Adam Cetra
D109
PJAS Introduction
Title: Effect of Acid Mine Drainage on Dissolved Oxygen
Category: Ecology
Introduction
My name is Adam Cetra and I am a 12th grade student at Pittsburgh Central
Catholic High School. The title of this experiment is Effect of Acid Mine Drainage on
Dissolved Oxygen.
Acid mine drainage refers to water draining or being discharged from abandoned
mining sites or from waste soils called mine tailings. This water is acidic due to high
concentrations of sulfuric acid, produced as a result of chemical reactions that occur
when sulfide minerals contact oxidants, usually oxygen, in a wet or humid environment.
Measurements of pH, hardness, dissolved oxygen, temperature, and conductivity can be
used to detect environmental damage resulting from a variety of reactions that occur
following mining activity.
Chemical pollutants including sulfites, sulfates, nitrates, ammonia, and heavy
metals produce direct chemical demands on oxygen in the water due to the oxidationreduction reactions that result. Dissolved oxygen levels lower than 3 parts per million are
stressful to most aquatic organisms.
Various other experiments seem to show that most if not all of the common
chemicals of acid mine drainage reduce dissolved oxygen levels through different
chemical reactions. Many of these processes also release hydrogen ions, which lowers
pH. Oxygen is obviously needed to support organisms that respire aerobically. The lack
of oxygen for respiration and the altered pH levels both pose great threats to aquatic plant
and animal life, and also affect bacteria and other living things.
The pH of a substance is an expression of the concentration of hydrogen ions.
Low pH corresponds to high hydrogen ion concentration and vice versa. A substance that
increases the concentration of hydrogen ions in water (lowers the pH) is called an acid. A
substance that reduces the concentration of hydrogen ions in water (raises the pH) is
called a base.
Purpose
The purpose of this experiment is to measure the effects of acid mine drainage on
the dissolved oxygen level and pH level of a water habitats.
Hypotheses
The hypotheses of this study are: 1. If the dissolved oxygen content of water is affected
by the pollutants in acid mine drainage, then the concentration measured will be lower for
higher concentrations of the pollutants. 2. The null hypothesis is that no variation in
dissolved oxygen or pH levels will be realized at any of the tested concentrations of
pollutants.
Materials
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Dissolved Oxygen Sensor with soaker bottle:
PASPORT (PS-2108) | ScienceWorkshop (CI-6542)
Computer Interface
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Distilled or deionized water
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Clamps and lab stand as needed to suspend sensor in solution
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Two 600-mL beakers, large and small graduated cylinders, pipette, stirring rod
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Wash bottles for rinsing sensors
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2-M sodium sulfite solution (25.2 g Na2SO3 / 100 mL)
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2-M sodium nitrate solution (17 g NaNO3 / 100 mL)
*** I discussed my project with Mrs. Graffia and Brother Muffley on Friday. They said
they will get me the dissolved oxygen sensor and the sodium sulfite and sodium nitrate
solutions after the Christmas Break. ***
Sources of Information:
http://www.mines.edu/fs_home/jhoran/ch126/index.htm
http://www.pasco.com/experiments/earth/january_2002/home.html
http://en.wikipedia.org/wiki/Acid_mine_drainage
http://ewr.cee.vt.edu/environmental/teach/gwprimer/acidmine/acidmine.html
http://www.osmre.gov/amdint.htm