Ap environmental Science Name: Mr McDowell Date


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AP Environmental Science Name:

Mr McDowell Date:


  • Eutrophication basically means lowering the quality of the environment by using too much nitrogen and phosphorous.

Nutrient poisoning affects streams and waterways. It happens after farmers spread nitrogen based fertilizers on the fields. The Nitrate (NO3) version of nitrogen is particularly water soluble, and will quickly wash off of farm field when it rains. Phosphate fertilizer is also very water soluble.

It is not always the farmers fault. He may have spread too much fertilizer or he may have spread it and then it rained washing all of the fertilizer into the field.
Once the nitrogen containing fertilizer has been washed into the streams and rivers by the processes of runoff or leaching it causes problems. The fertilizer in the water causes weeds and algae in the water to grow. The plants then die and sink to the bottom.
Bacteria called decomposers then break the plants down. They breed rapidly with all the food they have. The large numbers of bacteria use up all the oxygen in the water. Once the water has no oxygen in it the fish and other tiny animals begin to die.
Review Questions

  1. What does Eutrophication mean?

  1. Which two things can lead to there being too much nitrogen on the fields?

  1. What is the name of the processes for nitrogen fertilizers moving from the fields to the waterways?

  1. What does the nitrogen fertilizer do to the algae and the weeds in the stream?

  1. What is the name for bacteria which break down dead plants?

  1. Which gas do these bacteria use up from the water?

  1. What is the final problem caused by the loss of all this important gas from the water?

  • The story….

Mrs Swinson has a stream in her garden. One day there was a flood and a few days after that Mrs Swinson noticed a large brown trout in her stream. Trout are called an “indicator species” because they need large amounts of oxygen, and so are an indicator of good stream health. She called him Jaws and went to visit him every day.

After a while Mr Swinson also noticed the trout and decided he wanted to eat the trout. The trout lived in the stream for a year getting larger and larger.

One day in early June Mr Swinson decided to go and buy a fishing rod. The day after that it rained and the stream started to go cloudy. A few days after that the weather got a bit better and Mr Swinson went out with his fishing rod. To his dismay he found Jaws floating belly up in the stream.

Task 1: What do think had happened? Write an explanation for the death of Jaws.

Task 2: Extension activity

Using all the information above, write out the process of eutrophication as a series of short bullet points with accompanying diagrams/cartoons……


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