Ocean Water (63) Oceans are important sources of food, energy, and minerals. Energy sources such as oil and natural gas are found beneath the ocean floor. One-third of the world’s table salt is extracted from seawater through the process of evaporation. Oceans also allow for the efficient transportation of goods. For example, millions of tons of oil, coal, and grains are shipped over the oceans each year.

Origins of the Oceans When volcanoes erupt, they spew lava and ash, and they give off water vapor, carbon dioxide, and other gases. 4 billion years ago, this water vapor began to be stored in Earth’s early atmosphere. m/watch?v=BvrzM- BavDghttp:// m/watch?v=BvrzM- BavDg

Over millions of years, it cooled enough to condense into storm clouds. Torrential rains began to fall. Oceans were formed as this water filled low areas on Earth called basins

Composition of the Ocean Ocean water contains dissolved gases such as oxygen, carbon dioxide, and nitrogen. Oxygen enters the oceans in two ways— directly from the atmosphere and from organisms which photosynthesize. Carbon dioxide enters the ocean from the atmosphere and from organisms when they respire.

Composition of Oceans Ocean water contains many dissolved salts. Chloride, sodium, sulfate, magnesium, calcium, and potassium are ions in oceans Ions come from rocks that are dissolved slowly by rivers and groundwater. watch?v=iSJggIWlH9whttp:// watch?v=iSJggIWlH9w

Salts Salinity is a measure of the amount of salts dissolved in seawater. One kilogram of ocean water contains about 35 g of dissolved salts, or 3.5 percent. Elements are added to the oceans at about the same rate that they are removed.

Desalination Salt can be removed from ocean water by a process called desalination. As seawater evaporates, salt is left behind. Some methods of desalination include evaporating seawater and collecting the freshwater as it condenses on a glass roof. Other plants desalinate water by passing it through a membrane that removes the dissolved salts.

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Earth’s oceans were formed when water filled low areas called __________. A. basins B. depressions C. sinks D. troughs

The measure of the amount of salts dissolved in seawater is __________. A. acidity B. basicity C. pH D. salinity

Which of these is the most abundant in seawater? A. calcium B. chloride C. sodium D. potassium