SEPA United States Office of Water Environmental Protection 4601 Agency EPA 570/9-90-007 ApriM990 Science Demonstration Projects in Drinking Water (GradesK-12) ------- ------- i lit r od u ct ron This pamphlet includes a brief selection of science demon- stration projects related to drinking water for K-12 students. The projects are organized according to the following grade categories: primary (K-4); middle/junior high (5-8); and secondary (9-12). The divisions between grade categories are arbitrary. The projects are essentially applicable to all grade levels. By simply varying the vocabulary and expand- ing or contracting the background and discussion sections, each project can be made relevant to a specific grade level. The general areas covered by the demonstration projects include the chemical/physical aspects of water, contamina- tionand treatment of drinking water, distribution and supply of drinkingwater,andwaterconservation. While the projects presented are complete activities, teachers are encouraged to expand the projects to meet the needs and goals of their respective teaching situations. The demonstration projects included in this pamphlet are representative of many such projects developed by talented professionals in the science, engineering, and education communities. The projects have been reprinted in whole or in part with the permission of the appropriate publishers. Reference and/or credit information is included with each activity. In addition, a list of organizations that have devel- oped or are developing projects related to drinking water are included at the back of this document. ------- pir i m a ry The Never Ending Cycle of Water Background Water is very abundant on Earth. It circulates continu- ously between the air, the ground, and plants and animals. This constant circulation of water is known as the water cycle. Water is carried through air where it eventually condenses into small droplets which form clouds. From the clouds, water falls to the Earth in the form of rain or snow (precipitation). This water is absorbed into the ground or runs over the surface of the ground into rivers and lakes. Plants and animals use the water to live. Water then evaporates from soil, the leaves of plants, the lungs and skin of animals, and from the surface of puddles, streams, and lakes to the air. Woodland plants (e.g., violets, ferns, or mosses—gathered in backyards or available from nurseries) Water Light source or a sunny window gill Tight-fitting jar lid (or plastic wrap secured by rubber band or masking tape) Procedure 1) Place a one-inch layer of gravel on the bottom of the clear glass jar. Cover this layer with one of sphagnum or peat moss, followed by a layer of soil (see illustration at right). 2) Set woodland plant(s) into the soil mixture. 3) Water terrain lightly. 4) Evaporation Cover glass jar tightly with lid (if available) or with plastic wrap secured' by a rubber band or masking tape and place urtder or near a light source. 5) Observe the glass jar over several hours. Discussion Objective To demonstrate that water moves in a continuous cycle. Source: Science Activities for Children Suggested Activities DWhat collected on the sides of the glass jar? (con- densed moisture) 2) Where did the moisture on the sides of the glass jar come from? (evaporated water from plants) 3) What provided the en- ergy for the changes ob- served in the water's form? (the sun) Materials Large, wide-mouthed clear glass jar Gravel* Sphagnum or peat moss* Soil* Prior to conducting this activity, the teacher may wish to more fully demonstrate the processes of precipita- tion, evaporation, and condensation. In addition, a discussion or demonstration Of water in its three states (solid, liquid, gas) might also be useful. Samples of such experiments can be found in the source material noted below. '(available from hardware stores or nurseries) ------- primary Sources Activity #1 Background information adapted with permission from: Willard J. Jacobson and Abby B. Bergman. Science Activities for Children. (Englewood Cliffs, NJ: Prentice-Hall, Inc., 1983). p. 47. Activity adapted with permission from: Water Wizards. (Boston, MA: Massachusetts Water Resources Au- thority. 1983). pp. 2-4. "Water: We Can't Live Without It." National Wildlife Week Educators' Guide. (Washington, DC: National Wildlife Federation, March 18-24, 1984). p. 7. Source: National Wildlife Week Educators' Guide How People Get Their Water Background Nearly 80 percent of the Earth's surface is water, yet less than one percent can be used for drinking water. Water moves in a continuous cycle between the air, the ground, and plants and animals (see previous activity). Most water does not naturally exist in a pure form or in a form that is safe for people to drink. Consequently, water must be cleaned prior to consumption. Water utilities provide such treatment before water is sent through pipes to homes in the community. The demand for water by people varies. The availabil- ity of water also varies in different areas of the country. Consequent!)?