L11 Carbon Cycle Flashcards

1
Q

What is sequestration

A

Release of carbon dioxide from stores

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2
Q

Where is the most global carbon
What is the issue with this

A

In the crust below the land and ocean
It is locked up and cannot be used

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3
Q

Atmospheric reservoir is low but more useful as…

A

Cycling is very quick

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4
Q

How is atmospheric carbon dioxide determined

A

Balance between fixation and release by biogenic action

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5
Q

How much carbon does burning of fossil fuels add anually

A

6 * 10^15

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6
Q

How much carbon is fixed by autotrophy each year

A

10^17 gC

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7
Q

How much carbon is taken up by oceans

A

47%

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8
Q

How much of the extra carbon produced currently remians in the atmosphere

A

A tenth

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9
Q

What risk is assocated with oceans absorbing more carbon

A

Acidification

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10
Q

What does it mean for the ocean to be saturated

A

It can’t take up / absorb any more carbon

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11
Q

What has been the change in pH since the industrial revolution (both pH and *)

A

Preindustrial pH 8.2, currently pH 8.0
PH scale is logarithmic so this is 30* increase in acidity

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12
Q

How does carbon dioxide effect pH

A

Carbon dioxide mixes with water = carbonic acid
Dissociates to bicarbonate and hydrogen
Dissociates further to carbonate and 2H+

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13
Q

What organisms will be effected by changes in calcium carbonate concentrations

A

Coral reef, bivalves, coccoliths

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14
Q

What types of calcium carbonate are more vulnerable to increasing acidity

A

Amophorous and high magnesium

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15
Q

How much carbon is stored in vegetation

A

60%

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16
Q

The amount captured in terrestrial reservoirs (trees) can be impacted by:

A

Tree type
Environmental conditions (warmer = more turnover)
Limiting nutrients

17
Q

How much carbon dioxide specifically from fossil fuels is sequested by terrestrial plants

18
Q

How much carbon is sequestered in plant roots and mycorrhizal fungi

19
Q

If hetertrophs stopped existing, how long could photoautotrophs survive

A

300 years then run out of carbon

20
Q

What are the 3 main processes in biogenic carbon cycling

A

Reduction of carbon
Aerobic oxidation of carbon
Anaerobic respiration and fermentation

21
Q

Give examples of photoautotrophs

A

Cyanobacteria
Algae
Diatoms

22
Q

Describe where an oxic habitat would form in terms of photoautotrophy and heterotrophy

A

Where action of photoautotrophy exceeds that of heterotrophy e.g. Marine photic zone

23
Q

What environments can C cycling occur with no oxygen present

A

Sub-surface rock
Aquatic sils and sediments
Waterlogged soil
Animal guts
Microenvironments

24
Q

Is anaerobic biomass accumulation faster or slower than under aerobic conditions and why

A

Slower
Because anaerobic resperiation is less efficient - terminal electron acceptor oxygen yields more energy therefore most biomass created

25
Do anaerobic conditions favpur full or partial breakdown of organic matter
Partial
26
What is radiative forcing
Amount of sun’s energy retained on earth compared with how much is lost to space
27
How much carbon is stored in permafrost compared to the atmosphere
2 times
28
Describe runaway climate change in terms of permafrost
Melting of permafrost causes warming which causes more permafrost to melt - viscous cycle
29
What is the electron donor and terminal electron acceptor in methanogenesis
Hydrogen is electron donor Carbon dioxide is terminal electron acceptor
30
What is the role of cofactors in methanogrnrsis
Carry carbons from carbon diocide, removing oxygen at each step to form water
31
What carries out the proton motive force in methanogenesis and why
Sodium channels rather than proton pumps as the hydrogen is needed to produce water
32
What microbes do methanogens form a close physical association with
Sulphur reducing bacteria
33
What is the sulphate-methane transition zone and what environments will it be found in
The point where the products of suphate reduction meets regions of methane produciton, can be cm or metres thick Found in all anoxic environments
34
What products of methanotrophic archaeon are scaveneged by SRB and what are they used for
Hydrogen or other unknown intermediates which are used as electron donors
35
What is usually limiting in methane oxidation
Sulphate
36
What utilises methane in fresh water and soil habitats
Gamma and alpha proteobacteria
37
What is produced by prteobacteria utilising methane
Use monooxygenase enzyes to convert methane into formaldehyde and biomass