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 WATER POLLUTIONAND SOCIETY

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مُساهمةموضوع: WATER POLLUTIONAND SOCIETY   الأربعاء سبتمبر 15, 2010 12:09 pm

WATER POLLUTIONAND SOCIETYByDavidKrantz and Brad Kifferstein INTRODUCTION Comprising over 70% of the Earth�s surface, wateris undoubtedly the most precious natural resource that exists on our planet. Without the seemingly invaluable compound comprised of hydrogen and oxygen,life on Earth would be non-existent: it is essential for everything onour planet to grow and prosper. Although we as humans recognize thisfact, we disregard it by polluting our rivers, lakes, and oceans. Subsequently,we are slowly but surely harming our planet to the point where organisms
are dying at a very alarming rate. In addition to innocent organismsdying off, our drinking water has become greatly affected as is our abilityto use water for recreational purposes. In order to combat waterpollution, we must understand the problems and become part of the solution. POINT AND NONPOINT SOURCES According to the American College Dictionary, pollutionis defined as: �to make foul or unclean; dirty.� Water pollutionoccurs when a body of water is adversely affected due to the addition oflarge amounts of materials to the water. When it is unfit for itsintended use, water is considered polluted. Two types of water pollutantsexist; point source and nonpoint source. Point sources of pollutionoccur when harmful substances are emitted directly into a body of water. The Exxon Valdez oil spill best illustrates a point source water pollution. A nonpoint source delivers pollutants indirectly through environmentalchanges. An example of this type of water pollution is when fertilizerfrom a field is carried into a stream by rain, in the form of run-off
which in turn effects aquatic life. The technology exists forpoint sources of pollution to be monitored and regulated, although politicalfactors may complicate matters. Nonpoint sources are much more difficultto control. Pollution arising from nonpoint
sources accounts for a majority of the contaminants in streams andlakes.
CAUSES OF POLLUTION Many causes of pollution including sewage andfertilizers contain nutrients such as nitrates and phosphates. Inexcess levels, nutrients over stimulate the growth of aquatic plants andalgae. Excessive growth of these types of organisms consequentlyclogs our waterways, use up dissolved oxygen as they decompose, and blocklight to deeper waters.
This, in turn, proves very harmful to aquatic organisms as it affectsthe respiration ability or fish and other invertebrates that reside inwater.
Pollution is also caused when silt and othersuspended solids, such as soil, washoff plowed fields, construction andlogging sites, urban areas, and eroded river banks when it rains. Under natural conditions, lakes, rivers, and other water bodies undergoEutrophication, an aging process that slowly fills in the water body withsediment and organic matter. When these sediments enter various bodiesof water, fish respirationbecomes impaired, plant productivity and waterdepth become reduced, and aquatic organisms and their environments becomesuffocated. Pollution in the form of organic
material enters waterways in many different forms as sewage, as leavesand grass clippings, or as runoff from livestock feedlots and pastures. When natural bacteria and protozoan in the water break down this organicmaterial, they begin to use up the oxygen dissolved in the water. Many types of fish and bottom-dwelling animals cannot survive when levelsof dissolved oxygen drop below two to five parts per million. Whenthis occurs, it kills aquatic organisms in large numbers which leads todisruptions in the food chain.PollutedRiver in the United KingdomThe pollution of rivers and streams withchemical contaminants has become one of the most crutial environmentalproblems within the 20th century. Waterborne chemical pollution enteringrivers and streams cause tramendous amounts of destruction. Pathogens are another type of pollution that provevery harmful. They can cause many illnesses that range from typhoidand dysentery to minor respiratory and skin diseases. Pathogens includesuch organisms as bacteria, viruses, and protozoan. These pollutantsenter waterways through untreated sewage, storm drains, septic tanks, runofffrom farms, and particularly boats that dump sewage. Though microscopic,these pollutants have a tremendous effect evidenced by their ability tocause sickness.
