Materials Included In Kit

Additional Materials Required

Prelab Preparation

1. Make enough copies of the Raymond Town Master Map so every group receives a map.
2. Label three 400-mL beakers (or similar containers) Stream Sample 1, Stream Sample 2 and Stream Sample 3 with a wax pencil.
3. Prepare 200 mL of each stream sample in the respective beakers before class.
4. This laboratory activity may be presented as any one of the following three scenarios:

Scenario A: Leakage at Raymond Sewer Treatment Plant

Stream sample 1 = 200 mL of distilled water
Stream sample 2 = 1 mL of 0.1 M sodium phosphate solution

30 mL of 0.1 M sodium nitrate solution
169 mL of distilled water

Stream sample 3 = 1 drop of 0.1 M sodium phosphate

3 mL of 0.1 M sodium nitrate
197 mL of distilled water

Scenario B: Valley Detergent Discharge

Stream sample 1 = 1 mL of 0.1 M sodium phosphate solution

30 mL of 0.1 M sodium nitrate solution
169 mL of distilled water

Stream sample 2 = 1 drop of 0.1 M sodium phosphate solution

5 mL of 0.1 M sodium nitrate solution
195 mL of distilled water

Stream sample 3 = 1 mL of 0.1 M sodium nitrate solution

199 mL of distilled water

Scenario C: Fertilizer Runoff from Countryman Farms and/or Runoff of Water from Downtown Raymond

Stream sample 1 = 200 mL of distilled water
Stream sample 2 = 200 mL of distilled water
Stream sample 3 = 1 mL of 0.1 M sodium phosphate solution

30 mL of 0.1 M sodium nitrate solution
169 mL of distilled water

Safety Precautions

Nitrate Wide Range TesTabs^® and Phosphate TesTabs contain chemicals, which may irritate skin or be harmful if swallowed. 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. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory. 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. All solutions and testing samples may be disposed of according to Flinn Suggested Disposal Method #26b.

Lab Hints

• Enough materials are provided in this kit for 30 students working in pairs or for 15 groups of students. This laboratory activity can reasonably be completed in one 50-minute class period.
• Be sure to use clean glassware when preparing the stream sample solutions. Rinse the beakers with distilled water before use.
• Three color comparison charts for each test factor are provided in the kit. Divide the cards up between the student groups accordingly.
• The stream sample containers may be placed in one central location for dispensing or may be subdivided between student groups before class.
• Be sure students return the pipets for each solution to the correct beaker after the sample has been dispensed to their water testing tubes.
• TesTabs^® are a vendor product of the LaMotte Company. SDSs are available through the manufacturer website.

Teacher Tips

• Three possible scenarios are presented in this activity. The scenarios may be changed to keep the identity of the responsible party unknown from class to class.

• Have students write reports on different 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 actual water samples from various locations of a stream, lake, river or pond and use TesTabs to test the water quality. Compare the values of pollutants in these different areas. Have students brainstorm possible explanations of why the contamination levels may differ in these various locations.
• Introduce and discuss real-life examples of water contamination. 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.
• Here are the reactions that take place for each sample:
  Nitrate: Nitrate Wide Range TesTabs contain zinc, which reduces the nitrate to nitrite, and chromotropic acid which reacts with the nitrite ion to form a pink color.
  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.

Sample Data

Answers to Questions

1. In general, what do the phosphate and nitrate levels indicate about water quality?

   Water high in phosphates can result in an overgrowth of algae which causes algae to die at a high rate and deplete oxygen from the water. Water high in nitrates may be unfit to drink and will result in increased growth of algae and other organisms.

2. In general, what water quality conditions could lead to a massive fish kill?

   A fish kill could be associated with increased algae growth, depletion of oxygen in water, and high levels of nitrates and phosphates.

3. Which stream sample showed the highest phosphate level?

   A: Sample 2, B: Sample 1, C: Sample 3

4. Which stream sample showed the highest nitrate level?

   A: Samples 2 and 3, B: Samples 1 and 2, C: Sample 3

5. What facility or facilities in the town of Raymond may be responsible for the conditions that caused the fish kill?

   A: Raymond Sewage Treatment Plant.
   B: Valley Detergent Company.
   C: Countryman Farms or Runoff from Downtown Raymond.

6. What type of pollution occurred—point or non-point pollution. Explain.
   Scenarios A and B are a result from point pollution. Scenario C is most likely non-point pollution from runoff of the farm or town.

Teacher Handouts

12762_Teacher1.pdf

Introduction

Why are all the fish dying in Raymond Township? In this activity, forensic problem-solving skills will be used to determine the cause of the massive fish kill and who is ultimately responsible.

Concepts

• Forensics

• Water pollution

Background

Water is an essential resource for all life on Earth. In fact, water is the main component in cells and it composes up 60 to 70 percent of the weight of living organisms. Water is used for almost every activity in today’s world. Some examples are seen in agricultural and industrial applications, drinking, transportation and recreation. Water seems to be available in an almost endless supply, but as Earth’s population increases 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 as well as its distribution and 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 identified and controlled 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 from 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 streams or any other water source, the concentrations of certain chemicals may alter the water’s purity. 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 paragraphs describe a couple common pollution indicators and how they commonly affect our water sources.

Nitrates—Nitrates accumulate from decaying vegetation, the atmosphere, fertilizers 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 nitrates exceeds 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.

Phosphates—Phosphates originate from fertilizers, wastewater of domestic origin, such as human, animal and plant residue, and from wastewaters of industrial origin. Phosphates are often added to farm and city water systems to control water hardness. Phosphates from laundry detergents can result in overgrowth of algae and aquatic plants, 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 greater than 0.03 parts per million may lead to an overgrowth of aquatic plants.

Experiment Overview

A massive fish kill has occurred in the Rachville stream in the town of Raymond. The townspeople of Raymond are in an uproar and extensive efforts are being made to determine why the fish kill has occurred. Your job, as the forensic scientist, is to determine what and who may be responsible for the fish kill.

Materials

Safety Precautions

Nitrate Wide Range TesTabs^® and Phosphate TesTabs contain chemicals which may irritate skin or be harmful if swallowed. 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. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

1. Obtain a copy of the Raymond Town Master Map.
2. Three water samples have been extracted from the Rachville stream.
3. Obtain a graduated water testing tube.
4. Using the designated pipet, place a 5-mL sample of the stream sample container 1 into a water testing tube.
5. Obtain and add one phosphate TesTab^® to this water testing tube.
6. Cap the tube and shake until the tablet has dissolved.
7. Wait for five minutes.
8. Compare the color of the sample to the Phosphate Color Comparison Chart. Record the result in the appropriate location as parts per million phosphate in the Stream Contamination Data Table.
9. Obtain a second, clean graduated water testing tube.
10. Using the designated pipet, place 5-mL sample of the stream sample container 1 into a water testing tube.
11. Obtain and add one nitrate TesTab to this water testing tube.
12. Cap the tube and shake until the tablet has dissolved.
13. Wait for five minutes.
14. Compare the color of the sample to the Nitrate Color Comparison Chart. Record the result in the appropriate location as parts per million nitrate in the Stream Contamination Data Table.
15. Rinse the graduated water testing tubes twice with distilled water.
16. Repeat steps 3–15 for stream samples 2 and 3.
17. Record all data in the Stream Contamination Data Table.
18. Answer all Post-Lab Questions.
19. Consult your instructor for appropriate disposal procedures.

Student Worksheet PDF

12762_Student1.pdf