Grade Levels

7 - 12

Objectives

• modelling pollution conceptually;
• testing water samples;
• interpreting data collected.

Standards of Learning

Science:

• Grade Seven: LS.1, LS.4, LS.6, LS.7, LS.11, LS.12
• Physical Science: PS.1, PS.2, PS.4, PS.7
• Earth Science: ES.1, ES.2, ES.9
• Biology: BIO.1, BIO.3, BIO.9
• Chemistry: CH.1, CH.6

Background

    Indicator species--plants and animals associated with water of various quality--are also useful in evaluating water. Dissolved oxygen is an important indicator, since most species require oxygen. Sometimes oxygen levels can drop dramatically because of sudden algae population explosions or "blooms", caused by excess nutrients. In daylight, the algae produce more oxygen than they consume. However, such blooms usually result in a net loss of oxygen, since it is consumed by the aIgae in darkness and by decay organisms when the algae die. Estuaries are particularly vulnerable to low dissolved oxygen in summer, when warmer water promotes algae growth, yet holds relatively less oxygen than cooler water.

    Turbidity (or lack of water clarity) may be measured with a Secchi disk. The Secchi disk is a black and white weighted disk attached to a line. The depth at which one can no longer distinguish between the light and dark areas is the Secchi reading. Low water clarity indicates a large number of particles suspended in the water. The particles may be inorganic, such as silt, or organic, from plankton or decaying matter. Low water clarity decreases the amount of sunlight available for photosynthesis. Suspended particles can interfere with filter feeding and respiration through gills.

    pH is a measure of how acid or basic the water is. pH is usually measured with papers or meters. A neutral pH is 7, with 1 being most acid and 14 being most basic. The pH scale is logarithmic, so the difference between two pH units represents a ten-fold difference in pH. The pH of normal rain water is around 5.6.

    Pollution sources are frequently referred to as "point" or "nonpoint" sources. Point sources have an identifiable origin, such as a waste pipeline from an industry or sewage treatment plant. Nonpoint pollution is carried into waterways primarily by rain water runoff from urban areas and the countryside.

      The question of what constitutes clean water is somewhat subjective--different standards apply to different uses: clean enough for sailing is not necessarily clean enough for swimming. Perception of pollution is generally associated with levels known or suspected to impact on the natural biota and biological processes. Distortions of reproductive processes, changes in species reproduction rates, abundance, distribution and diversity, and abnormal physiological responses all suggest water quality problems. These changes may, however, also be caused by natural factors or combinations of natural processes and man-made effects. This complicates the definition and setting of standards for water quality.

    Lessons in water quality testing need to be presented within the context of the setting. While readings do furnish hard data, their evaluation is usually subject to various interpretations.

Materials

• test kits and equipment as needed
• topographic and/or land use maps

Resources

Carolina Biological Supply Company.

1989-90. Biology/Science Materials. Catalog 60. Main Office and Laboratories, Burlington, NC 27215. (919) 584-0381.

Citizen's Program for the Chesapeake Bay, Inc.

Baybook-A Guide to Reducing Water Polution at Home. 6600 York Road, Baltimore, MD 21212 (301) 377-6270.

HACH Chemical,

P.O. Box 907, Ames, IA 50010. 1-800-247-3990.

Mitchell, M. and W. Stamp.

Field Manual for Water Quality Monitoring - an Environmental Education Program for Schools. 2050 Delaware, Ann Arbor, MI 48103. (313) 761-4854. ($6.50).

Terrell, C. and P. Perfetti.

Water Quality Indicators Guide: Surface Waters. United States Department of Agriculture, Soil Conservation Service, Publication SCS-TP-161, P.O. Box 2890, Washington, DC 20013. (202) 447-3839.

Save Our Streams (SOS), Izaak Walton League of America.

Offers workshops, information, references and a video for teachers. Call (703) 528-1818 for information, or write SOS, IWL, 1401 Wilson Blvd., Arlington, VA 22209.

Virginia Water Control Board.

(804) 367-0056.

