Materials Included In Kit

Additional Materials Required

Safety Precautions

See the Safety Precautions section in the student section. Wear chemical splash goggles, chemical-resistant apron, and chemical-resistant gloves. Please review current Safety Data Sheets for additional safety, handling, and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. In the field, reacted samples may be poured into a designated container for later disposal. Dispose of reacted samples down the drain with plenty of water according to Flinn Suggested Disposal Method #26b.

Teacher Tips

• This is a Super Value Kit. It contains enough materials for five classes of 30 students working in pairs (75 total student groups).

• One color comparison chart is provided for each test. Have students share each color comparison chart. Lab stations may be setup for each test.
• It’s a good idea to collect several samples from each site that is tested. It is also wise to test the samples within one hour of collection if possible.
• The water samples can be collected in a clean, glass or plastic container with a lid. Handle the samples in a manner that will prevent any physical changes or chemical reactions.
• Rinse the container with sample water and fill the container completely with the sample water to prevent the loss of dissolved gases.
• Perform the dissolved oxygen test at the sample site as soon as possible.
• If a test sample reaction is darker than the darkest color on the color chart, the concentration of the sample is greater than the test range of the test. Combine equal parts of the sample water and distilled water. Follow the test procedure with the water sample that has been diluted. Then multiply the test result by two. This method can not be used for the dissolved oxygen test.
• TesTabs are a vendor product of the LaMotte Company. MSDS are available through the manufacturer web site. Links to the specific TesTabs used in this kit are listed below.

  Chlorine — http://www.lamotte.com/pages/common/pdf/msds/6899.PDF
  Dissolved Oxygen — http://www.lamotte.com/pages/common/pdf/msds/3976.PDF
  Nitrate — http://www.lamotte.com/pages/common/pdf/msds/3703.PDF
  Phosphate — http://www.lamotte.com/pages/common/pdf/msds/5422.PDF
  Wide Range — http://www.lamotte.com/pages/common/pdf/msds/6459.PDF

Further Extensions

Have students write reports on certain pollutants, their sources and effects. Encourage students to use the Internet and local libraries to explore the wide range of water pollution information available.

Take water samples from various locations of a stream, lake, river or pond. Compare the values of pollutants in these different areas. Have students brainstorm possible explanations of why the pollutant levels may differ in these various locations.

Introduce and discuss real-life examples of pollution. A good example is the water pollution that occurred on the Cuyahoga River. The Cuyahoga (which eventually empties into Lake Erie) is a river that runs through Akron and Cleveland, Ohio. In the 1950s and 60s, chemical and steel factories dumped up to 155 tons a day of toxic chemicals, sludge and solvents into the river. The river was also bombarded with animal manure, pesticides, fertilizers, and raw and poorly treated sewage. In 1959, oil slicks from these substances caught fire and burned for a total of eight days. Firefighting measures only complicated the situation, as water was sprayed from the fire hoses the blaze was spread even further. Ten years after this incident the river caught fire once again. These incidents were strong factors leading to the passage of the Clean Water Act in 1972.

Answers to Questions

1. What are the two main types of water pollution? Define each type and list examples. 
   Point specific pollution and nonpoint pollution. Point specific pollution is contamination that comes from a specific location. An example of point specific pollution is a factory that has a chemical discharge pipe that leads directly to a water source. Nonpoint pollution does not come from a specific location. Some examples are runoff of water from city areas, agricultural land or from poor forestry practices.
2. List possible sources and effects of each of the pollutants in this activity. 
   See Background section (answers may vary).
3. Compare and contrast your results with the values given in the Background section of this handout for each pollutant tested for in this activity. 
   Answers will vary depending on results.
4. Compare your values to your classmates’ values. List possible sources of error. 
   Answers will vary depending on results.
5. What can be done to help minimize the amount of each pollutant in your local sources of water? Give some specific examples. 
   Answers will vary with each pollutant.
6. Would you describe your tested water source as polluted or non-polluted? Defend your answer. 
   Answers will vary.

Discussion

Here are the reactions that take place for each sample: 

Chlorine: Chlorine DPD #4R TesTabs contain diethyl-p-phenylenediamine (DPD). When chlorine oxidizes DPD, a pink color is formed in proportion to the chlorine concentration. 

