In this lesson students will identify the causes of acid rain, research ways to reduce the negative effects of acid rain, learn about government regulation and monitoring of acid rain and investigate acidity data of surface water for different areas of the United States.

This lesson can be incorporated into a Chemistry unit on pH and its applications. The actual pH values obtained on the Internet would be an interesting data set for mathematics or statistics students to analyze.

Basic Internet skills. Spreadsheet or graphing calculator familiarity is recommended. Ability to find the mean (average) and range of a set of data.

Internet access. Acid Rain Activity Worksheet. Spreadsheet or graphing calculator recommended.

To define the term "acid rain."

To research the causes of acid rain.

To learn what can be done to reduce the negative effects of acid rain.

To obtain actual pH data of surface water for different parts of the United States.

To decide if the pH means of different areas are statistically different by comparing confidence intervals.

To create tables, charts and graphs of pH data.

To look for patterns or relationships and make predictions using pH data.

Students should work on the Acid Rain Activity Worksheet in the computer lab. The instructor may let students choose the states for which to obtain acidity data or may assign states to students in order to obtain information about specific areas of the United States. After all students complete the activity, the class should share their data and charts to discuss similarities and differences of acid rain data throughout the United States. Students may work in small groups to make a poster display of acid rain information either as a required assignment or as an extra credit project.

Use the point assignments on the Acid Rain Activity Worksheet. Students should print out tables and graphs of their data to share with the class. After students share their data with the class, they should compare the data for different areas of the United States.

If a poster is assigned, it should include the following parts:

I. Title and appropriate labels.

II. Information about acid rain.

III. Data Analysis.

Other environmental issues like the greenhouse effect, water quality, or air pollution can be investigated.

!!!! Warning !!!! The Web sites given in this lesson may have changed! Before using this lesson with your students, be sure to check if the sites are still working or if you must find another site. Sometimes the sites still have the relevant data but you may need to change the directions to access the data.

Mathematics/statistics teachers may omit Questions #1-5 and #10 on the worksheet; the instructor could present some background information about acid rain.

To learn more about confidence intervals, see the following sites:

http://curriculum.qed.qld.gov.au/kla/eda/ws_ci.htm http://www.princeton.edu/~matalive/VirtualClassroom/v0.1/html/lab3/lab3_3.html

http://www.stat.ucla.edu/textbook/introduction/inference/Confidence_Intervals.html

http://marine.geol.sc.edu/BIOL/Courses/BIOL301/Lab/Manual/excel.html

In order to compute a confidence interval using Excel, click on the Tools menu on the top bar and select the Data Analysis option. (If this option is not showing you can add it to the Tools menu by clicking Add-Ins and then selecting Analysis Tool Pak.) In the Data Analysis window, select Descriptive Statistics. Input the range of your data. For Output Range type in any cell name that is empty and which has empty cells below it. Check Summary Statistics. Check Confidence Level for Mean. Excel will display a list of values, one of which is named Confidence Level. Add and subtract this value to the mean of your data to obtain the confidence interval.

To compute a confidence interval using the TI-83, press STAT, then choose TESTS, then choose 8:Tinterval. Under Inpt: highlight Data. Type in the list name of your data for List:. Choose Freq:1 and C-Level .95. Then highlight Calculate and press ENTER.

If you need more background about the statistical concepts involved in the lesson, some good sites to check are:

http://davidmlane.com/hyperstat/index.html

http://www.anu.edu.au/nceph/surfstat/surfstat-home/surfstat.html

http://www.math.unb.ca/~maureen/SSCEdCom/basicstats/basicstats.html

http://www.math.unb.ca/~knight/BasicStat/$content.htm

http://www.bbns.org/us/math/ap_stats

http://www.grad.cgs.edu/wise/linksf.shtml

http://www.cvgs.k12.va.us/DIGSTATS

http://www.statsoft.com/textbook/stathome.html

http://www.stats.gla.ac.uk/steps/glossary/index.html

http://www.crpc.rice.edu/CRPC/GT/sboone/Lessons/lptitle.html

http://forum.swarthmore.edu/library/topics/statistics

http://www.psychstat.smsu.edu/introbook/skb00.htm

TI-83 instructions:

http://www.ti.com/calc/docs/act/koehler001.htm

http://www.wku.edu/~neal/manual/ti83.html

The Calculator website at the Mathematics Department of the University of Wisconsin-La Crosse will perform basic statistical calculations. If you do not have access to a simple statistical computer package or calculators with statistics options, your students may access http://www.compute.uwlax.edu/stats_htdocs/newmenu.html to perform statistical computations on-line.

