Runoff is one of the main polluters of creeks, rivers and lakes. Rain that enters the storm water system includes bacterial, sediment, chemical and temperature pollution.
Curriculum expectations are always based on the Ontario Ministry of Expectations. Many of the activities will reinforce, rather than teach, those expectations. As such, no assessment ideas or rubrics are included.
Understanding Earth and Space Systems: Water Systems
Overall Expectations:
- assess the impact of human activities and technologies on the sustainability of water resources;
- investigate factors that affect local water quality;
- demonstrate an understanding of the characteristics of the earth’s water systems and the influence of water systems on specific regions
After a rainfall, take your students outside to check out how your school property contributes to the problem of polluted runoff.
- paper cups, a few for each student
- water testing kit, like this one. It includes 50 tests and costs around $60 dollars for 10 tests. This kit tests for various chemicals, minerals and the PH level. It does not test for bacteria!
- If you want to test for bacteria, source a kit that tests for E.coli. E.coli is an indicator bacteria (canary-in-the-coalmine). "Traditionally, [it] has been used as an indicator of general bacterial wastewater contamination" (U.S. Environmental Protection Agency).
- plenty of potential filtering supplies, although students can also source some of their choosing, based on their creative ideas
Preparations:
Most importantly, become familiar with the testing kit(s).
Decide how students will report their test findings: individually or in groups? Informally or as a presentation. How will their work be assessed?
Decide how groups will research the best water filtering system? How will their ingenuity be assessed?
Activity 1:
Make clear the boundaries and expectations of your Field Trip At School. Take the class outside to test puddles on the property. In a central and convenient location, have students gather around you in a large semicircle and show them how to use the testing kit. Impress upon them that puddle water is not potable under any circumstances. Even if students find no compounds in the water, make clear that the test kit does not test for bacteria.
- pH: acidity or alkalinity in drinking water is not a health problem except in extremes; it is more of a taste issue. Rain water typically has a pH of 5.6, a little on the acid side of neutral. Storm water runoff is more likely to have a pH of 6.5 -7.2 due to the alkalinity it picks up as it moves across pavement (vehicle emissions leave carbon dioxide and sulfur dioxide on the pavement), and that changes the habitat and health of aquatic life downstream.
- Copper: can be found in storm water runoff from wear on vehicle brakes, fungicides, or pressure-treated wood. It is toxic to aquatic life when concentrations are just a little higher than naturally found. Copper is more toxic if the pH of water is lower than 5.
- Iron: can be found in storm water runoff from wear on vehicle brakes and surface erosion. It is naturally occurring and necessary in water. High concentrations are more of a nuisance than an environmental concern. It leads to stains on things like bricks and laundry. (water-research.net)
- Nitrate: Nitrate can occur naturally in surface and groundwater at a level that does not generally cause health problems. High levels of nitrate in well water often result from improper well construction, well location, overuse of chemical fertilizers, or improper disposal of human and animal waste. Sources of nitrate include fertilizers, septic systems, animal feedlots, industrial waste, and food processing waste (cdc.gov)
- Phosphates: can be found in surface water from human and animal waste, phosphorus rich bedrock, laundry, cleaning, industrial effluents, and fertilizer runoff. These phosphates become detrimental when they over-fertilize aquatic plants and cause cultural eutrophication.
Natural eutrophication is the aging process of a body of water such as a bay or lake. This process results from plant growth. The plants die more quickly than they can be decomposed. This dead plant matter builds up and together with sediment entering the water, fills in the bed of the bay or lake making it more shallow. Normally this process takes thousands of years.
Cultural eutrophication is an unnatural speeding up of this process because of man's addition of phosphates, nitrogen, and sediment to the water. Maybe you have heard of algae bloom. It is an example of excess plant growth. Bodies of water are being filled in at a much faster rate than geological forces can create new ones. Algae bloom also hog too much of the water's oxygen, causing other aquatic life to die. (water-research.net)
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- Temperature: Rain that falls onto roads, roofs and parking lots is much warmer when it ends up in creeks and rivers than rain that percolates into soil through a lawn, field or forest. Water holds less oxygen as it becomes warmer, resulting in less oxygen being available for respiration by aquatic organisms. Certain species of fish, such as salmon and trout, are particularly sensitive and require relatively low water temperatures (epa.gov).
Introduce the water filtration competition below some days ahead of time, so that students have time to research possibilities. Tell the class what supplies you will have available, so that they have the opportunity to collect any additional ones that they might want to use.
Make sure that the (first) day of the competition is one with plenty of puddles outside. On that day, take your class outside again. Have available a variety of water filtration supplies. Examples of school filtration projects can be found here, here, here and here. An above-and-beyond filtration option is found here.
You can judge and compare the filtered water results visually and by another round of testing.
Explain that in communities with municipal water, filtration is the first step in making tap water drinkable. After the filtration process, the water goes through chemical disinfection, using chemicals such as ozone, chlorine, or fluoride. These are added to kill bacteria before water is piped to users. The cleaner we can keep our water, and the less we use, the easier it is on our treatment process.
Do unto those downstream as you would have those upstream do unto you.
Wendell Berry
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