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Flashcards in Fresh Water Pollution (T4) Deck (3):

What are the three main pollutants of fresh water?

- nitrates from fertilisers
- organic waste
- detergents


What is eutrophication and what can cause it?

Eutrophication is an increase in mineral ions in lakes and rivers which can occur naturally but also artificially as follows:

- farmers often add inorganic fertilisers to their crops to replace the minerals lost when crops are removed
- the nitrates in these fertilisers are very soluble and so are easily leached from the soils and can enter waterways
- the levels of nitrates and ions can rise rapidly in lakes and rivers which are affected, causing the increase in mineral ions known as eutrophication


Describe seven ways in which eutrophication can have disastrous and cumulative effects on waterways...

- as nitrate levels rise, algae are able to use the nitrates to produce extra proteins for growth and rapid reproduction
- the algae then form an algal bloom, preventing light from penetrating further into the water
- submerged plants cannot photosynthesise and so die
- the algae eventually die as they run out of nitrates
- bacteria decay the dead plants and algae, thus releasing more nitrates, and the cycle begins again
- the bacteria reproduce due to the large amount of dead matter, and their respiration uses up more and more oxygen
- the waterway eventually can become completely devoid of oxygen, and all like in the water will die

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