Eurtrophication

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  • Eurtrophication

    1. 1. Topic 5: Pollution Management 5.4: Eutrophication The Nitrogen Cycle and Eutrophication
    2. 2. Topic 5: Pollution Management 5.4: Eutrophication • All living organisms use nitrogen to make molecules such as protein and DNA. • Nitrogen is the most abundant gas in the atmosphere (about 80%). • Atmospheric nitrogen can not be used by most plants and animals, though some specialised micro-organisms can fix atmospheric nitrogen.
    3. 3. Topic 5: Pollution Management 5.4: Eutrophication • Plants get Nitrogen compounds from the soil • Animals get nitrogen compounds by eating plants
    4. 4. Topic 5: Pollution Management 5.4: Eutrophication • When animals excrete or defecate they return nitrogen compounds to the ground • When animals and plants die they rot and return nitrogen to the soil • Dead Organic Matter (DOM)
    5. 5. Topic 5: Pollution Management 5.4: Eutrophication • Farmers since prehistoric times have added manure to fields
    6. 6. Topic 5: Pollution Management 5.4: Eutrophication • Traditional Human Nitrogen gas in the atmosphere N2 Atmospheric fixation during lightning activities have formed storms part of the Nitrogen Cycle Plant and Animal Biomass Nitrates taken up containing nitrogen by plants Dead Organic Nitrogen Excretion Matter DOM Fixing bacteria Denitrifying bacteria Decomposition Ammonia NH3 Nitrite Nitrate NO2 NO3 Nitrifying Nitrifying bacteria bacteria Nitrogen Cycle
    7. 7. Topic 5: Pollution Management 5.4: Eutrophication • Since the First World War, traditional methods Chemical inorganic fertilisers; Organic fertilisers; animal manure, Dead Organic Matter (DOM); of maintaining soil fertility provide controlled amounts of mineral urine and compost natural remains of dead plants and have been augmented by nutrients animals the use of chemical fertilisers • Millions of tons of nitrogen based chemical fertilisers have been added to agricultural land Available mineral nutrients in the soil
    8. 8. Topic 5: Pollution Management 5.4: Eutrophication • Fertiliser in solution if used in excess can enter water systems • This can lead to the problem of Eutrophication
    9. 9. Topic 5: Pollution Management 5.4: Eutrophication N-P-K Increased growth of Fish begin to die algae shading out other as oxygen levels fall plants Excess use of Chemical Fertilisers leads to run of and ground water contamination The inorganic salts dissolved ground water eventually enter lakes, ponds and rivers Increased nutrients absorbed by algae Inreased decomposition of dead algae uses up oxygen in the water
    10. 10. Topic 5: Pollution Management 5.4: Eutrophication • Increasing nutrient loads can lead to Positive Feedback Increased Nutrient Inputs Increased Fewer Primary Consumers Productivity (Invertebrates and Fish) Increased Decomposition Increased Oxygen Consumption (BOD)
    11. 11. Topic 5: Pollution Management 5.4: Eutrophication Similar pathways exist for both eutrophication caused by Phosphates and Carbon
    12. 12. Topic 5: Pollution Management 5.4: Eutrophication Sources of Eutrophication Source Type of problem Point Sources Power plants Combustion of fossil fuels emit nitrogen products into the atmosphere, which are carried down by rainfall and other processes, causing eutrophication in water bodies Sewage Treatment Treatment process releases oxides of N and P in effluents, which drain Plants into water bodies Industrial Plants Industrial processes release N and P products in effluents, which drain into water bodies Non-Point Sources Agriculture Farming practices, including use of fertilisers rich in N and P, deposit increased amounts of these nutrients in the soil. Run-off from these farms cause eutrophication in water bodies Sewage Direct discharge of sewage from domestic sources, not connected to treatment plants, will eventually make its way into water bodies

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