Biogeochemical Cycles/Environmental Science

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The topic best fits for tertiary students taking environmental science subject. Hope it helps=)

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Biogeochemical Cycles/Environmental Science

  1. 1. a. Identify and describe the flow of nutrients in each biogeochemical cycle. b. Explain the impact that humans have on the biogeochemical cycles.
  2. 2. Solar Energy The Cycling of Matter Gravity
  3. 3. An ecosystem survives by a combination of energy flow and matter recycling.
  4. 4. 1. Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms. 2. Nutrients are the elements and compounds that organisms need to live, grow, and reproduce. 3. Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.
  5. 5. describe the flow of essential elements from the environment through living organisms and back into the environment.
  6. 6. Evaporation Condensation Precipitation Precipitation Transpiration Infiltration and Percolation Precipitation to land Transpiration from plants Runoff Surface runoff (rapid) Groundwater movement (slow) Evaporatio n from land Evaporatio n from ocean Precipitation to ocean Surface runoff (rapid) Ocean storage
  7. 7. We alter the water cycle by: Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils. Polluting surface and underground water. Contributing to climate change.
  8. 8. 1. Reservoir – oceans, air (as water vapor), groundwater, lakes and glaciers; evaporation, wind and precipitation (rain) move water from oceans to land 2. Assimilation – plants absorb water from the ground, animals drink water or eat other organisms which are composed mostly of water 3. Release – plants transpire, animals breathe and expel liquid wastes
  9. 9. 1. Reservoir – atmosphere (as CO2), fossil fuels (oil, coal), durable organic materials (for example: cellulose). 2.Assimilation – plants use CO2 in photosynthesis; animals consume plants. 3. Release – plants and animals release CO2 through respiration and decomposition; CO2 is released as wood and fossil fuels are burned.
  10. 10. We alter the carbon cycle by adding excess CO2 to the atmosphere through: •Burning fossil fuels. •Clearing vegetation faster than it is replaced.
  11. 11. (Nitrogen is required for the manufacture of amino acids and nucleic acids) 1. Reservoir – atmosphere (as N2); soil (as NH4 + or ammonium, NH3 or ammonia, N02 - or nitrite, N03 - or nitrate 2. Assimilation – plants absorb nitrogen as either NH4 + or as N03 -, animals obtain nitrogen by eating plants and other animals. The stages in the assimilation of nitrogen are as follows:
  12. 12. Nitrogen Fixation: N2 to NH4 + by nitrogen-fixing bacteria (prokaryotes in the soil and root nodules), N2 to N03 - by lightning and UV radiation. Nitrification: NH4 + to N02 - and N02 - to N03 - by various nitrifying bacteria. 3. Release – Denitrifying bacteria convert N03 - back to N2 (denitrification); detrivorous bacteria convert organic compounds back to NH4 + (ammonification); animals excrete NH4 + (or NH3) urea, or uric acid.
  13. 13. We alter the nitrogen cycle by: Adding gases that contribute to acid rain. Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. Contaminating ground water from nitrate ions in inorganic fertilizers. Releasing nitrogen into the troposphere through deforestation.
  14. 14. Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined.
  15. 15. Evaporation Condensation Precipitation Precipitation Transpiration Infiltration and Percolation Precipitation to land Transpiration from plants Runoff Surface runoff (rapid) Groundwater movement (slow) Evaporatio n from land Evaporatio n from ocean Precipitation to ocean Surface runoff (rapid) Ocean storage
  16. 16. 1. Reservoir – erosion transfers phosphorus to water and soil; sediments and rocks that accumulate on ocean floors return to the surface as a result of uplifting by geological processes 2. Assimilation – plants absorb inorganic PO4 3- (phosphate) from soils; animals obtain organic phosphorus when they plants and other animals 3. Release – plants and animals release phosphorus when they decompose; animals excrete phosphorus in their waste products
  17. 17. We remove large amounts of phosphate from the earth to make fertilizer. We reduce phosphorous in tropical soils by clearing forests. We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.

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