Post on 22-Feb-2016
description
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
SES
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