Carbon 2.1 Flashcards
What are some of the stores of carbon?
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
What is a flux?
Refers to the movement or transfer of carbon between stores
What are the two different types of carbon cycles on earth?
Geological carbon cycle and the biogeochemical cycle
What is the geological carbon cycle?
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
What are two different types of carbon and where do they come from?
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
What’s the process of outgassing like in the geological carbon cycle?
- terrestrial carbon in the mantle, is released into the atmosphere, as CO2, when volcanoes erupt (outgassing)
What’s the process of weathering like in the geological carbon cycle?
- 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.
What occurs during the process of carbon transportation?
- Rivers transport weathered carbon and calcium sediments to the ocean, where they are deposited. The ocean also absorbs carbon directly from the atmosphere.
What happens during the process of decomposition during the geological carbon cycle?
- 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
How does decomposed carbon end back up in the atmosphere in the geological carbon cycle?
- Carbon rich rocks are subducted along plate boundaries and emerge again when volcanoes erupt
What is the process of sedimentation and metamorphism like in the geological carbon cycle?
- 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
How does the carbon cycle remain balanced?
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
What % of biomass on earth (organic material from plants and animals) is carbon?
50%
What’s the biosphere store of carbon like?
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
What’s the atmospheric store of carbon like?
0.0017% of earth’s carbon. This store has recently increased by 36%. It holds CO2 and CH4.
PgC= 560
What’s the hydrosphere store of carbon like?
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
What’s the lithosphere store of carbon like?
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
What’s the store of the pedosphere like?
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
What is the biogeochemical carbon cycle?
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
What are some of the key processes of the biogeochemical carbon cycle?
Photosynthesis
Respiration
Decomposition
Combustion
What is the significance of photosynthesis in the biogeochemical carbon cycle?
this removes CO2 from the atmosphere to promote plant growth (also done by phytoplankton)
What is the significance of respiration in the biogeochemical carbon cycle?
Releasing of CO2 back into the atmosphere as animals consume plant growth and breathe
What is the significance of decomposition in the biogeochemical carbon cycle?
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
What is the significance of combustion in the biogeochemical carbon cycle?
Combustion of biomass and fossil fuels, releasing CO2 and other greenhouse gases into the atmosphere
How is carbon measured?
In gigatonnes (Gt) or petagrams (Pg). Each Gt or Pg of carbon equals one billion tonnes
How many Gt of carbon has been added to the atmosphere as a result of burning?
180Gt
What are the 3 forms of carbon?
Inorganic - found in rocks as bicarbonates and carbonate
Organic- found in plant material
Gaseous- found as CO2, CH4 and CO (carbon monoxide)
How can fluxes in the carbon system be shown?
Using proportional arrows
How do fluxes of carbon vary dependent on the cycle?
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)
What factors controls the speed of photosynthesis and respiration?
Sunlight, temperature, moisture and amount of CO2 in the atmosphere.
How does geographical patterns vary carbon fluxes?
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
How do carbon fluxes vary over a period of time?
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
How is limestone formed in the seabed?
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
How is shale formed in the seabed?
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
How long ago were fossil fuels made?
300 million years ago
How are fossil fuels formed?
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
How is oil and natural gas formed?
Formed from the remains of tiny aquatic animals and plants
How is coal formed?
Formed from the remains of trees, ferns and other plants
Why is the greenhouse effect important?
By slowing up the loss of the sun’s energy through the atmosphere, the Earth’s average temperature in 15 degrees rather than -18
How many ppm of carbon were in the atmosphere in 1700 and 2024
1700: 275ppm
2024: 424ppm
