Water & Seawater Part 3

What is an acid?

A substance that releases a Hydrogen Ion (H+) when dissolved in water

What is a base?

(alkaline) A substance that released a hydroxide ion (OH-) when dissolved in water

What is the pH Scale?

Measure of hydrogen Ion concentration

What is the average pH for seawater at the surface?

8.1

Why is pH for seawater the lowest at approximately 800 meters below the surface?

Due to marine animal respiration

Write the chemical names for the carbonate buffering system & draw in the arrows:

                      (Carbon Dioxide)  CO₂    +    H₂O  (Water)      ←→   H₂CO_{3 (Carbonate Acid)}  ←→      H⁺ (Hydrogen Ion)   +    HCO₃^{- (Bicarbonate)}       ←→  (Hydrogen     2H ²⁺    +    CO₃^2-  (Carbonate)

See top for example

What is a buffer?

a compound that tends to resist a change in pH

What adds CO3 into the ocean?

-Dissolving sea shells, coral & calcium carbonate tests (Coco & foranifers)

-Dissolving limestone

How does CO2 get added into the oceans?

-Volcanic outgassing

-Respiration of organisms

-Burning Fossil fuels

-Deforestation

What does anthropogenic mean?

Human made changes done to the environement

What is a Tipping Point?

When Sh!t hits the fan

What is the major concern regarding Anthropogenic Changes?

Rate of CO2 increase

With regards to anthropogenic changes, have the following increased or decreased?

Atmospheric CO2 (Increase)                            

Seawater pH (Decrease ; more acidic)

Atmospheric temperature (Increase)

Land temperature (Increase)

Sea surface temperature (Increase)

Sea Level (Increase)

What is the Keeling Curve and what causes the fluctuation?

The record of CO2 concentration in the atmosphere that illustrates the natural, annual fluctuation, since the 50’s

Changes in plants being dormant during the fall and immediately awakening in May is what cause the fluctuation

What is carbon sequestration?

The process of capturing and storing atmosphere carbon dioxide

What is the density of seawater dependent upon?

Temperature, Salinity and Pressure

What is the thermacline

Rapid change of temperature in the 1,000 m depth in low altitudes

What is the pycnocline?

Rapid increase in pressure in low altitudes

Briefly describe the three distinct water masses that are based on density.

Mixed Surface layer - above thermocline

Upper Water - Halocline, Thermocline, and pynoclione

Deep Water - below thermocline to ocean floor

Deep Water

Deepest

Coldest

Densest

Saltiest

List and briefly describe the different ways in which we can make freshwater from seawater.

a. Icebergs -From glaciers - towed to dry regions

b. Melted Sea Ice - Over a year old, melt upper layer of solid ice

c. Desalination Methods/Plants - about 18,000 plants worldwide, produce 12 billion gallons of freshwater daily, energy intensive, costly

d. Freeze Separation - Need multiple freezing to eliminate salts

e.Electrolysis - Use electrons to separate Na and CL from seawater

f. Solar Distillation - Evaporated seawater condesated into freshwater

g. Reverse Osmosis - Sea water is pressured through membrane ; salts are left behind while fresh water passes through

h. Brackish Water Desalination Plants