Imbalances in
Biogeochemical Cycles
Carbon Cycle – Combustion
• Fossil fuels are
carbon compounds
that have long been
removed from the
carbon cycle.
• What event caused
this increase in
CO2?
• What does more
CO2 in the
atmosphere lead
to?
Carbon Cycle – Decomposition &
Respiration
• The oil spill released billions of gallons of carbon based
oil into the water.
• Oil is a good source of nutrition for some bacteria in
the gulf.
• What happens to a population when given an abundant
food source?
• When bacteria use the oil they eat for energy, they
perform cellular respiration. What other chemical is
used? What chemical is made?
Carbon Cycle – Decomposition &
Respiration
• The area where large bacteria populations have
used most of the oxygen are called dead zones
• Why do you think it is called a dead zone?
Carbon Cycle - Photosynthesis
• Photosynthesis is the primary way for the environment
to remove CO2 from the atmosphere .
What impact does development have on the amount of
photosynthesis that occurs?
Carbon Cycle – Carbon in solution
• When CO2 from the atmosphere dissolves in
surface waters, it forms carbonic acid.
• What would carbonic acid do to the pH of the
water?
Carbon Cycle – Carbon in solution
What effect do you think this
has on ocean life?
Hydrologic Cycle – Precipitation and
Evaporation
• Flood
Drought
• What is the effect of each to your biome?
Hydrologic Cycle – Condensation
• Morning dew is an example of condensation.
• There are some plants and animals (especially in
the desert) that rely on dew for survival
Hydrologic cycle – Infiltration and Run
Off
• The most efficient infiltration of water occurs
in slow, steady precipitation. Why?
• Run off tends to occur when it pours. Why?
• Which is most common in our biome:
slow and steady, or when it rains, it pours?
Hydrologic Cycle – Infiltration and Run
Off
What are the
benefits of run
off?
What are the benefits of
infiltration?
Hydrologic cycle – Transpiration
• Evapotranspiration of a forest is
affected by ecological
disturbances, such as clearcutting and wildfire.
• These disturbances greatly
reduce the transpiration
evapotranspiration for several
years
• What effect do you think this has
on other hydrologic processes?
Hydrologic cycle – Transpiration
• Disruption in transpiration affects
timing and amounts of stream
flow, which may then have
effects on flooding and erosion.
• In addition, on sites that do not
drain well, substantial decreases
in transpiration can increase the
height of the water table.
Hydrologic Cycle – Freezing & Melting
• What is the
source of
some of our
rivers?
Hydrologic Cycle – Freezing & Melting
• Global climate change could affect when mountain
snow melts and how much precipitation the
mountains receive.
• How could this
impact our biome?
Nitrogen Cycle – Nitrogen Fixation
• Plants like beans have bacteria
that form nodules on their roots.
These nodules allow that plant to
“fix” nitrogen into a form that all
plants can use for nutrition.
• In conventional agriculture, the
same type of plant (Ex. Corn) is
often planted over and over
again in the same field.
• What happens to the available
nitrogen in the soil when this
happens?
• What are possible solutions to
this problem?
Nitrogen Cycle – Nitrogen Fixation
• When a field does not have
enough nitrogen to grow
crops, farmers often add
synthetic fertilizer to make
the field better able to
produce.
• Often, more fertilizer than
necessary is used to ensure
that enough of it makes it to
the plants.
• What will happen to the
excess nitrogen in rain
storms?
Eutrophication
Nitrogen Cycle – Denitrification
• Adding too much fertilizer not only causes
eutrophication, but can also lead to more
denitrification.
• Denitrification increases nitrous oxide in the
atmosphere.
• Nitrous oxide is a 300X stronger green house
gas than CO2
Nitrogen Cycle – Nitrification
• The nitrates and
nitrites made in
nitrification are
useable by plants.
• Disruptions to
denitrification or
nitrogen fixation
affects this
intermediary step.
Nitrogen Cycle – Ammonification
• Bacteria takes all of the feces, urine and
rotting organisms and turns it into ammonia
or ammonium.
• These are useful forms of nitrogen to plants.
Nitrogen Cycle – Assimilation
• Assimilation is where plants take in nitrates
and converts it to amino acids.
• What are amino acids the building blocks of?
• Fewer plants=more nitrates in the soil.
• What is wrong with more nitrates in the soil?