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 5.4.1

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 Eutrophication5.4.2

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 Strategies5.4.3

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 NatGeo Eutrophication Video Eutrophication Song BBC Bitesize Eutrophication

Sources

BBC USGS Lenntech WRI NBC Toledo Water Crisis