Chapter 20.3: Impacts on Water


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Grade 8 Integrated Science Chapter 20 Lesson 3 on human impacts on water. This lesson goes into detail on how humans positively and negatively impact our water resources. The objective is that students will be able to identify point and non-point source pollution, international cooperation and national initiatives to manage water resources, and how we can prevent polluting our water supply.

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Chapter 20.3: Impacts on Water

  1. 1. Chapter 20 Lesson 3 p734-740 IMPACTS ON WATER
  2. 2. Water as a Resource  Most of Earth’s surface is covered with water, and living things on Earth are made mostly of water.  Like other organisms, humans need water to survive.  Humans also use water in ways that other organisms do not.  People wash cars, do laundry, and use water for recreation and transportation
  3. 3. Water as a Resource  Household activities, however, make up only a small part of human water use.  Most water in the United States is used by power plants.  The water is used to generate electricity and to cool equipment.  The use of water as a resource also impacts the environment
  4. 4. Sources of Water Pollution  Water moves from Earth’s surface to the atmosphere and back again in the water cycle.
  5. 5. Point-Source Pollution  Point-source pollution is pollution from a single source that can be identified.  Discharge pipes that release industrial waste  Oil spilling tankers  Runoff from the mining operation
  6. 6. Nonpoint-Source Pollution  Pollution from several widespread sources that cannot be traced back to a single location is called nonpoint-source pollution  As precipitation runs over Earth’s surface, the water picks up materials and substances from farms and urban developments.  These different sources might be several kilometers apart.  This makes it difficult to trace the pollution in the water back to one specific source and is harder to control.  Examples:  Farm and urban development runoff  Construction site runoff which contain excess amounts of sediment
  7. 7. Positive Actions  Once pollution enters water, it is difficult to remove.  In fact, it can take decades to clean polluted groundwater!  That is why most efforts to reduce water pollution focus on preventing it from entering the environment, rather than cleaning it up.
  8. 8. International Cooperation  In the 1960s, Lake Erie, one of the Great Lakes, was heavily polluted by runoff from fertilized fields and industrial wastes.  Rivers that flowed into the lakes were polluted, too.  Litter soaked with chemicals floated on the surface of one of these rivers – the Cuyahoga River.  The litter caught fire which spurred Canada and the United States – the two countries that border the Great Lakes – into action.
  9. 9. International Cooperation  The countries formed several agreements to clean up the Great Lakes.  The goals of the countries are pollution prevention, as well as cleanup and research.  Although, the Great Lakes still face challenges from aquatic species that are not native to the lakes and from the impact of excess sediments, pollution from toxic chemicals has decreased.
  10. 10. National Initiatives  In addition to working with other governments, the United States has laws to help maintain water quality within its borders.  The Clean Water Act, for example, regulates sources of water pollution, including sewage systems.  The Safe Drinking Water act protects supplies of drinking water throughout the country.
  11. 11. How can you help?  Laws are effective ways to reduce water pollution. But simple actions taken by individuals can have positive impacts, too.
  12. 12. Reduce Use of Harmful Chemicals  Many household products, such as paints and cleaners, contain harmful chemicals.  People can use alternative products that do not contain toxins.  For example, baking soda and white vinegar are safe, inexpensive cleaning products.  In addition, people can reduce their use of artificial fertilizers on gardens and lawns.  Compost can also enrich soils without harming water quality.
  13. 13. Dispose of Waste Safely  Sometimes using products that contain pollutants is necessary.  Vehicles, for example, cannot run without motor oil.  This motor oil must be replaced regularly.  People should never pour motor oil or other hazardous substances into drains, onto the ground, or directly into streams or lakes.  These substances must be disposed of safely.
  14. 14. Conserve Water  Water pollution can be reduced simply by reducing water use.  Easy ways to conserve water include taking shorter showers and turning off the water when you brush your teeth.