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Salinity. Why is the Ocean Salty?. How Salty is the ocean?. Scientists estimate 50 quadrillion tons of dissolved solids Sea water is 220 times saltier than the fresh lake water. The hot sun causes evaporation of fresh water; salt is left behind.
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Salinity Why is the Ocean Salty?
How Salty is the ocean? • Scientists estimate 50 quadrillion tons of dissolved solids • Sea water is 220 times saltier than the fresh lake water. • The hot sun causes evaporation of fresh water; salt is left behind. • Red Sea and Persian Gulf—high evaporation rates • Low salinities in polar seas because salt water is diluted by melting ice and continued precipitation. • HMS Challenger/William Dittmar • Average of 35 0/00 • (parts per thousand)
Sources of Salt • streambeds and riverbeds • adjoining land areas • Sodium Chloride • ocean floor (hydrothermal vents)
Surface Salinity Variations • Red Sea • Mediterranean Sea • Latitude • Hot areas with high levels of evaporation and less precipitation. • Small, enclosed space with little circulation. • 20 degrees N latitude and 20 degrees S latitude = 36ppt • Lower at the equator because there is more precipitation.
Salinity variations, cont. Composition • Near the coast • Fresh water from a stream enters the ocean, making it less salty. • Marine life • Marine Organisms use dissolved solids from the ocean.
Salinity Variations and Depth • Salinity at the bottom of the ocean is greater than at the surface. • Halocline • Cold water • Warm water • Increases because of the temperature of the water. • 100-200 meters • Layer of water where there is a rapid increase in salinity. • Causes salt ions to move closer together • Surface water—ions are further apart—less salty.