Chapter 49 Outline
People and the Biosphere
I. Human Population
A. Population Growth
1. Many environmental problems loom large and seem urgent
today because of the rapid increase in human population. The huge numbers of humans on Earth are making enormous demands on the planet.
2. Birthrate: Birthrates very dramatically from one country to another and time to time. The birthrate of the present populations is supposed to double in 23 years.
3. Deathrate: Death rate has decreased worldwide. Better nutrition and health care have dramatically reduced infant mortality.
4. Effects of Human Population Growth: Land suitable and crops in many parts of the world are already in use. Scientists worry about the destruction of the tropical rainforests. The destruction of the rainforest may produce profound effects on the rest of the world- the world far removed from the rainforest.
a. Demand for food too high
b. Not enough land to farm on or live on
c. destruction of Forests
d. Overuse of natural resources.
B. Effects of Lifestyle
1. A lifestyle of a population also contributes to the extraordinary environmental demands made on the Earth. We must be aware of what we are doing to our planet and we must learn what we can do to solve the many environmental problems that face us.
Materials released into the environment fall into two broad categories: Biodegradable and nonbidegradable.
Biodegradable: materials that can be broken down by microorganisms into the essential nutrients from which they were made.
No biodegradable: materials that cannot be broken down by natural process or are broken down only very slowly.
1. Biological Magnification.
a. Biological Magnification: the amount of compounds in each organism in a food chain increases.
b. Increases concentration as they move through the food chain. EX: DDT edffected egg shells, killed fish.
2. Air Pollution
a. Smog: a dirty brown haze which gets its name from the combination of the words smoke and fog.
b. Temperature Inversions: Weather conditions that can make smog a serious health hazard.
c. Acid Rain: (sulfur) Certain pollutants in the air combine with water vapor to form droplets of acid. Acid rain is when these droplets fall to the earth as rain.
d. The effects of acid rain on the environment are numerous and serious to life.
e. Greenhouse Effect: the process when carbon dioxide and other gases in the atmosphere absorb this heat energy, forming a kind of heat blanket around the Earth.
f. Holes in the ozone layer: Scientists have recently discovered that the ozone layer is becoming thinner in certain places around the poles-this is what they call holes in the ozone layer. O3 is the molecule of the ozone, protects us from OV light.
3. Water Pollution
a. Chemical Contamination
i. The most common sources of water pollution are chemical wastes, raw sewages, and high temperatures.
B. Sewage Contamination
1. Increase plant growth,
2. Contains many harmful pollutants.
C. Thermal Pollution
a. Thermal Pollution: A kind of heated water that kills aquatic plants and animals.
B: Ocean pollution
D. Oil Spills
III. The Fate of the earth
1. Trees provoke us with many essential products.
2. Feforestation: Programs that plant new trees when old ones are cut down.
B. Endangered Species
1. Endangered SpeciesWhen an animal or plant the species becomes so rare that it is threatened with extinction.
C. Why Save the Endangered
1. Useful products- industrial compounds
2. Medicinal uses- antibiotics, anticancer, drugs, painkillers.
3. Food sources- genetically similar plants can help maintain crop yields by providing resistance to diseases.