WCC: Carbon Cycle - Global Distribution of Carbon Stores Flashcards
Global distribution and size of major stores of carbon in the lithosphere, hydrosphere, cryosphere, biosphere and atmosphere.
Name the 5 main physical systems that store carbon.
Biosphere Lithosphere Cryosphere Hydrosphere Atmosphere
What are fluxes?
The changes in the amount of carbon held in each store over timescales ranging from a few minutes to millions of years.
Amount of carbon in marine and sedimentary rocks
Up to 100 million GtC
Amount of carbon in the ocean
38,000 GtC
Amount of carbon in fossil fuel deposits
4,000 GtC
Amount of carbon in soil organic matter
1,500 GtC
Amount of carbon in the atmosphere
750 GtC
Amount of carbon in terrestrial plants and animals
560 GtC
Chemical formula for methane
CH4
Where is carbon stored in the hydrosphere?
In deep and shallow ocean waters in:
Ocean sediments
Dissolved CO2
Shells
Briefly outline why carbon is important (3 reasons)
It is needed by all plants and animals for life, and provides a source of food for plants and animals. It has has provided fuel for human industries since pre-history in the form of fossil fuels, for example in the industrial revolution which was essential in the UK’s development as a leading economy. Changes in the carbon cycle have led to climate change, making them arguably the greatest challenge facing the planet.
What is carbon?
A basic element needed by all life to survive
What is a carbon sink?
A store that absorbs more carbon than it releases
What is a carbon source?
A store that releases more carbon that it absorbs
What different geographical scales can carbon stores be identified at?
Individual plants
Seres
Global scales - oceans and continents
Briefly describe why carbon is unevenly distributed around the world.
The uneven distribution of land and sea has a large impact on the global distribution of carbon stores such as oceans, soils and rocks. Fossil fuels are only found in certain parts of the world, making carbon emissions high in these areas due do industrial burning of fossil fuels.
What is the carbon cycle?
The complex processes carbon undergoes as it is transformed from organic carbon into inorganic carbon and back again
Why does following the carbon cycle allow us to study energy flows on Earth?
Most of the chemical energy needed for life is stored in organic compounds as bonds between carbon atoms and other atoms
What is the name for the different forms in which carbon can move through the cycle?
Carbon compounds
How is carbon stored in a solid form? Which stores store solid carbon?
It is combined with other elements and stored in living things, minerals of rocks and soil, and ice.
What are the 2 pure solid forms of carbon?
Graphite and diamond
How is carbon stored as a liquid?
It is dissolved in water
What are 2 important liquid forms of carbon?
Carbonic acid
Dissolved organic carbon
How is carbon stored as a gas?
It is combined with other elements to form gases
What are 2 important gaseous forms of carbon?
Carbon dioxide
Methane
Name 5 important carbon compounds
Carbon dioxide Methane Calcium carbonate Hydrocarbons Bio-molecules
Why is carbon dioxide the most studied form of carbon?
It has a profound effect on climate
Why is it difficult to separate natural carbon cycles from those affected by human activity?
Human activity and anthropogenic CO2 fundamentally affect the carbon cycle and therefore climate
What stores is carbon dioxide found in?
Atmosphere
Oceans
Soils
What stores is methane found in?
Atmosphere
Oceans
Soils
Sedimentary rocks
What stores is calcium carbonate found in?
Calcareous rocks
Oceans
Skeletons and shells of ocean creatures
What stores are hydrocarbons found in?
Sedimentary rocks
What stores are bio-molecules found in?
Living things
What is carbon dioxide?
A gas formed when carbon combines with oxygen.
Chemical formula: CO2
What is methane?
A powerful greenhouse gas formed when carbon combines with hydrogen.
Chemical formula: CH4
What is calcium carbonate?
A solid carbon compound
Chemical formula: CaCO3
What are hydrocarbons?
Organic compounds consisting of hydrogen and carbon that can be solids, liquids or gases
What are bio-molecules?
