(p. 794)
38.1 Pollution (p. 794; Fig. 38.1)
A.
Global change occurs because of the wide-ranging effects of each of our activities.
B.
Chemical Pollution
1.
The growth of industry and the casual attitude many have toward industrial chemicals augments problems of chemical pollution.
2.
Chemical pollution comes from a wide variety of sources, such as oil from grounded tankers.
3.
Air Pollution a.
Air pollution is a major problem in the world’s large cities. b.
Certain cities are called gray air cities because of sulfur oxides emitted by industry. c.
Other cities have been called brown air cities because air pollutants undergo chemical changes in sunlight.
4.
Water Pollution a.
Water pollution is an ever-growing problem, even with advanced sewage treatment. b.
Lakes and rivers worldwide are becoming increasingly polluted.
C.
Agricultural Chemicals
1.
Agricultural chemicals are varied and widely used.
2.
Many different types of fertilizers, pesticides, and herbicides have been applied to agricultural fields, only to trickle into underground water or be washed down a river.
3.
Certain agricultural chemicals undergo biological magnification and are toxic to organisms high on the food chain.
38.2 Acid Precipitation (p. 795; Figs. 38.2, 38.3)
A.
Sulfur-containing air pollution from coal-fired power plants is the main cause of acid rain, rain that is considerably more acidic than would fall naturally.
B.
The effects of acid rain are far-reaching, especially when industries install tall smokestacks to distribute the pollutants high into the air.
C.
Forests are dying across the eastern United States and eastern Canada, in part because the soil becomes acidic, killing the symbiotic mycorrhizae.
D.
Lakes are becoming devoid of fish that cannot survive in acidic conditions.
E.
Amphibians are becoming increasingly scarce because they use lakes for breeding.
F.
The solutions are available, such as installing “scrubbers” on smokestacks to remove sulfur from the emissions.
G.
But these methods are costly, and industry does not want to pay the cost.
H.
New legislation has begun to address the problems of acid rain.
38.3 Global Warming (p. 796; Fig. 38.4)
A.
Our industrialized society has been built on a large supply of cheap fuels.
B.
When we burn fossil fuels, we add carbon dioxide to the atmosphere.
C.
Carbon dioxide is a natural feature of our atmosphere and contributes to the warmer climate we enjoy on the planet by the greenhouse effect.
D.
Global Warming
1.
Excess carbon dioxide, and other gases, could be intensifying the greenhouse effect and causing global warming.
2.
Scientists are not all in agreement that we are seeing global warming yet, but substantial evidence is mounting.
3.
The projected consequences of global warming could mean serious problems with our food supplies as rain patterns change over agricultural ground.
4.
World governments cannot agree on what to do about global warming.
38.4 The Ozone Hole (p. 797; Fig. 38.5)
A.
A layer of protective ozone formed in the earth's upper atmosphere after the early marine photosynthesizers began emitting oxygen.
B.
Since then, living creatures have been able to invade land under the protection of the ozone layer.
C.
But starting in 1975, the ozone shield surrounding the earth began to get thinner over the
South Pole.

D.
Scientists eventually determined that the cause was chlorofluorocarbons (CFCs) in the atmosphere.
E.
These chemicals had been invented in the 1920s and were used in abundance in refrigeration units, air conditioners, aerosol propellants, and Styrofoam.
F.
When CFCs drift upward in the atmosphere, they react with ozone, converting it back to gaseous oxygen.
G.
One CFC molecule can interact with huge numbers of ozone molecules without being altered.
H.
An ozone hole has now developed over Antarctica and has become larger.
I.
A drop in ozone is correlated with an increased rate of skin cancer because of increased exposure to ultraviolet radiation.
J.
A 1% drop in ozone content coincides with a 6% increase in skin cancer.
K.
Efforts have been undertaken to curtail the use of CFCs worldwide, but they are still being used.
38. 5 Loss of Biodiversity (p. 798; Figs. 38.6, 38.7)
A.
More than 99% of species known to science are now extinct.
B.
Factors Responsible for Extinction.
1.
Habitat loss is the single most important cause of extinction. a.
Natural habitats may be affected by the following human influences: destruction, pollution, human disruption, and habitat fragmentation.
2.
Species Overexploitation a.
Species that are hunted and harvested by humans are at a risk for extinction.
3.
Introduced Species a.
New species can enter a habitat and colonize it, usually at the expense of native species. b.
Species introductions are usually unintentional.
(p. 800)
38.6 Reducing Pollution (p. 800; Fig. 38.8)
A.
Humans have caused the world's great environmental problems, and humans can solve them.
B.
One of the first challenges is reducing pollution.
C.
When the true cost of industry is calculated, protecting the environment must be added in.
D.
Although it makes energy and products more expensive, the demand should decline, and the environment will then be preserved.
E.
Antipollution Laws
1.
Antipollution laws are an encouraging trend.
2.
The Clean Air Act of 1990 requires power plants to eliminate sulfur emissions.
F.
Pollution Taxes
1.
Pollution taxes are being considered, making each of us pay more for the option to pollute.
2.
These taxes are sometimes imposed as “pollution permits” and are becoming more common.
38.7 Preserving Nonreplaceable Resources (p. 801; Figs. 38.9, 38.10)
A.
Preserving nonrenewable resources, such as topsoil, groundwater, and biodiversity, are extremely important measures.
B.
Topsoil
1.
One-quarter of the topsoil in this country has been lost since 1950.
2.
If we can adopt ways of reducing tillage and saving our soils, we can ensure a means of growing food in the future.

