1.b. The carbon and water cycles are systems

What is the distribution of carbon in the atmosphere?

• 600Bt

What is the distribution of carbon in oceans - the hydrosphere?

• 38,700Bt

What is the distribution of carbon in sea floor sediments - the lithosphere?

• 6,000Bt

What is the distribution of carbon in sedimentary rocks - the lithosphere?

• 60,000-100,000,000Bt

What is the distribution of carbon in fossil fuels - the lithosphere?

• 4,130Bt

What is the distribution of carbon in soil - the biosphere?

• 2,300Bt

What is the distribution of carbon in vegetation - the biosphere?

• 560Bt

What is the distribution of global water in the atmosphere?

• 0.001%

What is the distribution of global water in oceans - the hydrosphere?

• 97%

What is the distribution of global water in groundwater - the hydrosphere?

• 0.7%

What is the distribution of global water in lakes - the hydrosphere?

• 0.01%

What is the distribution of global water in rivers - the hydrosphere?

• 0.0001%

What is the distribution of global water in polar ice and glaciers - the cryosphere?

• 2%

What is the distribution of global water in soil - the biosphere?

• 0.005%

What is the distribution of global water in vegetation - the biosphere?

• 0.0001%

What are the processes associated with inputs in the water cycle?

• Condensation

• Evapotranspiration

• Sublimation

What are the inputs of the water cycle?

• Precipitation

• Water vapour evapotranspired from the hydrosphere and leaves

• Ice and snow into water vapour

What are the processes associated with outputs in the water cycle?

• Evapotranspiration

• Ablation (melting and sublimation)

What are the outputs of the water cycle?

• Moisture leaves the atmosphere as precipitation

• The cryosphere releases water by ablation

• Run-off after infiltration and percolation into aquifers

What is a carbon sink?

• When inputs of carbon exceeds outputs of carbon

What is a carbon source?

• When outputs of carbon exceed inputs of carbon

What is a flux?

• Any movement of carbon between the reservoirs

What are the pathways of the carbon cycle?

• The slow and fast pathways

• Carbon moves between stores

How much carbon is circulated by the slow carbon cycle?

• 10-100Mt per year

How is sea floor sediment formed in the slow carbon cycle?

• Over millions of years, heat and pressure converts dead organisms with shells and skeletons (calcium carbonate) to carbon-rich sedimentary rock

How long are the residence times for carbon held in rocks in the slow carbon cycle?

• 150 million years

How do sedimentary rocks of volcanoes flux carbon in the slow carbon cycle?

• Some carbon-rich sedimentary rocks, subducted into the upper mantle, are vented to the atmosphere in volcanic eruptions

What happens to the exposed sedimentary rocks of volcanoes in the slow carbon cycle?

• Chemical weathering - carbonation (carbonic acid attacks carbonate minerals in rocks)

• CO₂ is released to the atmosphere, and in dissolved form to the hydrosphere

How are carbonaceous rocks formed in the slow carbon cycle?

• Decomposed organic material may be buried beneath younger sediments to form carbonaceous rocks (coal, lignite, oil and natural gas)

How much carbon is circulated by the fast carbon cycle?

• 1,000-100,000Mt

How long are the residence times for carbon in the fast carbon cycle?

• From a few years to decades

How are land plants and phytoplankton key components to the fast carbon cycle?

• Photosynthesis absorbs CO₂

• Respiration releases CO₂

• Decomposition of dead organic material returns CO₂ to the atmosphere

How does the atmosphere and oceans contribute to the fast carbon cycle?

• Atmospheric CO₂ dissolves in surface waters while the oceans ventilate CO₂ back to the atmosphere

What is natural sequestration?

• The process by which Earth’s biosphere (etc., oceans) absorb and store carbon dioxide from the atmosphere through mechanisms (etc., photosynthesis)