Chapter 20Lecture Presentation Preserving and Protecting Your Environment
Bursting with People: Measuring the Impact • Impact on other species • Impact on our food supply • Land degradation and contamination of drinking water • Impact on energy conservation
World Liquid Fuel Consumption by Region and Country Group, 2007 and 2035 (Projected)
Factors That Affect Population Growth • Total fertility rate is a measure of the hypothetical average of the number of children born to women between ages 15 to 44, given prevailing fertility and mortality rates. • In America, that rate is nearly 2 per woman, while in certain African countries and in the Middle East, the rate ranges from 5 to nearly 8.
Different Nations, Different Growth Rates • India is expected to increase its population by 600 million by 2050, surpassing China. • In developing nations, large families occur because of • High infant mortality rates • Children being the family’s “social security” • Low education and economic status of women
Different Nations, Different Growth Rates • In wealthier nations,with the exception of the United States, population sizes are either static or declining. • The United States ranks 123rd out of 233 nations in population growth, adding 3 million people each year or 8,000 per day. • Although the United States represents only 5% of the world’s population, it consumes nearly 25% of total global resources.
Zero Population Growth • Total zero population growth limits couples to two offspring. Once the parents die, these two children are their replacements, allowing the population to stabilize or even decrease. • There are over 20 countries with zero or negative population growth. • Education is the single largest contributor to zero population growth.
Air Pollution • Air pollution is either naturally occurring or anthropogenic (caused by humans). • Components of air pollution • Sulfur dioxide, particulates, carbon monoxide, nitrogen dioxide, ground-level ozone, and lead. • Photochemical smog • Contains particulates and gases that form when oxygen-containing compounds of nitrogen and hydrocarbons react with sunlight.
Air Quality Index • Like the weather, air quality changes day to day, hour to hour. • The Air Quality Index focuses on health effects that can occur within a few hours or days after a person breathes polluted air. • The scale runs from 0 to 500. When it rises above 100, it is considered unhealthy.
Acid Deposition and Acid Rain • Acid deposition (acid rain) is precipitation that has fallen through acid air pollutants. • Acid pollutants are deposited in two ways: • Wet deposition: acidic rain, fog, and snow • Dry deposition: chemicals that are incorporated into dust or smoke before falling to the ground • Sources of acid deposition are mostly processes that burn fossil fuels. • Acid deposition damages lakes and ponds, kills trees, and causes human health effects.
Indoor Air Pollution • Prevention of indoor air pollution • Source control • Ventilation improvements • Air cleaners • Environmental tobacco smoke is a form of indoor air pollution. • Home heating by woodstoves and oil- or gas-fired furnaces can emit particulates and carbon monoxide, respectively.
Indoor Air Pollution • Asbestos, if disrupted, produces tiny fibers that become airborne. • Formaldehyde is contained in many home materials. • Radon seeps into homes through cracks and pipes. • Molds and fungi live both in and outdoors. • “Sick building syndrome” is primarily related to poor ventilation.
Activity Break • Do you believe that if we do not change our current rate of population growth and our consumption of natural resources, we may face a situation where: • Electricity is available for only a few hours each day, so that you have to choose between using a refrigerator, TV, computer, or electric light? • Only limited amounts of gasoline are available for your car and there are shortages of grocery supplies?
Ozone Layer Depletion • The ozone layer forms a protective layer in Earth’s stratosphere. • It protects the planet from ultraviolet B (UVB) radiation. • In the 1970s, it was discovered that chlorofluorocarbons (CFCs) contribute to the rapid depletion of the ozone layer. • Aerosol sprays containing CFCs were banned in the 1970s.
Global Warming • Greenhouse gases • Carbon dioxide, CFCs, ground-level ozone, nitrous oxide, hydrocarbons, and methane form a gaseous layer that allows solar heat to pass through the atmosphere to Earth, but it also traps the heat and prevents it from escaping. • Kyoto Protocol • This is an international plan to reduce the human-made emissions responsible for climate change. It has been signed by more than 160 countries, including more than 30 industrialized nations. • This document, unsigned by the United States, would require us to reduce emissions by 33%.
Reducing Air Pollution and the Threat of Global Warming • Changes must occur in energy, transportation, and industrial practices. • Reducing consumption of fossil fuels in cars and shifting to alternate fuels, improving gas mileage, and using mass transportation are crucial to the reduction of air pollution. • In what ways can you reduce your carbon footprint?
Water Pollution and Shortages • About 75% percent of Earth’s surface is covered with water; only 1 percent of this water is available for human use. • Water contamination • Point-source pollutants enter a waterway at a specific location. • Nonpoint-source pollutants consist of runoff and sedimentation.
Water Pollution • Septic systems. • Landfills. • Gasoline and petroleum products. • Chemical contaminants designed to dissolve grease and oil. • Although polychlorinated biphenyls are now banned in the United States, some 500 million pounds have already been dumped into landfills and waterways. • Dioxins, commonly found in herbicides. • Pesticides. • Lead.
Which Fish Is Safest to Eat? • What types of fish have high levels of mercury and should be avoided by children and pregnant women? • What types of fish are lower in mercury and are safer to eat? • What is the greatest health danger of consuming too much mercury in your diet?
Land Pollution • Solid waste • Every day, 4 pounds of municipal solid waste per person is generated in the United States. • Although 90 percent of our trash is recyclable, only 26 percent is actually recycled. • Hazardous waste • The Superfund law was enacted in 1980 to provide money for the cleanup of hazardous chemical sites.
Land Pollution • The number of landfills has decreased in the past decade, but their mass has increased. • As communities run out of disposal space, it is becoming more common to take garbage out to sea and dump it there, thus contaminating the ocean ecosystem.
Land Pollution • Strategies to control waste: • Source reduction (waste prevention) • Recycling • Composting • Combustion with energy recovery
Crack Those Recycling Codes • Can you recycle on campus? Do you? • Were you aware of the Great Pacific Garbage Patch? In what way do you think it affects the environment? What should be done about it?
Radiation • Nonionizing radiation: radio waves, TV signals, microwaves • Ionizing radiation: the sun, uranium • Radiation absorbed doses (RADs) • Electromagnetic fields (EMFs) • Nuclear power plants • Nuclear meltdown occurs when a nuclear reactor’s core temperature increases to melt both the nuclear fuel and the containment vessel that holds it. • At the nuclear power plant in Chernobyl, there was a reactor core fire and explosion.