C.
Groundwater
1.
Groundwater is rapidly becoming depleted and polluted, mostly because it is under the jurisdiction of local governments that lack the authority to control groundwater usage.
D.
Biodiversity
1.
Biodiversity is another nonrenewable resource that adds to the stability of ecosystems.
2.
When we destroy habitat, species are destroyed too, and we will never know the potential benefit we might have gained from learning about them.
38.8 Curbing Population Growth (p. 803; Figs. 38.11-38.15; Table 38.1)
A.
The core problem behind much of the environmental degradation we cause is that our population is too large and growing too rapidly.
B.
Ten thousand years ago, the human population was 5 million.
C.
By the time of Christ, human population had increased to 130 million.
D.
Since 1650, the average birth rate for humans has stabilized at 21 births per thousand people per year.
E.
What has changed, with better sanitation and medical treatment, is the rate of death.
F.
In 2004, the world's population reached 6.5 billion people, and the annual increase amounts to about 78 million people.
G.
How each of these people will be fed and be able to lead a rewarding, meaningful life remains to be determined.
H.
Population Growth Rate Starting to Decline
1.
The United Nations announced a decline in the population growth rate due to increased family planning efforts and increased economic power and social status of women.
2.
Increased educational levels appear to follow a decrease in family size as a result of family planning.
I. Population Pyramids
1. Human population growth is not occurring uniformly over the planet.
2. The rate at which a population can be expected to grow in the future can be assessed graphically by means of a population pyramid.
3. The AIDS epidemic in Africa will have a huge impact on population sizes.
J. The Level of Consumption in the Developed World Is Also a Problem
1.
We in the developed countries need to pay more attention to lessening the impact of our resource consumption.
2. An ecological footprint is the amount of productive land required to support an individual at the standard of living of a particular population through the course of his or her life.
3. The ecological footprint of an individual in the US is ten times greater than that of someone in India.
(p. 806)
38.9 Preserving Endangered Species (p. 806; Figs. 38.16, 38.17, 38.18)
A.
Preserving ecosystems and monitoring species before they are threatened is the most effective means of protecting the environment and preventing extinctions.
B.
Habitat Restoration
1.
Pristine restoration is not usually possible because we rarely know the identity of all of the original inhabitants and the ecologies of each species.
2.
Removing introduced species can restore a habitat.
3.
Cleanup, such as pollution removal, and rehabilitation can successfully restore habitat.
C.
Captive Propagation
1.
Case History: The Peregrine Falcon a.
DDT use affected the egg shells of falcons causing them to break prematurely. b.
DDT was banned in 1972, and researchers were able to use falcons from other locations re-established populations that had disappeared.
D.
Sustaining Genetic Diversity
1.
Case History: The Black Rhino a.
Mitochondrial DNA analysis suggests that populations are genetically very similar. b.
This lack of genetic variability poses the greatest challenge to the species.

c.
Placing black rhinos from different locations together to increase genetic diversity can be problematic.
E.
Preserving Keystone Species
1.
Case History: Flying Foxes. a.
The bats known as “flying foxes” are often the only pollinators and seed dispersers of certain plant species. b.
Many plant species are suffering due to their dependence on the declining population of these bats, which are hunted by humans. c.
Some populations have been helped by legal protection, habitat restoration, and captive breeding programs.
F.
Conservation of Ecosystems
1.
Conservation biologists have recognized that the best way to preserve biodiversity is to focus on preserving intact ecosystems, rather than focusing on particular species.
38.10 Finding Cleaner Sources of Energy (p. 809; Figs. 38.19, 38.20)
A.
If we can find cleaner sources of energy, we can curtail much air pollution and reduce carbon dioxide emissions.
B.
Some countries have turned to nuclear energy to fill the gap.
C.
In order for nuclear energy to be a viable alternative, there must be safe operation of the power plant, proper waste disposal, and security against theft of plutonium, which can be used to make nuclear weapons.
D.
Alternative Energy Sources
1. Solar, wind, and biomass are renewable sources of energy.
E.
Looking Closer at Ethanol
1. Plants like corn and sugar cane can be used to produce ethanol, which can be used as a fuel.
38.11 Individuals Can Make the Difference (p. 811; Figs. 38.21, 38.22)
A.
Environmental problems can be solved, but it will take everyone's help.
B.
One person can make a difference in solving environmental problems.
C.
The Nashua River
1. In the 1960s, Marion Stoddart organized a citizen’s campaign to clean up the severely polluted Nashua River in Massachusetts.
2. Her efforts led to the recovery of the river and contributed to the passage of the
Massachusetts Clean Water Act of 1966.
D.
Lake Washington
1. In the 1950s, W. T. Edmondson began a campaign to clean up Lake Washington, which was being polluted by sewage plants.
E.
Solving Environmental Problems
1.
You cannot preserve what you do not understand.
2.
Knowledge of biology is an essential tool to help solve the world’s problems.