1. Biogeochemical Cycles

2. What is a “biogeochemical cycle”?  BIO = “life”  GEO = “earth”  CHEMICAL = “elements – C, O, N, P, S a cycling of nutrients (water, carbon, oxygen, nitrogen, phosphorus, sulphur) from the abiotic components of the ecosystem (water, air, soil, rock) through the biotic components (plants, animals, fungi, bacteria)

3. Objectives:  Identify and describe the flow of nutrients in each biogeochemical cycle.  Explain the impact that humans have on the biogeochemical cycles.

4. Objectives:  Identify and describe the flow of nutrients in each biogeochemical cycle.  Explain the impact that humans have on the biogeochemical cycles.

5. What Sustains Life on Earth? Solar energy, the cycling of matter, and gravity sustain the earth’s life. Figure 3-7

6. Two Secrets of Survival: Energy Flows and Matter Cycles  An ecosystem survives by a combination of energy flow (from Sun to Earth) and matter cycling.  Remember: the Earth is a CLOSED system Figure 3-14

7. MATTER CYCLING IN ECOSYSTEMS  Nutrient Cycles: Global Recycling Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms. Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms. Nutrients are the elements/compounds that organisms need to live, grow, and reproduce. Nutrients are the elements/compounds that organisms need to live, grow, and reproduce. Nitrogen, Carbon, Phosphorus, Water Nitrogen, Carbon, Phosphorus, Water Biogeochemical cycles move these substances through air, water, soil, rock and living organisms. Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.

8. Why are each of the following needed by living organisms?  Nitrogen? To make what macromolecule(s)? To make what macromolecule(s)?  Carbon? To make what macromolecule(s)? To make what macromolecule(s)?  Oxygen? To make what macromolecule(s)? To make what macromolecule(s)?  Phosphorous? To make what macromolecule(s)? To make what macromolecule(s)?

9. Water’s Unique Properties  Strong forces of attraction between molecules of water – due to what?  Water exists as a liquid over a wide temperature range – why?  Liquid water changes temperature slowly – why?  It takes a large amount of energy for water to evaporate – why?  Liquid water can dissolve a variety of compounds – why?  Water expands when it freezes- why?

10. Fig. 3-26, p. 72 Precipitation Transpiration Condensation Evaporation Ocean storage Transpiration from plants Precipitation to land Groundwater movement (slow) Evaporation from land Evaporation from ocean Precipitation to ocean Infiltration and Percolation Rain clouds Runoff Surface runoff (rapid) THE HYDROLOGIC (WATER) CYCLE

11. Effects of Human Activities on Water Cycle  Humans alter the water cycle by: Withdrawing large amounts of freshwater. Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils. Clearing vegetation and eroding soils. Polluting surface and underground water. Polluting surface and underground water. Contributing to climate change. Contributing to climate change.

12. Carbon Cycle  Based in the process of photosynthesis & cellular respiration  Combustion and decomposition also contribute

13. Fig. 3-27, pp. 72-73

15. Effects of Human Activities on Carbon Cycle  Humans alter the carbon cycle by adding excess CO 2 to the atmosphere: Burning fossil fuels. Burning fossil fuels. Clearing vegetation faster than it is replaced - deforestation Clearing vegetation faster than it is replaced - deforestation Figure 3-28

16. THE NITROGEN CYCLE

18. Effects of Human Activities on the Nitrogen Cycle  Humans alter the nitrogen cycle by: Adding nitrous oxide to the atmosphere from vehicles and factories which contributes to acid rain. Adding nitrous oxide to the atmosphere from vehicles and factories which contributes to acid rain. Contaminating ground water from nitrate ions in inorganic fertilizers. Contaminating ground water from nitrate ions in inorganic fertilizers. Releasing nitrogen into the troposphere through deforestation (less N assimilated by trees). Releasing nitrogen into the troposphere through deforestation (less N assimilated by trees).

19. Effects of Human Activities on the Nitrogen Cycle  Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. Figure 3-30

20. Fig. 3-31, p. 77 Dissolved in Ocean Water Marine Sediments Rocks uplifting over geologic time settling out weathering sedimentation Land Food Webs Dissolved in Soil Water, Lakes, Rivers death, decomposition uptake by autotrophs agriculture leaching, runoff uptake by autotrophs excretion death, decomposition miningFertilizer weathering Guano Marine Food Webs THE PHOSPHORUS CYCLE

21. Effects of Human Activities on the Phosphorous Cycle  Humans remove large amounts of phosphate from the earth to make fertilizer.  Humans reduce phosphorous in tropical soils by clearing forests/deforestation.  Humans add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers – excess phosphorus causes algal blooms (eutrophication)

22. Algal blooms