1. Factors that Disturb Biogeochemical Cycles
The Human Impact

2. Disturbing the Carbon Cycle
Natural Events
Forest fires – release large amounts of carbon dioxide
Volcanoes – break down rock containing carbon and releases it into the atmosphere, the ash also keeps the sun from reaching plants
Human Activities
Deforestation – the cutting down of forests
Burning fossil fuels – heat, automobiles, electricity

3. What can we do? Stop cutting down trees Plant more trees
Recycle wood and paper
Reduce the use of fossil fuels by walking or riding a bike
Reduce the amount of electricity we use in our homes

4. Disturbing the Nitrogen Cycle
Fertilizers – farmers add fertilizers containing nitrogen to their crops
Manure and human sewage – if not properly disposed of can make their way into the water system adding nitrogen
An excess of nitrogen in the water will cause algal blooms (an over growth of algae)
Algal blooms grow when there is an abundance of nitrogen, sunlight and warmth
These blooms produce dangerous toxins
They also deplete the oxygen supply killing fish and other organisms

5. What can we do?
Ensure proper disposal of sewage and waste (no leaks in septic tanks)
Don’t use fertilizers

6. Questions
Explain how deforestation, fire and burning of fossil fuels disrupts the balance between photosynthesis and cellular respiration?
What are some obstacles humans face when trying to reduce human disruption to the carbon cycle?
Why do algal blooms occur in the late spring?
How do algal blooms affect other organisms in their ecosystem? (consider the food web)
What can be done to prevent algal blooms?
How are the nitrogen and carbon cycle related? (at least 3 points)