different gasses in atmosphere and their effects

1. Assignment Of Anthropology
Roll # 1774
Submitted by : Asma Sattar
Submitted to : Ma’m Sobia
Department Of Environment Science
2nd Semester : 2011-2015
GCUF
Created by :
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2. Contents
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Atmospheric chemistry definition
Atmospheric composition
Visuals of composition of Earth’s atmosphere
Essential gasses and harmful gasses
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Carbon mono oxide
Nitrogen oxides
Hydro oxides
Sulphur oxides
Mercury emissions
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Atmospheric problems
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Acid rain
Smog
Global warming
Ozone depletion
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Slide no.
References
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3. • Definition:
Atmospheric chemistry is a branch of atmospheric science in which the
chemistry of the earth atmosphere and that of other planets is studied,
the was gases, liquids and solids in the atmosphere interact with each
other and with earth’s surface and associated biota, and how human
activities may be changing the chemical and physical characteristics of
the atmosphere.
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4. Atmospheric composition
The atmosphere is compose of mixture of gases in different proportions.
i.e.,
Average composition of dry atmosphere (mole fractions)
 Nitrogen, N2: 78.084%
 Oxygen, O2: 20.946%
 Argon, Ar: 0.934%
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Minor constituents (mole fractions in ppm)
Carbon dioxide, CO2: 383
Neon, Ne: 18.18
Helium, He: 5.24
Methane, CH4: 1.7
Krypton, Kr: 1.14
Hydrogen, H2: 0.55
Water
Water vapor : highly variable
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5. Visualization of composition by volume
of Earth’s atmosphere:
Diatomic molecules: nitrogen and oxygen are more dominant constituents of
atmosphere
Nobel gasses: Argon(Ar) is present in much higher concentration then neon,
helium, krypton and xenon.
Water vapors: accounts for roughly 0.25% of atmosphere, is a highly variable
constituent with concentration ranging from around 10 ppmv in coldest region
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and up to 5% by volume in hot region.

6. Essential gasses:
O2: requires for breathing
CO2: requires for plants photosynthesis
N2: used by nitrogen fixing bacteria
O3: absorb most of the cosmic rays and major proportion of
electromagnetic radiations coming from the sun
Water vapors: responsible for sustaining form of life on the Earth
Harm full gases:
Carbon monoxide
Nitrogen oxides
Sulphur oxides
Hydro carbons
Mercury emissions
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7. Carbon monoxide
Natural sources:
 Volcanic eruption
 Natural gas
 Oxidation of methane
Human activities:
 Fuel burning in various types of transportation
 Forest fires
 Combustion of fossil fuel
 Agricultural products
Impacts:
 Highly poisonous gas
 Causes suffocation if inhaled
 Bind blood hemoglobin
 Exposure to high concentration of CO results in headache, fatigue,
unconsciousness and eventually death.
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8. Nitrogen oxides
Natural sources:
 Bacterial action produces NOx mainly NO
Human activities:
 Combustion of coil, oil, natural gas gasoline
 Oxidation of nitrogenous compounds present in fossil fuels
N2+O2
2NO
2NO+O2
2NO2
Impacts:
 Acid rain
 Dust particles
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9. Hydro carbons oxides
Natural sources:
 Different trees and plants
 Paddy field
 Anaerobic decomposition of organic matter
Human activities:
 Auto mobiles
 Petroleum
 Coal , wood
 Incinerators
 Refuse burning
 Solvent evaporator
Impacts :
 Global warming
 Climate change
 Smog
 Air pollution
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10. Sulphur oxide
Natural sources:
 Volcanoes 67%
 Oxidation of sulphur containing gases produce by decomposition of
organic matter
Human activities:
 Combustion of coal (containing 1-9%) crude oil and other fossil fuels in
power plants and petroleum industry.
S+O2  SO2
2SO2+O2  2SO2
Impacts:
 Irritant and suffocating b/c of pungent odour
 Acid deposition in atmosphere
 Sulphate aerosols
 Respiratory troubles among older people
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11. Mercury emissions
Natural sources:
 Gold and silver mining
Human activities:
 Industries
 Fluorescent lamps
 The burning of coal
 Cement production
 Caustic soda production
 Pig iron and steel production from batteries
Impacts:
 Methyl mercury accumulates in fish affect water quality
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12. Atmospheric problem
Acid rain:
Acid rain is a mixture of sulphuric and nitric acids
Wet deposition:
 Rain
 Hail
Process involved in acid deposition
 Snow
 Fog
Dry deposition:
 Gasses and particles
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13. Causes & chemistry:
a)
Acid reaction with sulphur
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S+O
SO2
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2SO2+O2
2SO3
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SO3+H2O
H2SO4
b) Acid reaction with nitrogen
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N2+O2
2NO
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2NO+O2
2NO2
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4NO3+O2+2H2O
4HNO3
Environmental effects:
Water and marine life:
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Extinction of fishes in lakes
Flora:
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Damage of plants, forest, crops tissues and death of whole tree
Soil:
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Improper growth of plants
Human health:
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Respiratory problems
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14. Smog :
Smog is a combination of smoke and fog
Types :
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Reducing smog
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Oxidizing smog or photo chemical smog
Conditions required for formation of smog:
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Sufficient NO, hydro carbons, volatile organic compounds
Sunlight
Movement of air mass
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15. Sources of smog
Man made sources:
• Vehicle exhaust
• Industrial emissions
• Biomass burning
• Peg benzene
Natural sources:
• Vegetation
• Trees
• Rain forests
• Isoprene
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16. Global warming:
Global warming is the rising average temperature of earth’s atmosphere and
oceans and is caused by increasing concentration of green house gases.
Green house gases: water vapors, methane, CO2, ozone, nitrous oxides,
and chlorofluorocarbons.
Effects of global warming:
• Ice sheet melting
• Rise in sea levels
• Wildlife effects
• Human health
• Increase in hurricanes
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17. Ozone depletion:
ozone layer protects the earth from the ultra violet rays sent down by the
sun, if the ozone layer is depleted by human action are disastrous. Ozone is
a relation of oxygen and is made of three oxygen atoms (O3).
Reaction:
ozone itself can be photolysed with weak ultra violet light and even with the
light from the range of wavelengths which can be seen by the human eye.
From the splitting of ozone, oxygen molecules (02) and atoms (O) are
produced again. The atomic oxygen can collide with another ozone
molecule and split it up, to produce two oxygen molecules.
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18. The reactions of ozone synthesis and photolysis occur very quickly
CFCl3 ----------> CFCl2 + Cl
Cl + O3 ------------>ClO + O2
ClO + O--- -------> Cl + O2
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19. Natural cause:
Volcanoes and oceans releases large amount of chlorine
Human activities:
• chlorofluouro carbons (CFCs)
• hydrofluoric carbons (HFCs)
• ozone depleting substances (ODS)
• methyl bromide ( used as pesticide)
• halons (used in fire extinguishers)
• methyl chloroform
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20. References
Websites :
 www.environment.nationalgeographic.com
 www.atmospheric-chemistry-and-physics.net
 www.wikipedia.com
 www.stuffintheair.com
 www.amazon.com
 http://wiki.answers.com/Q/what are some of the harmful gases being
emitted into the atmosphere.
Books:
 Chemistry 12, 1st edition , publisher – Shaikh Barkat Ali & sons
Lahore by Dr.Jamil Anwar & M.Akram Kashmiri
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