Dissolved Oxygen: Dissolved Oxygen TesTabs contain sodium citrate and 2,4-diaminophenol dihydrochloride. Dissolved Oxygen, in a solution buffered by sodium citrate, oxidizes a proportionate amount of 2,4-diaminophenol dichloride to produce a colored solution. 

Nitrate: Nitrate Wide Range TesTabs contain zinc, which reduces the nitrate to nitrite, and chromotropic acid which reacts with the nitrite to form a pink color. 

pH: pH Wide Range TesTabs contain mixed pH indicators which are sensitive to pH and undergo specific color changes with variation in pH.

Phosphate: Phosphate TesTabs contain ammonium molybdate which reacts with phosphorus to form a phosphomolybdate complex. This complex is reduced to a blue complex by ascorbic acid. 

References

Cunningham, W. P.; Woodworth, S. B. Environmental Science A Global Concern; William C. Brown: Dubuque, IA, 1995; p 421.

Mitchell, M. K.; Stapp, W. B. Field Manual for Global Low-Cost Water Quality Monitoring; Kendall/Hunt: Dubuque, IA, 1997; pp 29, 35, 36, 47.

Sarkis, V. J. Chem. Educ. 1974, 51, 745–747.

Introduction

Are streams, lakes, rivers and ponds really polluted? What types of pollutants are in our local water sources? What are the levels of these pollutants? In this procedure, the amount of pollutants in local waters will be investigated and the effects of these pollutants studied.

Concepts

• Chemical pollution
• Water quality
• Sources of pollution
• Effects of pollution

Background

Water is an essential resource for all life forms. In fact, water is the main component in cells and it composes up 60 to 70 percent of the weight of living organisms. It is used for almost every activity in today’s world. Some examples are seen in agricultural and industrial applications, drinking, transportation, and recreation. Water often seems to be available in an almost endless supply, but as human populations rise and our world becomes increasingly industrialized, more and more water is being used. With this extensive use of water, a problem arises: the water becomes polluted and contaminated. This pollution leads to a strain on water’s ability to recycle and cleanse itself of contaminants. The amount of water available, its distribution, and its quality are critical issues that continue to affect all life. An increasing awareness of the need to monitor the quality of water and to locate the sources of pollution is becoming more prevalent in today’s society. 

There are two main types of water pollution—point specific pollution and nonpoint pollution. Point specific pollution is contamination that comes from a specific location. An example of point specific pollution is a factory that has a chemical discharge pipe that leads directly to a water source. This type of pollution can be pinpointed and limited much more readily than the second class of pollutants, nonpoint sources. 

Nonpoint water pollution does not come from a specific location. Some examples are runoff of water from city areas, agricultural land or poor forestry practices. This type of pollution occurs when runoff water such as snowmelt or rainfall travels over an area of land. As this water moves over the ground, it picks up waste and carries it to a body of water. This water then enters our streams, lakes, rivers and ponds. 

As polluted water enters the groundwater supply or any other water source, the concentrations of certain chemicals may alter the water’s purity. In this activity, the levels of some major factors that lead to the pollution of streams, lakes, rivers and ponds will be measured and studied. The actual amount of pollutants in these water sources plays a vital role in the biodiversity of aquatic organisms in nature. If levels of pollutants reach certain levels, the ability of specific organisms to reproduce and thrive is greatly dampened and in some cases even halted. If levels of pollutants become too highly concentrated, and certain species of individuals become scarce or even extinct, food chains could be altered. This, in turn, could change the structure of ecosystems as we know them today. 

The following is a list of some common pollution indicators and how they commonly affect our water sources. 

Chlorine—Chlorine is not naturally found in water at any appreciable levels. It is municipally added to public water systems and swimming pools as a bactericide. Chlorine in drinking water supplies is generally maintained under 0.75 parts per million. Large levels of chlorine introduced to streams, lakes, rivers, and ponds can be harmful and possibly fatal to aquatic organisms. 

Dissolved Oxygen—The concentration of dissolved oxygen is one of the most important indicators of the overall health of a body of water. Water with consistently high levels of dissolved oxygen (6 parts per million or more) typically supports the most diverse biological communities. Water with consistently low dissolved oxygen levels (below 3 parts per million) is extremely stressful to aquatic organisms and may be virtually void of aquatic life or may harbor only a few species adapted to such conditions. Dissolved oxygen levels below 2 parts per million will not support fish life. 