-, utilities store extra water in spaces known as reservoirs'. Water is usually contained in reservoirs by a dam. Reservoirs help ensure that communities do not run out of water at any given time regardless of the communities' total water use. Objective To illustrate how a reservoir works. Materials Plastic box Spray bottle Pebbles Soil Sand Leaves Source: Water Wizards Procedure 1) Construct a model of a reservoir using a clean, clear plastic box (see illustration). Line the bottom of the box with small pebbles and then layer sand, soil, and leaves on top (sloping the material downward toward the edges f>f the box). 2) Carefully spray water on the four corners of the model until the soil mixture is saturated and the water has seeped through to the open area—the reservoir. Discussion 1) What are the sources of water for a reservoir? (precipitation in the form of rain and snow) 2) How does water get into a reservoir? (It seeps over and through the soil above the reservoir.) 3) What contains or holds water in a real reservoir? (dams) 4) What kind of treatment does water receive in a . reservoir? (natural filtration through leaves, grass, and soil; also some settling occurs in the reservoir) ------- p r i m ary Activity #2 Source Oblectlve Achvities adapted with permission from: To build a model of a water delivery system from source water Wizards. (Boston, MA: Massachusetts Water Resources Au- to user, thority, 1983). pp. 10-14. Materials Large piece of paper or cardboard Paper towel tubes Different sizes of pasta (linguini, spaghetti, manicotti) Glue Reservoir built in Activity #1 (optional) Procedure 1) Using the pasta and paper towel tubes, create a community pipe system (see illustration). Connect the "pipes" with glue and lay out on the large sheet of paper or cardboard. 2) Either use the reservoir constructed in the previous activity or draw one on the cardboard; also draw houses, schools, and other buildings that receive water from the delivery system. Discussion Students should consider how water gets from reser- voirs to distribution systems and to individual homes. (The circumference of pipes decreases as the distribu- tion system expands into the community. As water travels through a distribution system, it is continuously diverted down different pathways. These pathways lead to individual homes and businesses. The circum- ference of a pipe determines the quantity of water that can be contained in the pipe at any one time arid deter- mines, in part, the rate at which the water will travel through the pipe. As the distribution system expands to homes and businesses, the volume of water needed per home or business represents only a portion of the Background total volume leaving the treatment plant. Consequently, smaller pipes are needed in these areas of the distribu- tion system, whereas larger pipes are needed near the treatment plant. Water treatment plants generally pump water from the reservoir to holding or water towers. The water flows by gravitational force from the water tower and throughout the distribution system.) Source: Water Wizards Conserving Water for The Future Water is very valuable to us. We all need approximately 2 liters of water each day. We can live several weeks without food, but can only live several days without water. Water makes up our body's blood (which is 83% water), transports bodily wastes, and helps us digest our food. We get most of our body's daily requirement of water from food. But water is a limited resource, which means that there is only so much water on Earth available for use. In order for water to be available when needed, it must be conserved. ------- primary Objective To emphasize the need for water conservation. Materials One 12 ounce clear glass Water Question and answer sheet for each student Procedure __^ 1) Explain to the students that they are conducting an experiment that will test what it is like to not have a drink of water. Inform the students that they may not drink water the entire morning or afternoon preceding the conclusion of the activity. 2) Place the glass of water on a desk in the front of the classroom to visually remind students of water. 3) About one half-hour before lunch or the conclusion of the school day, provide students with the following questions to answer individually or as a group. Discussion 1) An average glass can hold 12 ounces of a liquid such as water. An average drip from a sink can waste 5 gallons of water per day or 240 ounces per day. How many glasses of water could be saved per day by fixing the leak? (Answer: 20) 2) An average bathtub uses 36 gallons of water while the average short shower uses only 25 gallons — a difference of 11 gallons or 1408 ounces. Approxi- mately how many glasses of water could be saved if a person took a short shower instead of a bath? (Answer: 117.3) 3) Do you think that some glasses of water could be saved if people filled dishwashers or washing machines with partial rather than full loads? (No. Most dishwashers and washers use the same amount of water, no matter if there is a full or partial load; in some models the cycle can be changed.) 