AIR & THE
Activity 11 (Explore): Measuring Wet Deposition
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In this multi-day activity, students collect data to test the accuracy of one portion of their Chesapeake Bay Pollution models. The activity is written for students to collect and analyze rainwater to see if the air has nitrate or ammonium pollution in it. Since MWEEs are designed to be student-driven, this experiment can be modified to test other aspects of their models as well, including water from nearby streams or from the Chesapeake Bay itself.
Student Choice & MWEEs: MWEEs are designed to promote student choice, especially when it comes to the experimentation, field experiences, and data collection. What is presented here is one option for what students might do to collect data related to air pollution. Others might include collecting water from a local stream and testing for nitrates and ammonium (from runoff pollution), participating in a field experience with a partner organization to collect nitrate data from the Bay, or devising their own method for collecting emissions data from (for example) car exhaust. The important thing is to focus on the type of pollution that is local for students. For many students in the DC-Baltimore area, that pollution is air pollution from transportation.
Activity Objectives & Materials
Approximate Time: 2-3 class periods (120-180 minutes)
Students will collect and analyze data to determine if rainwater in the school community is polluted with nitrogen
Nitrate and ammonia test kits (see note on materials)
Additional glassware (ex. small beakers) to allow for multiple groups to test at the same time if necessary
Rainwater collectors (ex. jars)
Distilled water (to use as a control)
Safety & cleanup materials (safety goggles, paper towels, etc.)
Tips for Measuring Nitrogen Deposition in Rainwater (teacher guide)
Nitrogen Deposition in Rainwater
A Note About Timing for This Activity: This activity requires collecting rainwater from the school grounds. Since precipitation can be an unpredictable occurrence, consider having students make and put out their rainwater collectors as early as possible so that you have rainwater to use. The amount of nitrate and ammonium in the water will decrease if it is not tested soon after the rainfall, but they can be frozen and thawed without significantly affecting the nitrate and ammonium concentrations. Steps 1-4 of the activity introduce the experiment up through making rain gauges, and the remaining steps include water testing, data analysis, and conclusions.
A Note About Materials for This Activity: The amount of nitrate and ammonium in rainwater is relatively low, so sensitive tests are required to detect it. There are several companies that produce easy-to-use nitrate and ammonia water tests that are sensitive enough. Kits from CheMetrics are recommended because they are relatively inexpensive and very easy to use. To limit costs, you may consider using one test instead of both. In that case, the Nitrate kit is recommended because it is often present in higher amounts and so will be easier to detect. Refill kits are also less expensive, so if you use the kit in subsequent years, you only need to buy the refills.
Hach also produces similar test kits which are slightly more expensive, but which also have the required sensitivity.
1. Frame the Activity
2. Develop a Research Question
3. Develop a Hypothesis
4. Make Rain Gauges
5. Review Testing Procedures
6. Conduct the Tests
7. Pool Data
8. Convert Units
9. Comparing with Official Data (optional)
10. Data Analysis
11. Formative Assessment: Conclusion