Eutrophication

EUTROPHICATIONEUTROPHICATIONHarmful changes in water caused by too

much fertilizer or nutrients getting into thewater.

Oligotrophic lake with a low level of nutrients

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

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

bio-limiting element in freshwater lakes.

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

Turbidity (cloudiness) of water increases as doesrate of sedimentation.

Increased growth of rooted plants such as reeds

Algal blooms during the summer months. Note thatdissolved oxygen levels are at their lowest at night whenplants respire rather than undergo photosynthesis.

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

DEATH OF PLANTS

GROWTH OF PLANTS

ADDITION OF NUTRIENTS

Eutrophication process in 6 stages

LACK OF OXYGEN

GROWTH OF BACTERIA

SUFFOCATION

fertiliserssewage

(liquid domesticand industrial waste)

mineralsesp. nitrates

mineralsesp. phosphates

eutrophication

algal bloom

competitionfor light

consumers can'tconsume fast enough

dead plants dead algae

detritus

more decomposers

use up oxygenby aerobic respiration

(increased BOD)

aerobes die(invertebrates,

fish, etc)

anaerobic bacteriathrive. ReleaseNH , CH , H S4 4 2

organicm

aterialTh

e pr

oces

s of

Eutr

oph

icat

ion

fertiliserssewage

(liquid domesticand industrial waste)

mineralsesp. nitrates

mineralsesp. phosphates

eutrophication

algal bloom

competitionfor light

consumers can'tconsume fast enough

dead plants dead algae

detritus

more decomposers

use up oxygenby aerobic respiration

(increased BOD)

aerobes die(invertebrates,

fish, etc)

anaerobic bacteriathrive. ReleaseNH , CH , H S4 4 2

organicm

aterialTh

e pr

oces

s of

Eutr

oph

icat

ion

fertiliserssewage

(liquid domesticand industrial waste)

mineralsesp. nitrates

mineralsesp. phosphates

eutrophication

algal bloom

competitionfor light

consumers can'tconsume fast enough

dead plants dead algae

detritus

more decomposers

use up oxygenby aerobic respiration

(increased BOD)

aerobes die(invertebrates,

fish, etc)

anaerobic bacteriathrive. ReleaseNH , CH , H S4 4 2

organicm

aterial

The process of Eutrophication cont.

fertiliserssewage

(liquid domesticand industrial waste)

mineralsesp. nitrates

mineralsesp. phosphates

eutrophication

algal bloom

competitionfor light

consumers can'tconsume fast enough

dead plants dead algae

detritus

more decomposers

use up oxygenby aerobic respiration

(increased BOD)

aerobes die(invertebrates,

fish, etc)

anaerobic bacteriathrive. ReleaseNH , CH , H S4 4 2

organicm

aterial

Biochemical Oxygen Demand (BOD).

This measures the rate of oxygen consumptionby a sample of water, and therefore gives agood indication of eutrophication. A high BODmeans lots of organic material and aerobicmicrobes, i.e. eutrophication

Biochemical Oxygen Demand (BOD).

This measures the rate of oxygen consumptionby a sample of water, and therefore gives agood indication of eutrophication. A high BODmeans lots of organic material and aerobicmicrobes, 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

However, humans in their everyday activities canexacerbate 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 watercausing….

2. Increased plant growth on the surface ofwater, causing…..

3. Decreased light in lower levels of water,causing…

STEPS OFEUTROPHICATION

3. Decreased light in lower levels of water,causing…

4. Plants in lower levels of waterto die, causing….

5. Decay using up O2 and increasingCO2,causing…...

6. Death of fish and other animals.

These fish died due to eutrophicationremoving the oxygen.

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

Three Causes ofThree Causes ofEutrophication:Eutrophication:

• Fertilizer or manure runofffrom farmland.• Improper disposal of sewage.• Chemical and industrialwaste.

• Fertilizer or manure runofffrom farmland.• Improper disposal of sewage.• Chemical and industrialwaste.

Compare the water upstream from the dam todownstream, what differences do you see?

Compare these 2 ponds, the bottomone experiencing eutrophication.

Increased moss growth along thisshoreline due to eutrophication

What role does eutrophication play onpond succession?

Eutrophication speeds upsuccession.

It speeds it up causing the pond tofill in faster.

Eutrophication speeds upsuccession.