Compilation of answers we got on the effects of water pollution. This article will also guide you to learn about: 1. Effects of Water Pollution, 2. Harmful Effects of Water Pollution 3. In Points, Effects of Water Pollution on Human Health 4. Effects of Water Pollution on Aquatic Life 5. Effects of Water Pollution on Animals 6. What Are the Causes and Effects of Water Pollution 7.Future Effects of Water Pollution.
Answer # 1. Effects of Water Pollution:
Water, the wonderful natural resource, is extremely essential for survival of all living beings. But today clean water has become a precious commodity and its quality is threatened by numerous sources of pollution. Several waterborne infectious diseases are directly related to polluted water.
In addition, the aquatic food chain acts to concentrate several toxic substances as it ascends from micro or through various predators. Organochlorine and organomercury pesticides, PCBs and some radioactive pollutants are concentrated in this way.
Well water contaminated by nitrates from fertilizer run-off poses a hazard to health, particularly for infants.
Municipal waste is the principal contributor of water pollution. A recent report from Water Pollution Research Laboratory, London, indicates that domestic sewage contains trace quantities of toxic metals such as Cu, Cr, Zn, Pb, Co, etc.
Beaches are closed when the bacteria count of water is too high, indicating pollution by fecal matter. Beaches are also closed when the water contains deleterious substances which give off foul odour. In heavily contaminated areas where algae have thrived and died, rotting mats of floating debris wash-up on the shore.
Solid wastes sometimes wash- up also, and some oil spills have caused spectacular damage to valuable beach properties. Water containing considerable organic matter generally becomes depleted in oxygen as microbes that feed on dead and decay materials themselves die-out!
Decay consumes oxygen and desirable fish needing relatively high oxygen level either die out or go elsewhere. Mercury pollution or pollution by PCBs also reduces the recreational value of a fishing lake. Resort owners, commercial fisherman and the communities that are benefited from such recreational activities suffer considerable economic damage from different types of water pollution.
Oil pollution in marine water also affects public health critically in the following ways:
(i) Paraffins like methane and ethane are asphyxiants i.e., they cause acute suffocation. Some paraffins act as central nervous system depressants. Liquid paraffins can remove oil from exposed skin causing dermatitis and pneumonia in lung tissues.
(ii) Breathing higher concentrations of unsaturated cycloparaffins can result in irritation and anesthesia.
(iii) Aromatic thiophenes, benzothiophenes and mercaptans are lethal as they damage liver and kidneys.
(iv) Crude oil contains sulphur compounds, small amount of nitrogen, little olefins, and metals like iron, nickel and vanadium. These are extremely lethal. Carbonyl sulphide is dangerous poisonously. Actually it dissociates to hydrogen sulphide, which acts on central nervous system resulting in death mainly from respiratory paralysis.
Water has been a potential carrier of deleterious inorganic and organic materials, nonbiodegradable matters and pathogenic microbes which can endanger public health and life. The potable water contaminated with municipal sewage is the root cause of dangerous diseases in public life.
The waste-water coming from slums, hotels, restaurants, residential areas and animal waste, human fecal matters, organic wastes dissolved compounds as proteins, fats, carbohydrates, pathogens like bacteria, algae, viruses etc. which pollute water bodies directly or indirectly are nuisance to public health.
i. Parasites are considerably harmful for humans. Eggs of nematodes, hookworms and tapeworms occur mostly in crude sewage. When such sewages are discharged into water bodies without treatment, contamination of water takes place with resultant danger to human and aquatic life.
ii. Mainly, drinking contaminated water or swallowing food transmits the enteric diseases. The pathogens most frequently transmitted through water cause infections of intestinal tract like typhoid, paratyphoid, amebic dysentery, cholera, polio and infectious hepatitis.
iii. The disease-causing organisms present in the feces of infected persons get ultimately mixed with the water supply — spreading chronic diseases.
iv. The guinea worm, responsible for dracontiasis, is transmitted through open village-wells and ponds infested with the copepod intermediate host.
v. Several human diseases, whose epidemics recurrently detriment human population, occur when the populace get contaminated by water.
vi. Intestinal heliminths like Ascaris and Trichuris are also water-borne.
Man’s infectious diseases which spread especially through water and food are:
a. Typhoid fever, bacillary dysentery, cholera, poliomyelitis and hepatitis occur from contaminated water and food.
b. Staphylococcal and streptococcal infections may occur from water and food or also by contact and inhalation.
c. Coxsackie and Echovirus diseases occur from water through ingestion.
