Movement of Hazardous Wastes
Introduction:
Our lifestyles are supported by many complex industrial activities that produce a variety of chemicals and chemical wastes. The EPA (Environmental Protection Agency) estimates that more than 70,000 chemicals are currently being used on a regular basis by manufacturers around the world. For example, the industries that produce our clothing, cars, medicine, paper, food, fuels, steel, plastic and electric components use and discard thousands of chemicals every year.
At home, we may use lawn chemicals, solvents, disinfectants, cleaners, anto products to improve our quality of life. Does this behavior considered risky to ourselves and the environment? At what point do you consider a substance or material to behazardous? A chemical that presents a threat or unreasonable risk to human health or the environment is considered a hazardous material— when it is produced, used or disposed of. When this material can no longer be used it becomes a hazardous waste.
The following are characteristics of a hazardous substance:
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Ignitable:
Capable of bursting into flames. Can irritate the eyes, skin and lungs e.g. gasoline, paint, furniture polish.
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Reactive:
Capable ( under normal conditions) of changing into something else in the presence of other chemicals. When this happens a reactive substance can explode or create some poisonous gases, e.g. chlorine bleach and ammonia are reactive.
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Toxic:
Poisonous to people and other organisms. Can canse severe headaches, cancer or even death if swallowed or absorbed through the skin e.g. pesticides, weed killers.
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Corrosive:
Capable of chemically wearing substances away or destroying them. Capable of eating through metal, burn skin on contact and give off vapori that can burn the eyes, e.g. strong acids (HCL)
Once hazardous wastes are released, they can move about under the influences of water, wind and gravity. Dissolved and liquid hazardous wastes can occur in precipitation, runoff or surface water and can be moved down through the soil to ground water level. Contaminated ground water can also move into lakes, streams or rivers.
Objectives
Students will:
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1. Observe how a contaminant moves from land to water and between surface and ground water.
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2. Experience the difficulty of cleaning up contaminated water.
Materials
Each group will need:
One 500m1 beaker
Clean pea-size gravel to fill beaker 3/4 full
Three 300m1 paper cups
One pump dispenser from liquid-soap or hand-lotion containers
About 4 liters of water
One bottle of food coloring
Procedure:
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1. Divide students into groups of four.
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2. Have students display their posters titled “Hazardous Waste” from the previous activity on their desks.
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3. Fill the 500m1 beaker 3/4 full of clean pea-size gravel.
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4. Using a nail, punch 8-10 small holes in the bottom of one of the paper cups. When filled with water, this cup will be used to simulate rain.
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5. Fill one paper cup (without holes) 3/4 full of water.
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6. Provide each group with another paper cup and one pump dispenser.
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7. Instruct students to hold the paper cup with holes in the bottom over the cup containing the pea-size gravel then pour enough water into the cup with the holes until all but the top one centimeter of the pea-size gravel is saturated.
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8. Dig a hole in the center of the gravel to create a lake effect. The lake should be about 1/4 full of water. Have students observe the connection between the level of the water in the lake and how it corresponds to the level of the water in the gravel.
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9. Add two drops of food coloring to the pea-size gravel surrounding the lake. The food coloring represents contamination from improper disposal of chemicals. Have students hold the paper cup with holes in the bottom over the cup containing the pea-size gravel at the location where the food coloring was added. Pour a small amount of water into the cup with holes and observe what happens to the contaminant.
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10. Place the pump dispenser in the gravel down to the water level on the opposite side of the lake. Pump water into the paper cup with no holes. Observe the color of the water in the cup. Continue to pump until the color of the water being pumped changes to the color of the contaminant. Students should continue to add clean water and pump out contaminated water until the water becomes clear.
Interpretive Questions
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1. How was the contaminant transported?
2. Was it easy to clean up the contaminated water?
3. Identify some risks involved in the movement of hazardous wastes.
4. List some clean up methods that can be used for hazardous wastes.