4) What other conservation measures can you think of that would save glasses of water? (Answers will vary.) 5) How thirsty do you feel after not receiving water the entire morning or afternoon? (Answers will vary.) 6) How do you think you would feel if you could only have several ounces of water each day? (Very thirsty, sick, and eventually dead.) Suggested Activities Many other activities can teach students about water conservation, including "water audits" of personal, family, and even school-wide water use. A variation of the "Water Use Analysis" project presented later in this pamphlet may be appropriate to demonstrate how people use water differently. A discussion of how vari- ous cultures (e.g., desert versus city dwellers) value water as well as spend time and effort obtaining it might also be useful. Source ^_ Activity adapted with permission from: Water and Water Conservation Curriculum. (Aurora, CO: Aurora Utilities Department), p. 197. -5- ------- m id die How Substances are Measured in Water Background We often find references to parts per million, parts per billion, and even parts per trillion in our everyday reading and news reports. What do they mean? Most of us have difficulty imagining large numbers of objects. How many stars can you see in the clear night sky far away from the smog and lights of the city? What does it mean when we read that an insecticide has been found in our groundwater at a concentration of 5 parts per billion? Developing an understanding of extremely large and extremely small numbers is very difficult. Objective To visualize the concept of extremely small numbers. Material 1 bottle of food coloring 1 medicine dropper 1 white egg carton (6 or 12 eggs) or six small clear plastic cups 2 other containers to hold food coloring and water Procedure 1) Prior to conducting the activity, ask students to consider the following: a) What is the largest number of things you can clearly visualize in your mind? [Most of us can handle 5,10, perhaps even 20 if we use all of our fingers and toes.] b) Can you visualize a group of 100 people? [Many people think they can by describing a party or community meeting. If you try to visualize a group of 80 or 120 differently from the 100, it soon becomes apparent that our visualization is not that clear. The Rose Bowl full of people represents about 100,000. Trying to pick out just 1 individual in that crowd would be find- ing 1 in 100,000.] c) Food coloring from the store is usually a 10% solution. What does 10% mean? [It means 10 parts (by weight) of solid food coloring dye is dissolved in 100 parts (by weight) of solution. For example, 10 grams of dye dissolved in 90 grams of water make a total of 100 grams of 10% solution.] 2) Put some food coloring (5 or 6 drops from the bottle) into one small container and some tap water into the other. 3) Use the medicine dropper ,to place one drop of 10 percent food coloring (as it comes from the store) into the first container. [Since 10% means 10 parts of food coloring per 100 parts of solution, it is the same as 1 part food coloring in 10 parts of solution.] 4) Use the medicine dropper to add 9 drops of water to the first container. Stir well. What is the concen- tration of the food coloring? [You have 1 drop of the original food coloring in 10 drops of the new solu- tion. Thus the concentration of the new solution is 1/10 of the original. The original was 1 part in 10, so the concentration of the food coloring is now 1 / 10 of 1 part in 10. This is 1 part in 10 x 10, or 1 part of food coloring in 100 parts of solution.] 5) Use the medicine dropper to transfer 1 drop of solution to the next container. Add 9 drops of water. Mix. You have again changed the concentra- tion by a factor of one-tenth. What is the food coloring concentration in this container? [1 /10 of 1 part in 100 is 1 part in 10 x 100, or 1 part in 1000 parts of solution.] 6) Transfer one drop of the 1 part in 1000 parts of solution into the next container. Add 9 drops of water. Mix. What is the concentration? [1 part in 10,000 parts of solution.] 7) Continue to dilute 1 drop of each solution by add- ing water as before to obtain 1 part in 100,000 and then 1 part in 1,000,000. Your final solution is one part per million. Discussion 1) In which cavity do you first observe no visual evidence that food coloring is present? [This gener- ally occurs in the final container, which is 1 ppm of food coloring.] 2) Since you cannot see any color present, how do you know there is indeed food coloring present? 3) Can you think of an experiment that you could do to prove there is food coloring present in each cup? Do it. ------- middle 4) Which is more concentrated, one part per million Materials or 200 parts per billion? [A billion is a thousand million. Therefore, 1 ppm is 1000 ppb. 1 ppm is more concentrated than 200 ppb.] Sources Activity adapted with permission from: Chemicals in Society Participant's Guide. (Berkeley, CA: Chemical EducationforPublicUnderstandingProgram,UniversityofCalifor- The story begins: nia at Berkeley, 1989). pp. 5-6. A schoolyard or large room with a water source Two 122 L (32 gallon) trash cans Empty milk jugs and/or buckets (as many as possible) 100 L of water A watch or clock with a second hand A meter stick (optional) Conserving the Nation's Water Resources Background People require an average of 2 L of water per day to sustain life. However, the average American uses about 100 times more water than this every day at home. An average family of four