Eq1 Flashcards
What is sequestering
the natural storage of carbon by physical or biological processes such as photosynthesis
Why is the carbon cycle a closed system ?
it does not have any external inputs or outputs. So the total amount of carbon is constant and finite.
What are the 4 carbon stores ?
The atmosphere gasses such as carbon dioxide and methane
The hydrosphere ( oceans,lakes): dissolved carbon dioxide
The lithosphere: carbonates in limestone and fossil fuels
The biosphere: living and dead organisms.
What is the geological cycle ?
a natural cycle that moves carbon between land, ocean and atmosphere. This movement involves a number of chemical reaction that create new stores which trap carbon for significant periods of time
What is the biochemical carbon cycle
they determine how much carbon is available on the earths surface is stored or released at any one time. The role of living organisms is critical in maintaining the efficient running of this system, Bea they control the overall balance between the storage,release,transfer and absorption.
How does the carbon cycle maintain equilibrium?
The impact of emissions from volcanic eruptions is so to send extra co2 into the atmosphere,which leads to rising temperatures,increased evaporation and higher levels of atmospheric moisture. This leads to increase acid rain, which weathers rocks and creates bicarbonates that will eventually be deposited as carbon on the ocean floor. The process is slow - perhaps a few hundred thousand years - but this chemical weathering process slowly rebalances the carbon cycle.
Why is there concern about the emissions being added to the atmosphere by human activities
There is an increasing concern of carbon emissions being added to the atmosphere by human activities as even though they are small compared to those natural emissions they cause a the cycle to not be able to keep at equilibrium.
Why do carbon fluxes vary with latitude?
Carbon fluxes vary with lattitude because at lower levels of latitude there is more photosynthesis as there is more vegetation for example the Amazon and rainforests. Whereas at higher levels of latitude there is less vegetation and more deciduous forests causing there to be less photosynthesis so more carbon
Why are level of carbon dioxide higher in the northern hemisphere
They are higher due to the type of land that is in the northern hemisphere. As in the southern hemisphere there is mainly water as it is covered by mainly oceans. Whereas in the northern hemisphere it’s mainly land this means there are more people resulting in a higher level of carbon dioxide.
Explain how geological process store carbon for a long period of time ?
Limestone rocks contain a high concentration of calcium carbonate, which is formed partly from shell building organisms,such as corals, that extracted the mineral from the seawater, and also from marine phytoplankton that absorb carbon through photosynthesis. Their remains accumulate on the ocean floor where over long periods of time they are cemented together and lithified into limestone.
biologically derived carbon in rocks like shale is formed when carbon from organism is embedded in layers of mud. Over millions of years heat and pressure compress the mud and carbon,forming shale.
carbon fossil fuels (coal) were made up to 300 million years ago from the remains of dead organic material. Organisms once dead,sank to the bottom of rivers and seas, were covered in silt and mud, and then started to decay anaerobically. This process operates over a millennia. When organic matter builds up faster than it can decay, layers of organic carbon become fossil fuels instead of shale.
Explain the geological processes that influence levels of carbon in the atmosphere?
Chemical weathering of rocks - atmospheric carbon combines with precipitation to form a weak carbon acid which reacts with rocks to form carbonates which are carried by rivers to the oceans as well as sub-Ariel processes at the coastline also contributing carbonates to the oceans. These marine organisms in the oceans sequester carbon in shell building which eventually form sedimentary carbonate rocks
Volcanic outgassing - carbon is emitted into both the atmosphere and the ocean through a process known as outgassing. This is where CO2 that is contained in mantle fluids is vented from the terrestrial stores of carbon in subduction zones,subducted carbon sources such as kerogen,coal,petroleum,oil shales are oxidases into co2 and vented back into the oceans or the atmosphere.
Explain the role of the ocean in the carbon cycle ( 8 marks)
The ocean contain about 38,00 gigs tonnes of carbon,making them one of earths mot significant carbon stores
Biological pump - carbon is stored as dissolved carbon dioxide in water,or stored in algae,plants and coral. The biological pump sequesters carbon from the atmosphere through the growth of phytoplankton. These form the basis of the ocean food web. Passes along the food web,carbon is returned to the atmosphere by biological decay. The biological pump takes places on a timescale of hours to years and the flux between the atmosphere and ocean is 11 gigatonnes per year
Carbonate pump - only a small proportion of carbon enters the carbon pumps. This is when dead organic materials, eg dead shells and phytoplankton,sinks to the ocean floor and becomes sediment that will eventually become carbonate rocks like limestone (geological carbon store),although on timescales of millions of years
Physical pump - within the oceans, the physical pump, in the form of ocean currents and the thermohaline circulation,moves carbon vertically and horizontally. These pumps flux surface ocean Co2 to the deep ocean. With high latitudes and artic zones with deep oceans have cooler water, which sinks because of its higher density taking co2 accumulated at the surface downwards.
The ocean is in the earth largest carbon stores,being 50 times greater than that of the atmosphere. Small changes in oceanic carbon cycling can have significant global impacts. Significantly, the ocean has the capacity to store excess car
Explain the role of terrestrial primary producers and consumers in the carbon cycle?
Primary producers such as green plants use solar energy to produce biomass. These primary producers also remove carbon from the atmosphere through photosynthesis and release CO2 back into the atmosphere through respiration. The CO2 absorbed into plant growth during photosynthesis by the process of carbon fixation turning gaseous carbon into living organisms - 95% of a trees biomass is made up from CO2.
Primary consumers play an important role in the carbon cycle as they feed on producers that are already full of carbon. When they feed this carbon becomes part of the animals fats and proteins. Carbon is then released from the consumers into the atmosphere through respiration. Biological decomposers like insects feed on dead organisms, that are carbon also rich. Decomposition returns carbon to the atmosphere and, over a millennia, to the lithosphere.
Explain the significance of soil in the carbon cycle ?
Soils store 20-30 percent of global carbon, sequestering about twice the quantity of carbon as the atmosphere and three times that of terrestrial vegetation
There are two sources of carbon in soils. Arid and semi arid soils, and those developed on limestone, contain inorganic carbon. However, the most important store is from organic sources through plant photosynthesis and subsequent decomposition both above 5% of the total soil organic matter. They have seasonal as well as daily patterns and not all active at the same time.
Since all parts of plants are made of carbon, any loss to the ground means a transfer or flux from the plant to the soil. Litterfall and branch includes whole plants and branches shed during any year. Carbon is stored as dead organic matter in soil for years, in colder climates or wetlands environments, before being broken down by soil microbes and released back to the atmosphere.
After death there are thousands of compounds in the soil to be decomposed. The most long term process is the formation of humus. This is seen easily in soils as it has a dark rich colour. Humus soils are 60% carbon and are important for sequestration as well as for water storage.
What are the 3 reasons that temperature causes distribution across the earth ?
The angle of the suns rays
The lightness or darkness of the ground. Snow reflects heat and dark forest absorbs it
Hear is redistributed around the globe by air movement caused by pressure differences and ocean currents
