EutrophicationPollution Effects on Society

Eutrophication – What is eutrophication?

Eutrophication is a natural process by which lakes and reservoirs become more productive as a result of increased nutrient concentrations, especially nitrogen (N) and phosphorus (P) with time

• “Productivity” here essentially refers to the net rate of photosynthesis• The rate of productivity increase generally increases with time (100 yr.)

Eutrophication – stages of eutrophication

• Phytoplankton are defined as freefloating unicellular,filamentous, and colonial organisms that grow photo-autotrophically in aquatic environments.

• Phytoplankton is the base of food chainsweb anddirectly provide food for zooplankton, fishes, andsome aquatic animals.

• Phytoplankton responds quickly to environmentalchanges

• Phytoplankton abundance and diversity are widelyused as biological indicators of still-water quality inlakes

Eutrophication – phytoplankton (algae)

5Sediment decomposition of dead biomass, bacteria, bentic macrofauna

Non point and point sources

(N and P)

Photosynthesis

O2 CO2

H2OSugars and

other organic

molecules

N + P

N + P

EpilimnionUpper mixed

layer

HypolimnionVery slow/no mixed layer

T˚DO˚

Eutrophication – phytoplankton (algae)

6Sediment decomposition of dead biomass, bacteria, bentic macrofauna

Non point and point source

sources (N and P)

Respiration

O2

H2O CO2

N + P

N + P

Sugars and other

organic molecules

EpilimnionUpper mixed

layer

hypolimnionAphotic zone

Very slow/no mixed layer

T˚DO˚

Eutrophication – phytoplankton (algae)

Human activities that cause nutrient release, accelerate eutrophication• sewage discharges• storm sewer discharges • chemical fertilizer• livestock waste

Eutrophication – Cultural Eutrophication

Eutrophication – So what’s wrong with algae?

Oxygen Depletion• Decomposition of organic

material in the sediment causes hypoxia on the bottom of water bodies

• Odor and taste problems

• Degrading of the aesthetic and recreational value of water bodies

Lake Winnipeg (2010)

Eutrophication – So what’s wrong with algae?Some algae blooms are toxic Cyanobacteria– harm aquatic biota, animals, and humans

• Symptoms: nausea, vomiting, abdominal cramps, diarrhea

• Severe cases include neurological symptoms: headache, dizziness, seizures, disorientation, memory loss, respiratory difficulty, coma

10

Anabaena sp.

Aphanizomenon sp.

July 13, 2011

Eutrophication – Cyanobacteria

Eutrophication – harmful algae

Lake Erie(2011)

• Lake Taihu, China (2007)• low water level and high temperature

led to massive blue-green algae bloom

• 2 million residents in the City of Wuxi were without tap water for a week

• Lake Erie, USA (2014)• cyanotoxins were detected in the tap

water of Toledo, OH

• 500,000 residents were advised not to use tap water for three days

• Controlling phytoplankton bloom is a major challenge for the water quality management and water supply industry

• Raise awareness of eutrophication.• Eutrophication and its effects are not well understood by the

public or policymakers.• use cleaning agents and detergents that are biodegradable and

that do not contain phosphates• reduce the amount of nutrients that are causing an overgrowth of

algae in lakes and streams• More water treatment plants• Higher standards for water quality• Prevent illegal dumping

• find alternative ways to fertilize and control pests• Implement regulations to mitigate nutrient losses, such as

standards, technology requirements, or pollution caps for various sectors.

Eutrophication – How to prevent?