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Chapter 3: Earth’s
Environmental
Systems
Biogeochemical Cycles
Law of Conservation of
Mass
 Matter can not be created or destroyed
 It just changes form….
 Water cycle…changes state
 Biogeochemical cycles….changes into
different compounds through different types
of reactions
Nutrients
 Matter that organisms require for their life
processes.
 Macronutrients vs. Micronutrients
Nutrients required in
Large amounts like
Carbon, Oxygen,
Nitrogen and Phosphorus
Nutrients required in
Small amounts like
Potassium, Calcium,
Iron, etc.
Food chains/Food webs
 All of the substances that make up an
organism is made of carbon…where
does it come from?
 Depends on what type of organism you
are….
Ten Percent Rule
Producer vs. Consumer
 Primary producers produce their own food
via photosynthesis
 Plants, algae, phytoplankton (phyto- = plant)
 Consumers are organisms that must eat
(consume) other organisms (plant or animal) to
obtain nutrients
 Mostly animals
 Decomposers are organisms that break
down wastes and dead organisms
 Bacteria and fungi
Carbon Cycle
Needed for energy
 Also includes oxygen
 Carbon is found in most of the compounds on
earth…plastic, gasoline, carbohydrates, proteins, lipids,
nucleic acids, etc….
 A couple things to know in order to understand this
cycle….
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Food chains/Food webs
Producers, Consumers, and Decomposers
Photosynthesis
Respiration
Combustion
Decomposition
Fossil Fuels
Carbon Sinks vs. Carbon sources
Photosynthesis
 Producers use solar energy to convert
CO2 from the air into a usable form of
carbon (glucose) that organisms can use
for energy
(glucose)
Cellular respiration
 Process by which ALL organisms use
oxygen to release the chemical energy of
sugars (glucose)
Decomposition
 All organisms die…where does their
carbon go?
 To the soil and eventually into rock
(limestone) or as fossil fuels (coal or
petroleum)
Fossil Fuels and
Combustion
 Fossil fuels are used by humans for
energy through a process called
combustion
 This releases CO2 back into the
atmosphere
Carbon Sinks vs.
Carbon Sources
 Sinks: Holds Carbons
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Limestone and other sedimentary rock
Ocean
Plants: Land and Marine (phytoplankton/algae)
Permafrost: permanently frozen land
 Sources: Releases Carbon back to
atmosphere
 Combustion: transportation, industry, etc.
 Respiration
 Volcanoes
Phosphorus Cycle
Needed to
make
DNA and RNA
 Only involves the lithosphere (land)
 No atmospheric form
 Think…
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Fertilizer
Food chains
Runoff
Eutrophication
Phosphorus is bound up in
rocks
 Low amounts
 Limiting factor of plant growth
 Not needed as much as nitrogen…hangs
out in water ways
 Reason why it is main culprit of
eutrophication
Eutrophication
 The effect is an overgrowth of producers
(algae)
 Caused by runoff from fertilizer (high in
nitrogen and phosphorus) as well as
wastewater (phosphorus is found in
detergents)
 Can lead to hypoxia (low oxygen levels)
from bacteria decomposing all the dead
producers
Nitrogen Cycle
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Needed for proteins
Most abundant gas in atmosphere
Atmospheric nitrogen is unusable
Relies on bacteria to make it usable
Think…
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Fertilizer
Legumes
Food chains
Bacteria: nitrogen fixation
Nitrification vs. Denitrofication
Lightning
Eutrophication
Nitrogen “fixing”
 Nitrogen fixation: Conversion of nitrogen gas
(N2) to ammonia (usable by plants)
 Lightning
 Nitrogen-fixing bacteria (found naturally in soil or in
root nodules of legumes)
 Nitrification: bacteria convert ammonia (NH3)
into nitrites (NO2) then into nitrates (NO3)
 Denitrification: denitrifying bacteria convert
nitrates back into nitrogen gas (N2)
Secondary Nutrients
 Potassium
 Comes from weathered mineral salts
 Needed for nerve function
 Calcium
 Needed for plant growth and shell formation
 Iron
 Needed for photosynthesis and transporting
oxygen in blood