Intermediate Topic 1055 of 1102 Biochemistry, Environment & Industry

Eutrophication

Excess nutrients cause algal blooms that deplete oxygen in water.

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In-depth explanation of Eutrophication

Eutrophication is the enrichment of water bodies with nutrients, mainly nitrogen and phosphorus from fertiliser runoff, detergents and sewage. The added nutrients stimulate rapid growth of algae and cyanobacteria, forming dense blooms that block light from submerged plants. When the algae die, decomposing bacteria consume large amounts of dissolved oxygen, creating hypoxic zones where fish and other animals die. Some blooms also produce toxins that are harmful to people and animals. Reducing nutrient runoff, upgrading wastewater treatment and restoring wetlands are the main remedies.

Going deeper: Eutrophication

Key ideas: Excess nitrate and phosphate (fertilizer, sewage, detergents) causes algal blooms; when algae die, bacteria decomposing them consume dissolved oxygen, causing hypoxia and fish kills. Phosphorus is usually the limiting nutrient in freshwater and nitrogen in seawater. Dead zones such as the Gulf of Mexico reach thousands of square kilometers.

Common mistakes and connections: Mistake: thinking the lack of oxygen comes from the algae themselves in daytime; the crash is by decomposition and night respiration. Blooms block light so plants below die. Cyanobacteria can release toxins. Links to BOD, fertilizers and nitrogen cycle.

Visualization of Eutrophication

The Redfield ratio C:N:P of algae is 106:16:1. Since phosphorus is scarce, adding a little phosphorus to water can trigger a large algal bloom. The interactive lesson shows this as a live animation or chart.

Worked example and use case

The Gulf of Mexico has a seasonal dead zone fed by nutrient runoff from the Mississippi River.

Frequently asked questions about Eutrophication

What is Eutrophication?

Excess nutrients cause algal blooms that deplete oxygen in water.

Is Eutrophication a beginner, intermediate or advanced topic?

Eutrophication is a intermediate topic in Biochemistry, Environment & Industry. It builds on the vocabulary of beginner topics in this area.

What should I learn before Eutrophication?

Study these earlier topics in Biochemistry, Environment & Industry first: Particulate Matter, Air Quality Index, Water Pollution.

What comes after Eutrophication?

The next topics in Biochemistry, Environment & Industry are Biochemical Oxygen Demand and Dissolved Oxygen.

Can I practise Eutrophication with quizzes?

Yes. The interactive lesson includes a self-check question on Eutrophication, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.

Where Eutrophication fits in Biochemistry, Environment & Industry

Eutrophication is topic 80 of 127 in Biochemistry, Environment & Industry.