1. 2.2. Global Interactions (Part 2) – Nutrient Cycling
Human interactions through the use of energy affect environmental sustainability

2. 1. All of the nutrients that support life and all wastes are constantly recycled in the biosphere
a. Nutrients are chemicals that are required for plant and animal growth and other life processes
i. E.g. Carbon can be found in every living cell in various compounds such as carbon dioxide, carbohydrates such as sugar, even our DNA, proteins, and fats

3. c. Scientists refer to these accumulations as stores
b. These nutrients can be built up and accumulated for periods of time in the 3 main parts of our biosphere
i. Atmosphere
ii. Land masses - lithosphere
iii. Oceans and bodies of water – hydrosphere
c. Scientists refer to these accumulations as stores
i. Nutrients can move in and out of the nutrient stores through
Biotic processes such as decomposition
Abiotic processes such as river run off

4. 2. A nutrient cycle is a concept that describes how nutrients move from the physical environment into living organisms and subsequently is recycled back to the physical environment.
a. The cyclical movement of nutrients is essential to any given ecosystem, and it must be balanced and stable for the system to be maintained.
b. Nutrient cycles should be in balance, i.e. the amount of nutrients moving out of the store is equal to the amount moving in

5. i. Human activities have unfortunately thrown these cycles out of balance
Land clearing, agricultural methods, urban expansion, mining, industrial activities and increased use of motorized transportation can affect a nutrient cycle
We have increased the amounts of nutrients in the cycle faster than the abiotic or biotic processes can move them back into the store
ii. Increasing the amount of the nutrients in the biosphere can have large effects on the ecosystem

6. 3. Carbon is an essential component of all living things
a. Many compounds that contain carbon are called organic compounds

7. 4. Carbon is stored in the short term in
a. plants (both on land and in the water)
b. animals (both on land and in the water)
c. decaying matter in the soil (on land)
d. as carbon dioxide gas (both in the atmosphere and dissolved in waters)
i. Deeper depths of water store carbon dioxide for longer terms

8. 5. Carbon is stored in the long term in
a. Deposits of coal, oil and gas (fossil fuels)
i. Fossil fuels are formed from the dead bodies of ancient plants and animals
b. Marine sediments and sedimentary rock are the largest long-term stores of carbon
i. Soil particles and dead organic matter accumulate in layers on the ground at the bottom of bodies of water which forms into sedimentary rock
ii. Some sedimentation (especially marine) contain the shells of organisms like clams and corals
The shells contain large amounts of carbon in the form of calcium carbonate which form into limestone

9. 6. Many natural processes move carbon through the ecosystem
a. Photosynthesis – carbon in the form of CO2 move into plants and are converted into carbohydrates (C6H12O6)
i. 6CO2 + 6H2O + energy  C6H12O6 + 6O2
b. Cellular respiration - the process used by both plants and animals to release the energy from carbohydrates
i. C6H12O6 + 6O2  6CO2 + 6H2O + energy
ii. The carbon dioxide is released back into the atmosphere
c. Decomposition – the breaking down of dead organic matter by fungi and bacteria returns carbon back into the ground

10. d. Ocean mixing – at high latitudes, carbon dioxide dissolves into the cold ocean waters
i. The cold waters sinks to lower depths
ii. Deep ocean currents move the dissolved carbon to the warmer tropic waters
iii. The warmer water rises to the surface and some of the carbon dioxide is released out of the water and back into the atmosphere
e. Volcanic activity – carbon dioxide is released as magma is pushed out

11. 7. Many human activities have interfered with the carbon cycle
a. Carbon dioxide emissions from the burning of fossil fuels have increased the amount of carbon dioxide in the atmosphere by 30%
i. The carbon cycle is unable to move the carbon dioxide back into the stores quickly enough

12. b. Carbon dioxide in the atmosphere is a greenhouse gas
i. It causes heat to be reflected back towards the planet which causes global warming
ii. The increased temperature of our planet can have many effects
E.g. Melting of polar ice and glaciers

13. c. Urban expansion and agriculture is removing large amounts of native plant life
i. Farming may place new plants in the areas, but they usually remove less carbon dioxide