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Water Quality and Pollution
 

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    Water Quality and Pollution Water Quality and Pollution Document Transcript

    • Water Quality and Pollution in New York Adaptable for Various Ages Includes Topics for Standards: Grade 4: Units 1, 3, 4 Grade 5: Unit 4 Grade 6: Unit 4 Grade 8: Unit 2 Compiled by Katie Priebe Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page One Chemistry of the Hudson River EstuaryWhy We Love Our Estuary: The Estuary houses a multitude of ecosystems, species, and human uses.It acts in a surprising number of ways. Our Estuary can act as a... * Sponge! As excess rains floods rivers and streams, wetlands absorb water that may otherwise flood normally dry land. * Hotel! Birds migrating across North America stop in marshes and estuaries to eat and rest before continuing on their journeys. * Mixer! Mixing of nutrients and oxygen take place here. An Estuary is a place for nutrient-rich freshwater from a river or stream to mix with salt-water from the ocean. As plants photosynthesize, oxygen is added to the mix. Fishes and shellfish take advantage of this life-giving soup. * Cradle! Plenty of food and places to hide from predators provides a protective haven for young animals. Saltmarsh grass and other vegetation provide cover. * Strainer! The grasses of an Estuary act like a sieve. Soil, branches, leaves and even pollution that have washed in the Estuary can be trapped by estuarine plants and strained out. This allows clearer water to flow on downstream and into the Estuary. * Cereal! Plants absorb nutrients and help cycle them through the food web. Decaying grasses supply a nutritious food for animals and fertilizer for other plant life.Measuring Water Quality Water chemistry is a controlling factor in the amount and types of fish, macroinvertebratesand even plants that will be able to thrive and exist in a given section of the river.Water chemistry is impacted by adjacent land uses, tides and currents, time of day, time of year,type of substrate and interactions between these variables as well as other more subtle factors.These factors include: temperature nitrates salinity pH phosphates turbidity ammonia dissolved oxygen tides alkalinity coliform bacteria current Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page TwoTemperature Temperature is an important indicator of water quality and the health of plants and animals in the water.Water temperature affects the rate of the rivers processes, both biological and chemical; from photosynthesis ofestuarine plants to the metabolic rates of organisms. Many organisms cannot survive above or below certaintemperatures. For example, each species of phytoplankton has an optimal temperature for survival. Shifts in tem-perature cause variations in phytoplankton abundance and species composition. Growth rates of estuarine plantsand cold-blooded animals generally increase with temperature, up to the thermal optimum. Dissolved oxygen iscritical for the survival of aquatic organisms that use it in respiration (just as we do). As water temperatureincreases, the solubility of oxygen decreases. Additionally, many pollutants and nutrients in the water behavedifferently at different temperatures. Many factors affect water temperature: * air temperature * groundwater inflows * river depth * season * amount of riverbank vegetation, especially trees * turbidity or cloudiness of the water * season * wind * people - can you think of how? Thermal pollution is often caused by people. Stormwater running off warmed urban surfaces, such asstreets and parking lots, which are often constructed of black, heat absorbing asphalt, can increase temperature incooler streams. Cutting down trees that shade a river will expose it to sunlight and also increase temperature.Turbidity in water, which could be caused by man made machines like barges, increases the amount of heat absorbedfrom sunlight. Measurement of temperature change can help detect sources of thermal pollution and suggest thesize of habitat for organisms that are more sensitive to temperature variation. These parameters are important indicators of habitat quality for numerous estuarine species and to determine health criteria and human uses. One way to measure the temperature to use a thermometer. Make sure the thermometer is always set at zero to give an accurate measurement.pH The pH of a solution is a measure of its acidity. It is defined as the negative logarithm of the hydrogen ionconcentration in solution, therefore a change in one pH unit represents a tenfold change in the concentration ofhydrogen ions. The pH scale ranges from 0 to 14. Distilled water is neutral and has a pH of 7. Solutions with a pHless than 7 are acidic, and those with pH greater than 7 are basic (alkaline). Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page Three Many fish and invertebrates are sensitive to either very basic readings (above 8.6) or very acidic readings(below 6.5). The optimal range for most marine life is between 6.5 and 8.6, with the lower Hudson River and theEast River tending to be a bit on the basic side due to its bedrock geology and the presence of seawater, whichtends to be about 8.0. The pH in an estuary will tend to remain fairly constant because the chemical componentsof seawater resist large changes in pH; dissolved carbonate minerals present in seawater tend to minimize or“buffer” pH changes by reacting with the ions that change pH. Biological activity, however, may significantly alter pH levels in an estuary. The process of photosynthesisremoves carbon dioxide (CO2) from the water. Since CO2 becomes carbonic acid when dissolved, the removalof CO2 results in a higher pH (i.e., reduced acidity). An example occurs when algal populations increase duringthe growing season