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Chapter 3
Biogeochemical Cycles
Big Question
Why Are Biogeochemical Cycles Essential
to Long-Term Life on Earth?
• A biogeochemical cycle is the complete path a
chemical takes through the Earth’s four major
reservoirs:
– atmosphere
– h...
• Chemicals enter storage compartments - sinks
• Amount that moves between compartments is the flux
Essential Elements
• 24 elements are required for life
• Macronutrients are required in large quantities
– carbon, hydroge...
Geological Cycle
• The formation and change of Earth materials
through physical, chemical, and biological
processes
The Tectonic Cycle
• Lithosphere is comprised of several plates
floating on denser material
• Plates move slowly relative ...
• Divergent plate boundaries occur at spreading
ocean ridges
• Convergent plate boundaries occur when
plates collide
Biogeochemical Cycles in Ecosytems
• Begins with inputs from reservoirs such as
atmosphere, volcanic ash, stream runoff, o...
Carbon Cycle
• Carbon is vital for
life but is not
abundant
• Enters biological
cycles through
photosynthesis to
produce o...
Carbon Cycle in a Pond
• Large inorganic carbon reservoir in oceans
• Dissolved CO2 is converted to carbonate and
bicarbonate
• Transferred from ...
Fossil Fuels
• Decomposition of dead organisms may be
prevented by lack of oxygen or low
temperatures
• Burial in sediment...
Global Carbon Cycle
Global Carbon Cycle
Case of the missing carbon!
– Analysis shows contribution of 8 .5 bill. tons
into the atmosphere but less than ½ stays
the...
Case of the missing carbon!
– Appears oceans are acting as carbon sinks as are
forests and grasslands.
– But which area is...
Case of the missing carbon!
– Global tests of CO2 show less in the north than the south
despite larger northern outputs
– ...
Case of the missing carbon!
– Results (best guess):
• Ocean is soaking up 2.4 billion tons globally
• Land plants do the m...
Case of the missing carbon!
– Biggest threats:
• Decline in forest growth
• Killing of ocean phytoplankton due to rising s...
Nitrogen Cycle
• Essential for manufacturing proteins and DNA
• Although 80% of atmosphere is molecular
nitrogen, it is un...
Nitrogen Fixation
• Some organisms have a symbiotic relationship
with nitrogen fixing bacteria
• Found in root nodules in ...
Denitrification
• When organisms die, denitrifying bacteria
convert organic nitrogen to ammonia,
nitrate, or molecular nit...
Global Nitrogen Cycle
Phosphorus Cycle
• No gaseous phase
• Slow rate of transfer
• Released by erosion of exposed rock
• Absorbed by plants, al...
Global Phosphorus Cycle
Phosphate Mining
• Impact on
landscape by
open-pit mining
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Cikli biogjeokimik

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Cikli biogjeokimik

  1. 1. Chapter 3 Biogeochemical Cycles Big Question Why Are Biogeochemical Cycles Essential to Long-Term Life on Earth?
  2. 2. • 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. 3. • Chemicals enter storage compartments - sinks • Amount that moves between compartments is the flux
  4. 4. 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
  5. 5. Geological Cycle • The formation and change of Earth materials through physical, chemical, and biological processes
  6. 6. The Tectonic Cycle • Lithosphere is comprised of several plates floating on denser material • Plates move slowly relative to each other – plate tectonics
  7. 7. • Divergent plate boundaries occur at spreading ocean ridges • Convergent plate boundaries occur when plates collide
  8. 8. Biogeochemical Cycles in Ecosytems • Begins with inputs from reservoirs such as atmosphere, volcanic ash, stream runoff, ocean currents, submarine vents • Chemicals cycle through physical transport and chemical reactions (e.g. decomposition) • All ecosystems “leak” chemicals to other ecosystems.
  9. 9. Carbon Cycle • Carbon is vital for life but is not abundant • Enters biological cycles through photosynthesis to produce organic forms of carbon
  10. 10. Carbon Cycle in a Pond
  11. 11. • Large inorganic carbon reservoir in oceans • Dissolved CO2 is converted to carbonate and bicarbonate • Transferred from land by rivers and wind
  12. 12. Fossil Fuels • Decomposition of dead organisms may be prevented by lack of oxygen or low temperatures • Burial in sediments over thousands or millions of years transforms the stored organic carbon into coal, oil or natural gas
  13. 13. Global Carbon Cycle
  14. 14. Global Carbon Cycle
  15. 15. Case of the missing carbon! – Analysis shows contribution of 8 .5 bill. tons into the atmosphere but less than ½ stays there…where does it go? – 7 billion from fossil fuels and 1.5 billion from deforestation
  16. 16. Case of the missing carbon! – Appears oceans are acting as carbon sinks as are forests and grasslands. – But which area is more critical, and which one dominates. – Will these blessings last? • If they stop functioning we could face drastic changes even before 2050.
  17. 17. Case of the missing carbon! – Global tests of CO2 show less in the north than the south despite larger northern outputs – Why is this the case? – If land plants are doing the work then there should be a corresponding oxygen increase. – If it is dissolving in the oceans then there should be no added oxygen.
  18. 18. Case of the missing carbon! – Results (best guess): • Ocean is soaking up 2.4 billion tons globally • Land plants do the most work in the northern hemisphere – Forests literally breath in the carbon but appetite changes dramatically due to season, amount of sunlight, rainfall, and age of forests • Marine organisms undergo photosynthesis as well • So that leaves about 2.9 units unaccounted for between these groups.
  19. 19. Case of the missing carbon! – Biggest threats: • Decline in forest growth • Killing of ocean phytoplankton due to rising sea temperatures • Death of forests due to spread of disease and insects • Melting permafrost layer • Land clearing for development and agriculture • Ofcourse continued output of carbon from fossil fuel burning
  20. 20. 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
  21. 21. Nitrogen Fixation • Some organisms have a symbiotic relationship with nitrogen fixing bacteria • Found in root nodules in some plants, or in the stomach of some herbivores • Nitrogen fixation also occurs through lightning and industrial processes
  22. 22. Denitrification • When organisms die, denitrifying bacteria convert organic nitrogen to ammonia, nitrate, or molecular nitrogen
  23. 23. Global Nitrogen Cycle
  24. 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. 25. Global Phosphorus Cycle
  26. 26. Phosphate Mining • Impact on landscape by open-pit mining

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