5.4 EUTROPHICATION Connor

What is it?  excessive richness of nutrients (especially phosphates and nitrates) in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen.  Occurs in slow moving rivers and lakes primarily  Eutrophic means well nourished  When effects are undesirable it is considered a form of pollution

The Processes of Eutrophication  Fertilizer run-off and sewage discharge flow into the body of water  Run-off builds up at the bottom of the body of water  Excess promotes plant growth (primarily algae)  High level of organic matter and decomposing organisms deplete available oxygen in the water  Causes the death of other organisms ie. fish  Over time the increased amount of sediment can raise the bed of the lake/river and allowing plants to colonize the edges eventually turning the area into dry land (in some cases)

Impacts of Eutrophication  Species diversity decreases and the dominant biota changes  The animal and plant life of a particular region, habitat, or geological period  Plant and animal biomass increase  Turbidity increases  Turbidity is the amount of particulate matter that is suspended in water  Rate of sedimentation increases, shortening the lifespan of the lake  Anoxic conditions may develop  Anoxic waters are areas of sea water, fresh water or groundwater that are depleted of dissolved oxygen

Pollution Management Strategies  Implement research and monitoring programs for eutrophication  Raise awareness of eutrophication  Implement regulations to reduce nutrient losses  Create incentives to encourage nutrient reducing actions ie. tax subsidies  Preserve and restore natural bodies of water that are affected by eutrophication  Create institution to enforce policies and regulations

Example: Toxic Water in Toledo  What happened? Sewage from treatment plants and fertilizer from farms were discharged into the lake causing an algae bloom  The bloom was close enough to the city’s intake valve that the water being sent to the city was toxic rendering it undrinkable  Regulations have been set but officials have not mandated any restrictions as of yet.

Links  Animated video Animated video  NatGeo Eutrophication Video NatGeo Eutrophication Video  Eutrophication Song Eutrophication Song  BBC Bitesize Eutrophication BBC Bitesize Eutrophication

Sources  BBC BBC  USGS USGS  Lenntech Lenntech  WRI WRI  NBC Toledo Water Crisis NBC Toledo Water Crisis