Carbon Cycle and Ocean Acidification Inspiration 9 V. Soutar.

Carbon Cycle and Ocean Acidification

Investigating Mjhow the carbon Mj

cycle and Mjocean Mj

acidification are Mjrelated Mj

Inspiration 9 V. Soutar

pH Scale

Based on the dissociation of water into hydrogen ions and hydroxide ions

Scaled from 1 to 14 A pH of 7 is known as “neutral”, meaning

hydrogen (H) = hydroxide ions (OH) More hydrogen ions increase acidity Technical Definition:

pH = -log([H+])

3

The pH ScaleA single step from one

number to another number on the pH scale

is a large change or giant step. Most

organisms are very sensitive to changes in pH. Their survival is

usually within a relatively narrow pH range.

So, how many times greater is pH 7 than 6?

www.thegardenersresource.com

AC

IDS

BA

SE

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http://www.chem.ubc.ca/courseware/pH/section3/index.html

Interpreting the Diagram

Diagram tells me:

• Strong acids release more H+

• Strong bases release more OH-

• pH 7 has equal amount of H+ and OH-

• pH scale goes from 1-14; pH 1-6 acid; 7 neutral; 8-14 base

• pH 1 strongest acid; pH 14 strongest base

What is the trend?

H+ concentration increases pH decreases and the concentration of OH- decreases

OH- concentration increases pH increases and H+ decreases

Acids release more H+ and bases release more OH-

Connection to the Carbon Cycle and Ocean Acidification

What is a biogeochemical cycle? What are the sources and sinks for

carbon? How could excess carbon dioxide in

the atmosphere and the oceans cause ocean acidification?

What are some ideas for experiments to test the affect of ocean acidification on marine life?

http://www.google.com/imgres

Why is this called a biogeochemical cycle?

http://www.physicalgeography.net/fundamentals/9r.html

What are the sources and sinks in the carbon cycle?

atmospheric CO2

275

300

325

350

375

400

1950 1960 1970 1980 1990 2000 2010 20208.03

8.08

8.13

8.18

8.23

8.28

8.33

8.38

pH

Year

CO2

Mauna Loaoceanic

CO2

pH

Feely et al. 2008

Increasing CO2 and Ocean Acidification

What data supports acidification theories?

What are the impacts of increased atmospheric carbon dioxide on the ocean?

Carbon dioxide diffuses into the oceans increasing carbonic acid which reduces pH; makes ocean slightly less alkaline (slightly more acidic)

Concentration of carbonate ions decreases so less structural material for shell building

Less carbonate in solution for coral reef building

Carbon in Seawater

CO2

CO2 + H2O

H2CO3

Carbonic Acid

H+ + HCO3-

Bicarbonate

H+ + CO32-

Carbonate

K1 K2

K0

K1=[H+][HCO3

-]

[H2CO3]

Dr. Brian Hopkinson

Atmospheric CO2 in seawater

- Effective Reactions – Carbon buffering

- Reduces pH, CO32-

- Increases CO2, HCO3-

CO2 + H2O → H2CO3

H2CO3 + CO32- → 2HCO3

-

Dr. Brian Hopkinson