Summary of topic 5.4
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Eutrophication is caused by excess nutrients like nitrogen and phosphorus entering a water body, which causes algal blooms. As the algae and plants die, oxygen levels in the water decrease and the water becomes unsuitable for most species. Symptoms include increased turbidity, loss of submerged plants, toxic algal blooms, and decreased biodiversity. Management strategies include altering activities that contribute excess nutrients, clean-up of impacted water bodies, and regulations on sources of nutrients like sewage and fertilizers.
Summary of topic 5.4
- 1. Topic 5 Pollution Management 5.4 Eutrophication
- 2. What is Eutrophication? Water body receives too much nitrogen and/or phosphorus Algal blooms occur due to increased nutrient availability Increased levels of phytoplankton and algae cut off light to submerged plants Decomposition of plant material and build up of bacterial populations Oxygen levels in the water body fall significantly and it becomes anoxic and unable to support life
- 3. The Symptoms of Eutrophication • Increased turbidity • Increased sedimentation, reducing water flow, filling in lakes • Decreased dissolved oxygen concentration • Decreased biodiversity of primary producers. Loss of submerged macrophytes • Toxic cyanobacterial blooms • Decreased biodiversity of consumers: fish population dominated by surface-dwellers such as pike and perch http://www.youtube.com/watch?v=0JnKkit5ocI
- 4. The Impacts of Eutrophication • Economic losses to farmersdueto loss of fertiliser from soil • Health effects from drinking nitrate-rich water (some disputed links to increased rates of stomach cancer and blue baby syndrome) • Loss of water bodies as a public amenity and scarring of the landscape • Loss of biodiversity
- 5. Management Strategies 1. Altering human activities: – Avoid over-use of artificial fertilisers – Match fertiliser use carefully to the crop – Reduce use of fertilisers between mid-September and midFebruary when leaching rates are highest (in the Northern Hemisphere) – Give preference to leguminous plants – their roots fix nitrogen and reduce dependence on fertiliser – Match fertiliser use carefully to the crop – Do not apply fertiliser or keep animals close to water bodies – Do not plough-up grassland (this released nitrogen) – Use flat terrain for crops to reduce loss through leaching
- 6. Management Strategies 2. Clean-up: – Removal of nutrients by precipitation (e.g. aluminium or iron salts can be added in order to produce phosphate precipitates which can be easily removed and disposed of) – Removal of nutrient-rich sediments (e.g. by dredging) – Removal of biomass from affected water bodies (e.g. removal of predatory fish to allow primary consumers to recover) – Prevention of point-source pollution which is known to be responsible for eutrophication (e.g. nutrient stripping of effluents, or improved treatment of sewage effluents to remove nutrients)
- 7. Management Strategies 3. Regulation (and public campaigns): – Introduction of phosphate-stripping at sewage works (by biological nutrient removal or precipitation) – Switching to phosphate-free detergents – Using washing machines only for full-loads – Reduced use of fertilisers on lawns and public places – Punishments for not collecting animal poo – Compost organic waste rather than send it to landfill
- 8. Questions 1. Outline the process of eutrophication 2. Evaluate the impacts of eutrophication 3. Describe three different pollution management strategies with regard to eutrophication