Carbon 2.1

Question 1

What are some of the stores of carbon?

Answer 1

Terrestrial (biosphere) - in living and dead organisms

Lithosphere (the earth’s crust, usually referring to rocks) - carbonates in limestone and fossil fuels such as coal, oil and gas

Oceanic (hydrosphere) - dissolved CO2

Atmospheric- carbon dioxide and methane

Question 2

What is a flux?

Answer 2

Refers to the movement or transfer of carbon between stores

Question 3

What are the two different types of carbon cycles on earth?

Answer 3

Geological carbon cycle and the biogeochemical cycle

Question 4

What is the geological carbon cycle?

Answer 4

Centred around carbon stores in rocks and sediment. It’s also known as the long term carbon cycle because it’s very slow. It can take between 100 and 200 million years for carbon to move through it

Question 5

What are two different types of carbon and where do they come from?

Answer 5

Geologically derived carbon - results from the formation of sedimentary carbonate rocks (limestone and chalk) in the oceans

Biologically derived carbon is stored in shale, coal and other sedimentary rocks

Question 6

What’s the process of outgassing like in the geological carbon cycle?

Answer 6

1. terrestrial carbon in the mantle, is released into the atmosphere, as CO2, when volcanoes erupt (outgassing)

Question 7

What’s the process of weathering like in the geological carbon cycle?

Answer 7

2. CO2 in the atmosphere combines with rainfall to produce carbonic acid (acid rain) that dissolves carbon-rich rocks or silicate rocks, releasing bicarbonates (chemical weathering). This can also be done via mechanical processes, where rocks break up by frost, or biological weathering, where burrowing animals and the roots of plants will break up rocks. Some weathered carbon will be lost to the atmosphere.

Question 8

What occurs during the process of carbon transportation?

Answer 8

3. Rivers transport weathered carbon and calcium sediments to the ocean, where they are deposited. The ocean also absorbs carbon directly from the atmosphere.

Question 9

What happens during the process of decomposition during the geological carbon cycle?

Answer 9

4. calcium carbonate in organic matter from plants/animal shells and skeletons sink to the ocean bed when they die, building up strata of coal, chalk and limestone

Question 10

How does decomposed carbon end back up in the atmosphere in the geological carbon cycle?

Answer 10

5. Carbon rich rocks are subducted along plate boundaries and emerge again when volcanoes erupt

Question 11

What is the process of sedimentation and metamorphism like in the geological carbon cycle?

Answer 11

6. The presence of intense heat or pressure along subduction boundaries metamorphoses sedimentary rock, creating metamorphic rock. Shale becomes slate and limestone becomes marble. CO2 is released by the metamorphism of rocks

Question 12

How does the carbon cycle remain balanced?

Answer 12

It occurs in equilibrium via negative or positive feedback loops. For example, more volcano activity -> rise in CO2 and loss of carbon from rocks -> temperature rise -> more evaporation, condensation and rain -> More chemical weathering and erosion of rocks -> more ions deposited on the ocean floor -> more carbon stored in rocks.
This is a negative feedback loop

Question 13

What % of biomass on earth (organic material from plants and animals) is carbon?

Answer 13

50%

Question 14

What’s the biosphere store of carbon like?

Answer 14

In contains carbon in dead animals and organisms. 0.0012% of earth’s carbon. It can be split into two:
1. terrestrial soil, where micro-organisms break down organic matter into CO2
PgC= 1,500
2. terrestrial ecosystems, where CO2 is taken from the atmosphere by plant photosynthesis
PgC=560

Question 15

What’s the atmospheric store of carbon like?

Answer 15

0.0017% of earth’s carbon. This store has recently increased by 36%. It holds CO2 and CH4.
PgC= 560

Question 16

What’s the hydrosphere store of carbon like?

Answer 16

Overall, it contains 0.038% of carbon on earth
Can also be divided into two:
1.deep oceanic carbon, dissolved in inorganic material and stored at great depths - long term store.
PgC=38,000
2. oceanic surface stores, (shore term store) where exchanges are rapid. Exchanges are rapid due to physical processes, were CO2 gas dissolves in the water and because of biological processes through Plankton
Only 4% of carbon in the hydrosphere is in the upper surface
PgC= 1,000

Question 17

What’s the lithosphere store of carbon like?

Answer 17

This is the largest store and includes rocks in the crust as well as fossil fuels. Fossil fuels make up 0.004% of carbon, but the lithosphere makes up 99.9% of carbon on earth. This is a long term store as carbon can spend hundred of year to millennia here
PgC= 100 million with fossil fuels storing an extra 4,000

Question 18

What’s the store of the pedosphere like?

