Glencoe Health 2005.pdf

Water treatment and purity depend on actions taken by

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water coming from private wells, however. Water treatment and purity depend on actions taken by those who use the well. urban sprawl deforestation 774 Chapter 29 Environmental Health Using public transportation instead of driving reduces pollution and helps con- serve resources. How might an efficient public trans- portation system improve community health?
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All drinking water is susceptible to pollution. Because the water can come from large sources such as rivers, lakes, and aquifers (water- bearing layers of rock, sand, or gravel) that underlie several counties or states, the pollution source can be far away from where the water is used. Polluted Runoff About 40 percent of the nation’s rivers, lakes, and coastal waters are not safe for swimming or other types of water recreation. Water pol- lution is sometimes caused by illegal dumping of industrial chemical wastes, but a greater contamination problem is created by pollution that comes from many sources throughout the environment. Most surface water contamination is caused by polluted runoff—rainwater or snowmelt that runs over the land, picking up such contaminants as pesticides, fertilizers, and wastes. Polluted runoff can also contam- inate groundwater, the primary source of drinking water for millions of people in the United States. Wastewater used water that comes from homes, communities, farms, and businesses, is another source of water pollution. Along with sewage, wastewater includes water that is generated and dis- charged from industries, feedlots, and many other sources. Wastewater contains harmful substances such as human and animal wastes, metals, and pathogens. Some wastewater must be treated by cooling in order to prevent thermal pollution. Thermal pollution occurs when the temperature of discharged water is higher than the temperature of a body of water in the environment. Because this hot water can disrupt aquatic ecosystems, it must be cooled before it enters the environment. The EPA regulates the treatment and dis- charge of wastewater under the Clean Water Act. Treated water that is released back into the environment must be safe for humans and other living organisms. Other Sources of Water Pollution Other sources of water pollution include: Sediment. Sediment from land erosion can destroy aquatic ecosystems and clog lakes, stream channels, and harbors. Oil. Some oil contamination comes from the cleaning of oil tankers and the release of oil from offshore drilling rigs. Problems can also occur when people dump used motor oil and household chemicals down household and storm drains. Wastewater 775 Lesson 2 Protecting Land and Water Recycle engine oil. Just 1 quart of oil can contaminate up to 2 million gallons of drinking water. Be careful about what you put down the drain. In areas that use septic systems, harmful chemicals may end up in your drinking water.
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