1. Topic Two Biogeochemical Cycles

2. 2-3 Carbon-Oxygen Cycle

3. The Carbon Cycle Circulation of CO 2 Biotic Component Carbon is the key element in living compounds Carbon is trapped and stored in organic compounds by photosynthesis CO 2 is released to the atmosphere by respiration Abiotic Component CO 2 – found in atmosphere (0.03%) and in oceans Can be trapped in fossil fuels In oceans, it is incorporated into rocks, shells, corals CO 2 released into the atmosphere by combustion

4. Oxygen Cycle Movement of oxygen between the atmosphere and the biota 21% of atmosphere Released by photosynthesis\ Consumed by respiration

7. Carbon Oxygen Cycle

8. 1 Atmospheric pool of carbon dioxide 2 Plants take up carbon dioxide for photosynthesis 3 Animals eat plants 4 Carbon didxide released by respiration 5 Fossil fuels 6 Carbon dioxide released by combustion 7 Death of organisms and decay by bacteria

9. Human impact: burn excess fossil fuels Use up forests Result is more CO 2 added to atmosphere Leads to the greenhouse effect Greenhouse effect: Heat blocking action of gasses in the atmosphere Short waves converted to long – unable to escape atmosphere

11. Greenhouse Gasses Name of GasChemical Formula Source Carbon DioxideCO 2 Fossil fuels MethaneCH 4 Bacteria decay, farts Nitrous OxideN2ON2OFertilizers, animal wastes CFC’sStyrofoam, accelerants

12. Humans continue adding excess amounts of CO 2 Since 19 th century, levels have increased 25% Possible increase in global temperature

14. Human Population

15. Human Population and Technology

16. Carbon Dioxide Levels

17. Emission Levels

18. Past and Present C0 2 Levels

19. Greenhouse Gases

20. Effects: Melting ice caps Sea levels to increase – flooding Change in climate patterns More/less rainfall Large impact on agriculture Natural vegetation could change Some say that oceans are a large sink for CO 2

23. Image of a Dust Bowl

25. Ozone Layer Protects earth from UV radiation ~ 99% of UV radiation is screened and never reaches surface Ozone holes: Above the poles (N & S) Increase in skin cancer and eye problems Major cause? CFC’s

27. CFC’s released in sprays and as a waste product When in upper atmosphere, Chlorine reacts with ozone and breaks it down CFC’s stay in atmosphere for a very long time May continue to break down ozone layer Solution?