1. Ocean Water & Ocean Life
15.1 The Composition of Seawater
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2. Did You Know?
If you could remove the salt in the sea could be removed and spread evenly over the Earth's land surface it would form a layer more than 500 feet thick, about the height of a 40-story office building
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3. Introduction
What is the difference between seawater and drinking water?
Dissolved substances like sodium chloride (table salt) make seawater salty .
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4. The Composition of Seawater
What is salinity?
Salinity is the total amount of solid material (or salt) dissolved in water
The proportion of dissolved salt in seawater is very small, about 3.5%
Most of the salt in seawater is sodium chloride, common table salt
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5. Salts in Seawater
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6. The Composition of Seawater
Sources of Sea Salt?
Erosion of rocks on the continents is one source of elements found in seawater
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7. What causes salinity of ocean water to increase or decrease?
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Increase salinity
decrease salinity

8. Natural Processes Affecting Salinity
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9. Natural Processes Affecting Salinity
Increase Salinity
DECREASE WATER
1.Runoff of minerals from erosion of continents (adding salts to ocean)
2. Evaporation of sea water (especially at equator)
3. High Temperatures
Decrease salinity
ADD WATER
Precipitation (add rainfall dilutes the salt)
Melting icebergs and sea ice
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10. Ocean Density Variation
Density = mass per unit volume
It can be thought of as a measure of how heavy something is for its size
Factors Affecting Seawater Density
1. Salinity (more salt vs. less salt)
2. Temperature (hot vs. cold)
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11. Factors Affecting Seawater Density
Increase salinity = increase density
Decrease temperature = increase density
Question: Would seawater at the north pole be more or less dense than seawater at the equator?
Answer : more dense
Why? Cold water is denser than warm water
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12. Review 1. What is the source of dissolved salts in seawater?
- weathering and erosion of minerals in rocks on continents
2. What factors affect the density of ocean water?
- Temperature & Salinity
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13. Review 3. What is salinity? 4. What is the salinity of seawater?
The total amount of dissolved material in water
4. What is the salinity of seawater?
3.5% or 35 parts per thousand
5. What are the two most abundant elements in seawater?
Sodium and Chlorine, sodium chloride
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