AP Environmental Science

- Air Pollution

-Climate Disruption/ Ozone Depletion

Amanda HernandezRoberto Barrios

Structure and Science of the Atmosphere

The atmosphere is a thin layer of gases held close to Earth by gravity. The atmosphere is thinner at the poles,

thicker at the equator. Two major components is N2 78% and

O2 21% Atmospheric Pressure –measure of

the mass per unit are of air. Pressure increases as the density of

air increases. There is a higher density in the air we

breathe at sea level than the air we inhale on top of the world’s largest mountain.

Ozone protects us from about 95% UV radiation

Outdoor Air Pollution Air pollution– presence of chemicals in

the atmosphere where the concentration is high enough to affect climate and harm organisms. Primary pollutants – emitted directly

into the troposphere in a harmful form. (carbon monoxide)

Secondary pollutants – when primary pollutants react with the components of air.

Majority of pollutants come from natural sources, dust particles, organic chemicals, forest fires, volcanic eruptions, and sea spray

Pollutants from human activity such as burning oil, gasoline, and natural gas are the ones that cause more harm into the troposphere.

Outdoor pollutants examples: carbon monoxide, nitrogen dioxide, sulfur

dioxide, ozone, lead

Photochemical and Industrial Smog

Photochemical Smog – when nitrogen oxides and organic hydrocarbon compounds chemically react under the influence of UV radiation to produce a mixture of many primary and secondary pollutants.

Factors that increase outdoor pollution:• Urban buildings, hills, mountains, high

temperatures. Factors that help reduce outdoor

pollution:• Rain and Snow – cleanse the air of

pollutants• Salty sea spray from the oceans- wash

out particles from air that flows from land onto the oceans.

• Wind- sweep pollutants away, dilute them by bringing in new fresh air.

Regional Outdoor Air Pollution

Temperature Inversion – layer of dense, cool air trapped under a layer of less dense, warm air. (traps the pollutants near the ground and it becomes more dangerous)

Acid Deposition – also known as acid rain, falling of acids and compounds from the atmosphere into the earth’s surface. (Sulfur/ nitrogen main culprits.)

Acid deposition can deplete the nutrients from plants and also damage and weaken the plants.

On humans, it can produce lung cancer, corrosion, haze, and also kills fish.

Indoor Air Pollution Indoor air pollution is a much

greater threat to human health than outdoor air pollution. So dangerous due to

accumulation, concentration and lack of detection

Four most dangerous indoor air pollutants are:

Cigarette smoke, formaldehyde, radioactive radon-222 gas, and ultra fine particles.

New building are more commonly “sick” than the old ones because of reduced air exchange and chemicals released from new carpeting and furniture.

Effects of Air Pollution on Living Organisms and Materials.

Prolonged smoking and breathing air pollutants can lead to respiratory disorders like asthma, lung cancer, and chronic bronchitis. Mechanisms that protect us from

some air pollution. (hairs filter out large particles, sticky mucus captures smaller particles and dissolves some gaseous pollutants.

Each year, approximately 3 million people (average 8,200 per day) die prematurely from air pollution (mostly indoor pollution in developing countries)

Preventing and Reducing Air Pollution

Clean Air Act (1970) in the U.S has reduced outdoor pollution from six major pollutants by setting emission standards.

Preventions from indoor air pollution:- covering ceiling tiles and lining the AC ducts

to prevent release of mineral fibers- Ban smoking or limit it to well-ventilated

areas- Prevent radon infiltration- Use office machines in well-ventilated areas- Use less polluting substitutes for harmful

cleaning agents, paints, and other products. Solutions for Outdoor:

Improve energy efficiency to reduce fossil fuel use.

- Rely more on lower-polluting natural gas.- Rely more on renewable energy (solar cells,

wind)

Past Climate ChangeTemperature and climate have been changing throughout the earth’s history.

Geologic records and atmospheric measurements provide a wealth of information about past atmospheric temperatures and climate

Scientists from the U.S. National Academy of Sciences and the American Geophysical Union have also evaluated possible future climate changes.

