IB Environmental systems and societies Topic 4.4C Eutrophication Revision Notes (SL/HL)

IB Environmental systems and societies Topic 4.4C Eutrophication Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Eutrophication: how nutrient enrichment suffocates water bodies

Definition

Eutrophication

Eutrophication is a process where excess nutrients, primarily nitrates and phosphates, enter aquatic ecosystems, triggering a cascade of ecological changes.

Eutrophication is the enrichment of a water body with nutrients, especially nitrates (NO₃⁻) and phosphates (PO₄³⁻), that triggers excessive algal and plant growth.
This drives oxygen depletion, loss of biodiversity, and declining water quality.

Causes of eutrophication

Eutrophication can happen naturally over centuries.
It can also happen far faster through human activity (cultural eutrophication).
Agricultural runoff
1. Fertiliser washed off fields by rain carries nitrates and phosphates into rivers and lakes.
Sewage discharge
1. Untreated or partially treated domestic waste adds organic matter and nutrients.
Phosphate detergents
1. Phosphate-based cleaning products add to the nutrient load entering waterways.
Industrial effluent
1. Factories may release nitrogen compounds and organic pollutants.

Example

In the Chesapeake Bay (USA), fertiliser and animal-waste runoff drove persistent eutrophication.

The eutrophication process

Nutrient enrichment: runoff or discharge adds nitrates and phosphates to the water.
Algal bloom: algae and cyanobacteria grow rapidly on the extra nutrients.
Light limitation: dense surface algae block sunlight, cutting photosynthesis in submerged plants.
Submerged plant death: submerged macrophytes die from lack of light.
Decomposition: bacteria decompose the dead algae and plants, consuming dissolved oxygen.

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Definition

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Note

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Excepteur sint occaecat cupidatat non proident

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Tip

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Eutrophication: how nutrient enrichment suffocates water bodies

Definition

Eutrophication

Eutrophication is a process where excess nutrients, primarily nitrates and phosphates, enter aquatic ecosystems, triggering a cascade of ecological changes.

Eutrophication is the enrichment of a water body with nutrients, especially nitrates (NO₃⁻) and phosphates (PO₄³⁻), that triggers excessive algal and plant growth.
This drives oxygen depletion, loss of biodiversity, and declining water quality.

Causes of eutrophication

Eutrophication can happen naturally over centuries.
It can also happen far faster through human activity (cultural eutrophication).
Agricultural runoff
1. Fertiliser washed off fields by rain carries nitrates and phosphates into rivers and lakes.
Sewage discharge
1. Untreated or partially treated domestic waste adds organic matter and nutrients.
Phosphate detergents
1. Phosphate-based cleaning products add to the nutrient load entering waterways.
Industrial effluent
1. Factories may release nitrogen compounds and organic pollutants.

Example

In the Chesapeake Bay (USA), fertiliser and animal-waste runoff drove persistent eutrophication.

The eutrophication process

Nutrient enrichment: runoff or discharge adds nitrates and phosphates to the water.
Algal bloom: algae and cyanobacteria grow rapidly on the extra nutrients.
Light limitation: dense surface algae block sunlight, cutting photosynthesis in submerged plants.
Submerged plant death: submerged macrophytes die from lack of light.
Decomposition: bacteria decompose the dead algae and plants, consuming dissolved oxygen.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 4.4C Eutrophication Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Eutrophication: how nutrient enrichment suffocates water bodies

Causes of eutrophication

The eutrophication process

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Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Eutrophication: how nutrient enrichment suffocates water bodies

Causes of eutrophication

The eutrophication process

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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