AIR & THE
Activity 8 (Explain): Air Pollution in the
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In this activity, students use the definition of a watershed to help them define an airshed – an area of land that shares a common flow of air. They then perform a variation on the crumpled paper watershed activity to show how air pollution, in the form of dry and wet deposition, can get into the Chesapeake Bay.
Activity Objectives & Materials
Approximate Time: 45 minutes
Students will be able to describe how air pollution gets into the Chesapeake Bay
Students will know the definition of airshed
Students will know the term “deposition”
Word wall words: airshed, dry deposition, wet deposition
Spray bottle(s) with water (one or more)
Chocolate pudding mix in small cups
Water in small cups
Welcome to the Airshed
DCI: ESS3.C: Human Impacts on Earth Systems
What is a watershed? Name two watersheds that you are currently in.
Students should know that they are in the Chesapeake Bay watershed. If they don’t know another watershed they are in, have them consider what large rivers are nearby. They may be in the Potomac River watershed, the Patapsco River watershed, or one of the other major watersheds around the region. To find out exactly what local watershed you are in, go to this EPA website and type in your address. The waterway that comes up will be the name of your local watershed.
The purpose of this warmup is to refresh student’s memory of the term watershed, which will be important for this activity.
1. Frame the Activity
Framing will vary slightly based upon whether you did Activity 7 with students:
If you skipped Activity 7: Show students the infographic from Activity 5 again, and remind them that in the last Activity they learned know how pollution from the ground gets into the Bay. But 1/3 of the nitrogen pollution in the Bay comes from the air. How can that happen? Today they are going to answer that question.
If you did Activity 7: Remind students that they learned during their last activity how gases can get dissolved into water. Today they’re going to apply what they learned to explain how air pollution gets into the Bay.
2. Where Does Our Air Come From?
Pass out the student handout: “Welcome to the Airshed.” Have students look at the map on the left side, and ask them what the gray area is (as a reminder). They may or may not recognize the Chesapeake Bay watershed, so be sure to remind them. Have them write Chesapeake Bay watershed in the space below the map on the left.
Next have students look at the map on the right. Remind them that they’re trying to figure out where the air pollution that ends up in the Chesapeake Bay is coming from. Use questioning to see if they can figure out that the shape on the right represents the area that sends its air to the Chesapeake Bay and so it is called the Chesapeake Bay Airshed (the nitrogen airshed to be specific). Have students write Chesapeake Bay Nitrogen Airshed in the space on the right. Create a joint definition of “airshed” with students to write on their sheets. Airshed definitions can get very technical, but in general, an airshed is an area of land that shares a common flow of air. The Chesapeake Bay Nitrogen airshed defines the area of land that sends air and nitrogen air pollution to the Bay. Add the word airshed to the word wall.
Ask students what they notice about the Chesapeake Bay Nitrogen airshed. Key noticings:
The airshed is bigger than then watershed (because the air can travel further, and can travel over mountains)
The airshed include the 7 states from the watershed PLUS 9 more (Michigan, Ohio, Indiana, Kentucky, Tennessee, Georgia, North & South Carolina, and New Jersey)
Tell students that different kinds of pollution have different size airsheds. They are going to focus on the nitrogen airshed, because that is the pollutant they think is causing the algae to grow and kill the fish. Ask students to think about how big the nitrogen airshed for the Chesapeake Bay might be. After giving students a chance to share their ideas, put the actual nitrogen airshed. Have students draw the airshed on their handouts, and compare their guesses with the actual airshed.
Defining an Airshed: Because different air pollutants travel different distances, the airshed changes depending on what pollutant you are talking about. Since this module focuses on nitrogen pollution, students will look at the nitrogen airshed, which includes the airsheds for nitrogen dioxide pollution and ammonia. It is useful to make this clear to students, but don’t let it become overly confusing.
For another map of the Chesapeake Bay airshed and watershed, see this map from the Chesapeake Bay Foundation. This map is slightly different and may represent the airshed for additional pollutants.
