Science 20F
Factors that Influence Biogeochemical Cycles
Biogeochemical cycles are complex involving the transfer of nutrients from the
environment to an organism and back to the environment. Another way of defining
it is the use and reuse of materials of the Earth. Biogeochemical cycles involve
combinations of the carbon cycle, nitrogen cycle, oxygen cycle, and the cycles
found in ecosystems containing various trophic levels.
Natural events or human activities can disturb Biogeochemical cycles.
Human activities include:
 Overuse of fertilizers or herbicides
- runoff affects bodies of water causing algae blooms. When the algae
dies, bacteria decompose the algae but use oxygen in the process.
Eventually, most of the oxygen is used up resulting in the fish and other
animals dying. Fertilizers can also lead to bioaccumulation.
 Combustion of fossil fuels
- disrupts the balance between photosynthesis and respiration
 Deforestation
- disrupts the balance between photosynthesis and respiration
 Human and animal waste mismanagement
- affects bodies of water
Natural events include:
 Volcanic activity
- carbon cycle disrupted by a reduction in the intensity of sunlight due to
smoke and ash from a volcanic eruption
 Fire
- disrupts the balance between photosynthesis and respiration
Research Assignment
In your local newspapers, find 3 articles relating one of the factors mentioned
above that affect biogeochemical cycles. Paste article on sheet and underneath
report on:
1) The factor affecting the biogeochemical cycle.
2) What is being disturbed in the cycle?
3) What is being done about it to prevent further disruption?