Chapter 4 Summary

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Although the majority of the earth’s surface is covered by water and all human life depends upon it, this precious natural resource is in short supply. Most of the earth’s water contains too much salt to be used for drinking, so only a finite amount is available for human consumption.  In fact, the quantity of safe drinking water is limited and rapidly decreasing. Some areas of the world already face critical water shortages while other areas will soon be confronted with a life-threatening depletion of potable water.

Rather than preserve and protect the earth’s water supply, however, mankind has contaminated it with pesticides and chemicals. According to the text, the culprits are many. Water pollution is the result of chemical reactors, municipalities, industries, hospitals, and scientific laboratories. Moreover, the chemicals used to nurture crops, forests, and gardens have contributed to the problem. In fact, the combination of chemicals and waste products found in polluted water has made water purification very difficult. The intermixture of various chemicals often prevents scientists from accurately identifying or removing them during the purification process. Some chemical compounds, it appears, are too stable to destroy using ordinary techniques.

Streams, rivers, and drinking water are contaminated by chemicals that have been sprayed, directly applied, or borne along by rainwater that washes various contaminants seaward. One test of polluted water in a local orchard yielded horrifying results. Test fish were placed into the water; all were dead “in only four hours,” indicating the extreme toxicity of the water. In 1960, the United States Fish and Wildlife Service issued a report that intensified the alarm about water pollution. The poisonous chemical DDT was found in the tissues of fish located near an area where the DDT had been sprayed. In addition, fish found thirty miles upstream also suffered from DDT tissue contamination. There was no indication that spraying had ever taken place in the vicinity of these fish.

Because the earth’s water cycle is so comprehensive, it is not possible to prevent polluted water from reaching man’s supply of groundwater. A farming district in Colorado discovered that its groundwater was polluted when people in the area became ill after drinking the water. The contaminated water also caused illness in farm animals and damage to crops. The people in the area relied on shallow, underground wells for human consumption as well as to water livestock and irrigate crops. The wells were polluted by seepage from a pesticide production facility, which was located several miles away.

DDD, a chemical similar to DDT but believed to be less lethal, was applied to an area in California to rid a lake of a bothersome breed of gnats, but it destroyed a population of western grebes. Upon investigation, scientists found no natural cause for the birds’ deaths. Instead, an examination of bird tissue revealed that the birds were victims of DDD poisoning. Although the pesticide had been applied in “very low concentrations,” the consequences were devastating and irreversible. Regardless of the reason, introducing chemicals into the earth’s water source is always a risky proposition.

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