Complex carbon compounds produced in living things
What is anthropogenic CO2?
Carbon dioxide generated by human activity
What unit do the IPCC use to measure the amount of carbon in various stores?
GtC - A gigatonne of CO2
What is flux of carbon within the cycle measured in?
GtC/years - gigatonnes of carbon per year
What is the Earth’s primary source of carbon?
the Earth’s interior - carbon is stored in the mantle
Where can carbon escape from the mantle?
At constructive and destructive plate boundaries and hot-spot volcanoes
How is CO2 released at destructive plate boundaries?
Through the metamorphism of carbonate rocks subducting with the ocean crust
How is carbon moved into long-term storage?
By burial of sedimentary rock layers
Which sedimentary rocks store carbon in the long-term and in what form?
Coal and black shales store organic carbon from undecayed biomass
Carbonate rocks like limestone store calcium carbonate
Which physical system stores the largest amount of carbon?
The lithosphere
What is the largest store of carbon?
Marine and sedimentary rocks
What is the lithosphere?
The Earth’s crust and uppermost mantle
What is the pedosphere?
The uppermost layer of the lithosphere which chemically reacts to the atmosphere, hydrosphere and biosphere through the soil forming process
Amount of carbon in peat
250 GtC
Why is soil not entirely part of the lithosphere?
It is partly made of living organisms
Give 2 examples of sedimentary rocks that are largely composed of carbon.
Limestones
Dolomite
What forms fossil fuels?
Fossilised organic matter
What are the 3 main fossil fuels?
Coal
Oil
Natural gas
What are fossil fuels?
Hydrocarbons trapped within the lithosphere that release significant amounts of heat energy when they are burned
What is peat?
An accumulation of partially decayed vegetation or organic matter unique to natural areas called peatlands or mires
Why do sedimentary rocks contain large stores of carbon?
They are formed from the fossilised remains of marine organisms
What are limestones primarily composed of?
Calcium carbonate
Give an example of a limestone and why it stores a lot of carbon.
Chalk, which is composed primarily of the shells of single-celled, calcium carbonate secreting creatures
Give 2 stores of inorganic carbon in the lithosphere.
Fossil fuels
Carbonate-based sedimentary deposits
Give 3 stores of organic carbon in the lithosphere.
Litter
Organic matter
Humic substances found in soils
Give the 4 main carbon stores in the lithosphere?
Marine sediments
Soil organic matter
Fossil fuels
Peat
How much carbon is there approximated to be stored in the oceans?
38,000 GtC
How can ocean stores be divided up in order to measure the amount of oceanic carbon?
3 stores:
- surface layer
- intermediate and deep layer
- organic matter
How much oceanic carbon does the surface layer store?
900 GtC
How much oceanic carbon do the intermediate and deep layers store?
37,000
How much oceanic carbon does living organic matter store?
30 Gtc
How much oceanic carbon does dissolved organic matter store?
700 GtC
How do marine and sedimentary rocks form?
When organisms die, their dead cells and shells sink into deep water. Some material sinks right to the bottom where it forms layers of carbon-rich sediments. Over millions of years, chemical and physical processes may turn these sediments into rocks.
What defines the surface layer of the ocean?
The layer at which sunlight can penetrate so photosynthesis can occur
Briefly describe the global distribution of carbon within the hydrosphere.
Net sources of carbon in the eastern Pacific, Arabian Sea, south Atlantic and Southern Ocean. Also net sinks in the Southern Ocean and Pacific as well as the north Atlantic
Briefly describe the global distribution of carbon in the lithosphere.
Large amount of carbon stored in northern Russia, Canada and Saudi Arabia
What does the distribution of carbon within the terrestrial biosphere depend on?
The ecosystem
Which terrestrial ecosystems store the largest amount of carbon?
Boreal forests
Which terrestrial ecosystems store the largest amount of carbon?
Deserts
What are the 5 main stores of carbon in the terrestrial biosphere?