Answer # 2. Effect of Water Pollution:
Pollution by Sewage:
Pollution by sewage contributes organic and inorganic materials and large numbers of bacteria, all of which have an objectionable effect on the quality of the water in the stream and its usage for domestic and industrial purposes. The inorganic matter in sewage is in suspension and in solution. The suspended matter (sand, grit, ashes) is of importance only in relation to sludge deposits. The soluble substances affect the chemical composition of the water.
The organic matter is present in coarse or fine suspension or in solution and is composed primarily of carbohydrates, fats and proteins. The coarse and a portion of the finely divided materials, settle more or less rapidly to the stream bed forming sludge deposits. The oils and fats spread on the surface of the water forming unsightly sleek, while the remainder of the materials remain in suspension (depending on the velocity of the stream) and are acted upon in transit by microorganisms.
The effects of sewage pollution on the quality of the water may be –
2. Chemical and
1. Physical Effects:
The finely divided matter in sewage imparts turbidity and increases the suspended solids content of the water, makes the stream esthetically objectionable and increases the cost of treatment for domestic and industrial purposes. Suspended solids render the water unfit for process waters, boilers, condensers and creates fouling of tubes and pipe unless properly treated.
Tastes and odours are imparted to the water by sewage either directly or indirectly. Hydrogen sulfide may be present in sewage or may be produced as a result of biological activity in the stream from the reduction of sulfate or organic sulfur compounds. Sludge deposits exposed at low water or under certain conditions in a submerged state are particular sources of odour.
2. Chemical Effects:
The chemical composition of surface waters is altered appreciably by the discharge of sewage. The total salt content may be increased. An increase in chloride content is objectionable to domestic water supply; sulfates are objectionable from the standpoint of boiler waters and as a source of hydrogen sulfide production under anaerobic conditions. The ammonia nitrogen contained in sewage tends to increase the concentration of this constituent in the water.
Nitrates discharged with oxidized effluents and nitrates produced in the stream from the ammonia nitrogen stimulate the growth of algae in the water causing an indirect increase in tastes and odours and in some cases resulting in actual nuisances as a result of decomposition of large quantities of organic matter accumulated by the growth of these organisms.
The organic matter contained in sewage modifies the chemical composition of the water directly and indirectly. Directly, an increase in the organic matter of the water causes an increase in the turbidity. The indirect effects of organic matter on biochemical processes are discussed below.
3. Bacterial Pollution:
Unpolluted stream water has low bacterial numbers. Part of the natural bacterial population consists of coliform organisms which are derived from run off from fields and soil and are similar to the coliform organisms derived from sewage. The balance of the flora consists of bacteria native to the water and is specially adapted to grow under the environmental conditions prevailing in the stream.
It is doubtful whether many of the native bacteria are actually grown or counted in ordinary culture media. They are adapted to grow in a water environment of low food content by attaching themselves to inert surfaces forming slimy growths and deriving their food by adsorption on biological surfaces.
Sewage greatly increases the density of pollutional bacteria (coliform) in water. The daily per capita discharge of coliform organisms in sewage has been estimated at 100 to 400 millions. In addition there may or may not be present certain pathogenic organisms such as typhoid or dysentery bacteria. Generally, neither the pathogenic nor the pollutional forms of bacteria multiply in the water, although some initial increase in the numbers of coliform organism has been noted below a point of sewage discharge.
It is logical to expect that the numbers of native water bacteria increase greatly in response to the addition of food materials present in sewage. With increasing time of flow the pollutional forms decrease in number, as well as the native population, because of the exhaustion of food. Depending, therefore, on the distance of intake point from the source of pollution, water will contain variable numbers of bacteria.
It has been shown that for domestic supply a raw water containing coliform organisms in density greater than 5,000 per 100 ml cannot be adequately treated by the ordinary process of coagulation, filtration and chlorination. A water heavily contaminated with bacteria of either pollutional or native forms is unsuitable for cooling purposes and as process waters without sterilization and treatment because of slime formation. Bacterial pollution of surface waters also endangers the harvesting of shellfish and use of bathing places.
As a result of sewage pollution the numbers of protozoa increase in the water. Some of these organisms feed on bacteria and help keep their numbers down and thereby increase their biochemical activities. The numbers of filamentous organisms, such as sphaerotilus and Leptomitus, increase and attach themselves in long strands to sticks and stones and float downstream below sewer out falls.
Certain forms of filamentous algae such as blue greens and Spirogyra will also be found attached in the some environments as the filamentous bacteria, in coves and on the surface. As the stream recovers itself from the pollution the numbers and types of green algae increase.
