Protecting the Biosphere

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Protecting the Biosphere

• (Chapter 19)

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The Biosphere

• Human populations have important impacts on
  ecosystems, both locally and globally.
• An ecosystem refers to the collection of biotic
  and abiotic components and processes that
  comprise, and govern the behavior of some defined
  subset of the biosphere. Elements of an ecosystem
  may include flora, fauna, lower life forms, water
  and soil.
• Introduction of new elements, whether abiotic or
  biotic, into an ecosystem tend to have a
  disruptive effect. In some cases, this can lead
  to ecological collapse or "trophic cascading" and
  the death of many species belonging to the
  ecosystem in question.

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The Biosphere

• The biosphere is the outermost part of the
  planet's shell including air, land, surface
  rocks and water within which life occurs, and
  which biotic processes in turn alter or
  transform.
• The atmosphere supports all its ecosystems as
  most forms of life require oxygen.
• Atmosphere maintains Earths surface temp.
• Cooler if we had a much denser atmosphere
• Much warmer that no atmosphere at all.

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The Biosphere
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How the atmosphere formed

• The variations in concentration from the Earth to
  Mars and Venus result from the different
  processes that influenced the development of each
  atmosphere.
• While Venus is too warm and Mars is too cold for
  liquid water the Earth is at just such a distance
  from the Sun that water was able to form in all
  three phases, gaseous, liquid and solid.
• Through condensation the water vapor in our
  atmosphere was removed over time to form the
  oceans. Additionally, because carbon dioxide is
  slightly soluble in water it too was removed
  slowly from the atmosphere leaving the relatively
  scarce but unreactive nitrogen to build up to the
  78 is holds today.

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How the atmosphere formed

• The Primitive Earth.
• Theorized early primitive atmosphere consisted
  mostly of
• water vapor, nitrogen, and carbon dioxide, with
  small amounts of hydrogen and carbon monoxide.
• Little, if any, free oxygen
• At first the earth was very hot
• Water existed as a gas

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Figure 19.1 (1)
How the atmosphere formed
It is thought that the original atmosphere was
mostly H2. Most Carbon was combined with
Hydrogen into Methane (CH3). Most Nitrogen was
combined with Hydrogen into Ammonia (NH4). Most
Oxygen was combined with Hydrogen to form water
vapor.
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Figure 19.1 (2)
How the atmosphere formed
A heterotroph is an organism that requires
organic substrates to get its carbon for growth
and development. These simple bacteria gave off
CO2. So atmospheric CO2 levels increased.
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Figure 19.1 (3)
How the atmosphere formed
With the development of photosynthetic
organisms, the CO2 was used to make sugars with
the by product of oxygen! Over billions of years
the O2 level increased as CO2 was being
used. But wait! Where did the organic material
come from?
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Figure 19.2
How the atmosphere formed
Stanly Millers Experiment -1952. Amino acids,
simple sugars, and most of the building blocks
for DNA and RNA were produced. An energy source
is required for the formation of these
molecules. These expts, repeated thousands of
times have produced so many biologically
important products that the conclusion is not in
doubt All molecules important to life where made
in the primitive atmosphere
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Structure of the atmosphere

• In large measure, the atmosphere has evolved in
  response to and controlled by life processes.
• It continues to change as a consequence of human
  activities.
• Controls the climate and ultimately determines
  the quality of life on Earth

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Structure of the atmosphere

• The ground heats up due to the absorption of
  visible light from the Sun.
• The warm ground, in turn, heats the atmosphere
  via the processes of conduction, convection
  (turbulence) and infrared radiation
• The reason for the strange-looking temperature
  profile? Regions of high temperature are heated
  by different portions of the solar radiative
  output.

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Structure of the atmosphere

• The Troposphere
• where all weather takes place it is the region
  of rising and falling packets of air.
• The air pressure at the top of the troposphere is
  only 10 of that at sea level (0.1 atmospheres)
• The Stratosphere
• The thin ozone layer in the upper stratosphere
  has a high concentration of ozone, a particularly
  reactive form of oxygen.
• This layer is primarily responsible for absorbing
  the ultraviolet radiation from the Sun.

