The Carbon Cycle and Energy Security EQ1 Flashcards
What is the biogeochemical carbon cycle?
It is the short carbon cycle in which carbon moves from one store to another, driven by four key processes. It is a closed system meaning there are no external inputs or outputs.
What are the four main processes driving the biogeochemical carbon cycle?
- photosynthesis
- decomposition
- combustion
- respiration
What are the step in the biogeochemical cycle?
- Plants use atmospheric carbon dioxide to photosynthesis, allowing them to grow and produce organic matter full of carbon.
- This is organic matter eventually dies and falls to the ground as leaf litter.
- The leaf litter begins to decompose releasing the stored carbon back into the atmosphere, or into the soil.
- over a long period of time whent the build up of sediment in faster than the rate of decomposition, under great temperatures and pressures fossil fuels are formed.
- These fossil fuels and burned releasing all of the stored carbon into the atmosphere as carbon dioxide.
- Additionally, all animals are consistently respiring releasing carbon in to the atmosphere.
What is a fluxe?
The movement of organic carbon from one store to another, provide the motion in the carbon cycle.
What is a carbon store?
A carbon store is anything that stores carbon for a period of time. They can either function as sources (adding carbon form the atmosphere) or sinks (removing carbon from the atmosphere).
What units are used to measure carbon?
Petagrams (Pg) or Gigatonnes (Gt). A petagram/gigatonne is equal to a trillion kg or 1 billion tonnes.
What are the main types of carbon stores?
Atmosphere > as carbon dioxide and carbon compounds (CH4)
Hydrosphere (water) > dissolved carbon dioxide
Lithosphere (earths crust) > as carbonate in limestone, chalk and fossil fuels, or as pure carbon in diamonds and graphite
Biosphere > as carbon atoms in living and dead organisms
What are the main fluxes between stores in the carbon cycle?
Major fluxes are between
Oceans and atmosphere
Land (biological processes) and atmosphere
These fluxes vary in terms of flow but also in different timescales
What are anthropogenic causes?
Processes and actions associated with human activity.
What is the reservoir turnover?
The rate at which carbon enters and leaves a store.
Measured by
mass of carbon in any store / exchange fluxe
What is the geological carbon cycle?
This is the long carbon cycle, and is the process of storing carbon in underground geological formations such as rocks and sediment. It has a very large reservoir turnover rate of at least 100,000 years.
What is the key steps in the geological carbon cycle?
- Mechanical, chemical and biological weathering, beaks down the rocks insitu.
- Alongside decomposed organic matter are transported to oceans were they are deposited in the sea floor
- Over millions of years this sediment accumulates and sedimentation occurs, compression the sediment into sedimentary rock (limestone and slate)
- Deeper rock is under greater pressure and is converted to metamorphic rocks (marble)
- In some places the rocks will be taken back to the surface as molten magma or by tectonic uplift
- Volcano also play a part releasing carbon dioxide back into the atmosphere in an eruption this is known as outgassing
- The anthropogenic burning of fossil fuels releases a significant amount of carbon dioxide altering the equilibrium (releasing 35 Gt a year)
What is the carbon storage time and average Pg of Carbon in the crustal/terrestrial geological store?
Carbon storage time - Long term store, can be 100s of years to millennia
Consists of sedimentary rocks
100,000,000 PgC with fossil fuels adding an extra 4,000 PgC
What is the carbon storage time and average Pg of Carbon in the deep ocean store?
A long term store storing carbon for hundreds of year to millennia’s
Majority of the carbon is dissolved inorganic carbon at great depths.
38,000 PgC
What is the carbon storage time and average Pg of Carbon in the terrestrial soil store?
A short term store storing carbon for seconds to decades
This includes carbon stored as plant material (biomass), microorganisms breaks down the organic matter to CO2.
1,500 PgC
What is the carbon storage time and average Pg of Carbon in the surface oceanic store?
Short term store, storing carbon for seconds to decades
Includes fast exchange of carbon with the atmosphere though diffusion of carbon into the sea and biological process of plankton.
1,000 PgC
What is the carbon storage time and average Pg of Carbon in the atmosphere?
Short term store, storing carbon for seasons to decades.
Carbon is stored as CO2 and CH4 as greenhouse gases
560 PgC
What is the carbon storage time and average Pg of Carbon in the terrestrial ecosystem store?
A short term store, storing carbon for seconds to decades
Includes process such as photosynthesis converting the carbon into plant biomass and plant respiration
560 PgC
What is the definition of processes?
The physical mechanisms that drive the flux of material between stores.
E.g. weathering and sedimentation
How is the Himalayas an important carbon store?
The Himalayas is one of earths largest carbon stores. This is because the mountains started as ocean sediment rich in calcium carbonate (shells). The unfolding of the sediment and meant that the carbon contained has been weathered, eroded and transported back into the oceans.
How is carbon stored in fossil fuels?
When organic matter builds up faster than it can decay, layer of organic carbon become oil, gas and coal instead of shale. Under high heat and pressure.
What is oil and natural gas made from?
This is formed from the remains of tiny aquatic animals and plants.
What is coal made from?
Form the remains of trees, ferns and other plants.
Why are the two main geological carbon processes?
- chemical weathering
- volcanic outgassing
What is the steps of chemical weathering?
- Carbon dioxide in the atmosphere reacts with moisture to form weak carbonic acids and falls as precipitation
- Once the water reached the surface is reacts with surface minerals, dissolving them into its component ions
- The calcium ions are transported by rivers to the oceans which combine with bicarbonate ions forming calcium carbonate
- Deposition and burial turns the sediment into limestone
- Carbon is then released again in molten magma, tectonic uplifting or volcanic outgassing.
What is volcanic outgassing?
When pockets of carbon stored in the earths crust is released by volcanic eruption or tectonic activity. Occurs mainly along mid ocean ridges, subduction zones and magma hotspots.
They emit 0.15 - 0.26 Gt if CO2 annually.
E.g. Mt Pinatubo Philippines 1991