Applying the Rules to Environmental Science: Biogeochemical Cycles.

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


Biosphere

Carbon Cycle: Reservoirs

Atmosphere


Biosphere

1x(= 7.3x1017 grams

carbon)

3x

55x35,000x

Carbon Cycle

Atmosphere


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


Biosphere

Photosynthesis

Respiration& Decay

Burial &Lithification

Weathering& Volcanism

Dissolution

PhotosynthesisBurial &Lithification

Exsolution

Carbon Cycle

Atmosphere


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



Nitrogen Cycle

Atmosphere


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


Biosphere

Never enters the atmosphere


Weathering & Erosion

Absorption

SedimentationAbsorption

Phosphorous Cycle


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





Impact:Red Tide



Sulfur Cycle

Atmosphere


Biosphere

Volcanoes& Weathering


Deep Sea Vents

Absorption

Sedimentation

Absorption

Precipitation

“Evaporation” Weathering

BacteriaRelease

BacteriaAbsorption

Sulfur Cycle

Atmosphere


Biosphere

BurningFossil Fuels

Precipitation”Acid Rain

HumanImpacts

Net Effect:Increase in atmosphere (health effects) and acid rain


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)



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



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


are needed to see this picture.What happens if…we kill off all the mice?

Food Webs


are needed to see this picture.What happens if…we kill off all thecrab eater seals?

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:



Why does diet mater?



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


Bioconcentration

Bioconcentrationup the Trophic Pyramid

Energy degrades… but matter does not

Toxin(e.g. heavy metals)

Example:DDT



High concentrations of DDT weakens egg shells in fish-

eating birds & chicks die

Applying the Rules to Environmental Science: Biogeochemical Cycles.

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