Eutrophication
When fertiliser runs into water, algae grow too fast, then die and use up the oxygen so fish suffocate.
Last updated
Analogy
Overfeeding a pond until it chokes.
In practice
A green, smelly pond after heavy rain on fertilised fields may be eutrophic.
Practice
Flashcards
- What causes eutrophication?Too many nutrients from fertiliser or sewage entering water.
Interview questions
- Describe how eutrophication harms a lake.
- Fertiliser runs off into the water
- Algae grow rapidly and block light
- Plants and algae die
- Bacteria decompose them and use up oxygen so fish die
Questions people ask
How can eutrophication be prevented?
Farmers can use less fertiliser, apply it at the right time and not before heavy rain, and leave a strip of plants along rivers to soak up extra nutrients. Sewage can be treated to remove nitrates and phosphates before it is released. Detergents with less phosphate also help.
Why does eutrophication kill fish?
Extra nutrients make algae spread across the surface, blocking light from plants below, which die. Bacteria that decompose the dead material use up oxygen from the water as they respire. With too little oxygen left, fish and other water animals suffocate and die.