Climate – determined mostly by its average temperature and average precipitation.

The Earth’s Natural Greenhouse Effect

Global Warming – temperature increases in the troposphere, which in turn can cause climate change.

Global Climate Change – a broader term that refers to changes in any aspects of the earth’s climate, including temperature, precipitation, and storm intensity.

The greenhouse effect warms the earth’s lower troposphere and surface.

** The two major greenhouse gases are water vapor and carbon dioxide.

Humans have contributed to the increased level of carbon dioxide

Albedo – reflectivity of different parts of the earth’s surface. Colored surfaces of ice and snow help

cool the earth reflecting the incoming sunlight back into space.

Future Changes in the Earth’s Temperature

Coupled global circulation models – global climate models that are applied to the atmosphere to project the effects of increases in greenhouse gases on average global temperature.

The largest burden of the harmful effects of moderate global warming will fall on people and economies in poorer tropical and subtropical nations.

A decrease in high-elevation snow packs could lead to a sharp decline in agricultural productivity in heavily irrigated areas.

Threat of Global Warming

Disagreement on whether the world should respond to the threat of climate change.

•The economic costs of reducing greenhouse gas emissions are higher than the economic benefits

•Developed countries, developing countries, or both should take responsibility for reducing greenhouse gas emissions.

•Actions to reduce greenhouse gas emissions should be voluntary or required as a result of national laws and an international treaty

Solutions:

•Soil sequestration – plants such as switch grass are used to remove carbon dioxide from the air and store it in the soil.•Reduce the release of carbon dioxide and nitrous oxide from soil.•Remove carbon dioxide from smokestacks and pump it deep underground into unminable coal seams and abandoned oil fields.

Reducing Greenhouse Gas Emissions

Kyoto Protocol – requires 39 developed countries to cut emissions of CO2, CH4, and N2O, to an average of about 5.2% below 1990 levels by 2012.

A growing number of major global companies, such as Alcoa, DuPont, IBM, Toyota, BP Amoco, and Shell, have established targets to reduce their greenhouse gas emissions by 10-65% from 1990 levels by 2010.

Ozone Depletion in the Stratosphere.

Chlorofluorocarbon – an organic compound that is made up of chlorine, fluorine, and carbon, produced as a volatile derivative of methane and ethane. F. Sherwood Rowland and Mario

Molina proposed inc. CFC hypothesis Measurements indicate that CFCs

and other ODCs are the primary culprits of ozone depletion.

Widespread use of a number of useful and long lived chemicals has reduced ozone levels in the stratosphere.

Polar Vortex – a huge swirling mass of very cold air that is isolated from the rest of the atmosphere until the sun returns a few months later.

Protecting the Ozone Layer

In 1987, 36 nations got together in Montreal, Canada to develop a treaty that could end with the CFCs emissions.

Montreal Protocol – the goal was to cut emissions of CFCs into the atmosphere by about 35% between 1989 and 2000.

After hearing that no changed were made in the atmosphere and that the ozone was getting thinner and thinner, 93 countries got together in London and came up with another treaty.

Copenhagen Protocol – an amendment which accelerated the phasing out of key ozone-depleting chemicals.

FRQ 2007 #3

FRQ Solution

A. Class of Compounds Halocarbons/Halons

Fire retardant Soil fumigant/pesticide Solvent Foam Blowing Insulation

CFC’s Coolants/refrigerants/AC/refrigerator Aerosol** Needs to describe 1 class of compounds and

describe 2 major uses

FRQ Solution [cont.]

D. Effects of Ground Level Ozone Respitory Irritant Decreased photosynthesis due to

C. Consequences Increase in UV (specifically UVB) reaching Earth’s

surface. Effects: Skin Cancer Disruption of food chains

B. Description CFCs are broken down by UV radiation resulting in

the release of atoms– chlorine/bromine/flourine Halogens break the O3 into O+ O2

1998 APES Multiple Choice Samples

Other Multiple Choice Samples

A

E

D