Water/Carbon cycles

• Water cycle


  Closed system flows between atmosphere, ocean, land at varying time scales from days to millions of years
• Main stores of the water cycle

  • Ocean
  • Atmosphere
  • Land
• Water cycle


  1. Precipitation

  2. Evapotranspiration

  3. Groundwater flow
• On a global scale, the water cycle is a closed system driven by the Sun's energy
• Only energy crosses the boundaries of the water cycle system
• At smaller scales (drainage basin or forest ecosystem), both matter and energy cross the system boundary
• Reservoirs and stores of water

  • Oceans (97% of all water)
  • Ice caps and glaciers (2% of freshwater)
  • Groundwater (0.77% of freshwater)
  • Atmosphere (0.001% of freshwater)
  • Lakes (0.01% of freshwater)
  • Soils (0.003% of freshwater)
  • Rivers (0.0001% of freshwater)
  • Biosphere (0.00004% of freshwater)
• The Southern hemisphere has a greater proportion of the world's water
• Aquifer


  Permeable rock that holds groundwater
• Inputs to the water cycle

  1. Water vapour evaporated from oceans, soils, lakes and rivers

  2. Water vapour transpired through plant leaves (evapotranspiration)
• Outputs from the water cycle

  1. Precipitation and condensation

  2. Ablation from ice sheets, glaciers and snowfields

  3. Runoff into rivers and oceans

  4. Infiltration into soil and percolation into aquifers
• Carbon cycle


  Closed system flow between atmosphere, ocean, land and biosphere
• Sedimentary rock holds 99.9% of all carbon on Earth
• Most carbon in circulation moves rapidly between stores
• Carbon cycle


  1. Photosynthesis

  2. Respiration

  3. Oxidation (decomposition and combustion)

  4. Weathering
• Carbon sinks


  • Atmosphere (600 billion tonnes)
  • Oceans (38,700 billion tonnes)
  • Sedimentary rock (60,000,000 to 100,000,000 billion tonnes)
  • Sea floor sediments (6,000 billion tonnes)
  • Fossil fuels (4,130 billion tonnes)
  • Land plants (560 billion tonnes)
  • Soils and peat (2,300 billion tonnes)
• Slow carbon cycle


  1. Deposition of carbon compounds on ocean floor

  2. Burial and compression into sedimentary rock

  3. Uplift and weathering of sedimentary rock

  4. Volcanic release of carbon back to atmosphere
• The total amount of carbon circulated in the carbon cycle is between 10-100 million tonnes per year, taking 100-700 million years to move through the cycle
• Fast carbon cycle


  1. Photosynthesis

  2. Respiration

  3. Decomposition

  4. Combustion

  5. Atmosphere-ocean exchange
• The fast carbon cycle moves around 1000 times more carbon per year than the slow cycle
• Processes of the water cycle

  Precipitation