Biogeochemical Cycles

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Biogeochemical Cycles

• Energy Flow through and Nutrient Cycling in
  Ecosystems

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http//soils.usda.gov/sqi/SoilBiology/soil_food_we
b.htm
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Biogeochemical CyclesReservoirs Pathways
Atmosphere
Biosphere
Lithosphere
Hydrosphere
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Some Major Cycles of Matter

• Water Cycle
• Rock Cycle
• Chemical Cycles
• Carbon
• Nitrogen
• Phosphorous
• Sulfur

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Nutrient Cycles
Cycling maintains homeostasis (balance) in the
environment.
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• Water cycle-
• Evaporation, transpiration, condensation,
  precipitation

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Water cycle-
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• Carbon cycle-
• Photosynthesis and respiration cycle carbon and
  oxygen through the environment.

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Carbon cycle-
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Nitrogen cycle-

• Atmospheric nitrogen (N2) makes up nearly 78-80
  of air.
• Organisms can not use it in that form.
• Lightning and bacteria convert nitrogen into
  usable forms.

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Nitrogen Cycle

• Only in certain bacteria and industrial
  technologies can fix nitrogen.
• Nitrogen fixation-convert atmospheric nitrogen
  (N2) into ammonium (NH4) which can be used to
  make organic compounds like amino acids.
• N2 NH4

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Nitrogen cycle Nitrogen-fixing bacteria Some
live in a symbiotic relationship with plants of
the legume family (e.g., soybeans, clover,
peanuts).
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• Nitrogen cycle
• Some nitrogen-fixing bacteria live free in the
  soil.
• Nitrogen-fixing cyanobacteria are essential to
  maintaining the fertility of semi-aquatic
  environments like rice paddies.

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N movement in a watershed
Precipitation, NO3, NH3
Watershed View of Nitrogen Transport Use
Nitrogen Fixation
N
NO3 NH3

• NO3- ions relatively mobile-washes N out of
  terrestrial environment
• In pristine environment, most nitrogen moves as
  DON (dissolved organic N)

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Nitrogen Cycle
Atmospheric nitrogen
Lightning
Denitrification by bacteria
Animals
Nitrogen fixing bacteria
Plants
Decomposers
Nitrification by bacteria
Nitrites
Nitrates
Ammonium
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Bio-concentration
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Bioconcentrationup the Trophic Pyramid
Energy degrades
but matter does not
Toxin (e.g. heavy metals)
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• Toxins in food chains-
• While energy decreases as it moves up the food
  chain, toxins increase in potency.
• This is called biological magnification

Ex DDT Bald Eagles
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Carbon Cycle
Atmosphere
Biosphere
Lithosphere
Hydrosphere
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Carbon TransferBiosphere Atmosphere
Photosynthesis (Atmosphere to Biosphere)
Carbon Dioxide Water Sunlight --gt Sugar
Oxygen
Respiration (Biosphere to Atmosphere)
Sugar Oxygen --gt Carbon Dioxide Water Energy
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Carbon Cycle
Atmosphere
Biosphere
Lithosphere
Hydrosphere
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Carbon Cycle
Human Impacts
Atmosphere
Biosphere
Net Effect Increase in Carbon in Atmosphere
Lithosphere
Hydrosphere
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Nitrogen Cycle
Atmosphere
Denitification bacteria
Biosphere

• Nitrogen fixation
• bacteria
• lightning

Absorption
Waste Decomposition
Erosion
Lithosphere
Hydrosphere
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Nitrogen Cycle
Human Impacts
Atmosphere
Biosphere
Net Effect Increase in Nitrogen in water soil

• Nitrogen fixation
• industrial (fertilizer)
• combustion

Increased Erosion
Lithosphere
Hydrosphere
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Phosphorous Cycle
Never enters the atmosphere
Atmosphere
Biosphere
Absorption
Waste Decomposition
Weathering Erosion
Lithosphere
Hydrosphere
Absorption
Sedimentation
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Phosphorous Cycle
Human Impacts
Biosphere
Net Effect Increase in phosphorous in water
algal blooms Depletion in soils
Mining, use (fertilizer, detergent, etc.)
increased runoff
Lithosphere
Hydrosphere
More Phos. for organisms
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Sulfur Cycle
Bacteria Absorption
Atmosphere
Bacteria Release
Biosphere
Volcanoes Weathering
Absorption
Precipitation
Waste Decomposition
Weathering
Evaporation
Sedimentation
Lithosphere
Hydrosphere
Absorption
Deep Sea Vents
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Sulfur Cycle
Human Impacts
Atmosphere
Biosphere
Net Effect Increase in atmosphere (health
effects) and acid rain
Precipitation Acid Rain
Burning Fossil Fuels
Lithosphere
Hydrosphere