and pH levels tend to rise. During large increases in the populations of planktonic algae (or“blooms”), pH levels may increase significantly. Methods of measuring pH include pH paper or a pH meter.Nitrogen Nitrogen occurs in natural waters as nitrate (NO3), nitrite (NO2), ammonia (NH3), and organically boundnitrogen. As aquatic plants and animals die, bacteria break down large protein molecules containing nitrogen intoammonia. Ammonia is then oxidized by specialized bacteria to form nitrites and nitrates.Ammonia Ammonia changes between two forms, depending on the pH and temperature of the water. Concentrationsof ammonia as low as 0.01 ppm already show negative effects on fish, while 0.1ppm can be deadly to some species.Nitrates Toxic ammonia is filtered into nitrite by bacteria which act as natural filters in the water. Nitrite is onlyslightly less toxic than ammonia to aquatic life, however it is quickly transformed into nitrate, which is harmless tofish, by other bacteria in nature. Nitrates (NO3-), measured in mg/L, are another form of nitrogen. Nitrates and nitrites are essential nutrients used by plants and animals for maintenance and growth (buildingprotein) and normally occur in small levels of <1 mg/L. Excess nitrates can trigger sharp increases in plant growthcausing problems for aquatic animals, and if high enough, for humans as well. In saltwater ecosystems nitrate nitrogenis the generally the nutrient in shortest supply (called the limiting nutrient) - although it can fluctuate.Nitrates and You The levels of nitrate can affect the ecology of the water body as well as affect how humans use the water.Scientists monitor nitrate in drinking water for public safety. Scientists and resource managers also monitor watersites for high nitrate levels that might lead to eutrophication of the water body. High levels of nitrate may eventuallylead to low levels of oxygen, which may then lead to harm to aquatic animals such as fish kills. Scientists commonlylook at atmosphere, land cover, soil data, and human activities to find relationships with seasonal nitrate amounts. Forms of nitrogen occur naturally as a part of plant and animal growth and decay, and are abundant in sewage.The decomposition of nitrogenous materials in sewage generates ammonia, as does the hydrolysis of urea in urine.High concentrations of ammonia in flowing streams indicates recent pollution. Excessive amounts of nitrates cancause a reduction in salmon hatching success and a reduction in growth rate among other things. The criteria forammonia is dependent on other factors in the stream - such as pH and temperature. A way to measure nitrates is to use a test kit and observe the water’s color change. Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page FourPhosphates Phosphates are nutrients that specifically act as fertilizers for plants. They are often found in industrial andhousehold fertilizers and when in the river, they cause a great increase in plant growth, which results in a loss oflight and oxygen for the animals in the river. Phosphates (PO4 -3), measured in mg/L, are a second type of plantnutrient that occurs naturally in some rocks, soil & animal waste. Organic phosphate, found in plants and animals, is bound (unable to be used), but inorganic (orthophosphate)is what is available and required by plants. Excess phosphates can be the result of detergents, effluent or feedlotrun off. In freshwater ecosystems phosphorous is the nutrient in shortest supply. Simple eld test kits or laboratory analytical equipment are some ways to monitor phosphates.Dissolved Oxygen Oxygen is essential for most plants and animals. Although animals underwater do not “breathe” like we do,they intake oxygen into their body for survival. Dissolved Oxygen (DO) is a measure of the concentration ofoxygen gas dissolved in water and available for aquatic life. Remember, a wide variety of organisms (biodiversity) helpspreserve stability in an ecological system. Oxygen enters the Hudson and East Rivers primarily through diffusionfrom the atmosphere, turbulence caused by tides, winds and currents, and plant photosynthesis. When animals and plants take up oxygen from the water and produce carbon dioxide they undergo aprocess called respiration. Respiration is constant, as opposed to photosynthetic production of oxygen by plants,which only happens during daylight. Bacteria and fungi decompose organic matter produced in the estuary ordelivered from the uplands by streamflow and runoff, affecting DO levels in an estuary as they consume oxygen. The ratio of the dissolved oxygen content (ppm) to the potential capacity (ppm) gives the percent saturation,which is an indicator of water quality. Healthy ranges of DO are 5-11 mg/L (or ppm), and the most oxygen that canbe dissolved in water is about 14 mg/L. A reduction in oxygen levels could be caused by various situations, such asstorms leading to combined sewage overflows dumping sewage into the river or excessive nutrients causing algaeblooms which die and consume oxygen to decompose. Oxygen levels can drop to what is called hypoxic rates, orlevels that would be considered unhealthy for marine organisms. Anoxic rates are levels where there is no oxygenavailable for marine organisms. Concerns for hypoxia and anoxia are greatest in the summer months when the riverwater is warmest (therefore holding less oxygen), and the water tends to move through the system more slowlydue to a reduction in storms and winds.Levels of DO* Different living things require different levels of DO to exist and thrive. Certain fish such as trout require DO levels of at least 6 mg/L. Macroinvertebrates such as stonefly, caddisfly and mayfly also need higher levels of DO. In contrast, catfish- and carp-dominated aquatic systems prosper using lower levels.* Excess algae and suspended sediment can actually reduce levels of oxygen.