Jennifer H., Hanna R., and Amy S.
The purpose of the experiment is to discover whether Bluffton creates a
significant amount of pollution released into the
Will there be pollution before, in, or after Bluffton in the
Oxygen is a nonmetallic element constituting 21% of the atmosphere by volume that occurs as a diatomic gas. It combines with most elements, is essential for plant and animal respiration, and is required for nearly all combustion. The two main sources of dissolved oxygen in stream water are the atmosphere and aquatic plants. Aquatic plants introduce oxygen into stream water as a byproduct of photosynthesis. The amount of oxygen that can dissolve in water is limited by physical conditions such as temperature and atmospheric pressure (njnie.dl.stevens-tech.edu, 2004).
The solubility of oxygen is greater in colder water than in warm water. Oxygen slips into “pockets” that exist in the loose hydrogen-bonded network of water molecules without forcing them apart. The oxygen is then caged by water molecules, which weakly pin it in place (Antoine.frostburg.edu, 2004).
The dissolved oxygen level is an indication of how polluted the water is and how well the water can support aquatic plant and animal life. A higher dissolved oxygen level indicates better water quality. If dissolved oxygen levels are too low organisms may not be able to survive. Much of the dissolved oxygen in water comes from oxygen in the air that has dissolved in the water. Some of the dissolved oxygen in water is a result of photosynthesis of aquatic plants. Water temperature also can affect dissolved oxygen levels. The higher the temperature, the less oxygen can dissolve in water (njnie.dl.stevens-tech.edu, 2004).
A pH must be measured at the test site immediately because temperature affects pH value greatly (njnie.dl.stevens-tech.edu, 2004). A pH is a number used by scientists to indicate the concentration of hydrogen ions in a solution. A pH stands for potential hydrogen. A pH generally ranges from 0 to 14. A pH below 7.0 indicates that a solution is acidic, and a pH above 7.0 indicates that a solution is basic (alkaline). A pH is measured with an electronic pH meter or with special dyes called acid-base indicators (Rock, 2000).
A pH measures the relative acidity of the water. A pH level of 7.0
indicates that solution is neutral. Pure water contains a pH level of 7.0. A pH
reading between 6.5-7.5 is considered to be excellent, but if water’s pH level
is less than 5.5 is very acidic and it is impossible for fish and other
organisms to survive in the water. In the
The effects of water pollution by acid rain are varied. They include poisonous drinking water, poisonous food for animals, unbalanced river and lake ecosystems, and deforestation. Acid rain damages trees, crops, and buildings also. These effects are specific to the various contaminants (www.soest.hawaii.edu, 2004).
Nitrates/nitrates are nitrogen-oxygen chemical units, which combine with various organic and inorganic compounds. The body converts nitrates into nitrates and disposes of them primarily through urination (www.epa.gov, 2004).
Most nitrogenous materials in natural waters tend to be converted to nitrate. All sources of combined nitrogen, particularly organic nitrogen and ammonia, should be considered as potential nitrate sources. Primary sources of nitrates include human sewage and livestock manure. When nitrates are released into the environment, they tend to migrate to ground water. They do not evaporate and therefore remain present until consumed by plants or other organisms (www.epa.gov, 2004).
In 1974, Congress passed the Safe Drinking Water Act. The Environmental Protection Agency is required to determine safe levels of certain chemicals in drinking water. Nitrates and nitrites are included in the chemical selection to be monitored due to possible health risks and exposure. The limit permitted by the EPA for nitrates is set at 10 parts per million, and the nitrite level is set at 1 part per million. These limits are known as maximum containment level goals (www.epa.gov, 2004).
Excessive levels of nitrates in drinking water may cause many health effects. Young children may experience a shortness of breath and blueness of skin, which is caused by the chemicals interfering with the blood’s ability to carry oxygen. Long-term effects may include diuresis, increased starchy deposits, and hemorrhaging of the spleen (www.epa.gov, 2004).
The hypothesis is that there with be acceptable levels of dissolved oxygen and pH, with very little registering of nitrates/nitrites. This hypothesis was conceived due to regulations set and monitored by the EPA.