Answer 18

This refers to soils, such as peat and holds 0.0031% of global carbon. It holds little oxygen and stops decomposition, meaning it traps large levels of carbon

Question 19

What is the biogeochemical carbon cycle?

Answer 19

This is a much more rapid component, with large fluxes and a rapid turnover, also known as the short term carbon cycle. It’s unique to earth because it’s the flow of carbon through the biosphere

Question 20

What are some of the key processes of the biogeochemical carbon cycle?

Answer 20

Photosynthesis
Respiration
Decomposition
Combustion

Question 21

What is the significance of photosynthesis in the biogeochemical carbon cycle?

Answer 21

this removes CO2 from the atmosphere to promote plant growth (also done by phytoplankton)

Question 22

What is the significance of respiration in the biogeochemical carbon cycle?

Answer 22

Releasing of CO2 back into the atmosphere as animals consume plant growth and breathe

Question 23

What is the significance of decomposition in the biogeochemical carbon cycle?

Answer 23

the breaking down of organic matter by bacteria and fungi and releasing CO2 and methane and transferring a large amount back to soils as hummus

Question 24

What is the significance of combustion in the biogeochemical carbon cycle?

Answer 24

Combustion of biomass and fossil fuels, releasing CO2 and other greenhouse gases into the atmosphere

Question 25

How is carbon measured?

Answer 25

In gigatonnes (Gt) or petagrams (Pg). Each Gt or Pg of carbon equals one billion tonnes

Question 26

How many Gt of carbon has been added to the atmosphere as a result of burning?

Answer 26

180Gt

Question 27

What are the 3 forms of carbon?

Answer 27

Inorganic - found in rocks as bicarbonates and carbonate
Organic- found in plant material
Gaseous- found as CO2, CH4 and CO (carbon monoxide)

Question 28

How can fluxes in the carbon system be shown?

Answer 28

Using proportional arrows

Question 29

How do fluxes of carbon vary dependent on the cycle?

Answer 29

Inorganic carbon is released by weathering very slowly, but fluxes between the Earth’s surface, plants and atmosphere are much faster:
-The quickest components are completed in seconds as plants photosynthesise and respire.
-Dead organic material in soils may retain carbon for years, waiting to be broken down and taken to the sea via soil and decomposition
-some organic materials may be buried so deeply, they don’t decay at all and instead transform into sedimentary rocks like limestone or coal or hydrocarbons (oil and natural gas). CO2 is only released when they are burnt, or when limestone is used industrially (e.g. using cement)

Question 30

What factors controls the speed of photosynthesis and respiration?

Answer 30

Sunlight, temperature, moisture and amount of CO2 in the atmosphere.

Question 31

How does geographical patterns vary carbon fluxes?

Answer 31

CO2 fluxes vary with latitude due to climate. Level of carbon fluxes are always higher in the Northern Hemisphere, because it contains greater landmasses and greater temperature variations

Question 32

How do carbon fluxes vary over a period of time?

Answer 32

Diurnally - during the day, fluxes are positive, from atmosphere to ecosystems, whereas at night its negative, because there’s no photosynthesis , but some CO2 released through respiration
Seasonally- most trees are in the northern hemisphere, so during summer of the Northern Hemisphere, photosynthesis and carbon sequestration will be higher. In the winter, there is little growth, but much decay, so CO2 will be released

Question 33

How is limestone formed in the seabed?

Answer 33

80% of carbon containing rock is from shell building (calcifying) organisms and plankton. These are precipitated to the ocean floor, form layers, are cemented together and lithified into limestone

Question 34

How is shale formed in the seabed?

Answer 34

The other 20% of rocks contain organic carbon from organisms that have been embedded in layers of mud. Over millions of years heat and pressure compress the mud and carbon, forming sedimentary rock such as shale

Question 35

How long ago were fossil fuels made?

Answer 35

300 million years ago

Question 36

How are fossil fuels formed?

Answer 36

Organisms, once dead, sank to the bottom of rivers and seas and were covered in silt or mud, which started to decay anaerobically. The deeper the deposit, the more heat and pressure is exerted. When organic matter builds up faster than it can decay, layers of organic carbon became oil, coal or natural gas instead of shale

Question 37

How is oil and natural gas formed?

Answer 37

Formed from the remains of tiny aquatic animals and plants

Question 38

How is coal formed?

Answer 38

Formed from the remains of trees, ferns and other plants

Question 39

Why is the greenhouse effect important?

Answer 39

By slowing up the loss of the sun’s energy through the atmosphere, the Earth’s average temperature in 15 degrees rather than -18

Question 40

How many ppm of carbon were in the atmosphere in 1700 and 2024

Answer 40

1700: 275ppm
2024: 424ppm