A number of higher animals, such as rat-tail maggots. Tubifex (sludge worms) and chironomous (blood worms) are found in sludge deposits.
i. Physical Effects:
Many industrial wastes have similar effects on the turbidity of the water as sewage. The turbidity imparted to water by industrial wastes may be organic or inorganic in nature. Examples of the latter type of turbidity are muds from drilling operations and coal washeries. With few exceptions most industrial wastes impart organic suspended matter and increase the turbidity of water.
Many industrial wastes are highly coloured and are still detectable after high dilution. Wastes from dye manufacturing plants, textile wastes, wood and flux cooking waster, fermentation wastes and pickling liquor wastes are particularly objectionable from the standpoint of color.
Taste and odour producing substances such as phenols, gas and by product coke manufacturing wastes, oil and petroleum wastes, munition manufacturing wastes, sulfides, etc., make the water unfit for domestic consumption or require expensive treatment processes for their removal. Aside from these direct effects, tastes and odours are produced indirectly as a result of bacterial decomposition of organic industrial wastes as well as by algae.
ii. Chemical Effects:
Acid and alkaline wastes may change the pH value of the stream to the extent of interfering with self-purification processes and rendering the water corrosive for industrial and boiler usages or increasing the hardness. Wastes from chemical manufacturing plants, acid mine drainage and pickling liquor wastes have deleterious effects in all these respects. The chloride content of the water is increased by the discharge of oil drilling operations.
The discharge of toxic materials, such as cyanides and chromates affects the self-purification capacity of the stream and renders it unfit for drinking purposes. The effect of certain organic wastes as intestinal irritants is only vaguely understood.
iii. Bacterial Pollution:
Industrial wastes, in general, do not contain pathogenic bacteria with the possible exception of anthrax organisms found in tannery wastes and, therefore, their direct effect on bacterial quality of water is not important. Besides this they do not contribute large numbers of intestinal organisms of coliform type.
The effect of industrial wastes on bacterial population is indirect, produced as a result of the multiplication of the bacteria deriving their food from the organic matter or the destruction of bacteria by toxic materials present in the waste.
3. Effects of Waste on Fish Life:
It does not follow that the indiscriminate discharge of sewage and wastes is desirable from the standpoint of fertilization for biological growth and fish. Excessive amounts of sewage and waste will, on the contrary, have deleterious effects on fish life.
According to Ellis, the injurious effects of industrial wastes and sewage are caused by the following factors:
1. Materials in suspension such as in untreated sewage, paper pulp, mud, sawdust, rock powder, etc. cover the bottom and smother the biological life therein which is important as fish food.
2. Materials having an oxygen demand reduce the dissolved oxygen content of the stream to a point where fish cannot exist. It is not the organic matter per sec that kills the fish, but the low dissolved oxygen content resulting from the biochemical activities. A dissolved oxygen content of 5.0 ppm is taken as the minimum for game fish, but the value is affected by various other factors.
3. Acid or alkaline conditions created in the stream by the discharge of waste affect the fish life directly. Most fish require a pH value of 6.5 to 8.4. Wastes derived from chemical and plating works and coal mines seriously affect fish life.
4. Salinity of the water is important for fresh-water fish as they cannot tolerate sudden changes in osmotic pressure. Brines from oil wells are detrimental in this respect; about 7,000 ppm of NaCl is usually lethal to fresh water fishes.
5. Fish are killed specifically by toxic substances even when all other conditions of the environment are favourable. Most of these toxic materials are effective in very low concentrations. The effects may be cumulative or indirect by the destruction of their food supply.
6. High CO2 concentration in water is also inimical to fish.
Sensitivity to specific pollutants varies with the species, age, weight of fish and seasonal effects. Fish are most sensitive just after the breeding season and within a given species the smaller fish are more resistant than.
Answer # 3. Effects of Arsenic Pollution on Health:
Arsenic is a ubiquitous element in the earth’s crust. It is transported in the environment mainly through water; although other natural and anthropogenic sources of exposure to arsenic include burning of arsenic-rich coal, mining and smelter activities which are of increasing concern. While a wealth of epidemiologic studies have confirmed the carcinogenicity of inhaled and ingested arsenic, the pathological characteristics of arsenic-induced cancers have never been examined extensively.
Moreover, recent studies appear also to suggest that the health effects of arsenic are systemic and may involve multiple organs. In nearly all cases where internal cancers are attributed to arsenic exposure, there has been cutaneous evidence of arsenic adverse effects in the form of arsenical keratosis, hyperpigmentation, and multiple cutaneous malignancies.
Epidemiological and clinical studies reported in the medical literature have confirmed the role of arsenic in the induction of cancers of the skin. Arsenic-induced skin lesions may include keratosis, squamous cell carcinoma and basal cell carcinoma.