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Structure of the atmosphere

• The Mesophere Thermosphere
• Many atoms are ionized (have gained or lost
  electrons so they have a net electrical charge).
• The Thermosphere is very thin, but it is where
  aurora take place
• Is responsible for absorbing the most energetic
  photons from the Sun,
• Reflecting radio waves, thereby making
  long-distance radio communication possible
• Thermosphere is heated by the absorption of
  extreme ultraviolet (EUV) light

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The Biosphere

• The atmosphere sustains life and is sustained by
  life.
• The Gaia hypothesis
• The entire planet is a living breathing organism
  and will protect itself homeostasis of the
  whole planet!!!
• The biosphere works in cycles
• Nitrogen
• Carbon
• Water

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The Biosphere

• Water cycle
• The resulting water vapor mixes with the
  atmosphere
• At high altitudes where the air is cold enough it
  condenses to form rain and snow
• Falls back to Earth.

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The Biosphere

• Water cycle
• Water evaporates from bodies of fresh water and
  the oceans
• Much water is lost from the leaves of plants via
  transpiration.
• Also from respiration of almost all living
  species

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So, whats up with the biosphere?

• POLLUTION!!!!!!!!!!!!!!!
• This is any substance that is present in the
  wrong quantities or concentration, in the wrong
  place, at the wrong time.
• Toxic dumps and oil spills are the main two forms
  of pollutants that damage the biosphere.

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Figure 19.6
Acid Rain

• Occurs when sulphur dioxide and nitrogen oxides
  are emitted into the atmosphere, undergo chemical
  transformations and are absorbed by water
  droplets in clouds.
• The droplets then fall to earth as rain, snow,
  mist, dry dust, hail, or sleet.
• This can increase the acidity of the soil, and
  affect the chemical balance of lakes and streams

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Acid Rain

• Wet deposition
• Occurs when any form of precipitation (rain,
  snow, etc) removes acids from the atmosphere and
  delivers it to the Earth's surface.
• This can result from the deposition of acids
  produced in the raindrops or by the precipitation
  removing the acids either in clouds or below
  clouds.
• Wet removal of both gases and aerosol are both of
  importance for wet deposition.

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Acid Rain

• Dry deposition
• Acid deposition also occurs via dry deposition in
  the absence of precipitation.
• This can be responsible for as much as 20 to 60
  of total acid deposition.
• This occurs when particles and gases stick to the
  ground, plants or other surfaces

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Acid Rain

• Dry deposition
• Acid deposition also occurs via dry deposition in
  the absence of precipitation.
• This can be responsible for as much as 20 to 60
  of total acid deposition.
• This occurs when particles and gases stick to the
  ground, plants or other surfaces

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Surface Waters and Aquatic Animals

• Both the lower pH and higher aluminium
  concentrations in surface water that occur as a
  result of acid rain can cause damage to fish and
  other aquatic animals.
• At pHs lower than 5 most fish eggs will not hatch
  and lower pHs can kill adult fish.
• As lakes become more acidic biodiversity is
  reduced.
• Acid rain has eliminated insect life and some
  fish species, including the brook trout in some
  Appalachian streams and creeks.

Not all fish, shellfish, or the insects that they
eat can tolerate the same amount of acid for
example, frogs can tolerate water that is more
acidic (i.e., has a lower pH) than trout.
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Surface Waters and Aquatic Animals

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Figure 19.8
Ozone depletion

• Used to describe two distinct but related
  observations
• A slow, steady decline of about 3 percent per
  decade in the total amount of ozone in Earth's
  stratosphere during the past twenty years
• A much larger, but seasonal, decrease in
  stratospheric ozone over Earth's polar regions
  during the same period. The latter phenomenon is
  commonly referred to as the ozone hole.

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Figure 19.8
Ozone depletion

• Ozone (O3) is a triatomic molecule, consisting of
  three oxygen atoms.
• The highest levels of ozone in the atmosphere are
  in the stratosphere, in a region also known as
  the ozone layer between about 10 km and 50 km
  above the surface.
• Here it filters out the shorter wavelengths (less
  than 320 nm) of ultraviolet light (270 to 400 nm)
  from the Sun that would be harmful to most forms
  of life in large doses.