* Turbulence can increase levels of DO by mixing oxygen from the air with the water.* When collecting a DO sample it is very important to record the water temperature because warm water holds less DO than cold water.* Daytime rates of DO can increase due to plant photosynthesis, so it is important to record the time of day when completing DO measurements. Dissolved oxygen levels in an estuary also vary seasonally; lowest levels occur during the late summer months when temperatures climb to its highest annual levels. A possibility for measuring dissolved oxygen is to use a chemical test kit. Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page Five E. ColiColiform Bacteria Coliform bacteria is present in water where animal feces are present. These are bacteria that are naturallyabundant in the lower intestines of humans and other warm-blooded animals. They are called an “indicator”, whichmeans that they show that another pollutant is present. The presence of coliform bacteria often leads to illness inanimal life, increased plant growth, and is very dangerous to human health. Fecal coliform can enter water throughvarious sources, including mammal and bird discharge, agricultural and storm runoff, and human sewage discharge.Human causes and effects Unprocessed toilet wastes, farm animal wastes and pet waste that make it into a water supply or swimmingarea can contaminate that water body. Untreated overflow from wastewater treatment plants or sewer systems candischarge contaminated wastewater into a lake, river or estuary. Faulty septic tanks also allow harmful bacteria topass untreated into another water body. E. coli is a type of fecal coliform that is commonly monitored by statehealth labs that can be harmful to people. Diseases such as hepatitis, dysentery, typhoid fever and ear infections canbe contracted in water with high fecal coliform counts. Field kits, membrane ltration (MF) and most probable number (MPN) are common techniques for measuring coliform bacteria. Salinity Generally defined as the amount of dissolved solids in a volume of water, salinity is fascinating in that estuarine organisms have different tolerances and responses to salinity changes. For example, benthic (bottom-dwelling) organisms are able to tolerate changing salinities, but salinities outside an acceptable range will affect growth and reproduction. Different plants and animals thrive in different levels of salinity, ranging from freshwater, to brackish, to saltwater. Some aquatic species will actually move to different saline regimes at different times of the year, or in different parts of their reproductive cycle. In Our Estuary Salinity is a major part of the Hudson River Estuary. Salty seawater from the Atlantic Ocean enters as a wedge using gravity to push its way into the river along the bottom, as freshwater runs downriver washing over the top. The saltwater stays on the bottom since it is denser than freshwater. Remember mass measures how much there is of something, while density measures how tightly it is packed together. Salinity in the Hudson River estuary ranges from close to seawater (35,000 ppm) at the mouth of Sandy Hook, N.J., to background levels (20-30 ppm) in freshwater further north on the river. The East River is not as varied as the Hudson (remember, it’s not really a river, the East River is a tidal strait!) Most of the water in the East River is close to seawater salinity. One method for measuring salinity uses both a hydrometer (to nd the speci c gravity) and a thermometer. Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page SixTurbidity Turbidity measures the cloudiness of water, thus murky waters are turbid waters. Materials like soil particles(clay, silt, and sand), algae, plankton, and microbes can be suspended in the water column. Causes of turbidityinclude soil erosion, waste discharge, urban runo , bottom feeders like carp stirring up sediments, householdpets playing in the water, and algal growth. As suspended particles absorb heat from sunlight, turbid watersbecome warmer. Warm water holds less oxygen than cooler water, so this causes oxygen levels to fall.Photosynthesis decreases with lesser light, resulting in even lower oxygen levels. Populations of organisms thatare directly dependent upon light (phytoplankton and aquatic plants) and those who are in turn dependent onthem as a food source would be impacted. Suspended solids in turbid water can clog sh gills, reduce growthrates, decrease resistance to disease, and prevent egg and larval development. Settled particles smother eggsof sh and aquatic insects. Turbidity is also useful as an indicator of the e ects of runo from construction,agricultural practices, logging activity, discharges, and other sources.Turbidity affects fish and other aquatic life by:1. Limiting photosynthetic processes and increasing respiration, oxygen use and theamount of carbon dioxide produced;2. Clogging fish gills and feeding apparatuses of bottom dwelling animals bysuspended particles; and/or3. Obscuring vision of fish as they hunt food and smothering bottom-dwelling animals.Effects on People Organic and/or inorganic constituents comprise turbidity. Organic particulates may harbor high concen-trations of bacteria, viruses, and protozoans. Due to this, turbid conditions may increase the possibility for water-borne disease. Another concern of suspended sediments is that attached nutrients, metals, and pesticides can becarried throughout the water system. Usually the materials that cause turbidity in our drinking water either settleout or are ltered before the water arrives in a drinking glass at home. Some equipment that can be used to measure turbidity are: secchi disks, sight tubes, or a turbidimeter.Tides and CurrentsTides Tides are movements of water due to the gravitational pull of the moon and sun. They in uence waterdepth