Section 4: Air and Resources & Human Impact

Clean water and air are essential to maintaining life on Earth.  Water is a necessity to our survival as well as to the survival of plants and animals.  There are two ways to identify pollutants that contaminate our water supply.  Point source pollution means it comes from a specific location that we can point to.  Nonpoint source pollution enters the water from large or multiple areas.  About 75% of water pollution in the United States is from nonpoint sources.

Water quality is a measurement of substances in water that may affect appearance and taste, color, acidity, hardness, and safety of health.  Water can be polluted in many ways.  First, sediment is the largest source of water pollution, and this makes water cloudy.  It blocks sunlight from getting to plants and interferes with organisms living in the water.  Secondly, while pesticides may destroy a pest, they harm other living organisms.  Thirdly, fertilizers add too much nitrogen and phosphorus to water sources, which can cause algae to multiply.  This results in  oxygen being used up that would otherwise be used by fish and other organisms.  When the water is heated due to an industrial factory, it reduces oxygen and changes the temperature an organism needs to survive.  Finally, when oil and sewage seep into the water, the water supply is contaminated.

Air pollution is harmful to all living things.  Smog is a yellow-brown haze caused by pollutants in the air reacting in the presence of sunlight.  When warmer air traps colder air, it holds the cold air near the ground.  The warm air also traps a layer of pollution from cars, factories, and power plants.  Also, the burning of fossil fuels can release compounds that react with water in the atmosphere to create an acid precipitation.  Acid rain has a low pH that can harm organisms or corrode building structures.  Natural products such as materials from ash, dust and gases can also cause health problems in organisms.

The Clean Air Act and Clean Water Act regulate emissions, energy productions, and industrial wastes and pollutions.  Individuals can conserve water use, reduce driving, and change their lifestyles to help prevent pollution.


  1. Explain the difference between point source and nonpoint source pollution.
  2. Why is air pollution a problem?
  3. What is the goal of the Clean Air Act and the Clean Water Act?

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