oxygen regulation

Question 1

who conducted experiments to see the combustion sensitivity to O2?

Answer 1

Andy Watson using fuel

Question 2

what happens in the ocean oxygen regulator?

Answer 2

• recycling of P from marine sediments is enhanced under anoxic waters
• P in organic material
• P absorbed to iron oxides
• produces -ve feedback that can buffer decline in O2
• switches off when anoxia disappears

Question 3

what happens in the land based oxygen regulator?

Answer 3

• increased O2 makes photosynthesis less efficient and increases fore freq
• the suppresses P weathering input to the earth system
• produces -ve feedback on O2

Question 4

what happens in the second land based regulator?

Answer 4

• land plant organic matter has C/P-1000
• whereas marine organic matter has C/P-100
• therefore, if fires transfer P to the ocean, less organic matter will be buried per unit of P
• produces -ve feedback on O2

Question 5

what does abundant jurassic and cretaceous charcoal suggest?

Answer 5

• O2 rose above the present level

Question 6

what effect did O2 have on animal evolution?

Answer 6

• O2 peak of -30% of atm 300 Ma has been linked to the giant dragonflies at the time
• O2 diffusion only scales linearly with concentration yet these are 10x the size of modern dragonflies

Question 7

what did Falkowski et al suggest?

Answer 7

rising O2 triggered the evolution of placental animals