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AdelfaChampacaSampaguita
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THE EARTH’S ATMOSPHERE
The atmosphere is the envelope of gases that surround our planet
It is a very thin layer compared to the radius of the Earth
We refer to this layer informally as “air”
The majority of the energy that drives the atmosphere is from the Sun.
The atmosphere receives most of this energy from the surface.
Atmospheric CompositionDry air (neglecting water vapor) is
composed of the following gases:
Nitrogen (N2) = 78%
Oxygen (O2) = 21%
Argon (Ar) = 1%
Trace Gases
Dust, bacteria, and other particulates
Atmospheric Composition Trace Gases
Gases that are only found by examining a million or billion air molecules
Examples include:○ Carbon Dioxide (CO2) = 340 ppmv
○ Neon (Ne) = 18 ppmv○ Helium (He) = 5 ppmv○ Methane (CH4) = 2 ppmv
○ Hydrogen (H2) = 0.5 ppmv
Atmospheric Molecules
Note that the Oxygen, Nitrogen, and Hydrogen that we breathe are not single atoms of that gas, but instead are two atoms of that gas bonded together in what is called a diatomic molecule.
Ozone is an example of a triatomic molecule with three oxygen atoms.
Atmospheric Composition
Water vapor (H2O) is a variable gas. You will see it depends on temperature and the availability of liquid water. A volume of air can have between 0% and 4% water vapor, and this varies both in time and space.
THE EARLY ATMOSPHERE
Hydrogen and Helium as starting materials
Presence of methane and ammonia
Water vapor, carbon dioxide, nitrogen
OUTGASSING
Formation of oceans and other bodies of water
Formation of early limestone and rocks
Depletion of carbon dioxide and water abundance of nitrogen gas
Abundance of oxygen ?
H2O Oxygen
Hydrogen
LAYERS of the ATMOSPHERE
TROPOSPHERE
Innermost layer
Contains most of the air molecules necessary for life
Starts at the surface of the earth – 17 km vertically
Weather changes
Lowest Part Higher temperature
Higher Part Temperature decreases
Air pressure is lower
Above 11 km Temperature stops decreasing
(tropopause)
Remains constant with height
STRATOSPHERE
About 20 km above Earth’s surface
Extends from about 17 to 48 km
Temperature gradually increases
Ranges from -60C to -50 C
Calm air
Almost same composition as the troposphere but with greater water vapor and ozone
“global sunscreen”
Presence of OZONE molecules Absorbs UV radiation Formation of OZONE
O2 + UV 2O
O + O2 O3
O3 + UV 3O2
OZONE LAYER Region between 20 km and 30 km
The UPPER ATMOSPHERE
MESOSPHERE Above 50 km Air is very thin Very few oxygen molecules Average temperature is -90 C
THERMOSPHERE Outermost layer Very few molecules of air present High temperature ( 2000 C) auroras Ionosphere
EXOSPHERE
Very thin layer which merges into the outer space.
Global Processes
GREENHOUSE EFFECT
OZONE SHIELD
SHORT QUIZ
Why is the OZONE LAYER very important to human life ?
Greenhouse effect and ozone shield are natural processes essential to life that takes place in the atmosphere. What happens to these when we add chemicals to the atmosphere? Be specific.
The Air We Breathe
N2
CO2
Water vapor
Argon
- Unreactive
- Useful application in industry - Inert filler gas for light bulbs- Extends the life of light bulbs
What else could we possibly inhale when we breathe?
CO2
SO2
O2
Pb Other particulate matter
AIR POLLUTION
WHAT is AIR POLLUTION?
Stationary and Area SourceSTATIONARY SOURCE emission source that
does not move
large emitters who release relatively consistent qualities and quantities of pollutants.
Stationary and Area SourceAREA SOURCE smaller stationary
sources located together whose individual emissions may be low but whose collective emissions can be significant
Mobile Sources capable of moving
under its own power; imply on-road transportation
non-road or off-road category (gas-powered lawn tools and mowers, farm and construction equipment, recreational vehicles, boats, planes, and trains)
Agricultural Sources
raise animals and grow crops, can generate emissions of gases, particulate matter, and chemical compounds.
Agricultural Sources For example, animals
confined to a barn or area (rather than field grazing), produce large amounts of manure.
Manure emits various gases, particularly ammonia into the air.
Agricultural Sources In crop production, the
misapplication of fertilizers, herbicides, and pesticides can potentially result in aerial drift of these materials.
Natural Sources not caused by people
or their activities erupting volcano emits
particulate matter and gases
forest and prairie fires can emit large quantities of pollutants
Natural Sources not caused by people
or their activities plants and trees emit
hydrocarbons; and dust storms can create large amounts of particulate matter.
