Section 4: Air and Resources & Human Impact

Clean water and air are essential to maintaining life on Earth.  Water is a necessity for our survival as well as for the survival of plants and animals.  There are two ways to identify pollutants that contaminate our water supply.  Point source pollution comes from a specific location to which we can point.  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 health safety.  Water can be polluted in many ways.  First, sediment is the largest source of water pollution, making the water cloudy.  It blocks sunlight from getting to plants and interferes with organisms living in the water.  Secondly, pesticides may destroy a pest but 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.  Fourth, when the water is heated due to an industrial factory, it reduces oxygen and changes the temperature an organism needs to survive.  Finally, the water supply is contaminated when oil and sewage seep into the water.

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, burning fossil fuels can release compounds that react with water in the atmosphere to create 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 production, industrial waste, and pollution.  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?

Click here to go back to the Table of Contents