Chapter 18 – air pollution and global changesPresentation Transcript
Chapter 18 – Air Pollution and Global Changes How can local pollution cause global changes?
I. The air pollution problem
A. Pollutants – harmful materials that enter the environment
1. May be natural , such as sand and dust storms, volcanic eruptions, and forest fires
2. May be caused by human activities
1. Air pollution became a widespread problem during the Industrial Revolution of the 1700’s due to increased burning of fossil fuels and wood
2. Many air pollution disasters have been recorded, caused by everyday industrial pollution
a. 1952 – London, England: 3500-4000 dead
b. 1965 – New York, NY: 400 dead
II. Types of Pollutants
A. Outdoor Pollutants
1. Particulates – tiny solids suspended in the atmosphere
a. pieces of ash, dust, and soot from burning organic matter
b. liquid droplets in smoke or smog
c. traces of metals such as lead, iron, and copper released from industrial processes d. pesticide, herbicide, and fertilizer dust e. plant pollen
2. Oxides – compounds of oxygen and another element
a. most common oxides include carbon, nitrogen, or sulfur
b. released when fossil fuels or other organic materials are burned , especially from automobiles or coal-burning power plants
3. Photochemical Smog – a yellow-brown haze formed when sunlight reacts with pollutants produced by cars
a. Includes the chemical ozone (O3)
i. very corrosive, poisonous to plants and animals ii. A ground-level ozone scale has been devised that advises people of the dangers of ozone pollution on a particular day; code green = good , code orange = dangerous for sensitive groups , code purple = dangerous for all
b. Includes the chemical nitrogen dioxide (NO2) – a brown gas that gives smog its distinctive color
4. Hydrocarbons – compounds made mostly of hydrogen and carbon Ex. Methane – produced by microorganisms in the digestive systems of livestock, certain bacteria, and decaying organic matter
5. Chloroflurocarbons (CFC’s) - man-made chemicals once used in refrigerators, air conditioners, aerosol cans , and in the production of styrofoam.
1. Is air pollution a new problem? When did it become a major concern?
In the 1700’s during the industrial revolution.
2. Name 3 examples of natural air pollution.
Sand and dust storms
3. Which types of air pollutants can you see?
4. Name the 5 major types of outdoor air pollutants
ash, dust or soot
Smoke and smog
5. How is photochemical smog produced? Why do you think it’s such a problem during the summer months? When sunlight reacts with pollutants from cars. Because the temperature increases ground level ozone and there are more hours of sunlight in the summer.
B. Indoor Air Pollution
1. Indoor air can contain very high levels of pollution and can cause serious health problems
a. Products such as plastics, insulation, and cleaners give off harmful fumes b. Air circulation in buildings is often poor c. People generally spend 16-18 hours per day indoors
2. Major types of indoor air pollution
a. Cigarette smoke – contains a combination of particulates, gases and other chemicals
b. Microorganisms – bacteria and fungi can live in ventilation systems
c. Radon – a colorless, odorless, radioactive gas that enters homes from the soil through the basement
1. Give 2 reasons that indoor air can contain high levels of pollution and cause health problems
Because people spend a lot of time inside and there is inadequate air circulation.
2. Name 3 types of indoor air pollution
1. cigarette smoke
2. Micro organisms
3. If you hear on the news that ozone levels are high, would you always be better off going inside? Why or why not? Stay indoors if there is air conditioning .
III. Air Pollution and Living Things
A. Effects on human health
1. Long-term exposure may cause diseases and chronic health problems , or may worsen existing conditions
a. Carbon monoxide binds to hemoglobin in blood more easily than oxygen; exposure reduces the amount of oxygen in the bloodstream and causes headache, dizziness, and even death
b. Ozone , and nitrogen and sulfur oxides irritate the lungs and respiratory tract; cause difficulty breathing, or may trigger asthma, allergy attacks , or more serious diseases such as bronchitis and emphysema
c. Particulates in the air have been linked to cancers , especially lung cancers
B. Effects on other organisms
1. Ozone and sulfur oxides can damage plants directly; affects forests and crops
2. Loss of plants in an ecosystem can disrupt the food web and deprive animals of nourishment 3. Animals may suffer from the same pollution-related health problems as humans
4. Industrial air pollution can contaminate rangeland, accumulating on grasses and entering groundwater that grazing animals consume
Review Questions 1. Why do many people now have a carbon monoxide detector in their homes? Because CO can be deadly
2. Why is it dangerous to participate in strenuous outdoor activities on days when the ozone levels are high? Because ozone can impair respiratory function
