Transcript ATMOSPHERIC POLLUTION AND ALTERNATIVE SOURCES OF …

ATMOSPHERIC
POLLUTION AND
ALTERNATIVE SOURCES
OF ENERGY
Małgorzata Mendala
III „B”
WHAT IS THE EARTH’S
ATMOSPHERE?
The Earth's atmosphere (or air) is a layer of gases
surrounding the planet Earth that is retained by the Earth's
gravity. Dry air contains roughly (by volume) 78.08%
nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon
dioxide, and trace amounts of other gases. Air also contains
a variable amount of water vapor, on average around 1%.
The atmosphere protects life on Earth by absorbing
ultraviolet solar radiation, warming the surface through
heat retention (greenhouse effect), and reducing
temperature extremes between day and night.
There is no definite boundary between the atmosphere and
outer space. It slowly becomes thinner and fades into space.
An altitude of 120 km (75 mi) marks the boundary where
atmospheric effects become noticeable during reentry. The
Kármán line, at 100 km (62 mi), is also frequently regarded
as the boundary between atmosphere and outer space.
Three quarters of the atmosphere's mass is within 11 km
(6.8 mi; 36,000 ft) of the surface.
ATMOSPHERIC POLLUTION
GREENHOUSE EFFECT
The greenhouse effect is unquestionably real and helps to
regulate the temperature of our planet. It is essential for life
on Earth and is one of Earth's natural processes. It is the result
of heat absorption by certain gases in the atmosphere (called
greenhouse gases because they effectively 'trap' heat in the
lower atmosphere) and re-radiation downward of some of that
heat. Water vapor is the most abundant greenhouse gas,
followed by carbon dioxide and other trace gases. Without a
natural greenhouse effect, the temperature of the Earth would
be about zero degrees F (-18°C) instead of its present 57°F
(14°C). So, the concern is not with the fact that we have a
greenhouse effect, but whether human activities are leading
to an enhancement of the greenhouse effect by the emission
of greenhouse gases through fossil fuel combustion and
deforestation.
SMOG: classic and photochemical
Classic Smog
In its most primitive and basic form, smog air pollution is the
result of the burning of fossil fuels. It has several major
components:
1) Smoke, which is tiny particles of ash, is released from the
smokestacks of coal fired power stations. Coal power plants are
now on the whole designed to trap this ash, called fly ash,
which can be used to great effect in the concrete industry.
These tiny particles contain not only carbon residue, but also
silicon dioxide, calcium oxide and traces of heavy metals. If
inhaled these can pose significant health risks. The silicon
dioxide in the fly ash alone can cause lesions, scarring and
inflammation of the lungs.
2) Sulfur Dioxide. Sulfur is present in all fossil fuels and is
released as Sulfur Dioxide when the fuels are burned. Sulfur
Dioxide reacts with oxygen gas to give Sulfur Trioxide. This
then can react with water to to give Sulfuric Acid (H2SO4).
Another possibility is that the Sulfur Dioxide reacts
immediately with water to give Sulfurous Acid (H2SO3).
Either way, the acid produced is highly reactive and
capable of causing significant damage to crops, soil,
buildings and more. Several industrialized nations now
employ technology that captures approximately a third of
Sulfur Dioxide from the emission gases of power stations,
greatly reducing the problems of acid rain.
Photochemical Smog
This is a far more noxious mixture of chemicals than classic
smog air pollution. Significant inroads have been made to
reduce the main contributors to classic smog. Such efforts in
relation to photochemical smog are still in their early stages.
Photochemical smog air pollution is a mixture of various
chemicals that react with sunlight to produce new
chemicals. This is where the name comes from; photo
means light and chemical means chemical, or product of a
chemical reaction. The chemical reactions involved are
complex and while they are important, we need to know
the source of these pollutants and their effects.
The chemicals involved need to be addressed separately. The
three main ingredients are Nitrous Oxides, volatile organic
compounds and Ozone. Carbon Monoxide is a toxic
byproduct of fossil fuel combustion but is considered
separate to photochemical smog.
ACID RAIN
Acid rain is rain or any other form of precipitation that is
unusually acidic. It has harmful effects on plants, aquatic
animals, and infrastructure. Acid rain is mostly caused by
human emissions of sulfur and nitrogen compounds which
react in the atmosphere to produce acids. In recent years,
many governments have introduced laws to reduce these
emissions.
