Hands-On Experiments to learn about Acid Mine Drainage

​Overview

Acid mine drainage (AMD) is water contaminated when pyrite (iron sulfide) is exposed to air and water. The exposure often results in reactions that form sulfuric acid and dissolved iron. Some or all of this iron can precipitate to form the red, orange, or yellow sediments (yellowboy) on the streambed. The acid runoff further dissolves heavy metals such as aluminum, copper, lead and manganese. The rate and degree which acid can increase mine drainage proceeds by the action of certain bacteria. Note: There is also basic mine drainage (BMD).

The northern Appalachian coal fields (bituminous coal) extend from northwest Pennsylvania, south of the New York state line through western Pennsylvania, southeast Ohio, western Maryland, throughout much of West Virginia, southwest Virginia, eastern Kentucky, and northeast Tennessee. Mine drainage is particularly heavy in western Pennsylvania, and northern and central West Virginia. Northeast Pennsylvania is largely anthracite coal.

Let's get started

Each experiment includes a list of tools and things you will need and provides directions on what to do. You will also be asked to record what you see and what you conclude.

Safety first

These experiments should always be done with the proper supervision from a teacher or parent. Always use caution and the proper protective equipment such as, rubber boots, gloves, safety glasses when you are in or around a stream and especially when handling chemicals. Learn more about volunteer monitoring at USEPA.

Introductory materials

• Welcome letter to kids, teachers, parents, guardians and concerned citizens
  

  What questions do you have about acid mine drainage, the colors in the water, the critters in the water, or any other water quality questions? This document will help you answer some of those questions and more. It is full of simple experiments that will lead you to some of the answers, but more importantly it will help you understand how important it is to protect, preserve, and learn about our environment.

• Tips on designing your own experiments
  

  To use the Scientific Method you should design an experiment to test your hypothesis. A hypothesis is a question, which has been reworded into a form that can be tested by an experiment. Your hypothesis should be based on the background information you gathered. Make a numbered, step-by-step list of what you will do to answer your question. This list is called an "experimental procedure". Your procedure should be detailed enough that someone else could do your experiment without needing to talk to you about it.

• What is Science? -- The Basics
  

  Science is not just a collection of facts, it is so much more. We all need to know some basic science in order to better understand our environment.

