preface vii chapter 1
The State of the Environment—An Overview 1
Public opinion and knowledge about environmental issues have evolved over time and have led to federal and state laws protecting environmental resources. These laws have been debated on their economic impacts and on how well they protect citizens from environmental hazards and crimes. The international community is also concerned about the environment and has, with varying degrees of success, implemented environmental standards of protection.
Emissions of chemicals from automobiles, factories, and power plants are mostly to blame for air pollution, which can make people sick and harm the environment. Government regulation, along with the implementation of new technologies, is designed to promote clean air, but some people believe these measures do not go far enough.
The Enhanced Greenhouse Effect and Climate Change 37
Scientists generally agree that the Earth is getting warmer, and many scientists believe that an enhanced greenhouse effect accounts for this change. Gases such as carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons may be causing global warming, which could have severe effects on the Earth. Many nations have committed themselves to reducing greenhouse gas emissions.
A Hole in the Sky: Ozone Depletion 55
Ozone can be either a health hazard or a health protectant, depending on where in the atmosphere it is located. Manmade chemicals, such as chlorofluorocarbons, can deplete the protective layer of ozone found in the upper atmosphere, which protects humans, plants, and animals from excess UV radiation exposure. The international community plays an important role in safeguarding environmental health by protecting the ozone layer.
Combustion of fossil fuels emits sulfur oxides and nitrogen oxides into the atmosphere, leading to acid rain. Acid rain can harm human health and damage ecosystems. Politicians and environmental groups in the United States and worldwide have sought reductions in the pollution that causes acid rain through legislation and other measures.
The vast majority of waste generated by modern society is not inherently hazardous. It includes paper, wood, plastics, glass, nonhazardous metals and chemicals, and other materials. Land-filling, incineration, and combustion are the most common disposal methods for nonhazardous waste. These methods, however, have environmental consequences that must be mitigated through design and control techniques.
Nonhazardous Materials Recovery—Recycling and
Problems associated with the disposal of nonhazardous wastes have created a greater need for recovery of materials through recycling and composting. These methods save landfill space, conserve the energy that would be used for incineration, reduce environmental degradation and use of new resources, generate jobs and small-scale enterprise, reduce dependence on foreign imports of materials, and conserve water. However, their implementation and success are dependent upon public participation, government regulation, and economic factors.
The most toxic and dangerous waste materials are those classified by the government as hazardous or radioactive. The storage, transport, and disposal of these wastes require special consideration, subjecting them to strict regulatory control and intense public scrutiny. Federal and state governments try to ensure that these wastes are managed in a way to protect the environment and public health.
Water is an essential resource necessary for sustaining all forms of life, but human alteration of the environment and patterns of water usage can have a devastating affect on the water supply. Legislation, including the Clean Water Act, seeks to improve and protect the integrity of America's surface water, groundwater, oceans, coastal water, and drinking water. How effective such laws have been is a matter of debate.
Many of the substances naturally found in the environment or released by modern, industrialized society are poisonous at certain dosages. They may be found in the home, workplace, or backyard, in the food and water people eat and drink, and in medications and consumer products. Common toxins include metals, pesticides, and other chemicals; radiation, particularly from radon exposure; indoor air pollutants, such as asbestos and mold; and foodborne contaminants, including pathogens. These toxins can have damaging effects on the environment and human health.
Depletion and Conservation of Natural Resources. . .151
Forests, wetlands, soils, minerals, and oil, as well as entire ecosystems are endangered by the activities of humans. The diversity of life on Earth (biodiversity) is also at risk, with many species facing extinction. Local, national, and international efforts must be linked to deal with pressures on the environment.
important names and addresses 171
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