The carbon cycle Flashcards
Name the 4 stores carbon is present in
-atmosphere; (as Co2, methane)
-hydrosphere (dissolved CO2)
-lithosphere (as carbonate in limestones, chalk and fossil fuels,)
-biosphere (as carbon atoms in living & dead organisms)
What is the carbon cycle
biogeochemical cycle which carbon moves from one sphere to another
-acts as a closed system
What are fluxes
movements of organic compounds through an ecosystem
Name the 2 components that make up the carbon cycle
-stores
-flows/ fluxes
What are the organic stores and inorganic stores within the lithosphere store
organic stores -> litter, organic matter, humic substances found in soil
inorganic stores -> coal, oil, natural gas, oil shale, carbonate-based
What are the stores within the hydrosphere
oceanic stores;
-surface layer (euphotic zone) - 900 GtC
-intermediate (twilight zone) & deep ocean layer
-living organic matter - 30 GtC
-dissolved organic matter - 700 GtC
Name the 3 states carbon exists in
-gas
-organic
-inorganic
What are carbon fluxes measured in
petagrams or gigatonnes of carbon per year.
What does the carbon cycle show
how carbon moves from atmopshere through animas, plants & back into atmosphere
Name the 8 main processes (fluxes) which carbon is transferred around natural states
-weathering
-respiration
-precipitation
-decomposition
-volcanic eruptions
-photosynthesis
-combustion
-oceans
Precipitation and weathering
CO2 reacts with moisture in atmosphere to form weak carbonic acid
-carbonation (form of chemical weathering) -> when carbonic acid falls as rain it reacts with calcium carbonate rocks (sedimentary) & dissolves them
-transfers carbon from lithosphere to oceans
Photosynthesis and respiration
photosynthesis equation
co2 + water -> oxygen & glucose
respiration equation
glucose + oxygen -> co2 + water
Decomposition
decomposers break down complex cells and tissues of plants and animals into large biomolecules and then eventually individual atoms
-speed of decomposition is affected by vegetation (deciduous trees)
Biomass combustion
combustion of biomass is the burning of living or dead vegattation
volcanic activity
pockets of carbon dioxide exist in the Earth’s crust. Volcanic eruptions and earthquakes can release these gas pockets. Outgassing is the release of gas, previously dissolved, trapped, frozen or absorbed in some material (e.g. rock). It occurs mainly along mid-ocean ridges, subduction zones and at magma hotspots
-subaerial and submarine volcanic eruptions release CO2 from within the earths lithosphere
oceans
cold oceanic water can hold co2 better than warm ocean water
-cold water sinks (downdwelling) and warm water rises (upwelling) therefore you have vertical mixing of water
-co2 dissolves in the oceans from the air by diffusion, it is moved around within a giant carbon pump
-this is called the physical (inorganic pump)
Name the 3 types of oceanic caerbon pump
-biological pump ->
-physical pump
-carbonate pump
What is phytoplankton
microscopic plants and plant-like organisms drifting or floating in the sea/freshwater along with diatoms, protozoa and small crustaceans.
Explain the carbon cycle
carbon enters atmosphere as CO2 from respiration & combustion
-CO2 is absorbed by producers to make carbohydrates in photosynthesis
-animals feed on plant passing carbon compounds along food chain
-when animals and plants die -> dead organisms are eaten by decomposers & carbon in their bodies is returned to atmosphere as carbon dioxide
What is a carbon sink
store of carbon which takes greater amount of carbon in than ouit
What is a carbon source
store of carbon where amount of carbon leaving the store is greater than input
What is sequestering
natural storage of carbon by physical/ biological processes such as photosynthesis
Name the 5 key processes in the carbon cycle
-mechanical, chemical, biological weathering
-decomposition
-transportation
-sedimentation
-metamorphosis
Explain mechanical weathering in the carbon cycle
-breakup of rocks by frost; shattering & exfoliation produces small, easy-to-transport particles
Explain chemical weathering in the carbon cycle
-breakdown of rocks by carbonic aci in rain -> dissolves carbonate-based rocks
Explain biological weathering in the carbon cycle
-burrowing animals and the roots of plants can break rocks up
Explain decomposition in the carbon cycle
plant & animal particles that result from decomposition after death and surface erosion store carbon
Geological origins
-carbon in limestone and shale
-carbon in fossil fuels
carbon in limestone and shale
carbon fossil fuels
Describe the process of chemical weathering
-water reatcs with atmospheric co2 -> carbonic acid
-this water reaches the surface as rain reacting with surface minerals, dissolving them
-calcium ions transported by rivers from land -> oceans, combine with bicarbonate ions to form calcium carbonate & precipitate out as minerals such as calcite
-deposition & burial turns calcite sediment into limestone
-subduction of sea floor under continental margins by tectonic spreading
-this carbon rises back up and reenters atmosphere as co2
What is volcanic outgassing
when pockets of co2 that exist in earth’s crust are disturbed by eruptions/ earthquakes -> pulses/ more diffuse fluxes into the atmosphere
Name 3 situations where oitgassing occurs
-active/ passive volcanic zones
-places with no current volcanic activity
-direct emissions from fractures in the Earth’s crust
oceanic sequestering
What is the carbon cycle pump
processes operating in oceans to circulate & store carbon
-theres 3 types; biological, carbonate, physical
What is the thermohaline circulation
he global system of surface and deep ocean currents driven by temperature and salinity differences between different parts of the ocean
Name the 3 types of oceanic carbon pump
-biological pumps
-physical pumps
-carbonate pumps
Explain the biological pumps
-they move co2 from ocean surface to marine plants (phytoplankton) through photosynthesis
-this converts co2 into food for zooplankton (microscopic animals) & their predators
-these release co2 back into water & atmosphere
Explain the carbonate pump
Explain the physical pump
move carbon compounds to dif parts of ocean in downwelling & upwelling currents
Downwelling occurs in parts of the ocean where cold, denser water sinks.
These currents bring dissolved co2 down to deep ocean.
Once there, it moves in slow-moving deep ocean currents, staying there for hundreds of years.
Eventually, these deep ocean currents, part of the thermohaline circulation, return to the surface by upwelling.
The cold deep ocean water warms as it rises towards the ocean surface and some of the dissolved carbon dioxide is released back into the atmosphere.
-colder the water, the higher the potential for co2 to be absorbed
Explain what occurs in the terrestrial sequestering
plants sequester carbon out of atmosphere during photosynthesis
-carbon then enters food chains & nutrients cycles of terrestrial ecosystems
-when amilas consume plant matter -> carbon in plant becomes part of their fat & protein
-respiration by consumer animals returns carbon back to atmosphere
-waste from animals -> eaten by micro-organisms, detritus feeders
-when they die -> remains fall to ground -> carbons released into soil
Carbon fluxes within ecosystems vary on 2 timescales
-what are these 2 timescales
-diurnally; during day fluxes are positive, from atmosphere to ecosystem
-at night flux is negative -> loss from ecosystem to atmosphere -> due to rspiration not photosynthesis occuring
-seasonally; winter -> co2 increases -> low levels of plant growth
-in spring plants grow -> co2 decreases until autumn.
Explain primary producers and consumers within terrestrial stores
primary producers -> green plants -> co2 absorbed & convetred into new plant growth during photosynthesis
-as plants grow -> release co2 -> atmosphere -> through respiration
-primary consumers -> bugs, beetles, herbivores -> feed on producers -> return carbon to atmosphere during respiration