Nitrate—Nitrates accumulate from decaying vegetation, from the atmosphere, from fertilizer used in agriculture, animal excrement and sewage. Unpolluted water generally has an overall nitrate level less than 4 parts per million. If the concentration of nitrogen reaches more than 10 parts per million, water may be unfit to drink. Water high in nitrates cause the overgrowth of algae and other organisms which will foul the water found in our water sources. 

pH—The pH test is a standard test used during water analysis. pH refers to the relative abundance of hydrogen ions in a water sample. The pH scale has a range of 0 to 14 where 7 is neutral, values lower than 7 are acidic, and values greater than 7 are basic. Most aquatic organisms require a pH range between 6.5 and 8.2. Water with abundant algae and vegetation growth usually has a significantly high pH. This is due to the fact that rapidly growing algae and vegetation remove carbon dioxide from the water during photosynthesis.

Phosphate—Phosphate originates from fertilizers, wastewater of domestic origin such as human, animal, and plant residue, and from wastewaters of industrial origin. Phosphates are added to farm and city water systems to control water hardness. Phosphates from laundry detergents can result in overgrowth of algae, which in turn will cause the algae to die at a high rate and undergo decomposition. This decomposition process depletes oxygen from the water and will result in increased fish kill. Phosphate levels of more than 0.03 parts per million may lead to an overgrowth of aquatic plants. 

Materials

Safety Precautions

Chlorine DPD #4R TesTabs, Dissolved Oxygen TesTabs, Nitrate Wide Range TesTabs and Phosphate TesTabs all contain chemicals which may irritate skin or be harmful if swallowed. pH Wide range TesTabs all contain trace amounts of dyes and inert fillers. The TesTab reagents used in this kit were designed with safety in mind. The single-use, foil packaged TesTabs are easy to dispense. Store TesTabs in a cool, dry place and only open when ready to use the tablet. A single tablet, either alone or reacted with a sample, is not a health hazard. However, TesTabs should not be ingested. Wear chemical splash goggles, a chemical-resistant apron and chemical-resistant gloves. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Procedure

Part 1. Chlorine Test 

1. Fill the water sample tube to the 5-mL line with the freshwater sample.
2. Add one Chlorine DPD #4R TesTab to the tube.
3. Cap the tube and mix the solution until the tablet has dissolved.
4. Compare the color of the sample to the Chlorine color comparison chart. Record the findings as parts per million in the data table.
5. Dispose of the reacted sample according to the instructor and rinse the water sample tube twice with the water sample for the next test.

1. Fill a dissolved oxygen test vial to overflowing with the freshwater sample.
2. Add two dissolved oxygen TesTabs to the test tube.
3. Cap the tube and be sure that there are no air bubbles in the sample.
4. Invert the tube and mix until the tablets have dissolved.
5. Wait for five minutes.
6. Compare the color of the sample to the Dissolved Oxygen color chart. Record the findings as parts per million in the data table.
7. Dispose of the reacted sample according to the instructor.

1. Fill the water sample tube to the 5-mL line with the freshwater sample.
2. Add one Nitrate Wide Range TesTab to the tube.
3. Cap the tube and mix until the tablet has dissolved.
4. Wait for five minutes.
5. Compare the color of the sample to the Nitrate color comparison chart. Record the findings as parts per million in the data table.
6. Dispose of the reacted sample according to the instructor and rinse the water sample tube twice with the water sample for the next test.

1. Fill the water sample tube to the 5-mL line with the freshwater sample.
2. Add one Phosphorus TesTab to the tube.
3. Cap the tube and mix until the tablet has dissolved.
4. Wait for five minutes.
5. Compare the color of the sample to the Phosphate color comparison chart. Record the findings as parts per million in the data table.
6. Dispose of the reacted sample according to the instructor and rinse the water sample tube twice with the water sample for the next test.

1. Fill the water sample to the 10-mL line with the freshwater sample.
2. Add one pH Wide Range TesTab to the tube.
3. Cap the tube and mix until the tablet has dissolved.
4. Compare the color of the sample to the pH color comparison chart. Record the findings in the data table.
5. Dispose of the reacted sample according to the instructor and rinse the water sample tube twice.

Student Worksheet PDF

11917_Student1.pdf