carbon cycle

Cards (119)

  • Stores of carbon
    • Lithosphere
    • Hydrosphere
    • Atmosphere
    • Biosphere
  • Lithosphere
    Largest store of carbon, long term storage in marine sediment, sedimentary rock, fossil fuels and soil
  • Hydrosphere
    Carbon stored in ocean, dynamic store but deep ocean carbon stays longer
  • Atmosphere
    Very dynamic store, carbon constantly moving in and out, influenced by human activity
  • Biosphere
    Carbon stored in terrestrial plants, mid term store
  • The carbon cycle is a closed system
  • Stores
    Function as sources and sinks
  • Fluxes/flows
    Movement of carbon between stores
  • Photosynthesis
    Plants convert CO2 into oxygen, glucose and light energy
  • Respiration
    Plants and animals convert oxygen and glucose into water
  • Combustion
    Burning fossil fuels and organic matter releases CO2
  • Decomposition
    Living organisms are broken down by decomposers which respire releasing CO2, some CO2 released into soil
  • Diffusion
    Oceans absorb CO2
  • Sedimentation
    Shelled marine life die, become compacted to form limestone which traps CO2
  • Weathering and erosion
    Carbonation weathering where rocks like limestone are eroded by rainwater and CO2 creating carbonic acid
  • Metamorphosis
    Extreme heat and pressure forms metamorphic rock, during which some carbon is released and some becomes trapped
  • Volcanic outgassing
    Pockets of CO2 released through volcanic eruption
  • Size of carbon stores is measured in Pg/Gt
  • Geological carbon cycle
    1. Mechanical, chemical and biological weathering of rocks on land
    2. Decomposition of plant and animal particles
    3. Transportation of particles to ocean
    4. Sedimentation forming sedimentary rocks
    5. Metamorphosis forming sedimentary rocks
  • Carbon fossil fuels are made up of organic matter that builds up faster than it decays
  • Geological carbon release
    1. CO2 in atmosphere reacts with moisture to form carbonic acid, dissolving surface material and releasing CO2
    2. Pockets of CO2 in crust released through volcanic eruptions and earthquakes
  • Ocean sequestering
    Process of trapping carbon in the sea
  • Carbon pump
    Process operating in oceans that circulates and stores carbon
  • Types of oceanic carbon pumps
    • Biological pump
    • Physical pump
    • Carbonate pump
  • Biological pump
    Moves CO2 from ocean surface to marine plants like phytoplankton through photosynthesis, microscopic plants eaten and sink to deep ocean
  • Physical pump
    Moves carbon compounds to different parts of ocean in downwelling and upwelling currents, carbon stays in deep ocean for hundreds of years
  • Carbonate pump

    Forms sediment from dead organisms that fall to ocean floor, especially hard outer shells and skeletons
  • Thermohaline circulation

    Global system of surface and deep ocean currents driven by temperature and salinity differences
  • Terrestrial sequestering
    Trapping of carbon in the biosphere, a short term store
  • Terrestrial carbon sequestration
    1. Plants sequester carbon from atmosphere through photosynthesis
    2. Animals consume plant matter and carbon becomes part of their fat and protein
    3. Waste from animals eaten by micro-organisms and detritus feeders
    4. When plants and animals die, carbon released into soil
  • Diurnal carbon fluxes
    Positive during day, reverse at night
  • Seasonal carbon fluxes
    Increase in winter due to low plant growth, decrease in summer
  • Biological carbon stores
    Dead organic matter in soil, stored for many years before breakdown by microbes
  • Factors determining amount of carbon stored in soil
    • Climate
    • Vegetation cover
    • Soil type
    • Land use
  • Greenhouse effect
    Solar radiation passes through atmosphere, some absorbed by Earth, some reflected back, enhanced greenhouse effect reflects some back again
  • Balanced carbon cycle is outcome of different components working in harmony
  • Photosynthesis
    Plays essential role in keeping CO2 levels relatively constant and regulating Earth's mean temperature
  • Net primary productivity (NPP)
    Amount of organic matter available for humans and other animals to harvest or consume
  • NPP is highest in warm, wet parts of world like tropical rainforests and shallow ocean waters, least in tundra and boreal forests
  • Soil health
    Determined by balance between inputs (plant/animal remains, nutrients) and outputs (decomposition, erosion, uptake)