The technological revolution has changed dramatically the ways in which men carry on most of the businesses of their lives. But we still dispose of waste materials in the same way that our Paleolithic hunter ancestors did- we throw them away.
Some forms of pollution are merely ugly and annoying. Junked automobiles, discarded beer cans, annd candy wrappers are unsightly; but they do not pose any immediate hazard to our health or well-being. Other forms of pollution have more serious effect on us. One of the worst is water pollution. There are three main sources of water pollution. There are three main sources of water pollution; industrial wastes are often highly toxic and in many cases have destroyed all lie for several miles downstream from the point where they were dumped. Such pollutants, however, are usually easy to identify as to source, and relatively easy to control. Well written and enforceable legislation could effectively stop most of these industrial pollution.
Untreated sewage acts more subtly than industrial wastes, Sewage is normally broken down by bacterial action into water, carbon dioxide, and the nutritional minerals that are in all living things. Bacterial breakdown proceeds at a certain rate, and as long as there rate at which fresh sewage is added into a water system does not exceed the rate at which bacteria can break it down, no pollution results, when the amount of sewage increases, however, the numbers of bacteria increase. these bacteria need oxygen to live, and soon they increase to such an extent that they use up all the available oxygen. At this point, fish and other animals and indeed, the bacterial themselves can no longer live in those waters. They die, leaving the sewage to accumulate in now lifeless, waters. Sewage-treatment plants work by allowing the bacteria to get a good start on decomposing the sewage before it is dumped into the water. This reduces the strain on the water supply of oxygen and allows the normal processes of nature to keep up with the indotricution of organic wastes in the water.
Pesticides, in heavy enough concentrations, may kill all the water life outright. Even if the concentration is small there are certain organisms like crabs and shellfish. that are especially susceptible to pesticides. Many well-established beds of shellfish have been destroyed by the inadvertent introduction of insecticides residues into the water.
But the main danger from insecticides is their tendency to linger in the tissues of organisms exposed to them. Thus, water fleas, in a middle polluted stream may have only small concentrations of the insecticides in their bodies. But a minnow may eat numbers of these, and the accumulated concentration of pesticides and the fishes body will be greater than that in any single water flea. A duck may eat many minnows, and the concentration in ducks body will be great yet. Finally, an eagle may eat many ducks and the concentration in the duck’s body and in its eggs may be enough to kill the bird or to prevent the eggs from hatching. Our national emblem, the bald eagle, is probably doomed to extinction within the next 20 years, because its eggs, loaded with insecticides from animals on which the bird lives, fail to hatch.
Industrial plants in the four states that border Lake Erie dump more than a ton of waste chemical into the lake each minute. These chemicals added to the many more tons of sewage that are pumped into the lake, and the fertilizers and pesticides washed in from farms and suburban gardens, have virtually destroyed the lake’s ability to support life. Commercial fisheries that once made a living on Lake Erie have vanished.