in the United States might use about 900 L of water per day for the purposes identified in the table below. Approximate daily water use by a family of four in the U.S. Use Drinking and cooking Dishwasher (3 loads per day) Toilet (16 flushes per day) Bathing (4 baths or showers per day) Laundering clothes Watering houseplants Rinsing garbage into disposal unit Total daily use: Liters per Day 30 57 363 303 130 4 13 900 L (A reminder: 1 gallon = 3.8 L; 26.3 gallons daily water use of 900 L is equal to about 237 gallons.) Source: Earth: The Water Planet Objective To provide a real-life model of how much water a family typically uses on a daily basis; to allow participants to experience firsthand how much effort is required to transport water; and to illustrate that when people desire, they can sharply reduce their water usage. One cold January, the Smith family rent a house in the mountains for a ski vacation, the house, though old, has all the comforts of home — three bathrooms, a complete laundry room, dishwasher, and garbage dis- posal, plus a newly installed solar hot water heating system. Unfortunately, the weather gets so cold one night that a water main in town breaks, and the Smiths find out that the house will have no water service from the local utility for the entire week. What should they do — go back home or try to find another water supply? Mr. Smith learns from a neighbor that there is an unfro- zen spring 100 m from the house that could still be used for drinking water. Mrs. Smith, who is a mechanical engineer, discovers that if the municipal water line coming into the house were shut off, the water in the storage tank for the solar water heater could be routed directly into the plumbing system. The water system in the house will work as long as the storage tank is kept filled with water from the spring. Mr. and Mrs. Smith discuss the situation with their two children Alice (14) and Sam (12). The family decides to form a "family bucket brigade" from the spring to the house, fill the storage tank each day, and continue their vacation. The storage tank can hold about 900 L of water. Procedure 1) Place the two trash cans 100 m apart (measure with a meter stick or the distance is equal to approxi- mately 150 paces for an average size adult). 2) Place 100 L of water in one of the trash cans. This can will represent the spring. 3) Select four students to represent the Smith family; equip each person with as many buckets and milk jugs as he/she can carry; and have students trans- fer the 100 L of water from the spring to the house (the house being represented by the second trash can located 100 m away). — 7 — ------- middle 4) Have students record the time when the Smith family begins and finishes carrying the first 100 L of water. Students should then determine the total time that was required for the Smith family to transfer all of the water. 5) The Smiths may feel a little tired after transferring the 100 L of water. Thus far, they have only earned 11 percent of the water required to fill the tank. They still have 800 L to go. To save water (since this is role playing), have the Smiths bring the same 100 L back from the house to the spring rather than getting additional water out of the faucet being used. 6) The Smiths should continue carrying the water back and forth until the 100 L of water has changed cans a total of nine times, and the Smiths have carried the equivalent of 900 L of water 100 m to the house. 7) Have students record the time when the Smiths finish moving the entire 900 L of water from the spring to the house. Ask students the total amount of time (probably will be about 30 minutes) that was required to move the 900 L of water. The story continues: After carrying all of the water, the Smiths are too tired to ski very much. They come home early, have spaghetti for lunch, wash the dishes, and launder their bucket brigade clothes (which got muddy at the spring). After eating dinner, washing more dishes and clothes, water- ing the houseplants, and taking long, hot showers, they go to bed. any leaking plumbing fixtures,, taking quick showers, not flushing toilets after every use, reducing the amount of water required for toilet flushing, etc.) Source _____ Activity adapted with permission from: Jack E. Gartrell, Jr., Jane Crowder, and Jeffrey C. Callister. Earth: The Water Planaet. (Washington, DC: The National Science Teachers Association, 1989). pages 85-89. It is snowing too hard the next day to ski, so the Smiths stay in the house all day. When Mr. Smith tries to start Objective the dishwasher after lunch, he discovers that the family is out of water! Sam and Alice groan and say that they would rather be grounded until they are 21 than carry 900 L of water to the house every day. They point out that they haven't even been in the house a full 24 hours since previously carrying the water. How Water Is Cleaned Background Water in lakes, rivers, and swamps often contains impurities that make it look and smell bad. The water may also contain bacteria and other microbiological organisms that can cause disease. Consequently, water from surface sources must be "cleaned" before it can be consumed by people. Water treatment plants typically clean water