Chapter 4 Land and Soil Resources - PowerPoint by liwenting


									 Chapter 4
Land and Soil
             Section 1
      Conserving Land and Soil
 3 uses that change the land are
  agriculture, development, and mining.
 Less than 1/3 of Earth can be farmed.
  New farmland must be created for the
  growing populations.
 In the U.S. about a million hectares of
  farmland is developed each year.
 Development is the construction of
  buildings, roads, bridges, dams and other
   Mining is the removal of nonrenewable resources
    such as iron, copper, and coal from the land.
   Strip mining removes a strip of land to obtain minerals, and
    then replacing the strip. This exposes the soil and can be
    washed or blown away. These areas can remain barren for
    years before they are rich enough to support the growth of
    new plants.
         Protecting the Soil
 Poorsoil management can result in 3
 problems: erosion, nutrient
 depletion, and desertification.
   Litter: The very top layer of dead leaves and
   Topsoil: A mixture of rock fragments, nutrients,
    water, air, and decaying animal and plant matter.
   Subsoil: Below the topsoil, contains rock
    fragments, water and air, but less animal and
    plant matter.
   Bedrock: Soil that makes up Earth’s crust.
   It takes hundreds of years to form just a few
    centimeters of new soil.
Is the process by which water, wind,
  or ice moves particles of rocks or
               Nutrient Depletion
   Nutrient Depletion: When farmers plant the
    same crops in a field year after year. As a result,
    the plants use more nutrients than the
    decomposers can replace. The soil becomes less
 The  advance of desertlike conditions
 into areas that previously were
         Restoring the Land
 Land  Reclamation: The process of
  restoring an area of land to a more
  natural, productive state.
 Smooth and replace strip mines with
  new topsoil.
 Plant grass.
 List three ways that people use land.
 What are 3 problems that can occur
  when topsoil is not properly
 Describe the effects of strip mining.

 Describe two methods for reducing
  soil erosion.
                      Section 2
                     Solid Waste
   Every hour people throw away 2.5 million plastic bottles.
   Every year people throw away enough white paper to build
    a wall 4 meters high that stretches coast to coast.
   Every year people throw away 1.6 billion pens, 2.9 million
    tons of paper towels, and 220 million automobile tires.
   Problem of Waste Disposal
 Municipalsolid waste : Waste
 materials produced in homes,
 businesses, schools, and other places
 in a community.
Three methods of handling solid waste.
   You can bury it, burn it, or recycle waste.

   Leachate: Polluted liquid, from the rainwater that has
    dissolved chemicals from the waste.
 Sanitary   Landfills: Holds municipal solid
    wastes, construction debris, and some
    types of agricultural and industrial waste.
   The burning of solid waste is called incineration.

   The advantages of incinerators is that they do not
    take up as much space as landfills, they do not
    pose the risk of polluting groundwater, and the
    heat they produce can generate electricity.

   Disadvantage is that they are more expensive to
 Recycling: The process of reclaiming raw
  materials and reusing them.
 Biodegradable: A substance that can be
  broken down and recycled by bacteria and
  other decomposers.
 Most recycling focuses on 4 major
  categories of products: metal, glass,
  paper, and plastic.
Products to Recycle
   Metals such as iron and aluminum can be melted
    and reused. Recycling metal saves money and
    causes less pollution than making new metal.
   Glass is one of the easiest products to recycle
    because it can be melted down over and over to
    make new glass containers.
   Recycling glass is less expensive than making
    glass from raw materials. Less energy is
    required. It also reduces the environmental
    damage caused by mining for sand, soda, and
   Most paper products can only be recycled a few
   Each time the paper is recycled to make pulp, the
    new paper is rougher, weaker, and darker.
   It takes about 17 trees to make one metric ton of
   When oil is refined to make gasoline and other
    petroleum products, solid materials called resins
    are left over.
   These resins can be heated, stretched, and
    molded into plastic products.
   Numbers are found on the bottom of plastic
    containers. The numbers 1 & 2 are made from
    plastics that are often recycled.
        What Can You Do?
 These are sometimes called the 3 R’s –
  Reduce, Reuse and Recycle.
 Reduce: Refers to creating less waste in
  the first place. (Use cloth shopping bags
  than disposable paper or plastic bags.
 Reuse: Find another use for the object
  rather than discarding it.( Example ???)
 Recycle: Reclaiming raw materials to
  create new products.
   Composting: Is the process of helping the
    natural decomposition processes break down
    many forms of waste.
   Compost is an excellent natural fertilizer for
   Examples: (Raked leaves, grass, food waste,
    eggshells, coffee grounds and cow manure)
            Section 3
        Hazardous Wastes
 Hazardous wastes are classified into
 4 categories: Toxic, Explosive,
 Flammable, and Corrosive.
          Toxic Waste
 Arepoisonous wastes that an
 damage the health of humans and
 other organisms.
        Explosive Waste
 Arewaste that react very quickly
 when exposed to air or water, or that
 explode when they are dropped.
        Flammable Waste
 Arewaste that catch fire easily and
 can begin burning at fairly low
        Corrosive Waste
 Arewaste that dissolve or eat
 through many materials.
               Radioactive Waste
   Are waste that contain unstable atoms. They require
    special disposal.
          Health Effects
 Short-term  exposure to hazardous
  wastes, may cause irritation or more
  severe health problems.
 Long-term exposure to hazardous
  wastes, may cause diseases, such as
  cancer,, and may damage body
  organs, including the brain, liver,
  kidneys, and lungs.
 Disposal of Hazardous Waste
 Methods   of hazardous waste disposal
  include burial in landfills,
  incineration, and breakdown by living
  organisms. Another method involves
  storing liquid wastes in deep rock
 Scientists have not been able to
  develop completely safe methods for
  disposing of radioactive waste.

To top