Arsenical keratosis in its fully developed form is a well-established clinical syndrome, characterized by several specific pathological features, including hyperkeratosis, parakeratosis, arsenical pigmentation, and squamous cell carcinoma in situ (indistinguishable from Bowen’s disease).
The lesions are normally most pronounced on the feet and hands, although they can occur on the trunk and other areas of the extremities. In addition to skin lesions, including skin cancer, epidemiological studies have provided suggestive evidence linking arsenic exposure to various internal cancers, including angiosarcoma of the liver, lung cancer, and bladder cancer. In the majority of cases in which the internal cancer is ascribed to arsenic exposure, some dermatological hallmark of arsenic poisoning is identified.
Gastrointestinal manifestations have also been reported due to chronic arsenic exposure and include non-cirrhotic portal hypertension (NCPH), hepatic or splenic enlargement, hepatocellular carcinoma and liver angio-sarcoma. NCPH is a rare, but relatively specific effect that may occur after years of arsenic ingestion at concentrations of 0.01 mg/kg/d. The increased incidence of hepatocellular carcinoma in arsenic-exposed endemic areas of Taiwan may have an arsenic etiology in addition to a viral causation.
Non Carcinogenic Effects:
In addition to internal cancers, recent published studies have suggested an association between arsenic exposure and an increased risk for a variety of non-cancer effects. These include peripheral vascular disease, cardiovascular disease, diabetes, neurological effects, chronic lung diseases (shortness of breath and chest signs), diminished hearing, and cerebrovascular disease.
The evidence for a casual relationship between cancers of the skin and arsenic exposure is strong and indisputable. Arsenic-induced skin cancers are predictable from exposure biomarkers of the skin, including hyperkeratosis, and hyper- or hypopigmentation.
Cancers of the internal organs do not have such distinct exposure biomarkers and thus their association with a particular etiologic agent cannot be established with the same degree of confidence. Nevertheless, chronic arsenic exposure represents a significant risk factor for future development of liver cancer.
1. In sewage some chemicals (phenolic compounds, Cr, Hg, Pb, etc.), are present which advisely effects aquatic life plant and animals that leads to die of these living things.
2. Wastewater contaminated with feces leak out and gets mixed with ground water then drinking water may borne many diseases.
3. Extra nitrate in water leads to many problems.
4. Certain type of anemia in babies which cause suffocation and death.
5. Miscarriage (natural abortion) in women.
6. Cancer of digestive tracts.
7. Not good for plant roots are damaged and their stems and branches become thin.
8. Bacteria viruses or fluorides, nitrates, sulphate, etc., present in drinking water cause disease of serious nature.
9. Organic matter present in water, consumes the DO for biological decomposition, thus rendering it unfit for aquatic life.
10. When toxic chemicals from industrial effluents join the water sources, water becomes unfit for domestic use as well as for agriculture.
1. Effect on Man:
(i) Major cause for the spread of epidemics and chronic disease in man. It causes typhoid, jaundice, dysentery, diarrhea, tuberculosis and hepatitis,
(ii) Water contaminated by fibres i.e. asbestos cause fatal disease like asbestos and lung cancer, and
(iii) Ground water in excessive rainfall areas contains iron in toxic amount 20 ppm for drinking purpose permissible limit of iron is only 0.3 ppm,
(iv) Woolen industry contribute large amount of toxic metals such as Hg, Ni, Cu, Cr, Fe and cyanides to ground water causing skin and stomach disease in man effect of rain water.
2. Effect on Soil:
(i) Irrigating agricultural field severely damages crops as decrease grain production,
(ii) Effect on soil fertility by killing bacteria and soil micro-organism, and
(iii) Affect plant metabolism severely and disturbs the whole ecosystem.
Harmful Effect of Sewage and Domestic Water:
1. Sewage is an excellent medium for growth of pathogenic bacteria, viruses and protozoa. Vibriocholera found in sewage causes cholera, salmonella typhosa causes typhoid, even after treatment.
2. Domestic sewage, which is primarily, composed of spent water containing wine, soopy wastes, food materials.
3. Several pathogenic micro-organism introduced in water course cause deleterious effects and chronic diseases in human and animal.
4. Sewage containing oxidisable and fermentable matter causes depletion of DO in water bodies affecting aquatic life and production of objectionable odours in water.
5. Solid and suspended matter creates river or water beds and blanket which cause reduction of aquatic life.
1. Industrial effluent cause deleterious effects on living organisms and may bring about death or sublethal pathology of kidneys, liver, lungs, brain and reproduction system.
2. Effluent like methyl mercaptan and pentachlorophenol lower the photosynthetic rate of aquatic communities by hindering sunlight penetration into water column.
