The Atmosphere

• Troposphere

• Stratosphere

• Mesosphere

• Thermosphere

Troposphere

• Has 75% of mass of earth’s air

• Consists of 99% dry air, main two gases are nitrogen and oxygen.

• Also holds water vapor.

• Pressure decreases with altitude because average density decreases with altitude.

• Temperature abruptly rises at top.

Stratosphere

• Atmosphere’s second layer Ozone in this layer.

• Volume of water vapor is less and volume of ozone is greater than in troposphere.

• Our health depends on having enough ozone in stratosphere and little in troposphere.

Greenhouse effect

• Happens in troposphere

• Traps heat near earth’s surface

• Water, carbon dioxide, and methane involved

• Human inputs include carbon dioxide, methane, CFC’s, nitrous oxide.

• What results if global warming

Air pollution

• Presence of one or more chemicals in the atmosphere in quantities and duration that cause harm to human,s other forms of life, and materials.

Primary pollutants

• Products of natural event, dust storms, volcanic eruptions, human activities like emissions from cars and smokestacks.

• Can combine to form secondary pollutants

Primary PollutantsPrimary Pollutants

StationaryStationaryMobileMobile

SourcesSourcesNaturalNatural

Most Most hydrocarbonshydrocarbons

Most suspendedMost suspendedparticlesparticles

SOSO22 NONO NONO22

COCO COCO22 Secondary PollutantsSecondary Pollutants

SOSO33

HNOHNO33HH22SOSO44

HH22OO22OO33 PANsPANs

MostMost NONO33–– andand

SOSO4422 –– saltssalts

Sources of pollutants

• Stationary sources – power plants and factories.

• Mobile sources – cars and other mobile vehicles.

Photochemical smog

• Mixture of primary and secondary pollutants formed under the influence of sunlight.

Industrial smog

• Consists mostly of sulfur dioxide, suspended droplets of sulfuric acid, and a verity of suspended soil particles and droplets.

Temperature inversion/thermal inversion

• When a layer of dense, cool air beneath can be trapped beneath a layer of less dense warm air in an urban basin or valley.

Pollutants

warmair

cool air

• surface heated by sun• warm air rises (incl. pollutants)• cools off, mixes with air of equal density & disperses

cool air

warm air (inversion layer)

• surface cools rapidly (night)• a layer of warm air overlays surface• polluted surface air rises but cannot disperse remains trapped

What is Acid Deposition?

• Acid Deposition is the falling of

acids and acid forming compounds from the atmosphere to the earth’s surface.

• Acid deposition is also known as acid rain.

Acid Deposition Continued…

• Acidity of substances in water is pH

• Numerical measures of the concentration of hydrogen ions in a solution

• Solutions with pH less than 7

are acidic and those greater than

7 are alkaline or basic

Continued…

• Natural precipitation is slightly acidic- pH of 5.0-5.6

• Primarily because of acid deposition, typical rain in the US is

now about 10 times more acidic,

with a pH of 4.3

What areas are affected by acid deposition?

• It occurs on a rather regional

rather than on a global basis.

• Serious regional problems in areas downwind from coal burning power plants

smelters, factories, and larger urban areas.

Affected Areas continued…

• It is a growing problem in China, parts of the former Soviet Union, India, Nigeria, Brazil, Venezuela,

and Columbia.• How seriously vegetation and aquatic life

in lakes are affected depends mostly on whether its soils are acidic or basic.

What Are the Effects of Acid Deposition?

• Risk analysis experts rate acid deposition

as a medium risk to ecological

problems and his risk to human health.

• It has many harmful ecological effects.

• Contributes to human respiratory diseases such as bronchitis and asthma.

Effects Continued…

• It can damage statues, buildings, metals, and car finishes.

• It can also damage tree foliage,

and make it weaker and more susceptible to being damaged even more by other things.

Effects of Acid Deposition continued…

• The areas hardest hit by acid

deposition are mountaintop forests, which tend to have thin soils without

much buffering capacity.• A combination of acid deposition and other air

pollutants can make trees more susceptible to stresses such as cold temperatures, diseases, insects, drought, and fungi.

Continued…

• Excess acidity can contaminate fish in some lakes with highly toxic methyl mercury.

How Serious is Acid Deposition in the US?

• Numerous health studies have shown that the effects from exposure to the chemical components of acid deposition are a serious health problem and also damage materials.

Continued…

• Many scientists support greatly reducing emissions from coal and oil burning facilities to reduce their harmful effects on human health and materials and to prevent acidic acidic compounds in soil and aquatic systems from exceeding the tolerance levels of various species and eventually serious and costly ecological and economic damage.

What Can Be Done to Reduce Acid Deposition?

• Prevention Solutions:– Reducing energy use– Switching from coal to cleaner burning natural

gas– Removing sulfur from coal before it is burned– Burning low sulfur coal– Removing SO2 particles, nitrogen oxide, and

removing nitrogen oxides.

Types and Sources of Indoor Air Pollution

• Higher in homes and commercial building than outdoors, as much as 70 times.

• Pollution levels inside cars in traffic clogged urban areas can be up to 18 times higher.

• At greater risks are smokers, infants, children under age 5, the old, the sick, pregnant people, people with heart problem.

                                                       

      

Continued…

• Pollutants found in building to be: dizziness, headaches, coughing, sneezing, nausea, burning eyes, chronic fatigue, and flu like symptoms, known as sick building syndrome.

• New ones are more commonly “sick” than old ones because of reduced air exchange.

Continued…

• Can be mineral fibers falling from ceiling tiles and blowing in from the lining of the air conditioning ducts.