3. Why should we be concerned about how air pollutants affect plants? Because our food and oxygen comes from plants.
IV. Global Effects of Air Pollution
A. Acid Deposition
1. Rain or snow that is more acidic than normal precipitation is called acid precipitation
a. Normal rain is slightly acidic ( 5.6 on the pH scale) – water reacts with carbon dioxide in the atmosphere to form carbonic acid b. Much stronger acids form when water reacts with sulfur or nitrogen oxides in the atmosphere to form sulfuric or nitric acid
2. Sulfur and Nitrogen oxides are released through the burning of fossil fuels 3. As acid precipitation falls, it is deposited on land or in aquatic environments
a. Damages crops and trees directly , and also makes the soil less fertile b. Accumulates in lakes and lowers the overall pH, making them too acidic for many fish to survive c. Also causes economic damage by eroding stone and damaging paint
Review Questions 1. Why is normal rain slightly acidic? Because some acids are naturally occurring
2. Where do the pollutants that cause acid precipitation come from? BURNING FOSSIL FUELS!!!!
3. Name one way that acid precipitation affects humans and one way that it affects other living things Causes paint to peel and it can kill fish and trees .
B. Ozone Depletion
1. Although ground level ozone is a dangerous, corrosive gas, there is a layer of ozone in the stratosphere that protects Earth’s life from harmful UV radiation
2. In the early 1980’s, scientists discovered a “hole”, or thinning of the ozone near the South Pole
a. This thinning causes an increase in the amount of UV radiation reaching Earth
i. In humans, increased incidence of sunburn, vision problems, and skin cancer
ii. Also damages crop plants and forests , disrupting food webs
b. CFC’s are stable and inert (don’t react with other compounds) in the lower atmosphere, and therefore eventually rise into the stratosphere
c. In the stratosphere, CFC’s are exposed to UV radiation and break down , releasing chlorine and fluorine atoms that destroy ozone
d. CFC’s stay in the atmosphere for hundreds or thousands of years , so although the use of CFC’s has been banned in most products, they continue to cause problems
Review Questions 1. Is the ozone in the stratosphere a different chemical compound than ground-level ozone? They are the same chemical but react differently in the different atmospheric layers.
2. Why is the thinning of the ozone layer such a dangerous situation? Because harmful UV radiation gets in .
3. How do CFC’s break down ozone? Chlorine and flourine break down ozone .
4. If CFC’s are now banned in most of the world, why do they continue to cause problems? Because they stay in the atmosphere for 1000’s of years.
C. Global Warming
1. Earth’s atmosphere allows light energy from the sun to enter, but gases in the atmosphere trap heat and warms the surface of the Earth – this “ greenhouse effect ” allows life to exist on this planet
2. Greenhouse gases that trap heat include carbon dioxide, methane, nitrogen and sulfur oxides, ozone, CFC’s, and water vapor
a. Data on levels of greenhouse gases can be obtained through ice cores – long cylinders of ice that are drilled and removed from a sheet of polar ice
b. Ice cores contain air bubbles that have been trapped in the ice for 100’s or 1000’s of years
c. From ice core data, we have evidence that levels of CO2 and other greenhouse gases are rising steadily ; a similar increase in CO2 occurred at the end of the last ice age
3. Global warming – an increase in Earth’s average surface temperature caused by an increase in greenhouse gases
a. Computer models project a 2-4 degree Celsius rise in Earth’s temperature
b. Ice caps will melt, oceans expand, and sea levels rise c. Lowlands and coastal cities flood , displacing large populations of people
d. Saltwater enters groundwater , affecting drinking water supplies e. Weather patterns change , affecting agriculture and ecosystems
Review Questions 1. How is the greenhouse effect different from global warming? The global warming is caused by the the greenhouse effect.
2. Why is the Earth getting warmer? Because the greenhouse gases have increased and is trapping the heat from the sun .
3. How do we obtain data about gases in the Earth’s atmosphere 100’s of years ago? Ice core samples
4. Name 3 effects of global warming. - loss of habitats -rising sea levels -increase in intensity of storms
V. Controlling Air Pollution A. Natural Controls 1. Precipitation removes particulates from the air by binding the particle and carrying it to the ground 2. Carbon dioxide is removed by plants as they photosynthesize
B. Human Controls 1. Air Pollution Legislation a. 1963, 1965, 1977 – Clean Air Act and amendments b. 1987, 1990 – Montreal Protocol : International treaty to ban the use of CFC’s
2. Results of legislation
a. Emission control standards for cars have been set since burning
gasoline is a major source of air pollution
b. Coal-burning power plants use various techniques, such as “ scrubbers ”, to remove pollutants before they are released
3. There continues to be much debate between industries and environmentalists surrounding the use of pollution control devices – industries argue that these devices are too expensive and difficult to implement , while environmentalists argue that these steps are necessary to preserve our air quality
Review Questions 1. How can plants help us stop global warming Plants use the greenhouse gas CO2.
2. Name 2 pieces of legislation aimed at controlling air quality Clean air act Montreal protocol
3. Why do you think it’s so important to have your car inspected each year? Because a car that is not running properly can add more than normal amounts of greenhouse gases.