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Carbon Cycling - Coggle Diagram

- - - - Combustion Sources
      - Fossil Fuels
      - Organic compounds can become rich in hydrocarbons when compacted underground for millions of years
      - The heat and pressure over time triggers a chemical transformation that results in the compaction of the organic matter
      - The resulting products of this process are fossil fuels (coal, oil and natural gas)
      - Because this geological process takes millions of years to occur, fossil fuels are a non-renewable energy source
      - Biomass
      - An alternative to relying on fuels produced by geological processes is to manufacture fuels from biological processes
      - Living organisms produce hydrocarbons as part of their total biomass (either for use or as a waste product)
      - These hydrocarbons can be extracted and purified to produce an alternative fuel source (e.g. bioethanol and biodiesel)
      - Provided new raw materials are provided and waste products are removed, this source of energy is renewable
- - - - which are:
        
        Atmospheric gases – mainly carbon dioxide (CO2), but also methane (CH4)
        
        autotrophs convert inorganic compounds such as CO2 into organic compounds via photosynsthesis
        
        Heterotrophs cannot synthesise their own organic molecules and instead obtain carbon compounds via feeding
        
        methane
        
        When methane is released into the atmosphere as a result of anaerobic reactions, it only persists for ~12 years
        
        Methane will be naturally oxidised to form carbon dioxide and water (CH4 + 2 O2 → CO2 + 2 H2O)
        
        This is why methane levels in the atmosphere are not very large, even though significant quantities are being produced
        
        Oceanic carbonates – including bicarbonates dissolved in the water and calcium carbonate in corals and shells
        
        This calcium carbonate forms the hardened exoskeleton of coral, as well as forming the main component of mollusca shells
        When the organism dies and settles to the sea floor, these hard components may become fossilised in the limestone
        
        As organic materials – including the carbohydrates, lipids and proteins found in all living things
        
        As non-living remains – such as detritus and fossil fuels
        
        In many soils, saprotrophic bacteria and fungi will decompose dead organisms and return nutrients to the soil for cycling
        This decomposition process requires oxygen (cell respiration is required to fuel digestive reactions)