Natural Sources wild animals in their natural
habitat are also considered natural sources of pollution
given that there is a certain amount of natural pollution, it is very important to control the "excess" pollution caused by man’s activities.
Major Pollutants
PRIMARY
Enters the air as the direct result of a specific activity
SECONDARY
Formed by the further reaction of a primary air pollutant
Sulfur dioxide
4 FeS2 + 11O2 - 2Fe2O3 + 8 SO2
forms as coal and petroleum products burn an irritating gas with a harsh acrid odor
pyrite oriron pyrite
oxygen iron oxide sulfurdioxide
Primary or secondary?
Sulfur trioxide
2 SO2 + O2 - 2 SO3
Highly irritating gas Choking, irritating sensations
sulfurdioxide
oxygen sulfurtrioxide
Sulfur trioxide
2 SO3 + H2O - H2SO4
Dissolves in atmospheric water droplets to produce acid rain
sulfurtrioxide
water sulfuricacid
Primary or secondary?SOx
Nitrogen oxides (NOx)
Nitrogen comes from the air rather than from impurities in fuels
High temperature of lightning and combustion chambers of the internal combustion engine
N2 + O2 - 2 NO
nitrogen oxygen nitric oxide
Primary or secondary?
Nitrogen dioxide
Red-brown toxic gas Irritation to the eyes and the respiratory system Inflammation of the lungs, fatal in a few days Produce HNO3, a component of acid rain
2 NO + O2 - 2 NO2
nitric oxide oxygen nitrogendioxide
Primary or secondary?
OUTDOOR Air Pollution
Fuel Combustion
Carbon monoxide Odorless, tasteless,
and invisible
Drowsiness, headache, dizziness, and nausea
Has greater affinity to hemoglobin
Can lead to asphyxiation or even death
Soot
Soft black allotrope of carbon
Contains PAHs
Carbon dioxide Primary product of combustion
A greenhouse gas
Lead (Pb) Burning of leaded gasoline Neurotoxin
Other sources of lead ?
Airborne Pathogens
Disease-causing agents SARS
Particulate Matter
Very small solid or liquid droplets
Soot, pollen, smoke particulates, and dust
PM-10Lead, iron, copper, nickel particulates
Photochemical Smog
NO2 - NO + Onitrogendioxide
nitricoxide
oxygenatom
O + O2 - O3
oxygenatom
oxygenmolecule
ozone
sunlight
Photochemical Smog a still, sunny day
temperature inversion (pollutants accumulate in the lower inversion layer)
Organic compoundsVOC and VOS Volatile hydrocarbon components of consumer
products (paint thinners, roof tar, petroleum distillates)
Evaporating solvents and propellants (nail polish, deodorants, after-shave lotions, hair sprays, insecticides)
Ethyl acetate and more exotic additives that you exhale (chewing gum and breath fresheners)
Acid Deposition
Acid Rain
Acid Rain
Ozone DepletionOZONE
a form of oxygen, contains three oxygen atoms unstable and will readily combine with other atoms
found in the stratosphere, where it blocks the sun's ultraviolet (UV) waves and prevents them from reaching the earth's surface
also found in the troposphere, where it can damage livingtissue and human-produced objects. It is generated both from certain types of pollution and natural sources
ozone
absorbs the potentially harmful ultraviolet (UV) radiation from the sun
Ozone
Source: World Meteorological Organization, Scientific Assessment of Ozone Depletion: 1998, WMO Global Ozone Research and Monitoring Project - Report No. 44, Geneva, 1998
www.epa.gov/ozone/science/sc_fact.html
Ozone
Ozone Depletion
Chain Initiation
Chain Propagation
ozone
Southern HemisphereSeptember 17, 2001
The “ozone hole” forms over Antarctica during the Southern Hemisphere spring.
In 2001, the ozone hole extended over about 26 million square kilometers, larger than the area of the continental United States!
INDOOR Air Pollution
HW. Notebook
What is indoor pollution?
What are the sources of indoor pollution?
List at least 5 chemical found in your household that can be a source of indoor pollution.
INDOOR Air Pollution
Environmental Tobacco Smoke
ETS Combination of mainstream smoke and
sidestream smoke Contains about 4000 chemical
compoundsAmmonia, hydrogen cyanide, toluene
Nicotine
Common Household chemicals
Insects spray Toilet cleaners Moth repellants Dog sprays Shampoos Air freshener Colognes Perfumes
HW. Notebook Air Pollutant Description Health Risks
Dust Mite
ETS
VOCs
Combustion Product
Chlorinated Chemicals
Asbestos