Land Use Lesson 8 : Investigating Land Use, Water, and Air Relationships
1. Vocabulary development.
Because this lesson deals with the interactions that land use has with other attributes of the natural environment, students will need to understand a few key terms: water quality, air quality, and pollutant. If students are not familiar with these terms, prepare to introduce them by creating a jar of polluted water (dirty dishwater or water into which you have mixed some dirt). You can show polluted air by swirling some water around a jar so all sides are wet. Then pour out the water. Have students stand back at a safe distance and wear safety glasses. To simulate air pollution fold four to six strips of paper (4 inches x .5 inch) in half lengthwise. Hold them together and light one end. Drop the papers and match into the jar and put the lid on the jar. This will create smog in the jar.
Ask students if they know what it means if you tell them, “This student paper is high quality work.” [It means the work is excellent.] What do you think it means when we talk about water quality or air quality? [How good the air or water is.] Show the jars you have prepared and ask students to assess the water and air quality in the jars. [Students should conclude the quality is low.] What makes the quality of this air and water poor? [There are things in the water and air making it dirty.] Explain that the things in air and water that make it dirty are called pollutants. To pollute means to make dirty. So pollutants are things that make air or water dirty.
2. Introduce the place of land use in the ecosystem.
Ask students to imagine that they are studying one of their classmates. They have photos of the classmate from different angles. They have data about the student—height, weight, report card— from different years in the student’s life. They even have a DNA profile of the student. With this information, would they truly understand their classmate? [Accept all suggestions, but lead students to the realization that understanding the student would also require understanding people and activities that the student interacts with, such as their friends, family, classmates, teammates, etc.]
Tell students that the situation is similar to the study of land use. They have used many types of information as they have studied land use: air photos (Lessons 1 and 2), agricultural data for the State of Michigan (Lesson 5), and county land use data (Lesson 6). However, they cannot fully understand land use without looking at how it is connected to other parts of the environment.
In this lesson, students are going to use a poster to study how land use is connected to other natural systems, such as air and water. The poster will help students understand how land, water, and air fit together in the ecosystem and how human use of the land influences and is influenced by other systems.
3. Interpret the land use mini poster.
Assign each student a partner. Give each pair one mini poster. There are three different sections of the larger poster; one-third of the pairs should receive each section, which will be referred to in the lesson as 1, 2, and 3. Ask pairs of students to study their section of the poster and record their observations on the Mini Poster: Obtaining Information student activity page. Discuss answers to the questions on the handout, on which students identify the land uses shown on the mini-poster and estimate the amount of land in each use (small, medium, or large). Descriptions of small, medium, and large measurement estimates of area are on the Mini Poster: Obtaining Information student activity sheet. Note that the land uses students observe will vary depending on which section of the poster students have: 1 is mostly agriculture; 2 is largely urban, with residential, industry, business, and road land uses, as well as forest and open space; and 3 includes mining, forests, and open space. An answer key for this handout is provided for your convenience.
Give each pair of students the Land Use Effects on Water and Air student activity page and ask them to use their posters to identify ways that land use may affect water and air quality. An answer key is provided. In addition, you might draw on the following information during class discussion:
How could land use affect water quality? [For example, water will run off land that has no land cover and cause erosion. In the urban areas, the water will run from parking lots and paved surfaces quickly. Students can also follow matter that might seep into the groundwater and be transported to other places.]
How could land use affect air quality? [For example, air in urban areas often has industrial or automobile pollution. Tall buildings may slow the circulation of air. The air temperature may be warmer during summer since urban materials absorb light and retain energy. This is called the urban heat island effect. Air in agricultural areas may have residual crop spray at times.]
4. Put the mini posters together.
Combine the pairs of students into groups of six so that each larger group has the three mini posters. Discuss the following questions:
What comparisons can you see among the posters? [The posters have several similarities. They each show human use of the land; they show alteration of the natural environment; they show land being used as a resource. The miniposters are different in several ways as well.
The left poster shows mainly agriculture land use, with some land use change to suburban homes. The center poster shows mainly an urban environment with transportation and industrialization. The right poster shows rural land being used for several different uses that are not agricultural, but mining, forestry, and recreation.]
Which poster seems to have the most agricultural land? [1, the left section.] The most urban land? [2, the center section.] The most land? [3; uses dominant in section 3 are natural resources mining, forestry and recreation.]
How could land use affect air quality? [By putting dust or chemicals into the air.]
How could land use affect water quality? [Soil could be carried into streams or rivers. Chemicals could seep into ground water.]
Why is it important that we know how land use is related to air and water? [The way we use land has a big impact on our economy, but the air we breathe and the water we drink and consume in virtually all foods are the things of which we are made and they are needed for life.]
5. Tell the story of a pollutant.
Distribute the desktop size poster to each group of students. Pick a material on the poster that people are putting into the environment and have students tell its story. Road salt is presented as an example that the teacher may want to use prior to having the students select one of the several pollutants that are shown on the poster. (Note: Many of the land uses have ways of reducing or preventing pollution by choice of material, or by preventing movement, such as by lining a land fill or not using too much fertilizer or pesticide.)
What are some of the materials humans put into the environment that are associated with different land uses? [Many answers.]
What is the purpose of the material? How might it also be a problem? [Purposes are many. The materials could cause a problem by becoming a pollutant.]
Distribute the Tell the Story of a Pollutant student activity page. Explain that to tell the story of a pollutant, a student must answer the following questions:
What is the pollutant?
Where is it used in the poster?
Why is it being used?
Where would water or air move the pollutant next?
What impact could it have on fish, birds, plants, people?
With students, tell the story of road salt. Either have students write on the student activity page, Tell the Story of a Pollutant, or have a class discussion. Road salt is a nice example to use because most places in Michigan apply salt to the highways in winter.
To demonstrate this, the teacher can sprinkle some table salt on a surface and then apply several teaspoons of water. The salt will dissolve, and the water can be pushed along the surface with a spoon. When it reaches the new location, the water still has the salt, which serves as the pollutant in our example. Go on with the lesson and let the water evaporate from its new location on the surface. After an hour or so, observe that the water has evaporated but the salt now pollutes a new location on the surface. This is the same principle that applies to road salt as the ice melts and runs off into the side ditches along the roadway, runs into streams, and seeps into the groundwater.
What is the pollutant? [Road salt.]
Where is it used in the poster? [Being spread on roads as a non-point source pollutant.]
Why is it being used? [To melt ice and make driving safer.]
Where would water or air move the pollutant next? [It could run off to the side of the road and eventually seep into ground water.]
What impact could it have on fish, birds, plants, or people? [It could kill grass and plants by the roadside, and it could make drinking water taste salty.]
6. Review.
How can land use affect water? [Water runs off solid surfaces very quickly and does not have time to soak in. Land uses that entail leaking oil or other pollutants are the source for water pollution.]
How can land use affect air quality? [Dust and other soil material can be blown into the air. Cars in heavily traveled places pollute the air.]
Why is it important for us to understand how land use interacts with the air and water systems? [Land absorbs water. Urban land uses produce more pollution from cars that affects the air. Rain carries pollutants from the air to the land, where it is absorbed and affects plants, animals, and people.]