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Figure 19.8
Ozone depletion

• These same wavelengths are also responsible for
  the production of vitamin D, which is essential
  for human health.
• Since 1955, the ozone levels have steady
  declined each year.
• Main reason for this depletion
• Chlorofluorocarbons (CFCs)
• Used as nontoxic refrigerants
• Expellant in aerosols
• In 1987, 43 nations met to cut back on the use of
  these compounds.

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Figure 19.8
Ozone depletion

• Effects on Humans
• UVB (the higher energy UV radiation absorbed by
  ozone) is generally accepted to be a contributory
  factor to skin cancer.
• In addition, increased surface UV leads to
  increased tropospheric ozone, which is a health
  risk to humans.
• Effects on Crops
• An increase of UV radiation would also affect
  crop. A number of economically important species
  of plants, such as rice, depend on cyanobacteria
  residing on their roots for the retention of
  nitrogen. Cyanobacteria are very sensitive to UV
  light and they would be affected by its increase.

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Figure 19.9
CO2 and Global Warming

• The greenhouse effect
• The process in which the absorption of infrared
  radiation by an atmosphere warms a planet.
• Without these greenhouse gases, the Earth's
  surface would be up to 30 C cooler.
• CO2 is used in photosynthesis to make
  carbohydrates.
• CO2 levels rise at night and fall during the day
  naturally.
• Due to the photosynthetic activity of plants
• CO2 is released during respiration or when
  organic compounds are burned.

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Figure 19.9
CO2 and Global Warming

• An increase of CO2 decreases the amount of heat
  which can escape through the atmosphere.
• Thus the temperature of the Earth increases.
• This has many effects.
• Warmer Ocean layers.
• Atmospheric shifts.
• Warmer surface temperatures
• 2005 was hottest year on record.

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Figure 19.9
CO2 and Global Warming

• First detected in 1896
• Causes droughts in semi-arid grassland areas.
• Increase in number and severity of forest fires.
• Partial melting of the polar ice caps.
• Will lead to increase in sea level.
• Pathogens that exist in warm climates will become
  more widespread.

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Figure 19.9
CO2 and Global Warming

• As climates shift, many existing species of
  plants and animals will become extinct.
• Biodiversity would suffer a decline of uncertain
  scope.
• Following the start of the industrial revolution
  CO2 content has increased 25.
• Global temperatures and CO2 levels rise and fall
  together

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Bioremediation

• Some types of pollution can be reduced, and
  habitats restored, with the help of living
  organisms.
• Use microorganisms, fungi, green plants or their
  enzymes to return the environment altered by
  contaminants to its original condition.
• may be employed to attack specific soil
  contaminants, such as degradation of chlorinated
  hydrocarbons by bacteria.
• An example of a more general approach is the
  cleanup of oil spills by the addition of nitrate
  and/or sulfate fertilizers to facilitate the
  decomposition of crude oil by indigenous or
  exogenous bacteria..

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Bioremediation

• Remember the Chernobyl Nuclear Disaster?
• Use of genetic engineering to create organisms
  specifically designed for bioremediation has
  great potential.
• The bacterium Deinococcus radiodurans (the most
  radioresistant organism known) has been modified
  to consume and digest toluene and ionic mercury
  from highly radioactive nuclear waste.

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Bioremediation

• Septic tanks and leach beds removes waste from
  water and buts the water back into the ground.
• Larger scale sewage systems are actually very
  complex ecosystems
• Have wastewater lagoons
• Water sits here for 30 days
• Algae grow in the lagoon, photosynthesize and
  give off O2.
• Allows aerobic bacteria to grow and digest
  organic matter and kill fecal bacteria.

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Summary

• Photosynthesis, and the production of O2, used to
  balance out the release of CO2 from respiration.
• However, with the destruction of over half the
  worlds Rainforests, CO2 levels are much higher
• Also due to the growth of industry and modern
  transport systems
• The Earth is our mother. What befalls the Earth
  befalls all the children of the EarthMankind
  did not weave the web of life, we are merely a
  strand in it. Whatever we do to the web, we do
  to ourselves.

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The end!

• Any Questions?