L13 Oxygen Cycle

Question 1

What are Biogeochemical cycles?

Answer 1

• the tracking of elements
  through biological, geological
  and chemical transformations
• global conservation of mass
• redistributions of mass forms

Question 2

Explain the O2 Cycle

Answer 2

Refer to L13 slides 5-7 for a visual representation

NATURAL OXYGEN CYCLE ( all others is affected by human activity)

1) Photosynthesis: Plants, algae, and some bacteria use sunlight, carbon dioxide (CO₂), and water to produce food. During this process, they release oxygen (O₂) into the atmosphere as a byproduct.

2) Respiration: Animals, humans, plants, and other organisms breathe in oxygen to break down food for energy. This process releases carbon dioxide (CO₂) back into the atmosphere.

Question 3

What is special about photosynthesis in the O2 cycle?

Answer 3

it’s the only natural process that forms oxygen from water in large enough quantities to matter ecologically

Question 4

Explain Respiration

Answer 4

The biochemical oxidation of chemical compounds to produce energy needed for activity, growth, and reproduction

Question 5

Explain Combustion

Answer 5

a small part of the natural cycle (forest fires, grass fires), but increasing due to fossil fuel combustion

Question 6

Combustion in the O2 cycle

Answer 6

3) Combustion: Burning of fossil fuels or organic materials (like wood) uses oxygen. This releases carbon dioxide and other gases into the atmosphere.

Question 7

Nitrification in the O2 cycle

Answer 7

4) O2 contributes to Nitrification (creating NO3 from O2 and NH3) This happens naturally (lightning) or from human activity (fossil fuel combustion)

Question 8

Dentrification in the O2 cycle

Answer 8

5) The O2 cycle also leads to denitrification (creating N2) after NO3 formation. The N2 then contributes to creating H2O (goes back to plants). Happens at wastewater treatment plants

Question 9

Sulfur Oxidation in the O2 cycle

Answer 9

6) O2 contributes to sulfur oxidation (creating SO4 from S and O2) and can be formed through bacteriological oxidation (acid mine drainage, sewer corrosion) or fossil duel combustion

Question 10

Sulfur Reduction in the O2 cycle

Answer 10

7) SO4 contributed to sulfate reduction (creating H2S). This then contributes to creating H2O (goes back to plants)