Chapter 3: Biogeochemical Cycles

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Chapter 3 Biogeochemical Cycles
Big Question Why Are Biogeochemical Cycles
Essential to Long-Term Life on Earth?
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• A biogeochemical cycle is the complete path a
  chemical takes through the Earths four major
  reservoirs
• atmosphere
• hydrosphere (oceans, rivers, lakes, groundwaters,
  and glaciers)
• lithosphere (rocks and soils)
• biosphere (plants and animals).

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• 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.

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• New Carbon vs Fossil Carbon

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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

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Essential Elements
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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/g
  eologic-cycle

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• 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

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Hydrologic Cycle

• Evaporation
• Precipitation
• Runoff
• Groundwater

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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. Mississipi River drainage basin)
• Human impacts include dam construction,
  irrigation, stormwater runoff

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Rock Cycle
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Rock Cycle
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Biogeochemical Cycle of Ca in a Forest

• Soluble in water and easily lost through runoff

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Sulfur Cycle In a Forest Ecosystem

• Includes gaseous forms (sulfur dioxide and
  hydrogen sulfide) and cycles much faster than
  calcium

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N Cycle of 22-y-old Eucalyptus forest in Sao
Paulo State, Brazil. ntation, S. Brazil
N cycle of 60-y-old Douglas-fir forest near
Seattle, USA
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Carbon Cycle

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

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

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Global Carbon Cycle
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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

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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

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Global Nitrogen Cycle
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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

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Global Phosphorus Cycle