Lab 7

Water Quality, pH,
and Acid Rain

Introduction

Scientists noted the ill effects that industry and acidic pollution were having on people and vegetation as early as the late 1600's. Approximately two centuries later (1872), Angus Smith published a book called Acid Rain, coining the term we use today to describe the problems associated with acid being deposited in our environment.

Acidity is a normal part of the environmental cycle. In fact, rainwater is slightly acidic in its natural state. Acidity is important for a variety of applications. The acidity of soil determines what crops will grow. Heavily acidic water may kill valuable marine life. Improper acidity in the preparation of pesticides can render them less effective. Even something as simple as swimming pool maintenance depends on acidity. One way to determine acidity is with pH values.

Technology Problem

In order to explore acidity in the environment and acid rain in particular, you will act as a water quality technician. Your goal is to design and carry out a plan to monitor the acidity of a local body of water over a period of time. You will need to determine if acid rain is a problem for this body of water by measuring pH over time. You will learn how to use a pH probe, how to analyze the data you collect, and how to write a formal report. At the end of your laboratory, you will be expected to defend your conclusions with written and oral reports on your findings.

Note: All of your research, hypotheses, data tables, graphs, reports, data analysis, experimental methods, quizzes, etc., should be compiled in the model portfolio, a document which you will submit at the end of the laboratory. Make sure you update, collate, correct, and, especially, back-up this portfolio on a regular basis. Your professor may decide to do in-progress reviews of your model portfolio at various times.

In order to prepare you to design and carry out this scientific exploration, you will first go online and conduct basic research about concepts related to the technology problem. This bibliotechnology research will set the context for your project. Next, you will review some of the mathematics needed. Once you have demonstrated proficiency in the prerequisite mathematics, you will gain experience with data analysis and the use of a pH probe by performing an experiment on serial dilution and pH. After writing a report on serial dilution and pH to ensure you are ready for the final step, you will design and carry out your plan to monitor the pH for a local body of water. Your professor may provide grading rubrics for the written reports to help you create the model portfolio.

You will be using the scientific method to solve the technology problem. The scientific method has five steps: problem, question, hypothesis, test, and decision. The first two steps of the scientific method (problem, question) depend on exploring the technology problem and developing a better understanding of it. At this point, you may want to meet with your professor to develop a plan for accomplishing this initial exploration. With the help of your professor, you might develop a timeline with specific objectives and deadlines. You will probably begin exploring your technology problem with some bibliotechnology research.

Bibliotechnology Research

Bibliotechnology research is the main investigative avenue to gain information and answer questions as you employ the scientific method. Some questions that you might want to explore include: What is an acid and what are its effects? What is pH? What is acid rain, and what causes it? What are acceptable levels of pH? You may want to use the following outline of questions and topics to guide your investigation.

1. pH
   1. What is it?
   2. What methods/materials are used to determine it?
   3. Identify five common household items and look up their pH values.
2. Scientific method
3. Acid rain
4. Serial dilution
5. Linear regression
6. Water quality and water quality standards

You should explore general aspects of these topics as well as specific information about acid rain, water quality, and water quality standards in your local area.

You will need to select a body of water as your water site. It is important that you and your team have easy access to this water site on a regular basis. Discuss potential water sites with your professor before you choose the one you will investigate.

Following are some web sites that you may find helpful. This list is not meant to be complete. You are encouraged to search the web for other relevant sites.

Web sites for pH:

• http://www.miamisci.org/ph/
• http://www.ph-measurement.co.uk/

Web sites for the scientific method:

• http://teacher.nsrl.rochester.edu/phy_labs/AppendixE/AppendixE.html
• http://www.hobart.k12.in.us/jkousen/Sci_Meth/pmethod.htm
• http://teach.valdosta.edu/whuitt/materials/scientific_method.htm
• http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/node6.html<

Web sites for acid rain:

• http://www.ns.ec.gc.ca/msc/as/as_acid.html
• http://www.ec.gc.ca/acidrain/
• http://www.ns.ec.gc.ca/msc/as/acidfaq.html
• http://www.soton.ac.uk/~engenvir/environment/air/acid.home.html
• http://www.acidrain.org/

Web sites for serial dilution:

• http://www.woodrow.org/teachers/bi/1993/serial.html
• http://www.brooklyn.cuny.edu/bc/ahp/MBG/MBG4/Dilution.html<

Web sites for linear regression:

• http://www.mste.uiuc.edu/patel/amar430/intro.html
• http://infoweb.magi.com/~timusk/linhyd.html
• http://www.equis.com/free/taaz/linearegression.html
• http://www.math.csusb.edu/faculty/stanton/m262/regress/regress.html

Web sites for water quality and water quality standards:

• http://www.epa.gov/safewater/mcl.html
• http://www.epa.gov/ow/
• http://www.nalusda.gov/wqic/
• http://water.usgs.gov/owq/
• http://www.bae.ncsu.edu/bae/programs/extension/wqg/
• http://www.epa.gov/owow/monitoring/
• http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/index3.html

By applying the problem and question steps of the scientific method, you have gained a basic understanding of pH and acid rain. Now you are ready to tackle the technology problem.

