8th Grade Science

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8th Grade Science

• Unit 7
• Changes in the Earth
• Lesson 3
• Live from SAW News
• (Soil, Air, Water)
• Vocabulary of instruction

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1. Ozone Depletion

• Destruction of ozone in the ozone layer
  attributed to the presence of chlorine from
  manmade CFCs and other forces.
• The ozone layer is thinning because ozone is
  being destroyed at a faster rate than it is being
  regenerated by natural forces.

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Ozone Depletion - Facts

• The ozone layer is a belt of naturally occurring
  ozone gas that sits 9.3 to 18.6 miles (15 to 30
  kilometers) above Earth and serves as a shield
  from the harmful ultraviolet B radiation emitted
  by the sun.
• Ozone is a highly reactive molecule that contains
  three oxygen atoms. It is constantly being formed
  and broken down in the high atmosphere, 6.2 to 31
  miles (10 to 50 kilometers) above Earth, in the
  region called the stratosphere.

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Ozone Depletion - Facts

• Chlorofluorocarbons (CFCs), chemicals found
  mainly in spray aerosols heavily used by
  industrialized nations for much of the past 50
  years, are the primary culprits in ozone layer
  breakdown. When CFCs reach the upper atmosphere,
  they are exposed to ultraviolet rays, which
  causes them to break down into substances that
  include chlorine. The chlorine reacts with the
  oxygen atoms in ozone and rips apart the ozone
  molecule.

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Ozone Depletion - Facts

• Today, there is widespread concern that the ozone
  layer is deteriorating due to the release of
  pollution containing the chemicals chlorine and
  bromine. Such deterioration allows large amounts
  of ultraviolet B rays to reach Earth, which can
  cause skin cancer and cataracts in humans and
  harm animals as well.

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Loosing the Earths Protective Layer of Ozone
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Ozone Depletion - Facts

• The ozone layer above the Antarctic has been
  particularly impacted by pollution since the
  mid-1980s. This regions low temperatures speed
  up the conversion of CFCs to chlorine. In the
  southern spring and summer, when the sun shines
  for long periods of the day, chlorine reacts with
  ultraviolet rays, destroying ozone on a massive
  scale, up to 65 percent.

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Ozone Depletion - Facts

• About 90 percent of CFCs currently in the
  atmosphere were emitted by industrialized
  countries in the Northern Hemisphere, including
  the United States and Europe. These countries
  banned CFCs by 1996, and the amount of chlorine
  in the atmosphere is falling now. But scientists
  estimate it will take another 50 years for
  chlorine levels to return to their natural levels.

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2. Soil Profile

• The vertical section of a soil, showing the
  nature and sequence of the various layers, as
  developed by deposition or weathering, or both.
• The vertical sequence of recognizable horizons
  resulting from the development of a soil over
  time. Different soils have slightly different
  profiles because of local conditions and
  processes.

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2-A. Soil Profile Horizons

• A typical profile would comprise the following
  horizons or zones organic horizons (L, F, H, and
  O) mixed mineral and organic horizons (A)
  eluvial horizon (E) horizons of accumulation
  (B) rock undergoing alteration horizon (C).
  Soils that are periodically waterlogged may also
  have a gleyed horizon (G).

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2-B. Soil Profile Horizons
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3. Xeriscaping

• Landscaping designed specifically for areas that
  are susceptible to drought, where water
  conservation is practiced. Derived from the Greek
  xeros meaning "dry," the term, xeriscape means
  literally "dry landscape."
• Xeriscaping and xerogardening refers to
  landscaping and gardening in ways that reduce or
  eliminate the need for supplemental irrigation.

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3-A. Xeriscaping

• Xeriscaping and /or xerogardening recommended and
  promoted in areas that do not have easily
  accessible supplies of fresh water, and is
  gaining acceptance in other areas as climate
  patterns shift.

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Dry Landscapes
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Drought Resistant Plants and Adaptations
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Drought Resistant Plants and Adaptations
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Drought Resistant Plants and Adaptations
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Drought Resistant Plants and Adaptations
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Drought Resistant Plants and Adaptations
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Drought Resistant Animals and Adaptations
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Drought Resistant Animals and Adaptations
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Drought Resistant Animals and Adaptations
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Drought Resistant Animals and Adaptations
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Drought Resistant Animals and Adaptations