Unit 4 - Lesson 7: Water Pollution Flashcards
What can fertilisers cause?
Eutrophication.
How do fertilisers increase crop yields?
Fertilisers increase crop yields by providing all the minerals required for healthy growth.
Minerals from fertilisers can reach water sources like lakes. What two ways are they able to do this?
This is either through:
1. Run-off (directly running into the water)
2. Leaching (draining) through the ground
What can excessive phosphates and nitrates in the water cause?
Eutrophication.
What is in excess when eutrophication occurs?
Phosphates and nitrates.
What is eutrophication?
Eutrophication is when a thick blanket of algae (algae bloom) grows on the surface of the water.
What is caused by eutrophication (a thick blanket of algae growing on the surface of the water)? Give a reason for each of your examples of how eutrophication effects the environment.
The algae grow quickly and intensively due to the added fertiliser minerals. The bloom blocks sunlight from reaching plants below. They die because they can’t photosynthesise.
This build-up of dead plants causes an increase in microbes (aerobic bacterial decomposers). They use all the oxygen until there’s not enough for the fish, which then die.
Oxygen levels lower until only anaerobic bacteria survive. The water is anoxic.
The bacteria produce nasty smelling chemicals like hydrogen sulfide and methane.
Why does the algae from eutrophication grow quickly and intensively/
The algae from eutrophication grows quickly and intensively due to the added fertiliser minerals.
How does the algae bloom from eutrophication negatively impact plants?
The bloom blocks sunlight from reaching plants below. They die because they cannot photosynthesise.
What does a build-up of dead plants cause? How does this consequence negatively impact the environment?
A build-up of dead plants causes an increase in microbes (aerobic bacterial decomposers). They use all the oxygen until there’s not enough for the fish, which then die.
Due to eutrophication, plants die, which leads to a build-up of dead plants. This build-up of dead plants causes an increase in microbes (aerobic bacterial decomposers). These microbes use all the oxygen up. Once oxygen levels lower, what are the only surviving organisms?
Anaerobic bacteria are the only surviving organisms once microbes have used up all of the oxygen.
What does anoxic waters mean?
Anoxic waters means areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen.
What such chemicals does the surviving anaerobic bacteria (due to eutrophication) produce?
Nasty smelling chemicals such as hydrogen sulfide and methane.
What else (other than fertilisers) can cause eutrophication?
Raw/untreated sewage can also cause eutrophication.
What is sewage? What does sewage consist of?
Sewage is wastewater & excrement created by humans. It consists of things put down our sink (e.g. detergents & food items) and toilets (faeces and urine). Detergents (i.e. washing powder) contain phosphates and urine/faeces contain nitrates.
How can we minimise eutrophication? Explain your method of minimising eutrophication.
Using organic fertiliser i.e. manure can reduce eutrophication.
This is because the nitrogen compounds aren’t as soluble as those in non-organic fertiliser.
They are, therefore, less likely to leach so easily into the water.