Mathematics Tools

In the investigation of the technology problem, you will need to select mathematics tools that help explain the problem, best fit the problem, and provide a solution to the problem. You may wish to review proportions, linear equations, graphing, logarithms, and basic statistics concepts. To make sure that you are familiar with these fundamental mathematics concepts, your professor may ask you to complete a warm-up quiz, to be completed either individually or as a collaborative activity with other students.

Model Portfolio

As part of the solution to the technology problem, you will need to create a model portfolio. The model portfolio should contain a thorough description of the technology problem and its identifying characteristics. You need to explain the mathematics, technology, and science that you use to solve the problem. In addition, you need to include the mathematical and/or physical models you create. It is important to keep a careful record of all your work. It should be complete enough so that someone else could follow your work step by step. The model portfolio will be very helpful when you present your thesis defense.

The model portfolio will be built on the scientific method. The third step of the scientific method involves developing a hypothesis about the real-world situation under consideration. In this context, you can think of the model(s) that you create as a hypothesis. Your model constitutes a proposal that describes and explains the technology problem. It will mirror and explain the technology problem as well as reflect its solution. After you develop your hypothesis (model), you will conduct the last two steps of the scientific method – test the model and decide whether to retain, reject, or modify the model.

Model Development

As a water quality technician, you will create a model that will allow you to measure the pH of your water site and analyze the results to determine if it is being affected by acid rain. You will first need to complete the following training module to explore the meaning of pH. Then you will use this information to develop a model that can be used to test your water site.

I. Serial dilution and pH

Serial dilution is a procedure for diluting a substance in a series of steps. To learn about serial dilution, you will work in groups to conduct the Serial Dilution and pH Experiment. This will give you practice with serial dilution and with measuring pH. Your professor will give you the instructions and the equipment to perform the experiment. In addition, your professor may give you a rubric to evaluate how well you performed the experiment.

After completion of this experiment, your professor may ask you to answer some questions regarding serial dilution and pH to make sure that you understand the concepts. Your professor will tell you whether the questions are to be completed individually or in groups.

II. Monitoring acidity for your water site

After you have completed the bibliotechnology research and the training module to learn about pH and how to measure it, you can continue performing your job as a water quality technician. You will develop a model to monitor pH at your water site and decide whether it is being affected by acid rain.

Your model should include a plan for collecting the water samples. In the plan, it is important to identify who will collect the samples, how the samples will be collected, when the samples will be collected, and what additional information should be recorded. You will need to record special conditions such as whether the sample was taken after a rainfall, during drought conditions, after a significant temperature change, etc. Your model should define the data to be collected, the measures to be calculated, and the techniques of presentation, such as tables and graphs.

Some questions that you might want to answer include:

1. According to your state guidelines, what is the acceptable range of pH values for drinking water? Does the pH for your water site fall within this range?
2. What special conditions might affect the pH value?
3. What range of pH is required for most aquatic life? Were any of your data points outside this range?
4. What are sources of the precursors to the acids that form acid rain?
5. What are some of the environmental effects of acid deposition?
6. Identify at least three tests other than pH that are typically run on drinking water.

It will be important to have the professor approve your model before you begin collecting water samples.

You are now ready to apply the fourth and fifth steps of the scientific method – testing the hypothesis (the model), and making a decision about the hypothesis.

Test the Model

To test the model (the hypothesis), you will implement your plan by collecting water samples, measuring pH, and analyzing the data you obtain. Use your results to conclude whether the water site is being affected by acid rain.

Decide to Retain, Reject, or Modify the Model

After you have tested the model, you can make a decision regarding the model. This action depends on how well your model satisfies the conditions of the technology problem. For example, you may be able to compare your results regarding pH and acid rain to published information. If your model (your hypothesis) does not meet the needs of the technology problem, you will want to revise it.

Thesis Defense

You will be asked to give an oral presentation of your model portfolio. This is called the Thesis Defense. It might help to imagine that you are presenting the results of your research to the town council or to a community gathering. Be sure to include in your defense a discussion of the importance of pH as well as a discussion of the results of your decision regarding the pH of the water site. Your professor may give you a rubric that outlines a format for the thesis defense.