Living vegetation Plant litter Soil hummus Peat Animals
What percentage of carbon in the terrestrial biosphere is stored in plants?
19%
What 2 factors influence the amount of carbon in living vegetation?
Location
Vegetation type
Give an example of how location influences the amount of carbon stored in living vegetation.
It is estimated half of the carbon stored in forests is stored in high-latitude forests, and over a third is stored in low-latitude forests
What are the 2 largest forest stores of carbon?
Russia’s vast expanses of forest
Amazon Basin
What percentage of the world’s forest carbon is stored in Russian forests?
25%
What percentage of the world’s forest carbon is stored in the Amazon Basin?
20%
What percentage of terrestrial carbon is stored in boreal forests?
26%
What percentage of terrestrial carbon is stored in tropical forests?
20%
What percentage of terrestrial carbon is stored in deserts?
5%
What is plant litter?
Fresh, undecomposed and easily recognisable plant debris
What factor directly affects the type of plant litter found in area?
The type of ecosystem
Why is annual litter fall low in grasslands?
There is very little above ground perennial tissue in grasslands
Where does soil hummus originate from?
Litter decomposition
What is hummus?
A thick brown or black soil substance that remains after most organic litter has decomposed
How does hummus get dispersed throughout soil?
By soil organisms such as earthworms
In all forests combined, how is carbon distributed between biomass and soil?
Around 30% is stored in biomass and 70% in soil.
In tropical forests, how is carbon distributed between biomass and soil? How is this different to other forests.
Carbon is distributed evenly with 50% in biomass and 50% in soil. Other types of forests tend to store the majority in soil.
Amount of carbon stored in soil inorganic matter
1000 GtC
What does soil inorganic carbon consist of?
Carbon itself as well as carbonate materials such as calcite, dolomite and gypsum
Total amount of carbon stored in soil
2,500 GtC
Briefly describe how the magnitude of carbon stores varies between the hydrosphere, lithosphere, biosphere and atmosphere.
The lithosphere contains the largest amount of carbon, mainly in the form of marine and sedimentary rocks. The hydrosphere has the next largest carbon store within the ocean. The carbon stored in soil can be included in both the lithosphere and the biosphere, and is approximately 3 times larger than the atmospheric carbon store. However there is still more carbon stored in the atmosphere than in the rest of the biosphere, consisting of living plants and animals.
How do terrestrial animals get carbon?
From their diet
How do plants and marine animals get carbon?
They extract it from the atmosphere and oceans
What do plants and marine animals use carbon for?
To build organic structures such as plant material and sea shells
What happens to the carbon when plants and marine animals die?
They decompose and the carbon is returned either to the ocean, sea bed, atmosphere or soil
What conditions does peat form in?
Wetland conditions
How does peat form?
Almost permanent water saturation obstructs flows of oxygen from the atmosphere into the ground. This creates anaerobic conditions that slow down the rates of plant litter decomposition.
Describe the global distribution of peat.
Peatlands occur on all continents in nearly all ecosystems and altitudes.
How large an area do peatlands cover globally?
4 million km^2
What percentage of global land and freshwater surface is covered by peatlands?
3%
How are animals important in the carbon cycle?
They are important in generating the movement of carbon through the cycle
What percentage of the atmosphere is CO2?
0.04%
Give 2 important uses of atmospheric CO2
Regulates the Earth’s surface temperature
Used by plants for photosynthesis
How do atmospheric carbon stores affect rain?
Atmospheric CO2 makes rain slightly acidic, as CO2 reacts with water vapour to form carbonic acid. Increased atmospheric CO2 increases the acidity of rain.
What is the main impact of the natural acidity of rain?
Weathering
What is the largest store of cryospheric carbon?
Permafrost
What regions is permafrost found in?
Tundra regions
How does permafrost store carbon?
Upon death, plants and animals are frozen due to the cold climate, preventing decomposition. This means that the carbon is trapped in the permafrost and not released back into the atmosphere, water, or soil.