and create currents. Particularly because the East River is a tidal strait, it has hefty tides, ranging from around7 feet at Willets Point to 4.6 feet down at the southern end at The Battery. The East River and estuary section of theHudson River are subject to a tidal cycle. In the Hudson every 6 hours the tides will shift pushing water into theriver mouth on a ood tide, and pulling water back out the mouth on an ebb tide. Depending upon location inthe river, the vertical tidal range can be from less than 3 feet, to close to 5 feet. At the north side of the Piermontpier extensive mud ats are exposed during lowtide.Currents The di erence in elevation between high and low tides creates tidal currents. The timing of these currents mimics the rise and fall of the tides, following roughly a six-hour schedule. Extremes in weather, such as excessiverains or strong winds, can impact the currents by overwhelming or suppressing them. In some places on the river,change in water color can re ect the current. Generally the current can be evaluated by watching something oaton the river. The direction of current indicates which direction the waves are owing. It helps point out where things are coming from and where they are headed, including pollutants, plant and animal life, and nutrients. Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page SevenWhere are currents strong in our estuary?Hell Gate, about halfway between Throgs Neck and The Battery, is noted for its strong tidal currents. Thevelocity of current is 4 knots at Hell Gate, 3 knots at Brooklyn Bridge, and 1.5 knots north of Governors Island,The direction and velocity of the currents are affected by strong winds which may increase or diminish the periodsof flood or ebb.Let’s see how healthy the East River is... ACTIVITIES Vocabulary Tidal Strait: a narrow area of sea which connects two larger areas of sea Watershed: a dividing ridge separating one drainage area from others; the area that drains into a river or lake Non-point source pollution: pollution generated by scattered land use activities rather than from an direct source. It is brought to waterways through natural processes, such as rainfall, storm runoff, or groundwater seepage rather than by direct placement in the water. Point Source Pollution: pollution discharged directly from a specific site such as a municipal sewage treatment plant or an industrial outfall pipe. Activity 1 What are the physical properties of water? In this activity, you will be doing comparative testing of your two water samples: NYC drinking water and asample you collect from the East River. Direction of current, color, odor, temperature, and turbidity will all be recordedin the table below after observation and testing.Procedure:1. Direction of Current. Watch the waves of the river and determine which direction they are flowing towards.This will show you the direction of the current. Record the direction (N,S,E, or W) in the table below.2. Color and odor can tell us the following:Color: The color of the water helps you determine what substances may be in the water sample such as plant-life and organisms.Odor: The smell of the water also helps you determine what pollutants, animals, and plants, may be in the water and also may help with guessing the amount of salt in the water.Record the color and odor of both samples in the table below.3.Temperature. Use a thermometer at a measured depth to find the water temperature, and record your findings.4. Turbidity. To measure turbidity using a Secchi disk:a. Facing away from shadows, lower the Secchi disk straight down into the water until the disk just disappears fromsight. Mark the rope at the water level with a clothespin.b. Raise the disk slowly until it reappears. Using your fingers or a clothespin, mark the rope at the water level.c. To find the Secchi depth, grasp both clothespins in one hand and find the center of the loop of rope. Move oneclothespin to that point and remove the other. This point is one-half the distance between the point of disappear-ance of the disk and the point where it re-appeared. Measure the distance from this point to the surface using ayardstick. Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page EightRecord the Secchi depth in the table to the nearest inch.5. Repeat steps 1-4 so that you have done two trials for each sample. Table 1 Drinking Water Drinking Water East River East River Component Trial 1 Trial 2 Trial 1 Trial 2 Direction of Current Color Odor Temperature and Depth Turbidity What this can show us... 1. Why is water temperature important? 2. How does odor help you determine what’s in the water? 3. What are some human causes of increased turbidity? Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page Nine Activity 2 What are the chemical properties of water? Here we will record the chemical properties of our two samples, recognizing the significance of each test.Refer back to the terms defined earlier for information on each chemical aspect of water.Procedure: 1. pH. Determine the pH of water following these steps: a. Clean a test tube with water and get it ready to be tested. b. Fill the test tube to the 6ml mark with fresh water. c. Add 3 drops of the Ph sample and close the test tube with top and shake for 10 seconds. d. Compare the color with the color scale and determine Ph value. Record your value in the table below. 2. Alkalinity. Find Alkalinity with these directions: a. Clean a test tube with water to be tested. b. Fill the test tube to the 10ml mark with water. c. Add 5 drops of alkalinity sample. d. Close test tube with top and shake for 10 seconds. e. Compare alkalinity level of the sample in the test tube to the chart. Record the level in the table below. 