Eutrophication

EUTROPHICATIONEUTROPHICATIONHarmful changes in water caused by

too much fertilizer or nutrients getting into the water.

Oligotrophic lake with a low level of nutrients

Artificial input of nutrients from run-off and discharge of effluent.

Eutrophic lake with a high level of nutrients. Nitrogen and Phosphorus are usually the

bio-limiting element in freshwater lakes.

Rapid growth of algae and other biomass resulting in a decrease in the concentration of dissolved oxygen.

Turbidity (cloudiness) of water increases as does rate of sedimentation.

Increased growth of rooted plants such as reeds

Algal blooms during the summer months. Note that dissolved oxygen levels are at their lowest at night when plants respire rather than undergo photosynthesis.

Development of anoxic conditions and release of noxious gases such as hydrogen sulphide and ammonia.

LACK OF OXYGEN

GROWTH OF BACTERIA

DEATH OF PLANTS

SUFFOCATION

GROWTH OF PLANTS

ADDITION OF NUTRIENTS

Eutrophication process in 6 stages

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The process of Eutrophication cont.

Biochemical Oxygen Demand (BOD).

This measures the rate of oxygen consumption by a sample of water, and therefore gives a good indication of eutrophication. A high BOD means lots of organic material and aerobic microbes, i.e. eutrophication

Eutrophication is a natural process!However, humans in their everyday activities can

exacerbate the process:Point sources (can locate the cause)• Sewage treatment plant discharges• Storm sewer discharges• Industrial dischargesNon-point sources (can’t locate the cause, it’s

everywhere)• Atmospheric deposition• Agricultural runoff (fertilizer, soil erosion)• Septic systems

1. Fertilizer flows into water causing….

2. Increased plant growth on the surface of water, causing…..3. Decreased light in lower levels of water, causing…

4. Plants in lower levels of water to die, causing….5. Decay using up O2 and increasing CO2,causing…...

6. Death of fish and other animals.

STEPS OFEUTROPHICATION

These fish died due to eutrophication removing the

oxygen.

Lake Biwa, the largest lake in Japan during summer time showing overgrowth of aquatic plants.

Three Causes of Three Causes of Eutrophication:Eutrophication:

•Fertilizer or manure runoff from farmland.

•Improper disposal of sewage.•Chemical and industrial waste.

Compare the water upstream from the dam to downstream, what differences do you

see?

Compare these 2 ponds, the bottom one experiencing

eutrophication.

Increased moss growth along this shoreline due to eutrophication

What role does eutrophication play on pond succession?

Eutrophication speeds up succession.

It speeds it up causing the pond to fill in faster.