Identify why quality water is essential to all living things. Demonstrate the cumulative effects of non-point source pollution and explain ways to reduce or eliminate non-point source pollution in urban and agricultural settings.
4th to 12th graders, adults, and anyone learning about water quality and pesticide safety.
Depending on student level and discussions, this activity can be facilitated in 25-45 minutes.
Pennsylvania Academic Standards
|Environment and Ecology 4.5.4.C ||Describe how human activities affect the environment.|
|Environment and Ecology 4.5.5.C ||Explain the difference between point and non-point source pollution.|
- Large clear bowl
- Clear plastic cups (enough for 1 per student)
- Assorted food coloring
- Powdered cocoa, coffee, or hot chocolate
- Cooking oil
- Powdered drink mix (preferably grape)
- Copies of included water graphs
Water is the most critical molecule to all living organisms including plants, animals, insects, and even microscopic organisms like bacteria. Human adults are approximately 60 percent water. Water acts as a building material for our bodies. Water also helps regulate our internal body temperature, helps transport nutrients to our cells, assists in flushing wastes through urination, lubricates joints, forms saliva, and acts as a shock absorber for our brain and spinal cord. Humans can live for extended periods of time without food (several weeks), but without water intake, humans cannot live very long (three to five days).
Three-quarters or 75 percent of the earth’s surface is covered in water; however, 97 percent of that water contains salt and cannot be used; the other 3 percent is fresh water. Now consider that 80 percent of the fresh water on earth is unavailable because it is frozen at the poles in glaciers and icecaps, which means only 20 percent of the fresh water is available. However, 99.5 percent of the available fresh water is actually too far underground, trapped in the soil, or polluted. Thus, only a very small percentage of all water on earth is actually available for human use.
Water is found in a variety of places and phases throughout the earth. We find gaseous water in the clouds and frozen water in the glaciers. We find liquid water in the oceans, rivers, lakes, soil, groundwater, plants, and animals.
Water is consistently moving from one point or phase to another. We call this movement of water the water cycle. The water cycle does not have defined paths and the molecules do not move in a circle. Heat, energy, and gravity are the driving forces of the water cycle.
One of the most visible states in which water moves is the liquid form. Water is seen flowing in streams and rivers and tumbling in ocean waves. Water travels slowly underground, seeping and filtering through particles of soil and pores within rocks.
Although unseen, water’s most dramatic movements take place during its gaseous phase. Water is constantly evaporating, changing from a liquid to a gas. Evaporation occurs when water from the ground or bodies of water move into the atmosphere. Plants give off water vapor through transpiration. The combination of evaporation and transpiration is referred to as evapotranspiration. As a vapor, water can travel through the atmosphere over the earth’s surface. In fact, water vapor surrounds us all the time. Where it condenses and returns to earth depends upon loss of heat energy, gravity, and the structure of the earth’s surface.
Water condensation can be seen as dew on plants or water droplets on the outside of a glass of cold water. In clouds, water molecules collect on tiny dust particles. Eventually, the water droplets become too heavy and gravity pulls the water to the earth.
Living organisms also help move water. Humans and other animals carry water within their bodies, transporting it from one location to another. Water is either directly consumed by animals or is removed from foods during digestion. Water is excreted as a liquid or leaves as a gas, usually through respiration. When water is present on the skin of an animal (for example, as perspiration), evaporation may occur.
Point source pollution involves pollutants that are discharged from and can be traced back to an identifiable point or source, such as a factory’s discharge pipe or a sewage ditch. Non-point source pollution occurs when the source of a contaminant is unidentifiable; that is, the pollutant might have come from one of many places. Examples of non-point source pollution include runoff from agricultural fields containing fertilizer or pesticides, motor oil from urban areas, and sediment from eroded stream banks.
Take a copy of each water pie chart. Explain that the first pie chart shows 97 percent of the water on earth is salt water and 3 percent of the water on earth is fresh water. After showing the pie chart, cut out the fresh water wedge.
Then explain that the second pie chart represents the fresh water wedge that was cut out previously. This pie chart explains that 80 percent of the fresh water is actually frozen in glaciers and ice caps and the remaining 20 percent is considered flowable water. Proceed to cut out the flowable wedge.
Now show the third pie chart; this chart represents the flowable fresh water on earth. Explain that 99.5 percent of this water is actually unavailable for drinking because it is too deep in the ground, tied up in the soil, or polluted. This leaves us with a very small sliver of drinkable fresh water.
Give each student a clear plastic cup filled ½ to ¾ full of water. Explain that each cup represents a part of the water cycle. Explain the difference between point and non-point source pollution. Explain what substance matches what type of non-point source pollution.
Non-Point Source Pollution Example
Waste from livestock, pets, faulty septic systems
Heavy Metals or Mine Drainage
Powdered Drink Mix
Cocoa, hot chocolate, or coffee
Let each student choose a type of pollution to put into their cup. Each student is only to put one drop or a small pinch into their cup. How does that small amount of pollution affect the water in their cup?
Now have each student (one at a time) dump their cup of water into the large bowl. How does the cumulative effect of everyone’s water and pollution affect the large bowl of water?
Notice how each cup was only slightly polluted but once all the water was added to the watershed, the watershed becomes very polluted. This illustrates the cumulative effect of non-point source pollution and how easily we can contribute to it.
The protection of these water resources from non-point source pollution presents an enormous challenge because of the widespread diverse nature of the problem. We depend on methods called Best Management Practices or BMPs to reduce or eliminate non-point source pollution problems.
The following are a few BMPs that can be used to reduce or eliminate non-point source pollution.
Roads and Streets
- Fix automobile oil and fuel leaks
- Dispose of paints and petroleum products at approved disposal sites, not in storm drains or street gutters
- Construct a sediment catch basin to collect storm water and road construction runoff
- Use nonchemical deicers like sand and ash on roads, sidewalks, and driveways
- Read and follow all labels and ask for application directions before using chemicals, pesticides, and fertilizers
- Use conservation tillage and other agricultural conservation practices
- Use cover crops to protect exposed soil
- Fence waterways to reduce the impact of livestock on riparian zones
- Read labels prior to using chemicals, pesticides, and fertilizers
- Use nonchemical fertilizer like compost on gardens
- Dispose of household hazardous waste at approved disposal sites
- Maintain septic system if sewers are not available
Project Wet Curriculum and Activity Guide 2.0
Healthy Water Healthy People - Water Quality Educators Guide