3. Free chlorine discharged by factory cause heavy fish mortality in river.
4. Hg creates fetal disease like minimata in Japan.
5. As, Pb, CN, etc., cause cellular Regeneration in brain which result in figidita, coma, stupov and numbness,
6. Acid and alkali make water corrosive.
7. Excess minerals cause water hardness which are then unsuitable for domestic and industrial purpose.
8. Tannery contains pathogen bacteria Anthrax bacilli and chromium also cause skin and eye irritation problem and also decrease soil ferities.
9. Heated effluent create unpleasant for water bodies.
Plant nutrients, pesticides, insecticides herbicides, fertilisers, farm waste, manure, sediments, plant animal debris contain organic material which causes water pollution.
Excessive use of fertiliser lead the accumulation of nitrate in water which cause serious disease in children like methemoglobin anemia (blue bodies) and also nitrite interfere with O2 carrying capacity of blood causing suffocation and damage respiratory as vascular system.
10% in blood cause disease
20% headache and giddiness
60% unconsciousness, stiffness
80% death occurs.
1. Fertiliser crop yield but at the expense of protein loss.
2. Super phosphates may lead to Fe, Cu, Zn deficiency in plant.
Answer # 4. Dangerous Effects of Water Pollution:
Virtually all types of water pollution are harmful to the health of humans and animals. Water pollution may not damage our health immediately but can be harmful after long term exposure.
Different forms of pollutants affect the health of animals in different ways:
1. Heavy metals from industrial processes can accumulate in nearby lakes and rivers. These are toxic to marine life such as fish and shellfish, and subsequently to the humans who eat them. Heavy metals can slow development; result in birth defects and some are carcinogenic.
2. Industrial waste often contains many toxic compounds that damage the health of aquatic animals and those who eat them. Some of the toxins in industrial waste may only have a mild effect whereas other can be fatal. They can cause immune suppression, reproductive failure or acute poisoning.
3. Microbial pollutants from sewage often result in infectious diseases that infect aquatic life and terrestrial life through drinking water. Microbial water pollution is a major problem in the developing world, with diseases such as cholera and typhoid fever being the primary cause of infant mortality.
4. Organic matter and nutrients causes an increase in aerobic algae and depletes oxygen from the water column. This causes the suffocation of fish and other aquatic organisms.
5. Sulfate particles from acid rain can cause harm the health of marine life in the rivers and lakes it contaminates, and can result in mortality.
6. Suspended particles in freshwater reduces the quality of drinking water for humans and the aquatic environment for marine life. Suspended particles can often reduce the amount of sunlight penetrating the water, disrupting the growth of photosynthetic plants and microorganisms.
Water pollution can be damaging to the economy as it can be expensive to treat and prevent contamination. Waste that does not break down quickly accumulates in the Earth’s waters and eventually makes its way to the oceans.
Water pollution can be prevented by stopping pollutants from contaminating nearby waters. There are a number of water treatments to prevent pollution-
These simple techniques cost money to maintain, but prevention is much cheaper than cleaning up water pollution that has already occurred.
The cost of a pollution clean-up depends on many factors:
1. The location of the pollution is important in determining how much the clean-up will cost. If the contamination is in an area that is easy to get to, then the clean-up cost will be cheaper.
2. The contamination size also needs to be considered, the larger the area of contamination, the more expensive the cost of the clean-up.
3. The type of pollutant may also have an effect on the clean-up cost, some pollutants are more difficult to clean up than others, and therefore more expensive.
There are many different types of water pollution and all have a different adverse effect on the environment.
1. Heavy metals from industrial processes can accumulate in nearby lakes and rivers. These are toxic to marine life such as fish and shellfish, and can affect the rest of the food chain. This means that entire animal communities can be badly affected by this type of pollutant.
2. Industrial waste often contains many toxic compounds that damage the health of aquatic animals and those who eat them. Some toxins affect the reproductive success of marine life and can therefore disrupt the community structure of an aquatic environment.
3. Microbial pollutants from sewage often result in infectious diseases that infect aquatic life and terrestrial life through drinking water. This often increases the number of mortalities seen within an environment.
4. Organic matter and nutrients causes an increase in aerobic algae and depletes oxygen from the water column. This is called eutrophication and causes the suffocation of fish and other aquatic organisms.
5. Sulfate particles from acid rain change the pH of water making it more acidic, this damages the health of marine life in the rivers and lakes it contaminates, and often increases the number of mortalities within an environment.
6. Suspended particles can often reduce the amount of sunlight penetrating the water, disrupting the growth of photosynthetic plants and micro-organisms. This has subsequent effects on the rest of the aquatic community that depend on these organisms to survive.