by taking it through the following proc- esses: 1) aeration; 2) coagulation; 3) sedimentation; 4) filtration; and 5) disinfection. Demonstration projects for the first four processes are included below. To demonstrate the procedures that municipal water plants use to purify water for drinking. Materials Discussion Have students identify and defend water conservation measures. What steps could the Smiths have taken to conserve water and save their ski vacation? (Some conservation measures include washing clothes less frequently, running the dishwasher once per day, fixing 5 L of "swamp water" (or add 2 1/2 cups of dirt or mud to 5 L of water) One 2 L plastic soft drink bottle with its cap (or cork that fits tightly into the neck of the bottle) Two 2 L plastic soft drink bottles — one bottle with the top removed and one bottle with the bottom removed -8- ------- middle One 1.5 L (or larger) beaker or another soft drink bottle bottom 20 g of alum (potassium aluminum sulfate — approximately 2 tablespoons; available at a pharmacy) Fine sand (about 800 ml in volume) Coarse sand (about 800 ml in volume) Small pebbles (about 400 ml in volume) Fine land Beaker Source: Earth; The Water Planet A large (500 ml or larger) beaker or jar A small (approximately 5 cmx 5 cm) piece of flexible nylon screen A tablespoon A rubber band A clock with a second hand or a stopwatch Procedure 1) Pour about 1.5 L of "swamp water" into a 2 L bottle. Have students describe the appearance and smell of the water. 2) Aeration is the addition of air to water. It allows gases trapped in the water to escape and adds oxygen to the water. Place the cap on the bottle and shake the water vigorously for 30 seconds. Con- tinue the aeration process by pouring the water into either one of the cut-off bottles, then pouring the water back and forth between the cut-off bottles 10 times. Ask students to describe any changes they observe. Pour the aerated water into a bottle with its top cut off. 3) Coagulation is the process by which dirt and other suspended solid particles are chemically "stuck to- gether" into floe so that they can be removed from water. With the tablespoon, add 20 g of alum crystals fco the swamp water. Slowly stir the mixture for 5 minutes. 4) Sedimentation is the process that occurs when . gravity pulls the particles of floe (clumps of alum and sediment) to the bottom of the cylinder. Allow the water to stand undisturbed in the cylinder. Ask 5) students to observe the water at 5 minute intervals for a total of 20 minutes and write their observa- tions with respect to changes in the water's appearance. Construct a filter from the bottle with its bottom cut off as follows (see illustration at left): a) Attach the nylon screen to the outside neck of the bottle with a rubber band. Turn the bottle upside down and pour a layer of pebbles into the bottle — the screen will prevent the pebbles from falling out of the neck of the bottle. b) Pour the course sand on top of the pebbles. c) Pour the fine sand on-top of the course sand. d) Clean the filter by slowly and carefully pouring through 5 L (or more) of clean tap water. Try not to disturb the top layer of sand as you pour the water. 6) Filtration through a sand and pebble filter re- moves most of the impurities remaining in water after coagulation and sedimentation have taken place. After a large amount of sediment has settled on the bottom of the bottle of swamp water, care- fully — without disturbing the sediment — pour the top two-thirds of the swamp water through the filter. Collect the filtered water in the beaker. Pour the remaining (one-third bottle) of swamp water into the collection bucket. Compare the treated and the untreated water. Ask students whether treatment has changed the appearance and smell of the water. [Inform students that a water treatment plant would as a final step disinfect the water (e.g., would add a disinfectant such as chlorine gas) to kill any remaining disease-causing organisms prior to distributing the water to homes. Therefore, the demonstration water is not safe to drink.] Discussion __ 1) What was the appearance of the swamp water? (Answers will vary, depending on the water sou rce used. Water from some sources may be smelly and/or muddy.) 2) Does aeration change the appearance or smell of water? (If the original water sample was smelly, t he water should have less odor after aeration. Pouring the water back and forth allows some of the foul- smelling gases trapped to escape to the air of the room. Students may have observed small bubbles -9- ------- middle Source suspended in the water and attached to the sides of Suggested Activities the cylinder.) 3) How did the sedimentation process effect the water's appearance? Did the appearance of the water vary at each 5 minute interval? (The rate of sedimentation depends on the water being used and the size of alum crystals added. Large particles will settle almost as soon as stirring stops. Even if the water contains very fine clay particles, visible clumps of floe should form and begin to settle out by the end of the 20-minute observation period.) 