In order to print out just a copy of the student worksheet, highlight this section, then copy and paste it into your word processor. You may then revise the worksheet if you wish.

When you take a sample of items from a population, you obtain information about a relatively small group of items relative to the whole population size. For example, you may be interested in the areas of cities throughout the United States. There are thousands of U.S. cities and you probably don’t have time to find the areas of all of them. Hence you take a small sample of cities and just find the areas of these cities.

Next you may want to report what the average or mean area of all U.S. cities is. You would average the areas of the cities in your sample and report that this is approximately the average area of all U.S. cities. If the average area of the cities in your sample was, say 40 square miles, then it seems reasonable to say that the average area of all U.S. cities is approximately 40 square miles. However we don’t expect to be very accurate. So statisticians will report a "confidence interval" instead.

If you use a confidence interval, you might report the mean area of all U.S. cities as likely to be between 35 and 45 square miles. Or statisticians may say, "a 95% confidence interval for the mean area of all U.S. cities is (35,45)." This means that it is very likely that the mean area of all U.S. cities is between 35 and 45 square miles. Or we are "95% confident" that the mean area of all U.S. cities is between 35 and 45. If we want to be more sure, we might find a 99% confidence interval, which might be (30, 50). We would say that we are 99% sure that the mean area of all U.S. cities is between 30 and 50.

It is a little tricky to interpret a confidence interval in a mathematically correct way. The correct interpretation is based on repeated sampling. If samples of the same size are drawn repeatedly from a population, and a "95% confidence interval" is calculated from each sample (these will all be somewhat different since each sample is different), then 95% of these intervals should contain the population mean.

You can easily find confidence intervals using the TI-83. Enter your sample data in a list and use the command Tinterval in the STAT > TESTS menu. Choose the confidence coefficient you wish (90%, 95%, or 99% are often used).

Excel will also calculate confidence intervals. In the Tools menu, chose Data Analysis and then Descriptive Statistics.

Read more about confidence intervals in

http://curriculum.qed.qld.gov.au/kla/eda/ws_ci.htm

http://www.stat.ucla.edu/textbook/introduction/inference/Confidence_Intervals.html

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1. (3 points) Access the site http://water.usgs.gov and click on "Acid Rain" under "Water Data". Then scroll down and click on "Primer on acid rain – how it is measured and its effects". Skim through this site.

2. (6 points) What is acid rain?

3. (8 points) Describe two negative effects of acid rain.

4. (6 points) In the United States, where is excessive acid rain the most prevalent? For what reasons?

5. (6 points) Describe sources of pollution that contribute to acid rain formation.

6. (4 points) Access the site http://bqs.usgs.gov/acidrain and click on "View and download data on precipitation chemistry from the NADP/NTN". Then click on "Data". Now click on WI or another state that your instructor specifies. Click on one of the monitoring sites listed, scroll down and click on "Annual Data". You will now complete the "Data Selection Criteria" form.

Select 1989 as the start year, 1998 as the end year. For data type select "Precipitation weighted means (mg/L)". For report format select "HTML table". Select "K-12" for intended use and type "statistics project" for Brief description of specific application. For seasons to return select "Annual". Now click Get Data and Continue if a security warning appears. If you scroll to the right you will find a list of annual field pH values which of are interest to us.

7. (6 points) If you have access to a spreadsheet, you can copy and paste this table into the spreadsheet. The only two rows of interest in this project are the Year and the Field pH row. If you are using a graphing calculator you will need to enter this data into two lists. Print out or write the data values in these two lists to share with the class later.

8. (6 points) Make a graph in your spreadsheet or on your calculator showing pH levels over this 10-year time period. Print out this graph or draw it on graph paper.

9. (6 points) What does the graph indicate about pH levels over this 10-year time period?

10. (6 points) Using the equation [H₃O⁺] = 10^-pH calculate the [H₃O⁺] for each year. You can do this for all the data at once by using this equation in your spreadsheet or calculator. As pH changes, how does [H₃O⁺] change?

11. (16 points) Now pick another state or monitoring site and repeat #7, 8, and 9 above for this state.

12. (6 points) Compare and contrast the graphs of these two sets of data.

13. Find the mean (or average) pH level for the two states you researched.

State ____________________ Mean pH __________

State ____________________ Mean pH __________

Which state has "worse" acid rain? ____________________

14. If you have access to a spreadsheet or graphing calculator, you should be able to compute a "95% confidence interval" for the mean pH of these two states. Since the pH levels that are measured are only a sample of all possible measurements that could be taken, statisticians often compare the confidence intervals of two means rather than the means to decide if two sets of data are "significantly different". If the two confidence intervals do not overlap, then the two means are said to be significantly different.