Answer # 5. Ecological Effects of Water Pollution:
1. Minamata Disease – This disease is caused by mercury poisoning. It is characterized by crippling and death. This disease appeared in a coastal town, Minamata, in Japan.
The primary cause for this disease was a plastic industry which was started on the sea coast of Japan in 1905. From this factory a by-product called mercury was disposed into the sea. This mercury accumulated in marine animals.
Later birds, cats, dogs and men receive mercury when they eat marine fishes and animals. The accumulation of mercury leads to crippling and death. Their initial symptoms of minamata disease includes the numbness of limbs, lips and tongue, impairment of motor control deafness and blurring of vision.
Finally it affects and destroys the brain. As a result of the attack of minamata disease about 17 persons died and 23 became permanently disabled in the year 1953, in Japan.
2. Diarrhea – It is caused by mercury, cadmium and cobalt.
3. Mortality of Plankton and Fish – Chlorine which is added to water to control the growth of algae and bacteria in the cooling system of power stations may persist in streams to cause the mortality of plankton and fish.
4. Reduction in Productivity – Intensive agriculture increases the amount of silt in lakes and rivers. Silt prevents the penetration of light to depths and thus reduces primary production.
5. Siltation – Siltation is a phenomenon by which the gills of fishes are deposited with silt. This causes heavy mortality among fishes.
6. Poor Oxygenation – Oil present on the surface of water prevents water oxygenation. This reduces respiration and metabolism in aquatic organisms.
7. Poor Photosynthesis – Oil pollution prevents photosynthesis in phytoplankton.
8. Red Tide – When coastal waters are enriched with nutrients of sewage, dinoflagellates multiply rapidly and form bloom. These blooming dinoflagellates liberate into the water, produce toxic metabolic by-products which can result in a large scale death of marine fishes. This is called red tide.
9. Biochemical Oxygen Demand – Sewage enriches the water with nutrients. This causes rapid growth of plankton and algae. This leads to oxygen depletion in water. The oxygen depletion causes the death of algae. The decay and decomposition of algae consume more oxygen from water.
Biochemical Oxygen Demand or Biological Oxygen Demand (BOD) is the amount of oxygen required by the microorganisms in water. BOD is higher in polluted water (sewage) and lesser in drinking water. Increased BOD lowers the contents of dissolved 02 in water causing the suffocation and death of aquatic flora and fauna.
10. Water-borne Diseases – Diseases like jaundice, cholera, typhoid, diarrhea, etc. are transmitted through water contaminated with sewage.
11. Methaemoglobinema – The nitrate used in fertilizers enters the intestine of man through drinking water. In the intestine, it is converted into nitrite.
Nitrite is absorbed into the blood where it combines with haemoglobin to form methaemoglobin. Methaemoglobin cannot transport oxygen. This leads to suffocation and breathing troubles, especially in infants. This disease is called methaemoglobinema.
12. Eutrophication – Domestic sewage and fertilizers add large quantities of nutrients such as nitrates and phosphates to the freshwater ecosystems. The rich supply of these nutrients make blue green algae, green algae and other phytoplankton to grow abundantly. This increased productivity of lakes and ponds brought about by nutrient enrichment is known as eutrophication.
As the algae use O2 of the water for respiration, the O2 is depleted from the water. The rapid growth also consumes all the nutrients of the water. The depletion of O2 and nutrients lead to the death of algae and other phytoplankton.
As other organisms, such as zooplankton and fishes of the water, depend on the blue green algae and phytoplankton for their food, they also die. Thus eutrophication leads to the complete depletion of the fauna from the ecosystem.
Answer # 6. Effects of Water Pollution on Social Hygiene:
Water pollution treads heavily on health and hygiene of society. It has been estimated that “Two third of illness in India are related to water borne diseases, such as typhoid, ineffective hepatitis (Jaundice), cholera, diarrhoea and dysentery. Many of them became epidemic proportion”.
It is estimated by National Institute of Communicable Diseases, Delhi that 30 per cent of Mortality and 50 per cent of the morbidity due to infectious diseases in India is due to water borne diseases. According to the survey of eight developing countries by WHO, 90 per cent of all child deaths could be avoided by providing safe water and sanitation. About 15 Million children under the age of 5 die every year which accounts for one fourth of all deaths in the World. A majority of them in developing countries.
The disease caused by water pollution may be classified into five categories:
(a) Water borne diseases such as typhoid, Cholera, dysentery, gastroenteritis and infectious hepatitis.
(b) Water washed infection of the skin and eyes such as trachoma, seabies, yaws, and conductivities.
(c) Water based diseases such as Schistosomissis and guinea worm.
