6.1 Carbon stores and fluxes Flashcards
6.1a stores and fluxes
the carbon cycle
what is the carbon cycle?
is the carbon cycle an open or close system?
what are the two main components?
The carbon cycle is the biogeochemical cycle by which carbon moves from one sphere to another. It acts as a closed system made up of linked subsystems that have inputs, thoughputs and outputs. Carbon stores function as sources (adding carbon to the atmosphere) and sinks (removing carbon from the atmosphere)
It is a closed system, but made up of interlinked subsystems which are open and have inputs and outputs.
two main components are
- stores
- fluxes
6.1a stores and fluxes
stores
what are the 4 main stores of the carbon cycle?
atmosphere: as carbon dioxide and carbon compounds, such as methane
hydrosphere: dissolved carbon dioxide
lithosphere: as carbonate in limestones, chalk and fossil fuels, as pure carbon in graphite and diamonds
biosphere: as carbon atoms in living and dead organisms (both terrestrial and oceanic locations)
biggest store: sedimentary rock store 83,000,000 PgC
smallest store: marine biota 3 PgC
6.1a stores and fluxes
fluxes
what are carbon fluxes measured in?
what are the major fluxes between?
Carbon fluxes are movements of organic compounds through an ecosystem.
Carbon fluxes between the carbon stores of the carbon cycle are measured in either petagrams or gigatonnes of carbon per year.
The major fluxes are between the oceans and the atmosphere, and between the land and atmosphere via the biological processes of photosynthesis and respiration. These fluxes vary not only in terms of flow but also on different timescales.
biggest physical flux: photosynthesis 123PgC/yr
biggest anthropogenic flux: respiration and fire 118.7 PgC/yr
smallest physical flux:
smallest anthropogenic flux:
6.1a stores and fluxes
system feedback
earth systems normally operate by negative feedback
negative feedback (stabilising): any change is cancelled out, maintaining equilibrium, preventing the system from moving beyond certain thresholds
positive feedback (amplifying): a small change in one component causes changes in other components, shifting the system away from its previous state and toward a new one
6.1b formation of geological stores
geological stores
largest store is geological (STAT IN PREVIOUS FLASHCARD)
6.1b formation of geological stores
formation of sedimentary carbonate rocks: limestone
80% of carbon-containing rock is from shell-building (calcifying) organisms (corals) and plankton
these shells are precipitated on to the ocean floor, form layers, are cemented together and lithified (turned into rock) into limestone
6.1b formation of geological stores
biologically derived carbon stores: coal
Trees and vegetation die
they get buried under water
they don’t fully decompose but slowly turn into peat
sediment is deposited on top and compresses the peat
over time it turns into a soft brown coal called lignite
more compression (heat and pressure) due to more sediments on top slowly turns the lignite into anthracite (black coal)
6.1b formation of geological stores
biologically derived stores: shale
a
6.1b formation of geological stores
biologically derived stores: oil and gas
plankton in the sea die and settle to the bottom
no oxygen available for decomposition
sediment builds up on top and compresses
pressure converts it into a coal and the moisture is pushed out
the liquid moves up through the permeable rock layer and collects underneath the impermeable rock layer (gases collect up that)
6.1b formation of geological stores
key processes in the geological carbon cycle
what are the 5 key processes in the geological carbon cycle and how do they work?
- weathering: mechanical, chemical, biological
- decomposition:
- transportation:
- sedimentation:
- metamorphosis:
