Carbon cycle EQ1 Flashcards
When was gasses added to the atmosphere and how
Precambrian geological period, volcanic activity added carbon dioxide (CO,), water (H,0) and sulphur dioxide (SO,) to the atmosphere
Explain how oxygen was added to the atmosphere and when
cyanobacteria started photosynthesising 3 billion years ago
Whats the result of primitive bacteria photosynthesizing
allowed more complex organisms to develop about 2 billion years ago
How does CO2 enter the oceans
By dissolving
When has the carbon balance been altered and how
1800 by human activities such as deforestation and the burning of fossil fuels
What are carbon stores
Sources (adding carbon to the atmosphere) and sinks
What is carbon fluxes?
Movement of carbon from one store to another
Give examples of carbon stores
Atmosphere
Hydrosphere
Lithosphere
Biosphere
What are the major fluxes
between the oceans and the atmosphere
between the land and atmosphere
largest carbon store is?
geological
How much carbon is in the lithosphere?
over 100 million Pg of carbon
Where is most lithos carbon concentrated
Sedimentary rocks
Describe the formation of Sedimentary rocks
Sediment is deposited
Further layers are deposited and sediment undergoes diagenesis
compressed and chemical reactions cement particles together
lithification happens
What are the characteristics of limestone?
Composed of calcium carbonate
80% of lithospheric carbon is found in limestones
How can Geological carbon can also be released into the atmosphere?
Chemical weathering through carbonic acid
Outgassing
Explain chemical weathering of rocks by carbonic acid
carbon dioxide in the atmosphere reacts with moisture to form weak carbonic acid
reacts with some of the surface minerals and slowly dissolves them
Decomposition of rock minerals
What is diagenesis?
physical and chemical changes that occur during the conversion of sediment to sedimentary rock
Explain outgassing
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
Where does outgassing usually occur?
along mid-ocean ridges, subduction zones and at magma hotspots.
How much carbon sinks into deeper waters in the biological pump?
30%
Explain how sedimentary rocks are formed from phytoplankton?
Photosynthesis –> accumilates –> cemented
Explain the biological pump
These move carbon dioxide from the ocean surface to marine plants called phytoplankton through photosynthesis
converts carbon dioxide into food for zooplantic (microscopic animals) and their predators.
Most of the carbon dioxide taken up by phytoplankton is recycled near the surface. About 30% sinks into deaper waters before being converted back into carbon dioxide by marine bacteria.
Explain the physical pump
These move carbon compounds to different parts of the ocean in downwelling and upwelling currents
Downwelling currents bring dissolved carbon dioxide down to the deep ocean.
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.
Explain the carbonate pump.
These form sediments from dead organisms that fall to the ocean floor, especially the hard outer shells and skeletons of fish, crustaceans and corals, all rich in calcium carbonate.
What is the thermohaline circulation?
The thermohaline circulation is the global system of surface and deep ocean currents driven by temperature and salinity differences between different parts of the ocean
What are examples of terrestrial sequestering?
Plants photosynthesizing –> enters the food chains/nutrient cycles
Animals consuming plant matter –> fats and protiens –> respiration
Waste from animals eaten by micro organisms
When plants and animals die, carbon is released into the soil
How much of the human body is carbon in weight?
18%
How do Carbon fluxes vary?
Diurnally
Seasonally
What does the amount of carbon stored in the soil depend on? (List)
Climate
Vegetation cover
Soil type
Land use
Explain how carbon fluxes diurnally?
during the day, fluxes are positive - from the atmosphere into the ecosystem. The reverse applies at night when respiration occurs but not photosynthesis.