The experiments

1. Making Your Own Litmus Paper Litmus paper is one way to measure the strength of an acid or base substance.
2. What Is Acid, and How Do You Know It? Robert Angus Smith, a Scottish chemist, was the first to use the phrase "acid rain" in 1852. He noticed that the bricks in the buildings were falling apart, and through scientific experimentation, later found that there was a connection between London’s polluted skies and the pH of its rainfall. Most scientists today agree that normal rainfall is slightly acidic with a pH of 5.6. The rain naturally reacts with carbon dioxide in the atmosphere to form a weak carbonic acid. Therefore, scientists define acid rain as any wet precipitation (rain, sleet, and snow) with a pH of less than 5.6. The rain becomes more acidic when it reacts with other gases in the atmosphere such as sulfur dioxide and nitrogen oxides. These other gases are naturally present in the atmosphere in small amounts; Industrial activities have increased their amounts.
3. Why Does Acid Mine Drainage Form? In many areas, acid drainage forms naturally when certain minerals come into contact with water, air and bacteria. This contact and the chemical reactions that take place are part of the weathering process. The weathering of the rocks and minerals in the creek slowly releases the acids, salts, metals and sulfates into creeks, rivers, lakes and wetlands. Weathering is a natural process, but many times human activities interfere and can increase the amounts. When too much of these acids and minerals enter creeks, they become polluted and can no longer support animals.
4. Is the Groundwater Acid Also? Groundwater is an important part of our planet's water cycle. The surface water, mainly from rain, runs off over the ground and fills creeks, rivers, lakes and wetlands. A small amount of the surface water does not run off, but instead seeps underground. This underground water is called ground-water. Groundwater fills the spaces that are found in the soil and rocks and eventually flows downhill, just like creeks. The place that the groundwater is first observed as you dig down from the surface into the rocks and soil below is known as the water table. If you live in an area where your creek is acid, most likely the groundwater will also be acid.
5. Studying Aquatic Invertebrates An excellent way to learn about your creek is to study its benthic macroinvertebrate community. Biologist and other scientist have collected these organisms from many different places and many different types of creeks. By studying the macroinvertebrate in the creeks, you can learn something about the chemistry of the water and the physical environment, thereby determining the health of the creek.
6. What Kind of Plants Like Acid Water? There are very few plants that prefer acid conditions in creeks. However, some plants such as cattails can help to change the chemistry of the water by the uptake of pollutants and trapping of materials with their root systems. These wetland plants work in cooperation with bacteria in the soil to help improve the condition of the water. Today scientists are testing many of these plants to see how they are able to do this. By learning more, scientists are able to create new environments, such as wetlands, to help improve conditions in acid streams.
7. Who is Very Small and Living in Your Creek? Acidic environments are difficult places to live for many plants and animals; however, certain types of bacteria and algae can survive and flourish. These small one-celled life forms collectively known as microorganisms can be very colorful. The colors are a result of the many different types of chemical processes, of which these life forms are capable. For example, iron-oxidizing bacteria are able to "remove" dissolved iron in the water and form minerals that look like rust. Many types of algae and bacteria use energy from sunlight to produce food, similar to larger plants, in a process called photosynthesis. These processes also create changes in the chemistry of the water. The many different types of bacteria and algae produce brilliant colors such as yellow, red, green, brown and even purple.
8. Testing the Water In Your Creek A creek can carry an amazing amount of chemicals. (One reason is that any activity on the land that surrounds the creek affects the creek.) Some of these chemicals are so abundant that they mask "or hide" what is actually going on in the creek. For example, an abundant amount of minerals, metals, and sulfates may increase the pH of the creek, but when these substances drop out of the water, such as when the water flows over rocks or through wetlands, the chemistry of the creek changes and the pH may actually decrease.
9. How Many Colors Does Iron Have? Iron and the oxidation-reduction process: Iron is a common element of many creeks, especially in the Appalachian region. Iron (Fe) has many different forms and many different colors. Each color tells a different story about the chemistry of the creek. Iron that is naturally found in the creek normally does not cause problems (it is part of the soil and the sediments), but metals can be increased by human activities to a point where they may become harmful to life in a creek. With iron, red is oxidized and black is reduced.
10. What is the Black on the Rocks? Finding the minerals that coat the rocks in a creek is a very old profession. The prospectors of years ago used to scrape off the coatings from the rocks in a creek and send them to a laboratory for analysis. These prospectors were usually looking for gold and silver, but many times they found a wide variety of minerals and metals. The coatings and colors on the rocks can usually tell you about the most abundant minerals in a creek. Many times, the darkest mineral in a creek will cause the color. Manganese is almost always the darkest color mineral in the creek.
11. What is the White in the Creek? Both natural processes and pollution can cause foam (white soapy looking stuff) on a creek. It is usually caused by a combination of several different pathways. A simple definition of foam is "A gas (usually oxygen) mixed in a liquid containing some type of impurity." The foam is produced when air bubbles created by water flowing over rocks and over objects, combine or mix with the impurity. Sometimes foams are natural. White colors can tell you when the element aluminum is present, or when sulfur producing bacteria are present. The foam may also be the result of human activities in or around the creek.
12. How Can Acid Mine Drainage Be Treated? Acid mine drainage sometimes forms when certain minerals in the soil and rocks around mines are exposed to weathering processes during mining. These exposed minerals release their contents into creeks causing them to become acidic. This kind of pollution damages aquatic life and makes the water useless or harmful for others who depend on it for recreation or drinking water.
13. AMD Resources for Additional Study Reference material and related websites for additional study of AMD.

Developed By

Timothy Craddock
WVDEP - Watershed Improvement Branch
601 57th Street, SE, Charleston, WV 25304

Dr. Eleanora Robbins
Department of Geological Sciences
San Diego State University, San Diego, CA 92182

Sandra McSurdy
National Energy Technology Laboratory
Pittsburgh Research Center, Pittsburgh, PA 15236