State ____________________ 95% confidence interval for the mean_______________

State ____________________ 95% confidence interval for the mean_______________

Does the state you listed in #13 have a "worse" acid rain problem when you compare confidence intervals? Explain why.

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1. (3 points) Access the site http://water.usgs.gov and click on "Acid Rain" and then scroll down and click on "Primer on acid rain – how it is measured and its effects". Skim through this site.

2. (6 points) What is acid rain?

Rain or snow that has a pH lower than what is natural for a given area. pH is a measurement of how acidic or basic a material is and ranges from 0 to 14. Precipitation with a pH value less than 5 is considered acid rain.

3. (8 points) Describe two negative effects of acid rain.

a. Fish populations are dying.

b. Acid rain speeds up the natural decay of stone monuments and historical buildings. Materials such as iron, steel, zinc and paint can be damaged by acid rain.

4. (6 points) In the United States, where is excessive acid rain the most prevalent? For what reasons?

The eastern third of the United States, from the East coast to the Mississippi River, has pH levels lower than 5. The East has more coal burning power plants and is also more heavily populated than other parts of the U.S. More people mean more automobiles which also contribute to acid rain. (Less densely populated parts of the Eastern U.S. do not have as much acid rain.)

5. (6 points) Describe sources of pollution that contribute to acid rain formation.

The burning of fossil fuels like coal and oil products by automobiles and power plants releases large amounts of sulfur dioxide and nitrogen oxide gases into the air. When these gases come in contact with water droplets , chemical reactions occur, resulting in acid rain.

6. (4 points) Access the site http://bqs.usgs.gov/acidrain and click on "View and download data on precipitation chemistry from the NADP/NTN". Then click on "Data". Now click on WI or another state that your instructor specifies. Click on one of the monitoring sites listed, scroll down and click on "Annual Data". You will now complete the "Data Selection Criteria" form.

Select 1989 as the start year, 1998 as the end year. For data type select "Precipitation weighted means (mg/L)". For report format select "HTML table". Select "K-12" for intended use and type "statistics project" for Brief description of specific application. For "seasons to return" check "Annual"(be sure not other options are checked). Now click Get Data and Continue or Submit if a security warning appears. If you scroll to the right you will find a list of annual "field pH" values which of are interest to us.

7. (6 points) If you have access to a spreadsheet, you can copy and paste this table into the spreadsheet. The only two rows of interest in this project are the Year and the Field pH row. If you are using a graphing calculator you will need to enter this data into two lists. Print out or write the data values in these two lists to share with the class later.

8. (6 points) Make a graph in your spreadsheet or on your calculator showing pH levels over this 10-year time period. Print out this graph or draw it on graph paper.

9. (6 points) What does the graph indicate about pH levels over this 10-year time period?

The pH is fluctuating and is neither definitely increasing nor decreasing.

10. (6 points) Using the equation [H₃O⁺] = 10^-pH calculate the [H₃O⁺] for each year. You can do this for all the data at once by using this equation in your spreadsheet or calculator. As pH changes, how does [H₃O⁺] change?

Year Field pH [H₃O⁺] = 10^-pH

When pH decreases, [H₃O⁺] increases. Or smaller values of pH indicate a higher concentration of the hydronium ion H₃O⁺ (an acid).

11. (16 points) Now pick another state or monitoring site and repeat #7, 8, and 9 above for this state.

Massachusetts, MA01 data:

The pH fluctuates a lot, but it seems to be increasing slightly with time.

12. (6 points) Compare and contrast the graphs of these two sets of data.

The Massachusetts data seems to be increasing slightly. However the Massachusetts data is smaller than that of Wisconsin. The pH values for Wisconsin vary from 4.65 to 4.95, while those of Massachusetts vary from 4.35 to 4.65.

13. Find the mean (or average) pH level for the two states you researched.

WI, 4.769

MA, 4.507

Which state has "worse" acid rain? Massachusetts

14. If you have access to a spreadsheet or graphing calculator, you should be able to compute a "95% confidence interval" for the mean pH of these two states. Since the pH levels that are measured are only a sample of all possible measurements that could be taken, statisticians often compare the confidence intervals of two means rather than the means to decide if two sets of data are "significantly different". If the two confidence intervals do not overlap, then the two means are said to be significantly different.

WI, (4.707, 4.831)

MA, (4.457, 4.558)

Does the state you listed in #13 have a "worse" acid rain problem when you compare confidence intervals? Explain why.

Yes. Massachusetts appears to have "worse" acid rain because the whole confidence interval for its pH is smaller that any value in the confidence interval for Wisconsin pH. (There is no overlap between these two intervals.)