Lesson 1.6 - How Humans Affect the Nitrogen Cycle

Several chemicals cycle through the biosphere.  Unless something disrupts things, a balance exists between gases such as nitrogen and carbon dioxide, and things work as they are intended.  However, human activities can affect all cycles in negative ways.  On the page you will be asked to read, you will see how humans create more nitrogen in lakes, and you will see the negative effects this has on the environment.  When nutrients build up in a body of water, we call it eutrophication. 

Read How Humans Affect the Nitrogen Cycle on page 296 in the textbook. Then, answer the following questions.

  

Question 1. Answer Reading Check on page 296 of your textbook.

Question 2. Answer question 1 of Check Your Understanding on page 296 of your textbook.

Question 3. What is eutrophication?

Question 4. Explain briefly the five steps of eutrophication.

 

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. Answer Reading Check on page 296 of your textbook.

Synthetic fertilizers or manure can be carried into a lake  by rain water.

Question 2. Answer question 1 of Check Your Understanding on page 296 of your textbook.

Nitrates increase plant growth, but adding too much is possible so plant growth is hindered.

Question 3. What is eutrophication?

Eutrophication is excessive plant growth and reduced oxygen in a body of water because of a buildup of nutrients.

Question 4. Briefly explain the five steps of eutrophication.

1.    Rain carries nitrates into a water ecosystem.

2.    Surface plants grow quickly and block sunlight further down.

3.    Plants that are deep get no sunlight, so they die.

4.    Decomposers have lots of food and use up much oxygen.

5.    The lack of oxygen kills fish and other animals. 

 



Now, do Assignment 15A.  Page forward to access it.