4) How does the treated water (following filtration) differ from the untreated swamp water? (After filtration, the treated swamp water should look much clearer than the untreated water. It probably will not be as clear as tap water, but the decrease in the amount of material suspended in the water should be quite obvious. The treated sample should have very little odor when compared to the starting supply of swamp water.) A field trip to a local water treatment plant. Have the State or a certified testing laboratory conduct analyses of the students' treated and untreated water for various contaminants. Activity adapted with permission from: Jack E. Garirell, Jr., Jane Crowder, and Jeffrey C. Callister. Earth: The Water Planet (Washington, DC: The National Science Teachers Asso- ciation, 1989). pp. 97-101. How a water treatment system works. ^•Chlorination Filtered f Water Storage Source: The Official Captain Hydro Water Conservation Workbook ------- Secondary Concentrations of Chemical Pollutants in Water Background Concentrations of chemical pollutants in water are fre- quently expressed in units of "parts per million" (ppm) or "parts per billion" (ppb). For example, chemical fertilizers contain nitrates, a chemical that can be dan- gerous to pregnant women even in quantities as small as 10 parts per million. Trichloroethylene (TCE), a common industrial solvent, is more dangerous than nitrates and when present in drinking water in quanti- ties as small as 5 parts per million can cause a higher than normal incidence of cancer among people who drink the water regularly. Objective To demonstrate the concept of ppm and ppb as these units are used to explain chemical contaminant concen- trations in water; to explain how chemicals may be present in very small amounts in water such that they cannot of ten be detected by sight, taste, or smell; though, still possibly posing as a threat to human health. Materials Solid coffee stirrers or tooth picks Clean water for rinsing the dropper Medicine dropper Red food coloring (for "contamination") Set of 9 clear containers Clean water for diluting White paper Procedure 1) Line up the containers side-by-side and place a piece of white paper under each one. From left to right, number the containers 1 to 9. 2) Place 10 drops of food coloring into container #1 (food dye is already diluted 1:10). 3) Place one drop of food coloring into container #2. 4) Add 9 drops of clean water to container #2 and stir the solution. Rinse the dropper. 5) Use the medicine dropper to transfer 1 drop of the solution from container #2 into container #3. Add 9 drops of clean water to container #3 and stir the solution. Rinse the dropper. 6) Transfer 1 drop of the solution from container #3 to container #4. Add 9 drops of clean water to con- tainer #4 and stir the solution. Rinse the dropper. 7) Continue the same process until all 9 containers contain successively more dilute solutions. 8) Complete the discussion questions below. Discussion 1) The food coloring in container #1 is a food coloring solution which is one part colorant per 10 parts liq- uid. What is the concentration for each of the successive dilutions? (Have students use the table below; each dilution decreases by a factor of 10— 1/10, MOO, 1/1000, etc.) 2) What is the concentration of the solution when the diluted solution first appeared colorless? (Usually occurs in container #6,1/1,000,000 or 1 ppm.) 3) Do you think there is any of the colored solution present in the diluted solution even though it is colorless? Explain. (Yes. The solution is still pres- ent but has been broken down into such small particles that it cannot be seen.) 4) What would remain in the containers if all the water were removed? (Residue from the food coloring.) Suggested Activities 1) Allow the water in the containers to evaporate and have students record their observations on what remains in the containers. 2) Discuss chemical contamination of drinking wa ter. Use the list of maximum contaminant levels (MCLs) on the following page for some toxic or carcino- genic chemicals in drinking water (as regulated by Container No. Concentration 1 1/10 2 V 3 V 4 V 5 V 6 V 7 V 8 V 9 V Source: Water Wisdom ------- secondary the U.S. Environmental Protection Agency). These contaminated aquifers are quite costly. MCLs represent the maximum amount of a chemi- : cal that can occur in drinking water without the Objective water being dangerous to human health. [Note: Some of the MCLs listed are subject to revision by EPA shortly.] SubsUnca Concentration (ppb) Substance Concentration (ppb) Arsenic 50 Nitrate 10,000 Barium 1.000 Selenium Cadmium 10 Endrin Mercury 2 2,4-D (herbicide) To illustrate how water flows through an aquifer, how ground water can become contaminated, and how diffi- cult it is to clean up contamination. 10 0.2 100 Materials Note: The above substances do not represent a complete list of regulated drinking water contaminants. 3) 4) Explain the relationship between ppm and ppb and the conversion of these units to milligrams and micrograms per liter. For example: 1 ppm = 1000 ppb; 1 ppm = 1 mg/1; and 1 ppb = 1 ug/1. 6"x8" disposable aluminum cake pans or plastic boxes 2 Ibs. non-water soluble plasticine modeling clay or floral clay 3-4 Ibs. white aquarium gravel Pea gravel Small drinking straw Food coloring 6 oz. paper cups (no larger) Water Relate the previous conversions to the drinking Procedure water regulations. [MCLs are established in milli- grams per liter (mg/1)]. Convert the numbers in the above chart from ppb to mg/1. 