Pollution of the water from the natural processes of aquatic animal and plant life combined with man-made waste constitutes another hazard to the delicate state of man`s health. The water-pollutant list is long : phosphates in laundry detergents; acid contamination from mine drainage; and industrial effluent of toxins, acids, radioactive substances, and mineral particles such as mercury. Increasingly obvious causes are salinization of water from evaporation in the arid West, land erosion, heat from industrial processes, and oil spills.
Water pollutants causing much of the problem can be categorized as either common sewage, infection-causing organisms, nutrients, synthetic chemicals, inorganic chemicals, sediment, or heat. The common denominator of major water pollutants is called Biologic Oxygen Demand (BOD), which is the amount of free oxygen that extraneous substances absorb from water.
Common Sewage, traditional waste from domestic and industrial sources, is a significant problem because oxygen is required to render this waste harmless. This waste thus uses up oxygen needed by aquatic plant and animal life. With increasing amounts of sewage, the problem is becoming ever more serious because of the inability of the water to deal successfully with the waste. When bacteria in the water can no longer decompose the waste, widespread aquatic death results. Waste will then accumulate, and the water will become useless as a personal or industrial resource.
Infection-Causing Organisms pollute water when sewage carrying these bacteria enter a river or stream. A man or animal drinking this water can becomeill. Microbiology and pharmacology have done a great deal in helping prevent and treat such diseases by identifying the responsible microorganisms and developing appropriate vaccines and antibiotics. However, occasionally a whole community or area may be negatively affected because of a gross error that contaminates a large body of water with diseased microbes. These microbes may spread infectious hepatitis or typhoid fever, especially in rural and urban fringe areas where population density is high and public utilities are limited.
Nutrients that nourish plant life, especially phosphates and nitrates, are produced by sewage, industrial wastes, and soil erosion. These nutrients are not easily removed by treatment centers because they do not respond to the usual biological processes. Moreover, treatment centers may inadvertently change these substances into a more usable mineral form that stimulates excessive plant growth. This growth in turn becomes a problem by interfering with treatment processes, marring the lanscape, producing an unpleasant odor and taste in the water, and disturbing the normal food chain in a body of water. Because humans depend on many lower forms of life for food, this process could eventually affect their well-being if it occurred on a large scale.
Synthetic Chemicals that are used in everyday household chores, especially chemicals found in detergents, pesticides, and other cleaning agents, affect the water. Even in small proportions they may be poisonous to aquatic life. When they are resistant to local treatment measures, they can produce an unpleasant taste and odor in the water. The extent of the long-term problem is not known, but there might be a possibility of human poisoning over a long period by the consumption of small doses of these chemicals taken in drinking water. Further discussion of this problem follows later in the chapter.
Inorganic Chemicals or mineral substances from mining or manufacturing processes can destroy land animals (including people), and aquatic life when they are ingested. Industries sometimes improperly and illegally empty large quantities of toxic materials into sources of local water supply. This group of pollutants corrodes water-treatment equipment and makes waste treatment an even more expensive problem.
Sediment, particles of earth such as dirt and sand, composes a group of pollutants that is becoming a problem because of the magnitude of its debris. Sediment causes a nuisance and a hazard by covering food sources for aquatic life (and thereby eventually reducing sources for the other life), by filling streams, and by preventing natural reservoirs from filling during rainy seasons. Resultant floods destroy animal and plant life and property and can cause epidemics of such water-borne diseases as typhoid and salmonellosis. Because of its sheer volume, sediment also increases the cost of water treatment.
Heat becomes a problem because it reduces the ability of the water to absorb oxygen. If significant amounts of water are heated through industrial use, the water becomes less efficient in providing oxygen for aquatic life and in assimilating waste. Even more dangerous, the ecological balance of lakes and rivers can be permanently upset through prolonged alteration of water temperature. The food people eat either comes directly from water or has fed upon aquatic life somewhere in the food chain. Faced with an expanding world population, we must increasingly be aware of the significance of every organism in the food chain and its relationship to us.
Containing such a variety of pollutants in ever-increasing amounts, water, an essential to life, becomes a threat to the integrity of human health. It poses a threat first, because of its increasing unavailability for consumption, and second, because of the harmful proportion of dangerous pollutants contained in what does remain.
We can become diseased from drinking the contaminated water. Quality of water service must be improved to countless Americans; many in rural areas and small towns obtain their drinking water from polluted sources. Keeping potable water separate from water for other uses would help conserve water supplies and ensure greater purity, since water used for other things could be refiltered with less expense. We can no longer enjoy polluted water for recreational purposes. Pollution of marshes and shorelines has severely impaired breeding habitus for many kinds of shellfish and deep water species, which subsequently affects the nation`s food supply. The odor of decay and the unsightliness of polluted water most certainly destroy the beauty of any natural setting. This problem does not have an easy answer. But if the abuse of water resources exceeds purification, we will need more water than will be available. Our existence will then be threatened by one of the essential components of life.
Today, one-third of the water pollution comes from industry, one-third comes from communities, and one-third comes from agriculture. One of the most frightening consequences of water pollution is the threat to the oceans. The collective discharges of the world`s nations may permanently be polluting the oceans.
At this point, the first solution must be water purification systems and the second must be prevention. The pollution cycle must stop.
References :
Saltonstall, Richard, Your Environment and What You Can Do About It : A Citizen`s Guide. New York : Walker and Company, 1970.
Okum, Daniel, “Drinking Water for the Future, “ American Journal of Public Health, 1976.
Murray, RB and Zentner JP., Nursing Concepts for Health Promotion, Second Edtion, Prentice-Hall, Inc, Englewood Cliffs, N.J, 1979.