3. Return to the Crumpled Paper Watershed
Pass out plain paper and paper towels to each student. You can have them draw on the paper as before, but it is not necessary for this activity. Have students crumple and uncrumple (but not flatten) the paper just like they did for their watershed simulation in Activity 6. Spray each watershed like before so that the “ground” gets wet and creates small streams and ponds.
Hand out a small cup of chocolate pudding mix and cotton balls to each group of students. Have them stretch out the cotton ball to loosen it up. Tell students that for this activity, the cotton ball will represent clouds and air. The cup of pudding mix will represent a source of air pollution, and the pudding itself is the air pollution.
Have students use the cotton ball to pick up some of the air pollution. Ask students what they think will happen when the “air and clouds” pass over their watershed? (it will drop some of the pollution) Have them shake/tap their cotton balls over the watersheds to see what happens. They should see little specks of “air pollution” sticking to the watershed.
Tell students that this kind of pollution is called “dry deposition.” Ask them why they think it’s called “dry” (it’s because the pollution is dry – it is not dissolved in water). Tell them it is called “deposition” because the pollution is being deposited on the land just like you might make a deposit in the bank. Put “dry deposition” on the word wall and have students add a definition to their notes sheet. Dry deposition is when air pollution falls to earth in solid or gas form.
Ask students if the dry deposition is polluting their water. For the most part, the water should still be clean except if some of the dry deposition fell directly in the water. Spray the watersheds again. Some of the dry deposition should wash into the water. Ask students what happened – just like with the original crumpled paper watershed, much of the pollution got washed into the bigger bodies of water, although some of it sticks.
Pass out the small cups of water to students. Have them dunk their cotton balls in the pudding mix again, then the water. Ask them what they think this represents (a rain cloud that has pollution in it). Students probably know what to do next: squeeze the cloud out over the watershed. Ask them what this represents? (polluted rain/acid rain).
Tell students that this is kind of deposition is called “wet deposition” because it is pollution that is dissolved in water and then “deposited” in the watershed. Put “wet deposition” on the word wall and have students add the definition to their notes sheet. Wet deposition is air pollution that falls to the earth dissolved in water. Acid rain is a form of wet deposition.
Have students look at the water in their crumpled paper watershed. What color is it? (it should be brown). What does this represent? Water that is polluted. How did it get this way? (pollution fell directly in the water, or it washed into the water).
4. Drawing Conclusions
After cleaning up, have students turn to the back side of their papers and jot down some things that they learned from this activity about how air pollution gets into the Chesapeake Bay. When they have had a chance to write, have them discuss with a partner, and then have partners share out to the class. Write down key takeaways on the board or chart paper, and have students add new ideas to their papers. Key takeaways:
Air pollution can come into the watershed from an area called the airshed, which is bigger than the watershed
The pollution can fall onto the ground/water as “dry deposition”
The pollution can also mix with water in the atmosphere and fall into the watershed as “wet deposition”.
Dry and wet deposition can fall directly into the water, or it can fall on the ground and be washed into the water.
Connecting the Spheres: If you have time, this is another good opportunity to have students explain how the atmosphere is connected to the hydrosphere and the geosphere. The biosphere is connected as well, since much of the acid rain falls on land and is taken up by plants which filter the pollution out.
5. Return to the Clue Board
Ask students what information they learned today can help them identify where the pollution came from that caused the algae bloom. Students should recognize that the pollution could have come from anywhere in the airshed. Add this clue to the clue board, and have students add it to their sheets: “The pollution that caused the algae bloom could have come from anywhere in the airshed.”
6. Formative Assessment
Have students explain in their own words how air pollution from a power plant in Ohio could get all the way into the Chesapeake Bay.
Possible answer: The air pollution goes up into the atmosphere, and the pollution mixes with water in a cloud and dissolves. Then the pollution falls onto the Potomac River as rain, and washes into the Chesapeake Bay.