1) Source Activity adapted with permission from: Water Wisdom. (Boston, MA: Massachusetts Water Resources Authority, 1989). Exercise #16. Contamination of an Aquifer Background • Many communities obtain their drinking water from underground sources called aquifers. Water suppliers or utility officials drill wells through soil and rock into aquifers for the groundwater contained therein. Unfor- tunately, the groundwater can become contaminated by harmful chemicals that percolate down through soil androckinto theaquifer—and eventually into the well. Groundwater contamination by chemicals is caused mainly by industrial runoff and/or improper manage- ment of chemicals, including improper disposal of household chemicals such as lawn care products and cleaners. Such contamination can pose a significant threat to human health. The measures that must be taken by utilities to either protect or clean up Set up a model aquifer as shown in the diagram below. If a disposable aluminum baking pan is used, make a small hole in one end and insert a section of a drinking straw to serve as the drain spout. Seal the hole around the straw with glue or clay. In addition, seal the clay layers of the model against the side of the container. 2) Place 10 drops of food coloring on the surface of the model near the highest end. This dye represents chemicals or others pollutants that have been spilled on the ground. 3) Slowly pour one 6-ounce cup of tap water on the aquarium gravel areas as shown in the diagram. Collect the water as it runs out of the straw. Repeat this process starting with 6 ounces of tap water and continue the flushing process until all the food coloring is washed out and the discharge water is Add food coloring and flus|i water here. spoul ]'t-a Cra Aquurlum Crave! Clav I.:)} or Source: Water Wisdom ------- seco n d a ry clear. (Collecting the water in white paper cups or in test tubes held up against a white background will enable students to detect faint coloration.) 4) Record the number of flushings required until an output with no visible color is reached (may re- quire up to ten flushes). [Note: 6 ounces of water in this model equals about 1 inch of rain.] Discussion Before the Activity Source Activity adapted with permission from: Water Wisdom. (Boston, MA: Massachusetts Water Resources Authority, 1989). Exercise #11. Water Use Analysis D Where does the water go that falls on the surface of Backg rou nd an aquifer? How about any chemicals or other pollutants that fall on the ground? (Some chemi- cals/pollutants are washed away by rain, some become attached to rocks and soil, and some end up in the groundwater.) 2) What things might influence the time needed to flush an aquifer clean? (Depth and volume of the water table, type of underlying rock and soil, nature and concentration of the pollutant.) After the Activity 1) After flushing, is the water in the model aquifer completely free of food coloring? (Probably not; trace amounts may remain.) 2) Estimate how much contamination remains in the model aquifer. (Refer to previous exercise.) 3) What keeps the chemical contamination in the demonstration from reaching the lower levels of the model aquifer? (The clay layer.) 4) What are some of the problems that might result from a major chemical spill near a watershed area? (Answers will vary.) 5) What steps could be taken to avoid damage to an aquifer? (Answers will vary.) Suggested Activities 1) Discuss the need for proper disposal of hazardous industrial wastes and harmful household chemi- cals, including used motor oil. 2) Simulate nitrate pollution due to fertilizer runoff. Pollute the aquifer with a small amount of soluble nitrate and perform a standard nitrate test after each successive flushing (be sure to wear safety glasses). Although household and other municipal water use accounts for only about 9 percent of total water use in the United States, delivering adequate quantities of water of sufficient quality for this purpose is becoming increasingly expensive for individuals and communi- ties. It would, therefore, be useful for individuals and communities to employ conservation measures when using water. Objective To demonstrate the quantities of water that an average family uses on a daily basis. Procedure 1) Ask students to keep a diary of water use in their homes for three days. Students should make a chart similar to the one listed on the following page, adding any appropriate activities that are not listed. 