Applying the Rules to Environmental Science:
Biogeochemical Cycles
Earth:Matter does not come and go
Earth is aclosedsystem
to matter
So…matter is
constantly recycled on
Earth
Biogeochemical Cycles:Reservoirs & Pathways
Atmosphere
HydrosphereLithosphere
Biosphere
Some Major Cycles of Matter
•Water Cycle•Rock Cycle•Chemical Cycles
•Carbon•Nitrogen•Phosphorous•Sulfur
Carbon Cycle
Atmosphere
HydrosphereLithosphere
Biosphere
Carbon Cycle: Reservoirs
Atmosphere
HydrosphereLithosphere
Biosphere
1x(= 7.3x1017 grams
carbon)
3x
55x35,000x
Carbon Cycle
Atmosphere
HydrosphereLithosphere
Biosphere
Photosynthesis
Respiration& Decay
Carbon Transfer:Biosphere Atmosphere
Photosynthesis (Atmosphere to Biosphere)
Carbon Dioxide + Water + Sunlight --> Sugar + Oxygen
Respiration (Biosphere to Atmosphere)
Sugar + Oxygen --> Carbon Dioxide + Water + Energy
Carbon Cycle
Atmosphere
HydrosphereLithosphere
Biosphere
Photosynthesis
Respiration& Decay
Burial &Lithification
Weathering& Volcanism
Dissolution
PhotosynthesisBurial &Lithification
Exsolution
Carbon Cycle
Atmosphere
HydrosphereLithosphere
Biosphere
HumanImpacts
Burning fossil fuels:Increased combustion
Deforestation:Decrease Photosynthesis
Increase Respiration
Net Effect:Increase in Carbonin Atmosphere
Atmospheric Carbon Dioxide
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northernsummer
northernwinter
Impact
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Nitrogen Cycle
Atmosphere
HydrosphereLithosphere
Biosphere
Nitrogen fixation:• bacteria• lightning
Waste &Decomposition
Denitification:bacteria
Erosion
Absorption
Nitrogen-Fixing
Bacteria in Root
Nodules
Nitrogen Cycle
Atmosphere
Hydrosphere Lithosphere
Biosphere
Nitrogen fixation:• industrial (fertilizer)
• combustion
Increased Erosion
HumanImpacts
Net Effect:Increase in Nitrogenin water & soil
Phosphorous Cycle
Atmosphere
Hydrosphere Lithosphere
Biosphere
Never enters the atmosphere
Waste &Decomposition
Weathering & Erosion
Absorption
SedimentationAbsorption
Phosphorous Cycle
HydrosphereLithosphere
Biosphere
Mining, use (fertilizer, detergent, etc.)& increased runoff
HumanImpacts
Net Effect:Increase in phosphorous in water &“algal blooms”; Depletion in soils
More Phos. for organisms
Impact:Eutrophication
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Impact:Red Tide
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Sulfur Cycle
Atmosphere
Hydrosphere Lithosphere
Biosphere
Volcanoes& Weathering
Waste &Decomposition
Deep Sea Vents
Absorption
Sedimentation
Absorption
Precipitation
“Evaporation” Weathering
BacteriaRelease
BacteriaAbsorption
Sulfur Cycle
Atmosphere
Hydrosphere Lithosphere
Biosphere
BurningFossil Fuels
Precipitation”Acid Rain
HumanImpacts
Net Effect:Increase in atmosphere (health effects) and acid rain
Applying the Rules to Environmental Science:
Food Webs
Earth:Earth constantly gains & loses energy
Earth is aOpen
Systemto Energy
Heat
Sunlight
“Life is a struggle of an immense number of
organisms, weighing next to nothing, for a small amount of
energy.”
Producers( Autotrophs)
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Tall grass prairie
Energy enters the system
ProducersChlorophyll
Photosynthesis
Carbon Dioxide + Water + Sunlight --> Sugar + Oxygen
Producers
Chemosynthesis
Hydrogen Sulfide + Carbon Dioxide + Water + Oxygen+ Geothermal Heat --> Sugar + Sulfuric Acid
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Consumers --> Heterotrophs
Primary Consumers - eat producers(Herbivores)
Secondary Consumers - eat primary consumers(Carnivores)
Tertiary Consumers - eat secondary consumers(Carnivores & Omnivores)
Decomposers - break down dead organisms
Called “Trophic” (Feeding) LevelsRepresent the flow of energy (food)
Called “Trophic” (Feeding) LevelsRepresent the flow of energy (food)
ProducerPrimary
ConsumerSecondaryConsumer
TertiaryConsumer
Flow of EnergySun
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Forms a
Food Chain
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Food Webs
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Food webs are more stable than food chains.
Food Webs
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Food webs are more stable than food chains.
Lessons
1. Food webs are more stable than food chains2. The produces are the key to the entire food web3. Life is rough at the top
Energy & “Trophic” Levels
ProducerPrimary
ConsumerSecondaryConsumer
TertiaryConsumer
Flow of EnergySun
2nd Law of ThermodynamicsEnergy is lost during conversion
About 90% loss each step
1000units
100units
10units
1units
900lost
90lost
9lost
“Energy Units” Measured as
Biomass
Producers
Primary Consumers
Secondary Consumers
Tertiary ConsumersShown as aTrophic Pyramid
“Energy Units” Measured as
Biomass
Producers
Primary Consumers
Secondary Consumers
Tertiary ConsumersEnergy captured and turned into biomass by all producers is called
Net Primary Productivity
For example:
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Why does diet mater?
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If each person required 10 g/m2 food per day:
This ecosystem could feed:
80 people on plants4 people on herbivores
1 person on all carnivores
Applying the Rules to Environmental Science:
Bioconcentration
Bioconcentrationup the Trophic Pyramid
Energy degrades… but matter does not
Toxin(e.g. heavy metals)
Example:DDT
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High concentrations of DDT weakens egg shells in fish-
eating birds & chicks die