean temperature profile plots changing water temperatures with depth.
15 3. The bottom layer is cold and dark with temperatures near freezing. 1. The first layer is a relatively warm, sunlit, surface layer some 100 m thick.2. The thermocline is a transitional layer which is characterized by rapidly decreasing temperatures with depth.Seawater3. The bottom layer is cold and dark with temperatures near freezing.
17 SeawaterOcean LayeringBoth the thermocline and the warm surface layer are absent in polar seas, where water temperatures are cold from top to bottom.In general, ocean layering is caused by density differences of warm and cold water.Cold water migrates toward the equator as a cold, deep water mass along the ocean floor.
18 SeawaterWater MassesThree water masses account for most of the deep water in the Atlantic Ocean.1. Antarctic Bottom Water forms when antarctic seas freeze during the winter and water temperature drops below 0°C.2. North Atlantic Deep Water forms in a similar manner offshore from Greenland.3. Antarctic Intermediate Water forms when the relatively salty waters of the Antarctic Ocean decrease in temperature during winter and sink.
19 SeawaterWater MassesThe Indian and Pacific Oceans contain only the two deep antarctic water masses.
20 SeawaterSection Assessment1. By what processes are salts removed from seawater?Salts are removed from seawater through the formation of evaporites, sea spray that is carried inland by wind, and biological processes.
21 Section Assessment 2. What is a thermocline? SeawaterSection Assessment2. What is a thermocline?A thermocline is a transitional layer between warm surface waters and cold bottom waters in a body of water that is characterized by rapidly declining temperatures with depth.
22 SeawaterSection Assessment3. Identify whether the following statements are true or false.truefalse______ North Atlantic Deep Water overrides Antarctic Bottom Water.______ Photosynthesis can occur to a depth of 200 m.______ Sodium is the most prevalent ion in seawater.______ Salt water is always denser than freshwater, regardless of temperature.