3. Ammonia. Use these instructions to ascertain ammonia levels: a. Clean the test tube by rinsing it with water. b. Fill the test tube to the 3ml mark with water. c. Add 11 drops of ammonia sample A. Close test tube and shake for ten seconds. d. Next, add 4 drops of ammonia sample B. Then close and shake for 10 seconds. e. Now add 4 drops of ammonia sample C, close test tube and shake for another 10 seconds. f. Wait 15 minutes for color to develop. g. Compare the color of the test tube sample to the color scale. Record the value in the table below. 4. Nitrite/Nitrate. Read nitrite/nitrate levels according to these measures: a. Clean test tube with water. b. Fill the test tube to the 5ml mark with water. c. Shake nitrate sample A for 30 seconds then add 5 drops to the test tube. d. Add 5 drops of sample B. e. Add 8 drops of sample C. f. Close test tube and shake for 1 minute. g. Wait 5 minutes for color to develop and compare to color scale. Record the level in the table below. Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page Ten Table 2 Drinking Water Drinking Water East River East River Trial 1 Trial 2 Trial 1 Trial 2 Optimal Component pH pH 7.8 to pH 8.4 Alkalinity 100-125 ppm Phosphates <.03 ppm Ammonia <.01 ppm Nitrite/Nitrate <1 ppmLearning from observation…1. What does ammonia come from?2. What needs oxygen in water?3. How do phosphates help plants? Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page ElevenPollution and the East River Each day there is waste deposited into the East River. Whether accidental or on purposethe waste that goes into the river causes pollution, which will then affect the animals that livein it. When the animals are affected, people in turn are then affected as well. Between 1993 and2001, the amount of waste deposited increased from 2 million to 8.5 million tons. Waste depositedis increasing exponentially; between 2000 and 2001 the waste deposited was around 318 to 338millions tons. Pollutants can effect...Dissolved Oxygen Due to the buildup of organic waste, oxygen is limited and absorbed by the waste instead of the animals. Sincethere is a limited amount of dissolved oxygen in the water, the number of animals living in the waters is also decreasing.What can we do? We can monitor the dissolved oxygen and find out the periods of when it is low. Providing the waterswith an exposure to air frequently, spraying water across the surface waters, and removing dead plants and materialsfrom the water are some ways to increase the amount of dissolved oxygen in the East River.Turbidity When turbid waters become warmer because of particles absorbing heat, it causes the oxygen levels to fall.Without decreased oxygen levels, the animals find it hard to breathe. Warmer waters usually hold less oxygen thancold waters. Turbidity cause clogs in fish gills, decreases fishes’ resistance of disease, decreases growth rate, and preventsegg development. In addition to the above impacts of pollutants, many metals such as aluminum affect the gills of fish, making ithard for them to breathe. Metals also affect respiratory, circulatory, gastrointestinal, and central nervous systems ofanimals. Disease from pollution shows abnormal growth in the head, body, and fins, as well as reduced fertility andhatching rates, birth defects, deformed genital organs, retarded growth, cancer, anemia, metabolic abnormalities, poorimmune responses and neurological abnormalities in all sorts of animals living in and around the Estuary. Activity 3 What can we do about pollution in the East River? In this activity, you are going to take the data you have collected about your samples from the East River and use them to hypothesize what point and non-point sources of pollution might be in your water. Work with partners to create a “map” of your community and how your actions might have an impact on the East River and the quality of the water (think about the chemicals you encounter every day, littering, animals in the community, etc). Then, answer the questions below. 1. What daily activities of people pollute the water in your neighborhood? 2. Do you think car pollution effects the water quality in your neighborhood? How? Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • Water Quality and Pollution Page Thirteen Resources For Students: http://www.epa.gov/OW/kids.html http://ga.water.usgs.gov/edu/msac.html http://ga.water.usgs.gov/edu/navguide.html#special http://nyelabs.com/ For Teachers: http://www.ceismc.gatech.edu/busyt/eco_wa.shtml http://www.sasked.gov.sk.ca/docs/xsci/unplxsc.html http://www.epa.gov/water/education.html http://www.epa.gov/water/kids/watered2.htmlThe following activities from the EPA’s Wastewater Sourcebook are suitable for Grades K-5. Lower East Side Ecology Center | www.lesecologycenter.org | +1(212)477-4022
    • THE MAIN DRAINOBJECTIVES SUBJECTS: Science, Language Arts, MathThe student will do the following: TIME:1. Identify the septic tank as an alternative 45-60 minutes method of wastewater treatment. MATERIALS:2. Observe how a septic tank works. one plastic or cardboard box or lid (6-8 inches [15-20 cm] deep)3. Demonstrate how a septic tank works. one garbage bag (if cardboard box is used) potting soil or topsoil three empty paper milk cartons - one each: half gallon (2 L), quart (L) and pint (0.5 L) cartons plastic straws large needleBACKGROUND INFORMATION ice pick or awl scissorsPeople who live in small towns and rural areas are marking penoften not connected to a sewage treatment system; masking tapetherefore, they must depend on an alternative method modeling or florist clayof disposing of wastewater. Septic tank systems ruler with English/Metric measurementprovide a safe and effective means for waste teacher sheet (included)disposal if they are properly sited, installed, andmaintained.A septic tank is a large concrete or fiberglass tank that is buried underground. Drain pipes carry sewageand wastewater from buildings into the tank. By bacterial action, much of the sewage is reduced to