• Cigarette smoke, formaldehyde, asbestos, and radioactive radon are the most dangerous.

How human health is harmed?

• Lung cancer

• Asthma

• Chronic bronchitis

• Emphysema

What pollutants cause these problems?

• Suspended particulate matter: asthma– Fine particles– Ultrafine particles

• Sulfur dioxide: asthma/ bronchitis

• Nitrogen oxides: asthma/ bronchitis

• Volatile organic compounds: cancer

Humans Die from Pollution

• Annually, U.S. estimates 65,000-200,000 premature deaths from outdoor pollution

• Indoor pollution included: 150,000-350,000 premature deaths

• Worldwide: 2.7 million premature deaths

• Millions more face illness

Air Pollutants Damage Other Organisms

• Aquatic Life:– Acid shock; kills fish

• Plants:– Interferes with photosynthesis– Water loss– Susceptible to diseases

Laws Regarding Air Pollution

• EPA established:– national ambient air quality standards

(NAAQS)– National emission standards for toxic air

pollutants

• Clean Air Act of 1990

How Could Pollution Laws be Improved?

• Focus on pollution prevention, rather than cleanup

• Increase fuel efficiency standards

• Require stricter emission standards for fine particulates

• Reduce emissions of CO2 and other greenhouse gases

Reducing Outdoor Air Pollution

Clean-up Methods:

• Electrostatic precipitators

• Baghouse filters

• Cyclone separators

• Wet scrubbers

Reducing Outdoor Air Pollution con.

• Prevention Methods:– Burn low-sulfur coal– Remove sulfur from coal– Convert coal to a liquid or gaseous fuel– Shift to less polluting fuels

Reducing Indoor Air Pollutants

• Using simple stoves that burn more efficiently (reduces deforestation)

• Using simple solar cookers

• Breathing wall– Absorbs indoor dirty air– Exhales clean air

How do we Protect the Atmosphere?

• Focus more on pollution prevention

• Improve energy efficiency

• Slowing population growth

• Regulating air quality for larger regions

• Distribute cheap and efficient or solar cookstoves in developing countries

How do we Protect the Atmosphere? Con.

• Reduce use of fossil fuels

• Increase use of renewable energy

• Integrate air-pollution, water-pollution, energy, and land-use policies

• Phase in full-cost pricing, by taxing the production of air pollutants

Unit 7: Chapter 19

Ana KavianiKi Hong LeeAnne Penniall

Greenhouse effect

• Certain gases in the atmosphere trap heat in the lower atmosphere (troposphere).

• Mainly have to do with concentrations of heat-trapping or greenhouse gases and length of time they stay in the atmosphere.

Major greenhouse gases

• Carbon dioxide

• Chlorofluorocarbons (CFCs)

• Methane

• Nitrous oxide

Global warming

• Have been caused by human activities: burning fossil fuels, agriculture, deforestation, and use of CFCs.

• Developed countries account for about 60% of CO2 emissions and developing countries for 40%

Global warming (cont’d)

• United States 23% of CO2 emissions

• China 14%

• Russia 7%

• Japan 5%

Future of global warming and its effects

• IPCC projects that temperature should rise 1-3.5 degrees C between 1990 to 2100

• Northern hemisphere should warm more and faster than the southern, because southern has more heat-absorbing ocean than land.

Ocean's affect on climate

• Might amplify global warming by releasing more CO2 into the atmosphere or might dampen it by absorbing more heat.

• Currently it keeps moderate troposphere temperature by removing 29% of Co2 excess.

Albedo

• The ability of the earth’s surface (land, water, or ice) to reflect light.

• Dark colored surfaces absorb heat

• Light colored surfaces remain cool because they reflect heat back.

What has been Done to Reduce Greenhouse Gas Emissions?

• 38 developed nations required to cut greenhouse emissions

• European industrialized nations required to cut 8% below 1990 levels

• Forested countries given lee-way because trees absorb CO2

Preparation for Global Warming

• Waste less water

• Develop crops that use less water

• Stockpile 1-5 years of food

• Connect wildlife reserves with corridors

• Move hazardous wastes away from coastal areas

Ozone Depletion

• As more UV radiation reaches the earth:– Serious health effects occur– Fewer crops– More smog– Possible climate changes

What Chemicals Deplete Ozone?

• Collectively known as ODCs– CFCs– Halons: fire extinguishers– Methyl bromide: widely used fumigant– Carbon tetrachoride: solvent– Methyl chloroform: cleaning solvent

Effects of Increased UV Exposure

• Suppression of immune system

• Increase in eye-burning, damaging acid deposition

• Lower yields of key crops

• Decline in forest productivity of plant species sensitive to UV-B rays

Effects of Increased UV Exposure con.

• Reduction in productivity of phytoplankton

• Damage to ecological structure of lakes

• Increased degradation of materials – Paints, plastics, outdoor materials

How to Protect the Ozone

Stop producing ozone-depleting chemicals– Substitutes are available for almost all CFCs– Use hydrocarbons – Use HC refrigerator technology

What is Being Done to Reduce Ozone Depletion?

• Met in London, Copenhagen in early 1990s

• Montreal Protocol– 36 nations– Cut emissions of CFCs– Did not address other chemicals

Will These Treaties Work?

• Growing concern regarding whether or not requirements are being met

• Effectiveness of treaties is under consideration

• Regardless, treaties are an important precedent for global cooperation

Ozone Relating to Cancer

• 90% of melanoma comes from exposure to UV-A rays

• 10% from UV-B rays

• Avoid sun between 10am and 3pm

• Use sunscreen with UV-A and UV-B protection

The end