Applying the Rules to
Environmental Science:
Biogeochemical Cycles
Earth:
Matter does not come and go
Earth is a
closed
system
to matter
So…
matter is
constantly
recycled on
Earth
Biogeochemical Cycles:
Reservoirs & Pathways
Atmosphere
Biosphere
Hydrosphere
Lithosphere
Some Major Cycles of Matter
•Water Cycle
•Rock Cycle
•Chemical Cycles
•Carbon
•Nitrogen
•Phosphorous
•Sulfur
Carbon Cycle
Atmosphere
Biosphere
Hydrosphere
Lithosphere
Carbon Cycle: Reservoirs
Atmosphere
1x
(= 7.3x1017 grams
carbon)
Biosphere
3x
55x
Hydrosphere
35,000x
Lithosphere
Carbon Cycle
Atmosphere
Respiration& Decay
Photosynthesis
Biosphere
Hydrosphere
Lithosphere
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
Respiration& Decay
Photosynthesis
Biosphere
Dissolution
Exsolution
Weathering
& Volcanism
Burial &
Lithification
Hydrosphere
Lithosphere
Photosynthesis
Burial &
Lithification
Human
Impacts
Carbon Cycle
Atmosphere
Deforestation:
Decrease Photosynthesis
Increase Respiration
Biosphere
Net Effect:
Increase in Carbon
in Atmosphere
Hydrosphere
Burning fossil fuels:
Increased combustion
Lithosphere
Atmospheric Carbon Dioxide
northern
winter
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northern
summer
Impact
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Nitrogen Cycle
Atmosphere
Denitification:
bacteria
Nitrogen fixation:
• bacteria
• lightning
Biosphere
Absorption
Waste &
Decomposition
Erosion
Hydrosphere
Lithosphere
NitrogenFixing
Bacteria in
Root
Nodules
Human
Impacts
Nitrogen Cycle
Atmosphere
Biosphere
Net Effect:
Increase in Nitrogen
in water & soil
Nitrogen fixation:
• industrial (fertilizer)
• combustion
Increased Erosion
Hydrosphere
Lithosphere
Phosphorous Cycle
Never enters the atmosphere
Atmosphere
Biosphere
Absorption
Waste &
Decomposition
Weathering & Erosion
Hydrosphere
Absorption
Lithosphere
Sedimentation
Human
Impacts
Phosphorous Cycle
Net Effect:
Increase in phosphorous in water &
“algal blooms”; Depletion in soils
Biosphere
Mining, use (fertilizer, detergent, etc.)
& increased runoff
Hydrosphere
More Phos. for organisms
Lithosphere
Impact:
Eutrophication
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Impact:
Red Tide
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Sulfur Cycle
Bacteria
Absorption
Atmosphere
Bacteria
Release
Volcanoes
& Weathering
Precipitation
“Evaporation”
Biosphere
Absorption
Waste &
Decomposition
Weathering
Sedimentation
Hydrosphere
Lithosphere
Absorption
Deep Sea Vents
Human
Impacts
Sulfur Cycle
Atmosphere
Net Effect:
Increase in
atmosphere
(health
effects) and
acid rain
Biosphere
Precipitation”
Acid Rain
Hydrosphere
Burning
Fossil Fuels
Lithosphere
Applying the Rules to
Environmental Science:
Food Webs
Earth:
Earth constantly gains & loses energy
Heat
Earth is a
Open
System
to Energy
Sunlight
“Life is a struggle of an
immense number of
organisms, weighing next to
nothing, for a small amount of
energy.”
Producers
( Autotrophs)
Energy enters the system
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Tall grass prairie
Producers
Chlorophyll
Photosynthesis
Carbon Dioxide + Water + Sunlight --> Sugar + Oxygen
Producers
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Chemosynthesis
Hydrogen Sulfide + Carbon Dioxide + Water + Oxygen
+ Geothermal Heat --> Sugar + Sulfuric Acid
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) Levels
Represent the flow of energy (food)
Called “Trophic” (Feeding) Levels
Represent the flow of energy (food)
Sun
Producer
Flow of Energy
Primary
Consumer
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Secondary
Consumer
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Tertiary
Consumer
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Forms a
Food Chain
What happens if…
we kill off all the mice?
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Food
Webs
What happens if…
we kill off all the
crab eater seals?
Food webs are
more stable than
food chains.
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Food
Webs
What happens if…
we kill off all the
crab eater seals?
Food webs are
more stable than
food chains.
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Lessons
1. Food webs are more stable than food chains
2. The produces are the key to the entire food web
3. Life is rough at the top
Energy & “Trophic” Levels
Sun
Producer
1000
units
Flow of Energy
Primary
Consumer
900
lost
100
units
Secondary
Consumer
90
lost
10
units
Tertiary
Consumer
9
lost
About 90% loss each step
2nd Law of Thermodynamics
Energy is lost during conversion
1
units
“Energy Units” Measured as
Biomass
Shown as a
Trophic Pyramid
Tertiary Consumers
Secondary Consumers
Primary Consumers
Producers
“Energy Units” Measured as
Biomass
Energy captured and
turned into biomass by
all producers is called
Net Primary
Productivity
Tertiary Consumers
Secondary Consumers
Primary Consumers
Producers
For example:
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Why does diet mater?
If each person required 10 g/m2 food per day:
This ecosystem could feed:
1 person on all carnivores
4 people on herbivores
80 people on plants
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Applying the Rules to
Environmental Science:
Bioconcentration
Bioconcentration
up the Trophic Pyramid
Energy degrades…
Toxin
(e.g. heavy metals)
but matter does not
Example:
DDT
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High concentrations
of DDT weakens
egg shells in fisheating birds &
chicks die