Water & Seawater Part 2

Define Salinity

A measure of seawater total dissolved inorganic solids & gases

What is the average salinity of seawater?

3.5%

How do you ‘make’ seawater?

7 teaspoons of salt to ‘make’ 1 liter of sea water

How much salt does the world ocean own

5.5 trillion tons of salt

What are the two most abundant dissolved inorganic substances in seawater?

Chlorine and Sodium

What are the three abundant gases dissolved in seawater?

Carbon Dioxide, Nitrogen and Oxygen

How did the oceans get salty?

1. Rivers carry dissolved ions into oceans from weathering of rock

2. Circulation of seawater at mid-ocean ridge adds or takes away ions

3. Na & Cl over 85%

   1. Na derived from weathering of rock

   2. Cl derived from volcanic outgassing

How is salinity measured?

1.Measure the Cl content

Measure electrical conductivity (the ability of a substance to transmit electric current) using a salinometer

Salinity in the oceans decrease by adding freshwater. List the four processes that add freshwater to the oceans.

Precipitation (rain/snow)

Runoff (river & melting glaciers)

Melting Icebergs

Melting Sea ice

What processes cause an increase in ocean salinity?

-Evaporation of seawater

-Forming Sea Ice

What happens to salt when seawater freezes?

~10 ppts of salt get caught in ice

Most salts drop out, remaining seawater becomes saltier

What is the 'Principle of Constant Proportions'?

Amount of dissolved materials and gases in the seawater remains the same throughout time. Salinity change sby adding or subtracting seawater

What are the processes that ADD DISSOLVED SUBSTANCES?

1.Volcanic Eruptions

2.River discharge

3.Hypothermal activity

What Processes SUBTRACT DISSOLVED SUBSTANCES?

1.Sea Spray

2.Absorption & precipitation of solids

3.Hydrothermal activity

4.Bio-Processes

Which ocean has the highest salinity?

Atlantic Ocean

Which ocean has the least salinity?

Artic Ocean

Which sea has the highest salinity?

Red Sea

Which sea has the least salinity?

Baltic Sea

What is the saltiest water body of all?

Gael’ ale Pond

Define Brackish

Water that falls at 18 ppt of salinity, being close to the water found at the Black Sea

Define Hypersaline

Has 42 ppt salinity, close to the red sea so way beyond the safe amount to salt in water

Define Halocline

Layer of rapid change in Salinity

Define Pycnocline

Layer of rapid change in water density

Define Thermocline

Layer of rapid change for water temperature

At what depth do they generally occur?

Generally at 1000 meters

Why is the oxygen (O2) content in seawater higher near the surface?

Due to photosynthesis of plants and algae

Why is CO2 content in seawater higher between 300 – 1,000 meters below the surface?

Respiration of marine organisms