liquid,which flows out of the tank through the drainpipe to the drainfield. The solids (sludge) settle to the bottomof the tank. This solid material must be periodically pumped out of the tank and disposed of at a wastetreatment facility or an approved disposal site.The drainfield allows wastewater to seep into the soil. The soil filters bacteria and nutrients from thewastewater. The water is further purified by the microorganisms that live in the soil.Many states regulate the siting of septic systems and the distance between a septic tank and groundwaterresource. They also may specify the types of soil where the system can be placed. Some states and localgovernments have regulations requiring inspection and maintenance schedules for septic systems.Lagoons, wetlands, and sand filters are other alternative methods that rural areas may use to treatwastewater. However, if these methods are improperly sited, poorly constructed, and/or poorly maintained,they become a serious threat to groundwater quality and public health.Termsdrainfield: the part of a septic system where the wastewater is released into the soil for absorption and filtration. 2-45
    • lagoon: an animal waste treatment method which uses a deep pond to treat manure and other runoff from a livestock operation. Lagoons can be aerobic or anaerobic. Both use bacteria to break down materials.sand filter: a filter system used to treat wastewater where sand and gravel are mounted on top of the natural soil.septic tank or septic system: a domestic wastewater treatment system into which wastes are piped directly from the home; bacteria decompose the waste, sludge settles to the bottom of the tank, and the treated effluent flows out into the ground through drainage pipes..siting: the process of selecting the correct location for a septic tank.sludge: solid matter that settles to the bottom of septic tanks or wastewater treatment plant sedimentation; must be disposed of by bacterial digestion or other methods or pumped out for land disposal or incineration.wetland: an area that, at least periodically, has waterlogged soils or is covered with a relatively shallow layer of water.ADVANCE PREPARATION A. Gather materials for septic tank model. Prepare the cartons and straws as follows: 1. Cut the top off the 1/2 gallon (2 L) milk carton. It should be 6 inches (15 cm) deep. Label this carton “house.” 2. Cut the quart (L) size to 3 inches (7.5 cm) deep and label it “septic tank.” 3. Cut the pint (1/2 L) size to 1/ 2 inch (1.3 cm) deep. Label it “drainfield tank.” 4. Cut the holes in the boxes for inserting the straws; use an ice pick or awl. 5. Make holes in the straws using a large needle. Make numerous holes, enlarging them by working the needle back and forth. B. If you do not have a plastic blanket or sweater storage box to use, cut a large cardboard box down (a copy paper box works fine); line it with plastic by inserting it in a garbage bag and tying off the bag with the box inside. C. Have copies of the model diagram (teacher sheet) for the students to refer to during the construction. D. Invite a water quality representative to come to speak to the class.PROCEDURE I. Setting the stage A. Put the following questions on the board or use sentence strips and place them on a pocket chart. (These assume that you are located in an area not served by a wastewater treatment plant.) 1. What happens to the wastewater and sewage when it leaves your house? 2-46
    • 2. Where does the sewage/waste water go when it leaves the school? B. Explain how a septic tank system works. Paraphrase the background information. C. Compare/contrast a septic tank system and a wastewater treatment plant. List advantages and disadvantages of both.II. Activities A. The students will construct a model of a septic tank system with a drainfield. B. Show the class the diagram of the model of a septic tank system. 1. Instruct the students to prepare the large box for the septic tank system model. The box should be filled 1/2 full of soil. 2. Cut the tops from the milk cartons (if this has not previously been done). C. Assemble the septic tank system. 1. Instruct the students to connect the three boxes, from the largest to the smallest, with the straws (refer to diagram). Use ice pick or awl to make holes in boxes (if not already done). Fit the straws into the holes, connecting the boxes with the straws. Use small pieces of masking tape to seal leaks by making “collars” of tape around the connection between box and straw. 2. Instruct them to assemble the drainfield. Connect straws following the diagram of model. (To make the connections between straws, you will have to make large holes in the straw crosspiece; use the ice pick or awl.) Use a large needle to punch drain holes through the straws. Plug the ends of the drains (straws) with modeling or florist clay. Use masking tape to seal any leaks. 3. Test for leaks by putting the model in a sink and filling “house” with water. Water should only come out of the holes in the drain (straws). D. As the assembly progresses, discuss with the students what each part of the model represents. E. Test the septic tank system. 1. Put the model in the box with the porous soil. 2. Pour water in the “house” slowly. Observe what happens. Ask the students to explain what happens. (The water should go to the drainfield and trickle into the soil.)III. Follow-Up A. Have the students ask their parents what type of wastewater disposal they have. Construct a bar or circle graph to represent the type of wastewater disposal the students have in their home: (1) wastewater treatment plant, (2) lagoon, (3) septic tank, (4) wetland, (5) sand filter. What percentage does each group represent? B. Did any parents tell what type of maintenance schedule has to be followed to keep the system working properly? 2-47
