Conserving Resources 8 th Grade Science Book Chapter 14

Resources Natural resources – parts of the environment that are useful or necessary for living organisms to survive.

Natural Resources A natural resource that is constantly recycled or replaced is a renewable resource.

Natural Resources Natural resources are used up more quickly than can be replaced are called nonrenewable resources; for example petroleum takes hundreds of millions of years to form.

Fossil Fuels Fossil fuels such as coal, oil, and natural gas are nonrenewable energy resources that form in Earth’s crust over very long periods of time.

Alternative Energy Alternative energy sources can be used to help conserve fossil fuels. Hydroelectric power – energy from falling water used to generate electricity.

Alternative Energy Wind – wind turns the blades of a turbine, which powers an electric generator.

Alternative Energy Nuclear Power – the fission of uranium atoms generates nuclear energy that is used to produce electricity.

Alternative Energy Geothermal power plants use geothermal energy from the heat in Earth’s crust to generate electricity.

Alternative Energy Solar energy can be captured in photovoltaic cells, which turn sunlight into electric current, or in materials that retain heat.

Section Two Pollution

A pollutant is a substance that contaminates the air, land, or water.

Air Pollution Air pollution sources include soot, smoke, ash, and gases such as carbon dioxide, carbon monoxide, nitrogen oxides, and sulfur oxides.

Pollution Smog is created when sunlight reacts with pollutants.

Pollution Acid precipitation results from air pollutants reacting with water in the atmosphere. Acid rain can kill plants and animals. Reducing the use of high sulfur coal and lowering pollutants from vehicle exhaust can help prevent acid rain.

Pollution The atmosphere traps heat through the greenhouse effect; increased carbon dioxide trapped in the atmosphere may cause global warming. Ozone depletion, the thinning of the ozone caused by chlorofluorocarbons (CFCs) and can result in increased UV radiation reaching Earth’s surface.

Pollution Insulation can trap indoor air pollutants such as carbon monoxide or radon.

Water Pollution Water is polluted when air or land pollutants enter the rivers, lakes, or oceans.

Water Pollution Surface water pollutants include chemical pesticides, raw sewage, and fertilizer. Rivers and streams dump pollutants into the ocean; oil spills are also a source of seawater pollution. Groundwater can become polluted as it seeps through particles of rock and soil or collects in underground pools called aquifers.

Erosion Erosion is the movement of soil from one place to another; it causes the loss of fertile topsoil. Soil can be polluted by solid wastes in landfills or by hazardous waste such as dangerous chemicals or radioactive materials.