Procedure

1. Prepare a water quality testing plan. Many of the tests described in "Habitat Hunt" can be used to determine certain types of water quality. Water quality testing usually involves the use of chemicals and chemical testing procedures. Before attempting these activities with students, teachers need to become competent with the specific kits they will be using, learn how to read and interpret results, and be prepared to implement appropriate safety procedures. Many types of test kits are available at different price ranges, sensitivities, and levels of user friendliness. Some school systems check with the science supervisor) already own water testing equipment. Kits by LaMotte and HACH are used by many teachers.

2. The organization Save Our Streams (see "Resources") offers a one-day training program for water quality analysis. Workshops are held periodically throughout Vir;inia. At an SOS workshop, participants learn how to conduct chemical tests and biological stream surveys, becoming qualified to adopt a stream and become part of SOS's citizen monitoring program, but are not obligated to do so.

3. The FieId Manual for Water Quality Monitoring offers practical advice on water quality tests. Sources of kits are included, as is a detailed plan which enables students to organize environmental data into an index figure which provides a convenient summary rating. Each park has a reference copy of this publication.

4. Select and pre-test kits and equipment to be sure everything performs as it should. Check the uses for which tests and equipment are intended. Not all work equally well in salt and fresh water.

5. Develop a data sheet for field work. The sample data sheets included with the activities "Habitat Hunt" and "Mainstream" cover some easily assessed pollution indicators.

6. Visit the park to become familiar with the aquatic environments suitable for testing. Select several test sites.

7. With the class, develop a concept map for "pollution" with at least 35 terms (see the activity "Researching the Bay" for concept development directions). Break the class into small groups and charge each with developing a definition of pollution, based on the concept developed. Share definitions and discuss what pollution Is (and is not). Put the best consensus definition on the board.

8. Ask Students to give their ideas about how they can tell if pollution is present, or if it is not. List their responses on the board. Lead this exercise towards recognizing the need to identify and quantify presence of individual pollutants.

9. Tell the class about the planned field trip. Familiarize them with the equipment and test kits and point out how they can be used to test for various types of water quality.

10. In class, practice doing all of the tests with appropriate safety procedures and equipment care. Use plain tap water, which you may enhance with a pinch of something (nontoxic) for which you will be testing (e.g., salt, vinegar, fertilizer).

11. Review the park map and plan logistical details. Organize items for taking measurements at each site.

12. If topographic or land use maps of the area are available, examine them for uses and features which could favorably or unfavorably affect water quality.

1. With the class, examine site maps to locate test sites. Proceed according to the Plan.

2. Take time to enjoy the natural features of the park. Water quality exists within the context of the environment. Hopefully, serious pollution will be hard to find in the park, but there will be opportunities to observe proper land use management and some nearly pristine areas. These values and benefits are among the reasons for pollution control and are important to environmental education, so enjoy.

1. On the return trip, have everybody on the left side of the bus look out the left windows, and record as many sightings of sources of pollution problems as possible. Students on the right side of the bus look out the right window and list examples of pollution control.

2. Back at school, compile the two lists, compare and discuss.
   • What negatively impacts the local environment?
   • What cancels out or compensates?
   • What improves?
   • What goes into the wafer? The air? The earth?
   • Which are point source problems? Nonpoint sources?

3. Compile data from the trip. Look for patterns and trends.

4. Based on the data, ask each student to draw his or her own tentative conclusions about the water quality of the test sites, in a written statement which includes justification for the conclusions and suggestions for how to verify them.

5. Students take into consideration all that they have seen, thought about and done for this activity and rate their local environment A, B, C, D or F. They then compose individual (or small group) letters to the mayor, city manager, commissioner of parks, or other official informing him or her of the grade and the reasons why it was awarded. (Whether or not to actually send some of these letters is discretionary.)

Extensions

Where in the Parks

When

Time Required at the Park:

Varies with number and complextiy of tests.

Time of Year:

Any time of year.

Variations

Younger students:   Use only a few tests and discuss very thoroughly.