Lesson 3: Biogeochemical Cycles

1. Lesson 3: Biogeochemical Cycles Big Question: Why Are Biogeochemical Cycles Essential to Long-Term Life on Earth?

2. What is a Biogeochemical Cycle? • A biogeochemical cycle is the complete path a chemical takes through the Earth’s four major reservoirs: • atmosphere • hydrosphere (oceans, rivers, lakes, groundwaters, and glaciers) • lithosphere (rocks and soils) • biosphere (plants and animals).

3. Chemical Sinks • Chemicals enter storage compartments - sinks • Amount that moves between compartments is the flux • net sink - when input exceeds output • net source - if output exceeds input.

4. New Carbon versus Fossil Carbon

5. Essential Elements 24 elements are required for life Macronutrients are required in large quantities • carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Micronutrients are required in small/medium quantities, or not at all in some organisms • copper, sodium, iodine • See dhmo.org for a discussion of the deadly chemical dihydrogen monoxide.

6. Essential Elements

7. Geological Cycle The formation and change of Earth materials through physical, chemical, and biological processes. Here is a great move about the Geological Cycle: http://www.britannica.com/EBchecked/topic/229677/geologic-cycle

8. Tectonic Cycle The lithosphere is comprised of several plates floating on denser material. Plates move slowly relative to each other – plate tectonics, Divergent plate boundaries occur at spreading ocean ridges. Convergent plate boundaries occur when plates collide. Plate movements change the location of continents and alter atmospheric and ocean circulation patterns. Plate boundaries are geologically active, producing volcanoes and earthquakes.

9. Major Tectonic Plates

10. Hydrologic Cycle Evaporation Precipitation Runoff Groundwater

11. Where Is the Earth's Water? 97% of water is stored in oceans, 2% in glaciers and ice caps, 1% as freshwater on land or atmosphere. Drainage basins or watersheds are the area contributing runoff to a stream or river. Vary in size from a hectare to millions of square miles (e.g. Mississippi River drainage basin). Human impacts include dam construction, irrigation, stormwater runoff.

12. Rock Cycle

13. Rock Cycle

14. Biogeochemical Cycle of Ca in a Forest Soluble in water and easily lost through runoff

15. Sulfur Cycle In a Forest Ecosystem Includes gaseous forms (sulfur dioxide and hydrogen sulfide) and cycles much faster than calcium

16. Nitrogen Cycle In a Forest Ecosystem

17. Carbon Cycle Carbon is vital for life but is not abundant Enters biological cycles through photosynthesis to produce organic forms of carbon

18. Carbon Cycle in a Lake Rob's daughter Joanna (on right) removes C in trout.

19. Fossil Fuels • Fossil Fuels are created by the accumulation of carbon from dead organisms in rock strata. Their decomposition is prevented by lack of oxygen or low temperatures after their burial in sediments. After thousands or millions of years of burial the stored organic carbon is transferred into coal, oil or natural gas.

20. Global Carbon Cycle

21. Missing Carbon Sink Several hundred million tons of carbon released from the burning of fossil fuels cannot be accounted for. Possible sinks include terrestrial forests, soils, and ocean ecosystems.

22. Nitrogen Cycle Essential for manufacturing proteins and DNA Although 80% of atmosphere is molecular nitrogen, it is unreactive and cannot be used directly Nitrogen fixation converts nitrogen to ammonia or nitrate

23. Global Nitrogen Cycle

24. Phosphorus Cycle No gaseous phase Slow rate of transfer Released by erosion of exposed rock Absorbed by plants, algae, and some bacteria Exported from terrestrial ecosystems by runoff to oceans May be returned through seabird guano

25. Global Phosphorus Cycle

26. Chapter 3: Biogeochemical Cycles Questions? E-mail your TA.