ADDITIONAL FORMS OF WATERPOLLUTION Three last forms of water pollution exist in theforms of petroleum, radioactive substances, and heat. Petroleum oftenpollutes waterbodies in the form of oil, resulting from oil spills. The previously mentioned Exxon Valdez is an example of this type of waterpollution. These large-scale accidental discharges of petroleum arean important cause of pollution along shore lines. Besides the supertankers,off-shore drilling operations contribute a large share of pollution. One estimate is that one ton of oil is spilled for every million tons ofoil transported. This is equal to about 0.0001 percent. Radioactivesubstances are produced in the form of waste from nuclear power plants,and from the industrial, medical, and scientific use of radioactive materials. Specific forms of waste are uranium and thorium mining and refining. The last form of water pollution is heat. Heat is a pollutant becauseincreased temperatures result in the deaths of many aquatic organisms. These decreases in temperatures are caused when a discharge of coolingwater by factories and power plants occurs.DemonstratorsProtest DrillingOil pollution is a growing problem, particularlydevestating to coastal wildlife. Small quantities of oil spread rapidlyacross long distances to form deadly oil slicks. In this picture, demonstratorswith "oil-covered" plastic animals protest a potential drilling projectin Key Largo, Florida. Whether or not accidental spills occur during theproject, its impact on the delicate marine ecosystem of the coral reefscould be devastating. OilSpill Clean-upWorkers use special nets to clean up a Californiabeach after an oil tanker spill. Tanker spills are an increasing environmentalproblem because once oil has spilled, it is virtually impossible to completelyremove or contain it. Even small amounts spread rapidly across large areasof water. Because oil and water do not mix, the oil floats on the waterand then washes up on broad expanses of shoreline. Attempts to chemicallytreat or sink the oil may further disrupt marine and beach ecosystems. CLASSIFYING WATERPOLLUTION The major sources of water pollution can be classifiedas municipal, industrial, and agricultural. Municipal water pollutionconsists of waste water from homes and commercial establishments. For many years, the main goal of treating municipal
wastewater was simply to reduce its content of suspended solids, oxygen-demandingmaterials, dissolved inorganic compounds, and harmful bacteria. Inrecent years, however, more stress has been placed on improving means ofdisposal of the solid residues from the municipal treatment processes. The basic methods of treating municipal wastewater fall into three stages:primary treatment, including grit removal, screening, grinding, and sedimentation;secondary treatment, which entails oxidation of dissolved organic matterby means of using biologically active sludge, which is then filtered off;and tertiary treatment, in which advanced biological methods of nitrogenremoval and chemical and physical methods such as granular filtration andactivated carbon absorption are employed. The handling and disposalof solid residues can
account for 25 to 50 percent of the capital and operational costs ofa treatment plant. The characteristics of industrial waste waterscan differ considerably both within and among industries. The impactof industrial discharges depends not only on their
collective characteristics, such as biochemical oxygen demand and theamount of suspended solids, but also on their content of specific inorganicand organic substances. Three options are available in controlling industrialwastewater. Control can take place at the point of generation inthe plant; wastewater can be pretreated for discharge to municipal treatmentsources; or wastewater can be treated completely at the plant and eitherreused or discharged directly into receiving waters.WastewaterTreatmentRaw sewage includes waste from sinks, toilets,and industrial processes. Treatment of the sewage is required before itcan be safely buried, used, or released back into local water systems.In a treatment plant, the waste is passed through a series of screens,chambers, and chemical processes to reduce its bulk and toxicity. The threegeneral phases of treatment are primary, secondary, and tertiary. Duringprimary treatment, a large percentage of the suspended solids and inorganicmaterial is removed from the sewage. The focus of secondary treatment isreducing organic material by accelerating natural biological processes.Tertiary treatment is necessary when the water will be reused; 99 percentof solids are removed and various chemical processes are used to ensurethe water is as free from impurity as possible. Agriculture, including commercial livestock and poultry farming,is the source of many organic and inorganic pollutants in surface watersand groundwater. These contaminants include both sediment from erosioncropland and compounds of
phosphorus and nitrogen that partly originate in animal wastes andcommercial fertilizers. Animal wastes are high in oxygen demandingmaterial, nitrogen and phosphorus, and they often harbor pathogenic organisms. Wastes from commercial
feeders are contained and disposed of on land; their main threat tonatural waters, therefore, is from runoff and leaching. Control mayinvolve settling basins for liquids, limited biological treatment in aerobicor anaerobic lagoons, and a variety of other methods.
GROUND WATER Ninety-five percent of all fresh water on earthis ground water. Ground water is found in natural rock formations. These formations, called aquifers, are a vital natural resource with manyuses. Nationally, 53% of the population relies on ground water asa source of drinking water. In rural areas this figure is even higher. Eighty one percent of community water is dependent on ground water. Although the 1992 Section 305(b) State Water Quality Reports indicate that,overall, the Nation�s ground water quality is good to excellent, many localareas have experienced significant ground water contamination.
Some examples are leaking underground storage tanks and municipal landfills.
