Nitrogen cycle
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Nitrogen cycle

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Nitrogen cycle Nitrogen cycle Presentation Transcript

  • TheNitrogenCycle
    IB Biology
  • What is nitrogen?
  • Periodic Table
    Nitrogen is in the Nonmetals/BCNO Group
  • Where is nitrogen found in the environment?
  • The largest single source of nitrogen is in the atmosphere.
    Nitrogen makes up 78% of our air!
  • It is one of nature’s great ironies…
    Nitrogen is an essential component of DNA, RNA, and proteins—the building blocks of life.
    Although the majority of the air we breathe is nitrogen, most living organisms are unable to usenitrogen as it exists in the atmosphere!
  • How does atmosphericnitrogen get changed into a form that can be used by most living organisms?
    N
    N
  • By traveling through one of the four processes in the Nitrogen Cycle!
    (1) Nitrogen Fixation
    (4) Denitrification
    Nitrogen Cycle
    (3) Nitrification
    (2) Ammonification
  • Nitrogen in
    the air
    animal protein
    nitrogen fixing plant
    eg pea, clover
    plant made
    protein
    dead plants & animals
    urine & faeces
    denitrifying
    Pseudomonas
    denitrificans
    root nodules
    (containing Rhizobium)
    decomposition by bacteria & fungi
    nitrates absorbed
    ammonia
    nitrates
    nitrites
    Azobacter
    Nitrobacter
    (nitrifying bacteria)
  • Yourtask!
    Imagine you are a nitrogenatom!
    Sendpostcardtoyournitrogenfriendsexplainigthefollowing:
    -Whereyouwere…
    -Whereyou are now….
    -Whereyou are goingnext….
    Don´tforgettoexplainanymeetingswith bacteria orhowyouhavechanged as a molecule!
  • Sewage
    IB Biology
  • Flushed with success?
    To draw attention to the
    people who do not have toilets or proper sanitation
    Built by Sim Jae-Duck, involved with World Toilet Association
    Seoul, South Korea
    Why?
    2 billion
  • Sewage
    What is it?
    Untreated raw sewage is waste which has come from our toilets, sinks, baths etc.
    What does it contain? examples
    • organic material
    • mineral salts
    • bacteria
    Faeces, food fragments, enzymes, soap, gel, hair
    Phosphates, nitrates
    Some from detergents & washing powders
    Food poisoning, disease-causing
  • Environmental damage
    14 July 07
    14 Sept 07
    • In rivers can cause algal blooms (as sewage is a good food source for them), killing animals and plants living in water.
    • May release methane and ammonia gases (foul smelling).
    Eutrophication
    Sussex River Ouse
    Sea trout nursery
  • Eutrophication
    High concentrations of inorganic substances can cause algal blooms
    Substances encourage rapid growth of algae and blue-green bacteria
  • Biological Oxygen Demand
    Sample of water measured at 20˚C over 5 days
    2. Increase in organic pollutants increases number of bacteria
    BOD will increase
    Copy the steps above and give a reason as to why each step is occurring
    -use your handout to help!
  • Sewage treatment works
  • Why treat it?
    • May cause disease if it contaminates drinking water, due to harmful bacteria present.
    Examples of diseases which may be spread by untreated sewage.
    dysentery, typhoid, cholera
  • Sewage treatment process
    0
    Untreated raw sewage enters the sewage works
    1a
    1b
    Aerobic conditions
    Sedimentation tank
    2
    3
    Anaerobic conditions
    4
    5
    Sewage water to:
    Screening (coarse filter)
    Metal grids strain out large objects
    Grit tank
    Stones and heavy solids sink to the bottom
    Lighter solids such as faeces sink to the bottom and form a sludge
  • Anaerobic conditions
    Aerobic conditions
    3
    4
    5
    6
    *or biobeads
    Sludge digestion tank
    Bacteria feed on sludge, producing methane. Can be used as a fuel.
    Activated sludge tank
    Sludge mixed with
    extra air (oxygen), stirred, bacteria produce harmless liquids.
    Biological filter tank
    Fluid from tank sprinkled over stones* coated with microbes. Bacteria produce harmless liquids
    Treated waste emptied into rivers
  • Now complete yourSewageTreatmentcut and paste sheet!
  • Increasing energy levels
    Biofuels
    The main fuels which can be obtained from biomass:
    • Methane
    • Alcohol
    Methane (biogas) production occurs naturally by fermentation (anaerobic respiration) when animal or plant material decays.
    Both are products of fermentation
  • Generation of methane from biomass
    Fermentation of faeces
    -aerobic bacteria hydrolysecarbs, proteins, fats
    Oxygenused up
    -acetogenic bacteriaconvertsugarsto short chainfattyacids (e.g.acetate), CO2 and H2
    -acetogenesisstage
    Methanogenesis
    -final stageisanaerobicand involvesmethanogenic bacteria
    -conversion of actetatetomethane
    Temp: 30-40˚C