2) Ask students to review the table of average water volumes required for typical activities and then answer the following questions using the data from their three-day water use diary. a) Estimate the total amount of water your family used in the three days. Give your answer in liters. b) On average, how much water did each family member use during the three days? Give your answer in liters per person per three days. c) On average, how much water was used per family member each day? Give your answer in liters per person per day. d) Compare the daily volume of water used per person in your household (Answer c) to the average daily water volume used per person in the United States (325 L per person per day). What reasons can you offer to explain any differences? ------- secondary Discussion Source Ask students to identify ways in which their families couldreducetheirwaterconsumpHon. Activity adapted with permission from: Average water volumes required for typical activities Use Volume of Water (in liters and gallons) Tub bath Shower (per min) Washing machine Low setting High setting Dish washing By hand By machine Toilet flushing 130L (35 gal) 19 L (5 gal) 72 L (19 gal) 170L (45 gal) 40 L (10 gal) 46 L (12 gal) 11 L (3 gal) Reprinted with permission from diemutry in Otc Comntimi(y. C1988, American Chemical Sodety _ Data Table Number of persons in family Number of baths Number of showers Length of each in minutes Number of washing machine loads Low setting High setting Dish washing Number of times by hand Number of times by dishwasher Number of toilet flushes Other uses and number of each: Cooking Drinking Making juice and coffee Days 123 Reprinted with permission from Chemistry m the Community. 01988, American Chemical Sodety ------- notes -15- ------- references The organizations below have developed or are in the process of developing science projects related to drinking water for K-12 students. This list is not intended to be inclusive. American Chemical Society (ACS), 1155 16th St., NW, Washington, DC 20036, (202) 872^600 [Chemistry in the Community— Secondary 9-12]. American Water Works Association (AWWA), 6666 West Quincy Ave., Denver, CO 80235, (303) 794-7711 [Primary K-4; Middle/ Junior 5-9]. Chemical Education for Public Understanding Program (CEPUP), Lawrence Hall of Science, University of California, Berkeley, CA 94720, (415) 642-8718 [Middle/Junior 5-8]. City of Aurora, Utilities Department, 1470 South Havana St., Aurora, CO 80012, (303) 695-7381 [Middle/Junior 5-8]. City of Seattle, 710 2nd Ave., Dexter-Horton Building, Seattle, WA 98104, (206) 684-5883 [Middle/Junior 5-8]. East Bay Municipal Utility District (EBMUD), P.O. Box 24055, Oakland, C A 94623, (415) 835-3000 [Primary K-4; Middle/Junior 5- 81. Massachusetts Water Resources Authority, Charlestown Navy Yard, 100 First Ave., Boston, MA 02129, (617) 242-6000 [Upper Primary 3-4; Middle/Junior 7-8; Secondary 9-12]. National Science Teachers Association (NSTA), 1742 Connecticut Ave., NW, Washington, DC 20009, (202) 328-5800 [Middle/ Junior 5-8]. National WildlifeFederation (NWF), 140016th St., NW, Washington, DC 20036, (202) 797-6800 [Primary K-4; other citizen oriented material]. South Central Connecticut Regional Water Authority, 90 Sargent Dr., New Haven, CT 06511, (203) 624-6671 [Primary and Middle K-6]. s u p p I i e r s The following are some firms that provide general supplies and equipment for all areas of science teaching and also specific items for chemistry teaching. Addison-Wesley Publishing Co., 2725 Sand Hill Rd., Menlo Park, CA 94025, [800-447-2226]. Aldrich Chemical Co., P.O. Box 355, Milwaukee, WI53201, (414) 273-3850, [800-558-9160]. Carolina Biological Supply Co., 2700 York Rd., Burlington, NC 27215, (919) 584-0381 [800-621-4769]. Central Scientific Co., 11222 Melrose Ave., Franklin Park, IL 60131-1364, (312) 451-0150. Connecticut Valley Biological Supply Co., Inc., 82 Valley Rd., Southampton, MA 01073, (413) 527-4030 [800-628-7748]. Edmund Scientific Co., 101 East Gloucester Pike, Barrington, NJ 08007, (609) 573-6250 [800-222-0224]. Hsher Scientific Co., Educational Materials Division, 4901 West LeMoyne St., Chicago, IL 60651, (312) 378-7770 [800-621-4769]. Flinn Scientific Inc., P.O. Box231,917 West Wilson St., Batavia, IL 60510, (312) 879-6900. [The Flinn Chemical Catalog also serves as a reference manual on chemical safety, storage, and disposal.] Frcy Scientific Co., 905 Hickory Lane, Mansfield, OH 44905, [800-225-FREY]. Hach Chemical Co., Box 907, Ames, IA 50010. [Test kits for environmental studies.] Lab-Aids, Inc., 249 Trade Zone Dr., Ronkonkoma, NY 11779, (516) 737-1133. Lab Safety Supply, 3430 Palme#Dr., P.O. Box 1368, Janesville, WI 53547-1368, (608) 754-2345. [Specialize in safety equipment and supplies.] LaMotte Chemical Products, Box 329, Chestertown, MD 21620, (301) 778-3100. [Test kits for environmental studies.] Nalgene Labware Division, P.O. Box 367, Rochester, NY 14602. [Specialize in transparent and translucent plastic laboratory equipment.] NASCO, 901 Janesville Ave., Ft. Atkinson, WI 53538, (414) 563-2446 [800-558-9595]. Ohaus Scale Corp., 29 Hanover Rd., Florham Park, NJ 07932, (201) 377-9000 [800-672-7722]. Sargent-WelchSdent-ncCo.,"7300 North Linder, Skokie, IL 60077, (312) 677-0600. Science Kit and Boreal Laboratories, Inc., 777 East Park Dr., Tonawanda, NY 14150-6782, (716) 874-6020 [800-828-7777]. Wards Natural Science Establishment, Inc., 5100 West Henrietta Rd., P.O. Box 92912, Rochester, NY 14692, (716) 359-2502. (The majority of suppliers listed above appeared in Chemistry in the Community, American Chemical Society. (Dubuque, 1 A: Kendall / Hunt Publishing Co., 1988).] ------- ------- EPA United Stales Environmental Protection Agency (4601) Washington, DC 20460 Official Business Penalty for Private Use $300 ------- |