    • C. Brainstorm with the group the answers to these questions: 1. What happens if the system does not function properly? (Malfunctioning septic systems will have a smell or have noticeable wetness on the ground above them. Such systems represent a threat to public health and to nearby groundwater supplies.) 2. What do you think will happen to the water supply in the area if the waste disposal system does not work properly or is not maintained adequately?IV. Extensions A. Invite a water quality representative to come and speak to the class about wastewater treatment in their area. 1. Ask what type of waste disposal systems are represented in the area. 2. What kind of local or state regulations or restrictions are mandated for maintenance, siting, and construction of wastewater facilities in the area? B. Write to a local or state water quality agency and ask them to send information about septic tanks.RESOURCESBranley, Franklyn M., Water for the World, Thomas Y. Crowell Junior Books, New York, 1982, p. 77.Environmental Resource Guide: Nonpoint Source Pollution Prevention (Grades 6-8), Air and Waste Management Association, Pittsburgh, Pennsylvania, 1992.Jorgensen, Eric P., ed, The Poisoned Well: New Strategies for Groundwater Protection, Island Press, Washington, DC, 1989. 2-48
    • Teacher Sheet SEPTIC TANK MODEL2-49
    • SETTLING THE WASTEWATERPROBLEMOBJECTIVES SUBJECTS: Science, Language ArtsThe student will do the following: TIME:1. Name models that are representations of larger 90 minutes objects. MATERIALS:2. Suggest ways that industry, agriculture, and 3 large jars mining affect water quality. charcoal 6 smaller containers (such as small buckets)3. Demonstrate the use of lagoons for treating ammonia wastewater. funnel or liter bottle with bottom cut off pieces of wood soilBACKGROUND INFORMATION paper towels coffee grounds (or sterile gardening manure)Water pollution remains a serious problem in most nylon hosieryparts of the United States. Sediment, nutrients, flourbacteria, and toxic material still find their way into medium rocksthe nations waters where they damage ecosys- vegetable oiltems, cause health hazards, and prevent the full cotton ballsuse of water resources. bleach sandIn agriculture, all livestock operations face the iron filingsgrowing concern of animal waste disposal. Animal 3 paper or plastic cupswastes pollute the environment when not disposed small rocksof properly. Because of its nutrient value, animal vinegarwaste should be viewed as a resource rather than asa waste. It provides the producer with a valuable soil conditioner and source of fertilizer. Animal wastedoesnt have to be a pollution problem. A well designed and maintained waste management system benefitsnot only the producer, but the community as well.Pollutants carried by runoff from such urban features as streets and roadways, commercial and industrialsites, and parking lots affect between 5-15 percent of surface waters. Urban runoff contains salts and oilyresidues from road surfaces and may include a variety of nutrients and toxic material as well.Higher temperatures associated with industrial wastewater can result in “thermal pollution.” Up to 10 percentof surface waters are adversely affected by acid drainage from abandoned mines, pollution from mill tailings,mining waste piles, and pollution from improperly sealed oil and gas wells.All of these kinds of wastewater can be treated by allowing them to rest in settling/treatment ponds to cleanthe water for discharge. 2-73
    • Termsgroundwater: water that infiltrates into the earth and is stored in usable amounts in the soil and rock below the earth’s surface; water within the zone of saturation.lagoon: an animal waste treatment method which uses a deep pond to treat manure and other runoff from a livestock operation. Lagoons can be aerobic or anaerobic. Both use bacteria to break down materials.model: a small representation of a larger object.surface water: precipitation that does not soak into the ground or return to the atmosphere by evaporation or transpiration, and is stored in streams, lakes, wetlands, reservoirs, and oceans.water treatment: the conditioning of water to make it acceptable for a specific use.ADVANCE PREPARATION A. Fill the 3 large jars (use gallon jars from the lunchroom) with clean water. B. During the demonstration you will create models of agricultural, industrial, and mining wastewater by “dumping” the waste substitutes into the appropriate jar. Gather the following materials for the demonstration: 1. To simulate agricultural wastewater, obtain 1 cup (250 mL) ammonia, 2 cups (500 mL) soil, and 2 cups (500 mL) used coffee grounds or sterile gardening manure for the substituted waste. 2. To simulate industrial waste, obtain 1 cup (250 mL) flour, 1 cup (250 mL) vegetable oil, and 1 cup (250 mL) bleach. 3. To simulate mining wastewater, obtain 2 cups (500 mL) soil, 1 cup (250 mL) iron filings, 1 cup (250 mL) small rocks, and 1 cup (250 mL) vinegar (for acidic smell). (NOTE: Iron filings are readily available from auto parts stores where they work on brakes; these are usually free.) NOTE: Take extra care to make sure ammonia and bleach aren’t accidentally mixed. Mixing them can release poisonous chlorine gas. C. Gather the other materials. Try to avoid giving the students glass containers.PROCEDURE I. Setting the stage A. Divide the class into 6 teams. Tell members of the first two teams they represent farmers; the third and fourth teams represent manufacturers; and the fifth and sixth teams represent miners. B. Each group should have a funnel and several items available to them to attempt to purify the wastewater. Suggested items might include charcoal, pieces of wood, paper towels, nylon hosiery, rocks (small and medium size), moss, cotton balls, or sand. C. You will divide the 3 wastewater supplies in half. Each group should have a large jar or pitcher (or a small bucket) of its own. 2-74
