Download Protecting the Biosphere

An Ecological Perspective
(BIOL 346)
Talk Four:
The Biosphere
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.
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.
The Biosphere
SURFACE
PRESSURE
VENUS
EARTH
MARS
100,000 mb
1,000 mb
6 mb
COMPOSITION
CO2
>98%
0.03%
96%
N2
1%
78%
2.5%
Ar
1%
1%
1.5%
O2
0.0%
21%
2.5%
H2O
0.0%
0.1%
0-0.1%
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.
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
How the atmosphere formed
Figure 19.1 (1)
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.
Biological
Evolution
Figure 6.2
• First true cells were
prokaryotic.
– Eukaryotic cells evolved
later, followed by the
other kingdoms.
Biological evolution is a
change in life forms that
has taken place in the
past and will take place in
the future.
Adaptation is a
characteristic that makes
an organism able to
survive and reproduce in
an environment.
How the atmosphere formed
Figure
19.1
(2)
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.
How the atmosphere formed
Figure 19.1 (3)
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?
How the atmosphere formed
Figure 19.2
Stanly Miller’s 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
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
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 strangelooking temperature
profile? Regions of high
temperature are heated by
different portions of the solar
radiative output.
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.
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
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
So, what’s 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.
Acid Rain
Figure
19.6
• 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
• Wet deposition
Acid Rain
• 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.
• Dry deposition
Acid Rain
• 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
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.
Surface Waters and Aquatic Animals
Ozone
depletion
Figure
19.8
•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.
Ozone depletion
Figure 19.8
•Ozone (O ) is a triatomic
3
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.
Ozone
depletion
Figure
19.8
•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.
Ozone depletion
Figure 19.8
•When ultraviolet light waves
(UV) strike CFC (CFCl3)
molecules in the upper
atmosphere, a carbonchlorine bond breaks,
producing a chlorine (Cl)
atom.
•The chlorine atom then
reacts with an ozone (O3)
molecule breaking it apart
and so destroying the ozone.
Provided for use by the National Oceanic
and Atmospheric Administration (NOAA)
Ozone depletion
Figure 19.8
•This forms an ordinary
oxygen molecule(O2) and a
chlorine monoxide (ClO)
molecule.
•Then a free oxygen atom
breaks up the chlorine
monoxide. The chlorine is
free to repeat the process
of destroying more ozone
molecules.
•A single CFC molecule can
destroy 100,000 ozone
molecules.
Provided for use by the National Oceanic
and Atmospheric Administration (NOAA)
Ozone
depletion
Figure
19.8
•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
Ozone Changes
CO2 and
Global
Warming
Figure
19.9
•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.
CO2 and
Global
Warming
Figure
19.9
•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
•2014 was hottest year
on record.
Reviewing extreme weather during 2014, the
WMO highlighted a number of recordbreaking events:
• In September, parts of the Balkans received more than double the
average monthly rainfall and parts of Turkey were hit by four times
the average.
• The town of Guelmin in Morocco was swamped by more than a year's
rain in just four days.
• Western Japan saw the heaviest August rain since records began.
• Parts of the western US endured persistent drought, as did parts of
China and Central and South America.
• Tropical storms, on the other hand, totaled 72 which is less than the
average of 89 judged by 1981-2010 figures. The North Atlantic,
western North Pacific and northern Indian Ocean were among regions
seeing slightly below-average cyclone activity.
CO2 and
Global
Warming
Figure
19.9
•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.
CO2 and Global Warming
Figure 19.9
•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
Fracking
• According to the U.S.
Energy Information
Administration:
– In 2000, the USA had
342,000 natural gas wells.
– By 2010, more than 510,000
were in place — a 49% jump!
• Twenty states have shale
gas wells
– they tap rock layers that
harbor the gas in shale
formations
Taken from USA Today
29th May 2012
Fracking
• Drill down to gas layer
– Pump in
sand/water/chemicals
• Mixture cracks shale
rock and fills in with
sand
– Allows gas to move up
well hole
• Gas collected.
• Water recover for
reuse or sent to
treatment plant.
Fracking
• The most commonly used in
the USA:•
•
•
•
Methanol
Cellulose
Boric acid
zirconium, chromium, antimony,
and titanium salts
– The first three are known
carcinogens!
Used with permission from Fracfocus.com
Potential hazards due to
Fracking
• Blowout
– gas can explode out the wellhead, injuring people and spewing pollutants.
• Gas leak
– Methane could travel into the water table.
• Air pollution
– When methane is released without being burned, it acts as a potent greenhouse gas,
trapping 20 times as much heat as carbon dioxide.
• Wastewater overflow
– If stored in open pits that emit noxious fumes and can overflow with rain.
• Other leaks
– spills or illicit dumping.
• Home explosions
– If methane does get into the water table — because of cracked cement, local geology
or the effects of old wells — it can build up in homes and lead to explosions.
Then why Frack in the first
place?
• Good
• Bad/Ugly
• According to the National
Petroleum Council:
• Ground water contamination
– Without it, we would lose
45 percent of domestic
natural gas production and
17 percent of our oil
production within 5 years
• Development of shale
resources supported
600,000 jobs in 2010
• Natural Gas prices will
continue to drop
•
CO2 in shale released
• Radioactive isotopes
released from shale
– Mostly Radium & Radon gas
• Silicon dioxide released
from shale
– Natural compound, but too
much – stunted plant growth
and lung cancer
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..
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.
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.
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 end!
Any Questions?