LEGISLATION Several forms of legislation have been passedin recent decades to try to control water pollution. In 1970, theClean Water Act provided 50 billion dollars to cities and states to buildwastewater facilities. This has helped control surface water pollutionfrom industrial and municipal sources throughout the United States. When congress passed the Clean Water Act in 1972, states were given primaryauthority to set their own standards for their water. In additionto these standards, the act required that all state beneficial uses andtheir criteria must comply with the �fishable and swimmable� goals of theact. This essentially means that state beneficial uses must be ableto support aquatic life and recreational use. Because it is impossibleto test water for every type of disease-causing organism, states usuallylook to identify indicator bacteria. One for a example is a bacteriaknown as fecal coliforms.(Figure 1 shows the quality of water for eachevery state in the United States, click on the US link). These indicatorbacteria suggest that a certain selection of water may be contaminatedwith untreated sewage and that other, more dangerous, organisms are present. These legislations are an important part in the fight against water pollution. They are useful in preventing Envioronmental catastrophes. The graphshows reported pollution incidents since 1989-1994. If stronger legislationsexisted, perhaps these events would never have occurred. figure1GLOBAL WATER POLLUTION Estimates suggest that nearly 1.5 billion peoplelack safe drinking water and that at least 5 million deaths per year canbe attributed to waterborne diseases. With over 70 percent of the planetcovered by oceans, people have long acted as if these very bodies of watercould serve as a limitless dumping ground for wastes. Raw sewage, garbage,and oil spills have begun to overwhelm the diluting capabilities of theoceans, and most coastal waters are now polluted. Beaches around the worldare closed regularly, often because of high amounts of bacteria from sewagedisposal, and marine wildlife is beginning to suffer. Perhaps the biggest reason for developing a worldwideeffort to monitor and restrict global pollution is the fact that most formsof pollution do not respect national boundaries. The first major internationalconference on environmental issues was held
in Stockholm, Sweden, in 1972 and was sponsored by the United Nations(UN). This meeting, at which the United States took a leading role, wascontroversial because many developing countries were fearful that a focuson environmental protection was a means for the developed world to keepthe undeveloped world in an economically subservient position. The mostimportant outcome of the conference was the creation of the United NationsEnvironmental Program (UNEP).
UNEP was designed to be �the environmental conscience of the United Nations,�and, in an attempt to allay fears of the developing world, it became thefirst UN agency to be headquartered in a developing country, with officesin Nairobi, Kenya. In addition to attempting to achieve scientific consensusabout major environmental issues, a major focus for UNEP has been the studyof ways to encourage sustainable development increasing standards of livingwithout destroying the environment. At the time of UNEP's creation in 1972,only 11 countries had environmental agencies. Ten years later that numberhad grown to 106, of which 70 were in developing countries. WATER QUALITY Water quality is closely linked to water use and tothe state of economic development. In industrialized countries, bacterialcontamination of surface water caused serious health problems in majorcities throughout the mid 1800�s. By the turn of the century, citiesin Europe and North America began building sewer networks to route domesticwastes downstream of water intakes. Development of these sewage networksand waste treatment facilities in urban areas has expanded tremendouslyin the past two decades. However, the rapid growth of the urban population(especially in Latin America and Asia) has outpaced the ability of governmentsto expand sewage and water infrastructure. While waterborne diseaseshave been eliminated in the developed world, outbreaks of cholera and othersimilar diseases still occur with alarming frequency in the developingcountries. Since World War II and the birth of the �chemical age�,water quality has been heavily impacted worldwide by industrial and agriculturalchemicals. Eutrophication of surface waters from human and agriculturalwastes and nitrification of groundwater from agricultural practices hasgreatly affected large parts of the world. Acidification of surface watersby air pollution is a recent phenomenon and threatens aquatic life in manyarea of the world. In developed countries, these general types ofpollution have occurred sequentially with the result that most developedcountries have successfully dealt with major surface water pollution. In contrast, however, newly industrialized countries such as China, India,Thailand, Brazil, and Mexico are now facing all these issues simultaneously. CONCLUSION Clearly, the problems associatedwith water pollution have the capabilities to disrupt life on our planetto a great extent. Congress has passed laws to try to combat water pollutionthus acknowledging the fact that water pollution is, indeed, a seriousissue.But the government alone cannot solve the entire problem. It is ultimatelyup to us, to be informed, responsible and involved when it comes to theproblems we face with our water. We must become familiar with ourlocal water resources and learn about ways for disposing harmful householdwastes so they don�t end up in sewage treatment plants that can�t handlethem or landfills not designed to receive hazardous materials. Inour yards, we must determine whether additional nutrients are needed beforefertilizers are applied, and look for alternatives where fertilizers mightrun off into surface waters. We have to preserve existing trees and plantnew trees and shrubs to help prevent soil erosion and promote infiltrationof water into the soil. Around our houses, we must keep litter, petwaste, leaves, and grass clippings out of gutters and storm drains. These are
just a few of the many ways in which we, as humans, have the abilityto combat water pollution. As we head into the 21st century, awarenessand education will most assuredly continue to be the two most importantways to prevent water pollution. If these measures are not takenand water pollution continues, life on earth will suffer severely.
Global environmental collapse is not inevitable.But the developed world must work with the developing world to ensure thatnew industrialized economies do not add to the world's environmental problems.Politicians must think of sustainable development rather than economicexpansion. Conservation strategies have to become more widely accepted,and people must learn that energy use can be dramatically diminished withoutsacrificing comfort. In short, with the technology that currently
exists, the years of global environmental mistreatment can begin tobe reversed.
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