(d) Diseases with water related insect vectors (mosquitoes and black files need water for breeding).
(e) Infections that are primarily caused because of defective sanitation such as hookworm.
The estimated people suffering from water related diseases are immense. At any time in the world there are probably 500 million people with trachoma 250 million with elephantiasis 200 million with bilharzia or schistosomissis, 160 million with malaria and 100 million with diarrhoea. Approximately 50 per cent of the people suffering from these diseases are found in Asia at any one time.
Answer # 7. Effects of Toxic Water Pollutants on Human Health:
i. Coliform Bacteria:
The first causal epidemiological connection between human faeces and disease was made by Dr. John Snow in 1854 when he unrevealed the mystery of London cholera epidemic by observing that the common link between all the victims in the Broad Street area was that they obtained their drinking water from the same well.
Today we know that coliform bacteria make up something like one-fifth to one-third of the average person’s wastes and billions of them are released into the sewage systems every day. They cause cholera, typhoid fever and gestro-enteritis. Chlorination of water is the only remedy but we should not forget that chlorination may pose health hazards of its own.
Nutrients like phosphorus, nitrogen, and carbon are essential to aquatic life. However, excess of these nutrients in a water body causes paradoxical kind of pollution known as “eutrophication” the term derived from Greek word meaning “well nourished”. Lake Erie in U.S.A. and Dal Lake in India are facing severe eutrophication problems.
Nitrates occur naturally in water at low levels. However, heavy application of artificial fertilizers most of which contain nitrogen in the form of urea may become a health problem. Nitrate levels above 10 mg/l in water can cause methemoglobinemia known as “blue body”. Nitrate levels as high as 40 mg/l have been found in some parts of Midwest.
Sediments are the particles of sand, grit and other inorganic matter that flow into waterways from mining sites, construction sites, logging sites and urban run-off. Severe sedimentation can physically fill small ponds and lakes. They may cause turbidity. Mining activities are one major cause of sedimentation problems.
The problem of acid rain first came to the attention of scientist in Northern Europe more than thirty years ago when lakes of southern Sweden and Norway were found losing their fish populations. In 70 percent of some 1500 lakes analyzed in Norway, pH values were below 4.3 and they contained no fish at all.
Acid mists caused by coal-fired plants in Great Britain across the North Sea were carried by prevailing atmospheric currents to Scandinavia. Soon, scientists from other countries reported increased acidity in their waterways. Nearly 200 lakes have been found dead in North America and Canada.
In 1956, an epidemic of organic mercury poisoning broke out in Minamata, a small town of 50,000 residents located on the coast of Kyushu, Japan’s southernmost island. It was caused by dumping of mercury wastes dumped into Minamata Bay by Chisso Corporation. Samples taken from the mud of Minamata Bay near Chisso’s effluent outlet were found to be contaminated with over 2,000 ppm of mercury.
Fish and shellfish samples also contained high methyl-mercury levels ranging from 10 to 40 ppm. Autopsies of the victims revealed levels as high as 70 ppm in liver and 144 ppm in kidney, and 24 ppm in brain which is acutely sensitive to methyl-mercury. Even residents of Minamata town with no outward sign of disorder had levels ranging from 100-150 ppm in hair samples, normal levels run about 8 to 90 ppm.
Until the early 1960s, it was widely assumed that elemental mercury emitted or dumped into the biosphere was not a hazard because it does not react easily with other substances, is quite stable, and above all, is only very slightly soluble in water. However, Swedish environmental scientists began to wonder that mercury dumped into the water was in an inorganic elemental from but the fish that inhabited these waters contained more toxic alkyl from, the methylmercury.
By 1972, it had been repeatedly demonstrated that aquatic micro-organisms living in the bottom sediments of natural waterways had the power to transform the relatively insoluble form of elemental mercury into highly soluble and highly toxic form of methylmercury. Once it has been “biotransformed” in this way, methyhnercury was easily absorbed by the tissues of fish and from these it easily passed to man and other predators that consumed the contaminated fish.
Shortly after the 1956 outbreak, Chisso’s own physician Dr. Hajime Hosokawa had quietly begun to test Chisso’s wastes by feeding them to laboratory cats and observing the effects. On Oct, 7, 1959 he found that cats convulsed, salivated and suddenly died while crashing into laboratory walls. However, Hosokawa did not publish his results and lull followed for almost ten years.
In 1966, an identical case of mercury poisoning broke out in the town of Niigata in Central Japan. In this case Shown Denko Company was proved guilty of dumping toxic substances into the Agano River. The victims promptly sued the suspected source. Their success united anger in Minamata and suits were filed against Chisso. Finally Chisso stopped dumping mercury wastes into Minamata Bay in 1968.