Ecology test kit (dissolved oxygen, pH meter, and nitrate/nitrite)
500 mL plastic cup
String (enough to span from the top of the bridge to the river)
Weight (optional for sinking the cup so it will fill with the water)
Computer (to type the lab and gather information)
Before beginning the lab gather all of the required materials. Learn to use the kits by first practicing
with samples of any water. Make sure
that all participants understand how to accomplish the tests so that the water
samples can be tested at the river, because some tests can be affected by time.
Three different tests will be performed at the
Part 1: Collecting the Water Samples
In this part of the lab, a sample
of water will be collected from the
1. Tie the weight to the 500 mL plastic cup very tightly with the string. Be sure to have plenty of excess string, which the experimenter can hold onto while the sample is being taken.
2. Place the cup and weight into the river, while still holding onto the attached string, and let the cup fill with water. Then retrieve the filled cup by gently drawing in the string.
Part 2: Testing the Water Samples
In this part of the lab, the collected water sample is tested for pollution indicators in the form of pH, nitrate/nitrite levels, and dissolved oxygen.
Water testing for levels of pH. The pH level was tested first due to its relationship with temperature. A pH meter was placed directly into the water and the result was recorded.
Water testing for nitrate/nitrite levels. Nitrate/nitrite levels were indicated by using specific nitrate/nitrite test strips. The strip was placed into the water for approximately 2 seconds, then laid flat for 30 seconds. Results were then compared to the color chart.
Water testing for dissolved oxygen. The ecology test kit comes with all necessary materials to test for dissolved oxygen levels. The glass bottle was rinsed three times with the water sample and filled to overflow. The stopper was then inserted to the glass bottle to ensure that a small part of the sample spills over. Next, remove the stopper. Add 5 drops of both Manganous Sulphate Solution and Alkali-Azide Reagent to the sample. Add more of the water sample so that the bottle is completely filled. Replace the stopper into the bottle to ensure that no air bubbles are trapped in the bottle. Invert the bottle several times. The sample will become orange-yellow and a flocculent precipitate will form if oxygen is present. Let the sample stand; the flocculent precipitate will start to settle. Approximately 2 minutes later, when the upper half of the bottle becomes limpid, add 10 drops of Sulphuric Acid Solution. Again replace the stopper into the bottle and invert it until all particulate material is dissolved. The sample will be ready for measurement when it becomes yellow and completely limpid. Remove the cap from the plastic vessel. Rinse the plastic vessel with the water sample, and then fill it to the 5 mL mark and replace the cap. Add 1 drop of Starch Indicator through the hole in the cap and swirl it carefully. The solution will then change to a violet or blue color. Push and twist pipet tip onto the tapered end of the syringe ensuring an air tight-fit. Take the titration syringe and push the plunger completely into the syringe. Inset tip into HI 3810-0 Titrant solution and pull the plunger seal to the 0 mL mark of the syringe. Place the syringe tip into the cap hole of the plastic vessel and slowly add the titration solution. After each drop, swirl the plastic vessel to mix the solution. Continue adding the titration solution until the solution in the plastic vessel changes from a violet or blue color to a colorless composition. Read the milliliters of the titration solution from the syringe scale and multiply the reading by 10 to obtain a mg/L (ppm) oxygen level. If the results are lower than 5 mg/L, the test precision can be improved by adding more of the unused sample into the glass bottle to the 10 mL mark of the plastic vessel. Proceed with the test as described before and multiply the values on the syringe scale by 5 to obtain a mg/L dissolved oxygen level. Record the final results.
The first sample was taken at the
The next sample, taken at the
The final sample of water was taken from the
Will there be pollution before, in, or after Bluffton in the
Carbon Dioxide Test Kit. (2004). Directions used to test the oxygen in water. [Brochure]. Hanna Instruments.
Consumer Factsheet on:
Definition of dissolved oxygen.
How to predict oxygen solubility in
Information on pH and pH testing.
The effects of water pollution and how to decrease problems with pollution. Retrieved
Figure 1. This
representation shows how much pH, nitrites/nitrates, and dissolved oxygen was
found in the
*ppm represents less than 1% if value is 0
EPA Standard/Means: pH ~7.5, Nitrate/Nitrite ~less than 1%, DO ~10mg/L