Biogeochemical Cycles
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The biogeochemical cycles are described as being in dynamic equilibrium. Why?
Because the processes that add to a reservoir are equal to the processes that remove from a reservoir. So the reservoir has a constant volume.
The biogeochemical cycles move what 3 elements between reservoirs?
Carbon, Nitrogen and Phosphorus
Name the process that moves carbon from the atmosphere into the oceans.
Dissolving
Name the process that moves carbon from the biosphere into the atmosphere.
Aerobic respiration
Name the process that moves carbon from the atmosphere into plants and plankton.
Photosynthesis
Name the process that moves carbon from dead organic matter to fossil fuels.
Fossilisation
Name the process that moves carbon from dead organic matter to carbonate rocks.
Sedimentation
Name the process that moves carbon from dead organic matter to methane in the atmosphere.
Anaerobic respiration
Name the process that makes carbon from methane to carbon dioxide in the atmosphere.
Oxidation
Name 2 human activities that move carbon from the lithosphere to the atmosphere.
Combustion of fossil fuels. Leakage of methane gas.
Name 2 ways that humans can reduce carbon moving from the lithosphere to the atmosphere.
Renewable fuels. Carbon capture and storage.
Name 2 ways that carbon capture and storage can be made more effective before the fuel is burnt (Pre-combustion).
• Gasification of fuels • Burn gases in pure oxygen
Explain why precombustion technology in CCS can make the process more effective.
As the products are only carbon dioxide and water.
Name 2 ways that carbon capture and storage can be made more effective after the fuel is burnt (Post-combustion).
• Dissolving the combustion products in a solvent • Separating combustion products using high pressure membrane filtration. • Adsorption and desorption processes
Name a human activity that reduces carbon moving from the atmosphere to the biosphere.
Deforestation
Name 2 ways that humans can increase carbon moving from the atmosphere to the biosphere.
• Conservation of biomass using legal designations E.g. MNR • Carbon sequestration
Describe the process of carbon sequestration.
Afforestation (planting trees), using the wood (e.g. building material), replanting.
Name 2 human activities that move carbon from the biosphere to the atmosphere.
Ploughing (CO2), landfill (CH4), rice paddies (CH4) and cattle (CH4)
Explaining how ploughing causes carbon to move from the biosphere to the atmosphere.
Ploughing exposes the dead organic matter to the air, increasing the rate of respiration of the decomposers, so more CO2 is emitted.
Name a human activity that reduces carbon dioxide being emitted by ploughing.
Planting perennial (long term) crops so that the frequency of ploughing reduced.
Name a human activity that reduced the methane emitted by the biosphere.
Drain rice paddies, eat less meat so less cattle are required, recycling so less waste goes to landfill.
What form of nitrogen is found in the air?
N2, inert gas.
What forms of nitrogen could be found in a sample of soil?
NH4+ (ammonium compounds), NO2- (nitrites), NO3- (nitrates) and NH3 (ammonia)
Explain how nitrogen in the air is converted to ammonium compounds.
Nitrogen is converted to ammonium compounds in a process called nitrogen fixing. Azotobacter, a genus of bacteria, are required for this process.