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 clear-cutting 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?