"Acid rain" is a popular term referring to the deposition of
wet (rain, snow, sleet, fog and cloudwater, dew) and dry
(acidifying particles and gases) acidic components. A more
accurate term is “acid deposition”. Distilled water, which
contains no carbon dioxide, has a neutral pH of 7. Liquids
with a pH less than 7 are acidic, and those with a pH greater
than 7 are bases. “Clean” or unpolluted rain has a slightly
acidic pH of about 5.2, because carbon dioxide and water in
the air react together to form carbonic acid, a weak acid (pH
5.6 in distilled water), but unpolluted rain also contains
other chemicals.[1]
 H2O (l) + CO2 (g) → H2CO3 (aq)
Carbonic acid then can ionize in water forming low
concentrations of hydronium and carbonate ions:
 2 H2O (l) + H2CO3 (aq) CO32− (aq) + 2 H3O+ (aq)
OZONE LAYER
Ozone is a gas that occurs naturally in our atmosphere. Most
of it is concentrated in the ozone layer, a region located in
the stratosphere several miles above the surface of the Earth.
Although ozone represents only a small fraction of the gas
present in the atmosphere, it plays a vital role by shielding
humans and other life from harmful ultraviolet light from
the Sun. Human activities in the last several decades have
produced chemicals, such as chlorofluorocarbons (CFCs),
which have been released into the atmosphere and have
contributed to the depletion of this important protective
layer. When scientists realized the destructive effect these
chemicals could have on the ozone layer, international
agreements were put in place to limit such emissions. As a
result, it is expected that the ozone layer will recover in the
coming decades.
Ozone is also a greenhouse gas in the upper atmosphere and,
therefore, plays a role in Earth's climate. The increases in
primary greenhouse gases, such as carbon dioxide, may
affect how the ozone layer recovers in coming years.
Understanding precisely how ozone abundances will change
in a future with diminished chlorofluorocarbon emissions
and increased emissions of greenhouse gases remains an
important challenge for atmospheric scientists in NOAA
and other research centers.
ALTERNATIVE SOURCES OF
ENERGY
Solar Power
Solar energy is one the most resourceful sources of
energy for the future. One of the reasons for this is that
the total energy we recieve each year from the sun is
around 35,000 times the total energy used by man.
However, about 1/3 of this energy is either absorbed by
the outer atmosphere or reflected back into space (a
proccess called albedo)1.
Solar energy is presently being used on a smaller scale in
furnaces for homes and to heat up swimming pools. On a
larger scale use, solar energy could be used to run cars,
power plants, and space ships.
WIND POWER
Wind power is the conversion of wind energy into a useful
form, such as electricity, using wind turbines. At the end of
2008, worldwide nameplate capacity of wind-powered
generators was 121.2 gigawatts.[1] Wind power produces
about 1.5% of worldwide electricity use,[1][2] and is
growing rapidly, having doubled in the three years between
2005 and 2008. Several countries have achieved relatively
high levels of wind power penetration, such as 19% of
electricity production in Denmark, 11% in Spain and
Portugal, and 7% in Germany and the Republic of Ireland in
2008. As of May 2009, eighty countries around the world
are using wind power on a commercial basis.[2]
GEOTHERMALN ENERGY
Geothermal energy is the heat from the Earth. It's clean and
sustainable. Resources of geothermal energy range from the
shallow ground to hot water and hot rock found a few miles
beneath the Earth's surface, and down even deeper to the
extremely high temperatures of molten rock called magma.
TIDAL POWER
The tide moves a huge amount of water twice each day, and
harnessing it could provide a great deal of energy - around
20% of Britain's needs.
Although the energy supply is reliable and plentiful,
converting it into useful electrical power is not easy.
There are eight main sites around Britain where tidal power
stations could usefully be built, including the Severn, Dee,
Solway and Humber estuaries. Only around 20 sites in the
world have been identified as possible tidal power stations
HYDROELECTRIC POWER
Hydroelectricity is electricity generated by hydropower, i.e.,
the production of power through use of the gravitational
force of falling or flowing water. It is the most widely used
form of renewable energy. Once a hydroelectric complex is
constructed, the project produces no direct waste, and has a
considerably lower output level of the greenhouse gas
carbon dioxide (CO2) than fossil fuel powered energy
plants. Worldwide, hydroelectricity supplied an estimated
816 GWe in 2005. This was approximately 20% of the
world's electricity, and accounted for about 88% of
electricity from renewable sources.
THE END