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Chapter 15. Ocean Water and Ocean Life. Section 15.1. The Composition of Seawater. The Composition of Seawater. Salinity – is the total amount of solid material dissolved in water.
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Chapter 15 Ocean Water and Ocean Life
Section 15.1 The Composition of Seawater
The Composition of Seawater Salinity – is the total amount of solid material dissolved in water. • Because the proportion of dissolved substances in seawater is such a small number, oceanographers typically express salinity in parts per thousands. • Most of the salt in seawater is sodium chloride, common table salt.
The Composition of Seawater • Sources of Sea Salt • Chemical weathering of rocks on the continents is one source of elements found in seawater. • The second major source of elements found in seawater is from Earth’s interior. • Volcanic eruptions emitted water vapor and elements – chlorine, bromine, sulfur and boron.
The proportion of dissolved substances in seawater is usually expressed in • Parts per hundred. • Parts per thousand. • Parts per ten thousand. • Parts per million.
Which of the following is a source of dissolved substances in the ocean? • Chemical weathering of rocks • Evaporation of water from the seas and ocean • Excretions from marine organisms • Melting icebergs and sea ice
The Composition of Seawater Salinity • Processes Affecting Salinity • Processes that decrease salinity: • Precipitation • Sea ice melting • Icebergs melting • Runoff from land
The Composition of Seawater Salinity • Processes Affecting Salinity • Processes that increase salinity: • Evaporation • Formation of sea ice
Which does NOT decrease salinity? • Precipitation • Runoff • Evaporation • Ice melting
The Composition of Seawater Ocean Temperature Variation • The ocean’s surface water temperature varies with the amount of solar radiation received, which is primarily a function of latitude. • Temperature Variation with Depth • The thermocline is the layer of ocean water between about 300 meters and 1000 meters where there is a rapid change of temperature with depth. • The thermocline is a very important structure because it creates a barrier to marine life.
The Composition of Seawater Ocean Density Variation • Density is defined as mass per unit volume. It can be thought of as a measure of how heavy something is for its size. • Factors Affecting Seawater Density • Seawater density is influenced by two main factors: salinity and temperature.
The Composition of Seawater Ocean Density Variation • Density Variation with Depth • Thepycnocline is the layer of ocean water between about 300 meters and 1000 meters where there is a rapid change of density with depth.
Differing amounts of solar radiation across Earth’s latitude affect the ocean’s • Salinity in the thermocline. • Density at the surface. • Temperature at the surface. • Density in the thermocline.
Which of the following occurs when the ocean’s salinity increases? • Density increases • Density decreases • Temperature increases • Temperatures decreases
Which of the following occurs when temperature decreases? • Density decreases • Density increases • Salinity increases • Nothing happens
The layer of ocean water between 300 meters and 1000 meters where there is a rapid change in density. • Thermocline • Transition zone • Pycnocline • Deep zone
The Composition of Seawater Ocean Layering • Oceanographers generally recognize a three-layered structure in most parts of the open ocean: a shallow surface mixed zone, a transition zone, and a deep zone. • Does not exist in high latitudes because there is no rapid change in temp or density. • Surface Zone • Shallow (300 to 450 meters) • Zone of mixing • Sun-warmed zone
The Composition of Seawater Ocean Layering 2. Transition Zone • Between surface layer and deep zone • Thermocline and pycnocline 3. Deep Zone • Sunlight never reaches this zone. • Temperatures are just a few degrees above freezing. • Constant high-density water
Which of these is NOT one of the three layers of the ocean? • Photic zone • Surface zone • Transition zone • Deep zone
Where would you not find this three-layered structure of the open ocean? • High latitudes • Low latitudes • Deep ocean zone • Intertidal zone