    • D. Tell the teams not to touch the jars until they are ready. This helps avoid spills and accidents.II. Activity A. Explain and give examples of a model representing a larger object. (globe = earth, model car = vehicle, doll = baby) 1. Tell the students that it is sometimes impossible to show real objects (like the earth) because of their size. 2. Have them cite other examples to show comprehension. B. Show one of the jars of clean water. Tell the students that this jar is a model that represents 1 million gallons of water that falls on a large farm with fields and cattle operation. 1. Ask the students to suggest ways the water could become polluted. (runoff from animal waste, fertilizer, etc.) 2. Simulate the agricultural wastewater by "dumping" in the agricultural pollutants to make wastewater. 3. Explain what each pollutant represents: The ammonia represents animal urine. The soil represents eroded topsoil, and the coffee grounds or gardening manure represents solid animal waste. 4. Divide the agricultural wastewater between the 2 groups of "farming representatives," leaving about 1/3 of it for a further demonstration. C. Select another jar of clean water. Tell the students that this jar is a model that represents 1 million gallons of water that flows from a manufacturing plant. 1. Ask the students to suggest ways the water could become polluted. (dumping, cleaning, mixing chemicals) 2. Simulate the industrial wastewater by "dumping" the industrial pollutants into the second jar. Explain what each pollutant represents: The flour represents biological wastes like paper pulp; the oil represents wastes like lubricating (motor) oil; and the bleach represents, and is very similar to, chemicals used by many factories. 3. Divide the industrial wastewater between the 2 groups of "manufacturing representatives," leaving about 1/3 of it for a further demonstration. D. Select the third jar of clean water. Tell the students that this jar is a model that represents 1 million gallons of water that flows from a mine. 1. Ask the students to suggest ways the water could become polluted. (runoff, washing equipment, washing work clothes, etc.) 2. Simulate the mining wastewater by "dumping" the mining pollutants into the jar. Explain what each pollutant represents: The soil and rocks obviously represent the tons of earth material disturbed by mining; the iron filings represent the minerals exposed by mining; and the vinegar represents the acids that can leach from rocks dug up by mining. 3. Divide the mining wastewater between the 2 groups of "mining representatives,” leaving about 1/3 of it. 2-75
    • E. Explain that the different land uses represented are necessary for us to live our lives the way we do, but the by-products of the activities represented in each of the three jars is the same: it is called “wastewater.” 1. Ask that students the following questions. (NOTE: Remind the students that their jars each represent 1/2 million gallons of water.) a. Would you drink this water? b. Would you dump this water into the river or lake? c. If you dumped this water down a drain, where would it go? 2. Tell the teams they must find a way to make the wastewater reusable since there is so much of it. Take the class outside; this is a messy process. a. They are to use the materials available and attempt to remove as much of the odor and pollutants as possible using paper cups and smaller containers provided. (CAUTION: Containers may become slippery when wet.) b. Allow the students to work on their own in their teams for about 15-20 minutes. Supervise for safety. F. Let representatives from each team explain their processes and results. G. Explain that there is another treatment method (if no one mentions it) that is less expensive and more feasible called a “holding pond” or lagoon. H. Label each jar (agriculture, mining, and industry). Demonstrate the lagoon by allowing each jar to sit undisturbed overnight. (This allows settling to occur.) 1. Allow the students to observe and smell each jar after 24 hours. 2. Discuss the differences in the appearance of the wastewater.III. Follow-Up A. Compare the various methods the groups used to treat wastewater with the lagoon method. 1. Ask which method would be less expensive to treat large amounts of wastewater. (lagoon) 2. Ask which method would be easier to use with large amounts of wastewater. (lagoon) 3. Ask the students what else needs to be considered before the wastewater could be of better quality. (get rid of pollutants that did not settle—like smell and color) 4. How could the water from lagoons be used? (irrigation, discharge into streams, etc.) B. Have each group write a report of their wastewater treatment results. 1. What products did not settle? 2. Which teams jar settled the most? 2-76
    • 3. Which group would benefit the most from using a lagoon as a water treatment process? 4. How could the processed water be used? C. Dispose of the simulated lagoons by pouring the water off the settled solids. Allow the jars to dry and, then dispose of the dry material in the trash, and wash out the jars for reuse.IV. Extension A. Visit a wastewater treatment plant. B. Plan a field trip to a large farm, manufacturing plant, or a mining area that utilizes a lagoon. C. Have a representative from each category above visit the classroom and discuss using a lagoon as a treatment method.RESOURCESEnvironmental Resource Guide: Nonpoint Source Pollution Prevention (Grades 6-8), Air & Waste Management Association, Pittsburgh, Pennsylvania, 1992.EPA Journal Vol. 17, No. 5, U.S. Environmental Protection Agency, Washington, DC, November/December 1991.Leopold, Luna, Water Use and Development, U.S. Government Printing Office, Washington, DC, 1960.“Nonpoint Source Pollution” (Water Quality Factsheet #4), Tennessee Valley Authority, 1988. 2-77