Science1206 Final topics and review

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Science1206Final topics and review
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• The atmosphere is a mixture of particles and
  gases which provides air, retains heat that warms
  the Earth, and has a layer of ozone that protects
  us from UV radiation.
• The atmosphere is made up of several layers. Two
  regions the troposphere and the stratosphere are
  relatively closer to the Earth than the others.
• The troposphere extends from the Earth's surface
  to an altitude as high as seventeen kilometers
  above the Earth. In this region the temperature
  decreases as altitude increases.
• The stratosphere is located above the troposphere
  to about fifty kilometers above Earth and the
  temperature increases as altitude increases.

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Sources of Water Pollution

• Water pollution is any physical or chemical
  change in surface or ground water that can harm
  living things.
• Five categories
• Organic solid waste
• Disease causing organisms
• Inorganic solids and dissolved minerals
• Heat
• Organic chemicals
• Water is defined by its intended use. There are
  three main indicators of water quality
• Bacteria count
• Concentration of dissolved oxygen
• Biochemical oxygen demand

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Bacteria Detection is expensive and difficult.
Detecting coliform bacteria is used to see if
disease causing bacteria is present. The presence
of coliform bacteria indicates that more
dangerous bacteria may be present. Dissolved
Oxygen Different solutions are used to test for
oxygen. They change color in the presence of
oxygen. Another way is to examine living things
in the water. Trout indicate high oxygen levels.
Catfish and carp indicate low oxygen levels.
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BOD Biological Oxygen Demand This is the measure
of the amount of dissolved oxygen needed by
decomposers(bacteria) to breakdown the organic
matter in a sample of water over a 5 day period
at 20 degrees C. It indicates the amount of
available organic matter in a water sample. As
the number of organisms in an ecosystem
increases, so does the BOD. A productive lake
with many living things will have a high BOD. As
the number of organisms increases and biological
demand increases , more organisms use oxygen from
the water. This will cause dissolved oxygen to
drop. (eg. Low value2 mg/L high value 20 mg/L)
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Sewage, Decomposers and Oxygen Levels
Too many nutrients can create problems for
lakes. For example when raw sewage is released
into an aquatic ecosystem. The greater the
amount of decaying matter introduced into the
water, the greater will be the population of
decomposing bacteria. Both bacteria and fish use
oxygen, and fish will die if oxygen levels drop
too low. Dead fish create detritus which further
promotes bacteria growth. To prevent damage to
ecosystems cities install water treatment plants.
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Aquatic eutrophication

• One of the factors that determines how many of
  these microscopic organisms live in the water is
  the availability of nutrients.
• The nutrients that have the most profound effect
  on the number of microorganisms found in the
  water are nitrates and phosphates. Low levels of
  nitrates and phosphates reduce the number of
  micro-organisms. The water appears clear and
  sunlight can penetrate deeper supporting the
  production of oxygen by photosynthetic organisms.
• Under these conditions, the pond or lake can
  support large populations of fish and other
  organisms that are adapted to relatively high
  levels of oxygen. Such a lake in which oxygen
  levels are relatively high is known as an
  oligotrophic lake.

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Aquatic eutrophication

• Bodies of water enriched by nitrates and
  phosphates mainly from agricultural lands and
  from untreated human or animal sewage causes the
  number of micro-organisms to increase to the
  point that the water actually appears turbid
  (cloudy). As a result of the bacteria, less light
  is able to penetrate the water and oxygen
  concentrations tend to be reduced. Such a lake is
  said to be eutrophic.

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Go to Work

• Read 4.2 "Sources of Water Pollution" on pages
  132 - 134.

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Short Term Stress and Long Term Stress
Describe what is meant by short term stress and
long term change Identify factors that cause
extinction of animals including influence of
humans, climate change, and pressure of
competition Compare a natural and an artificial
ecosystem in terms of the influence of different
abiotic factors on the organisms that live there
Describe how acid deposition affects a forest
ecosystem Describe how the introduction of an
exotic species (zebra mussel) has affected life
in the great lakes
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• The way that a population responds to short term
  stress and long term change depends on the
  ability of the organisms within the population to
  continue to meet their biological needs for
  appropriate range of climatic conditions
  (temperature, light, moisture), food, water,
  shelter, space, and opportunity for reproduction.
  
• Most organisms are capable of withstanding a loss
  of one or more of these factors for a short
  period of time, but will die if one or more of
  these biological needs is not met for a long
  period of time. Some populations may become
  extinct as a result of long term change.

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Examples of short term stress include seasonal
peaks in temperature, sudden changes in water
supply, or sudden but limited human impact.
Climate change (global warming), infestation by
foreign plants and animals (exotic species), and
permanent human influence (habitat destruction,
acid deposition, etc.) are examples of long term
change.
Pine Marten
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Keystone Species

• A keystone species is one considered so important
  to the stability of the ecosystem, that if there
  was a decline in that species, the community
  would not be able to maintain its stability and
  may even collapse.
• Nearly any arctic organism could represent this
• Killer Whale
  Prairie dog
  European Beaver Flying
  Fox Grizzly Bear