Worksheet #18 ATOC 3600 October 31, 2000
NAME: ____________________

1.  If 100 kg of carbon dioxide is photosynthesized, does this contribute to the amount of free oxygen (O or O2) in the atmosphere or deduct from it? How much oxygen is produced or destroyed? How much carbon is produced or destroyed?

2. During the early evolution of the earth, what was an important source of free oxygen? Did it eventually help sustain a new processes of oxygen production? What was that new process?

3. If under global warming, the amount of photosynthesis decreases (due to reduced extent of boreal forests) from 200 Gt-O/yr to 100 Gt-O/yr, how long will the oxygen in the atmosphere last?

4. Identify at least one rapid process not mentioned in class that may constrain the amount of atmospheric oxygen  between certain minimum and maximum bounds.

5. Why is the amount of "free" oxygen in the atmosphere related to the amount of carbon in the atmosphere? If one increases the amount of carbon in the atmosphere does this increase or decrease the amount of "free" oxygen?