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Carbon Cycle and Ocean Acidification

Carbon Cycle and Ocean Acidification. V. Soutar. Inspiration 9. 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

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Carbon Cycle and Ocean Acidification

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  1. Carbon Cycle and Ocean Acidification V. Soutar Inspiration 9

  2. 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 Scale • A 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? ACIDS BASES 3 www.thegardenersresource.com

  4. Interpreting the Diagram http://www.chem.ubc.ca/courseware/pH/section3/index.html

  5. 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

  6. 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-

  7. 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?

  8. Why is this called a biogeochemical cycle? http://www.google.com/imgres

  9. What are the sources and sinks in the carbon cycle? http://www.physicalgeography.net/fundamentals/9r.html

  10. Increasing CO2 and Ocean Acidification 400 8.38 8.33 375 8.28 350 8.23 8.18 325 8.13 300 8.08 275 8.03 1950 1960 1970 1980 1990 2000 2010 2020 What data supports acidification theories? Mauna Loa oceanic CO2 atmosphericCO2 CO2 pH pH Year Feely et al. 2008

  11. 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

  12. Carbon in Seawater [H+][HCO3-] K1= [H2CO3] CO2 CO2 + H2O K0 K2 K1 H+ + CO32- Carbonate H2CO3 Carbonic Acid H+ + HCO3- Bicarbonate Dr. Brian Hopkinson

  13. Atmospheric CO2 in seawater Effective Reactions – Carbon buffering Reduces pH, CO32- Increases CO2, HCO3- CO2 + H2O → H2CO3 H2CO3 + CO32- → 2HCO3- Dr. Brian Hopkinson

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