On March 20, 1973, a Japanese court decided the case in favour of plantiffs and ordered Chisso to pay each one of them including the heirs of those who had died from sixty thousand to eighty thousand dollars. As of the end of 1979, 1401 individuals had been certified as victims of Mianamat disease. Of this number 353 had died. Chisso had paid over $ 200 million in damages.
The afflicting symptoms of Minamata disease are madness, muscle spasms, convulsions that arch the body like a taut bow, paralysis, loss of speech and vision, and in many cases the crippling of arms and legs. In the final stages, the victims’ muscles waste away and they become comatose. They lose all emotional control and eventually pass from coma to death.
In India, most of our rivers have become noxious sewers and veritable death traps of fish. Chaliyar River in Kerala has been reported to contain high level of mercury discharged by a nearby rayon factory. It has contaminated the fish that forms the popular diet of people living in surrounding villages.
Mercury poisoning is also evident in Orissa’s Rushkulya River and in the Thane creek near Bombay.
The Kalu River which flows through Bombay’s industrial suburbs of Ambernath and Ulhasnagar has been found to contain high concentrations of mercury.
Incidences of mercury poisoning have also been found in other countries like Iran and Sweden where mercury contaminated seeds were eaten by farmers and birds.
The word detergent has been derived from the Latin term “detergene” meaning to cleanse. Substances like soaps that possess considerable cleansing property are known as detergents. Soaps differ greatly physically and chemically, but they have one property in common-they lower surface tension of liquids in which they are dissolved. That is why they are known as surface active agents or in short “surfactants”.
The detergents enter into the water from various sources i.e. industry (textile, leather, dyeing and finishing), agriculture and refuse of cities and towns. The increased personal and domestic consumption of detergents is certainly one of the main causes of pollution of surface waters.
The detergents are responsible for nuisances like foam. They affect the oxidation of dissolved matter and transfer of oxygen. They affect the bacterial and algal flora and influence the permeability of soils.
In animals the lethal dose varies between 1 and 223 of anionic detergent per kg of their weight, depending on the species. In one hour, 20 ppm will cause the death of 65- day old trout, while 15 ppm will cause the death of a 15 cm young through in the same time.
The amount of dissolved oxygen in the water is also very important. When the oxygen content is reduced, the effect of toxic substances is proportionately increased, and in polluted streams with a low oxygen content small concentrations of surface active agents can have a toxic effect.
In man, detergents may cause dermatitis. 131.1 percent of dermatitis cases in United States have been attributed to detergents. Owing to their peculiar physical properties the surface active agents are capable of penetrating into the skin either directly or through sweat glands. Their ability to denature proteins or reaction with keratin may trigger serious disturbances.
Pesticides are biologically active chemicals used for killing plants or animal pests. It is a general term embracing insecticides, herbicides, fungicides, nematocides etc. Sometimes a collective term biocide is used to include all these categories. Pesticides have been used in one form or another for more than 2,000 years, but the use became widespread only in the last century.
The primary problem with pesticides is that they are intentionally toxic and if they are toxic to undesirable organisms, they may also be toxic to desirable one including ourselves. The danger from pesticides was brought to public attention in 1962 with the publication of SILENT SPRINGS, a book by Rachel Carson. During the last two decades the use of pesticides has increased 12 times and millions of kilograms are produced every year.
Dichloro diphenyl trichloroethane (DDT), benzene hexachloride (BHC), chlordane, haptachlor, methoxychlor, toxaphene, aldrin, endrin and polychlorinated biphenyls (PCB) are the commonly used pesticides. Extensive and indiscriminate use of these biocides has made them an integral part of the biological, geological and chemical cycles of the earth. Today they are present in air, soil, water and each ecosystem.
DDT is a classic case of a pesticide thought to be safe and effective. Its discoverer Paul Muller was awarded a Nobel Prize. After World War II, DDT was found to be an amazing chemical. It controlled atleast 27 diseases, saved 5 million lives and prevented 100 million people from various illnesses. Although, it was recognized as early as 1948, that it is stored in body fat, no direct effect of DDT on man were noticed.
Its widespread distribution in the biosphere was evident when it was detected in Antarctic penguins, in cow’s milk and human milk. The drainage of DDT into rivers, swamps and coastal waters killed crabs, and fish. When these aquatic organisms were eaten by predators- their metabolism tended to favour the retention in body fat. Each step in the food chain resulted in an increased concentration of DDT. Finally the carnivorous birds contained sufficient DDT to cause toxic effects.
As the history of DDT illustrates, fat soluble pesticides can have subtle, hidden but important environmental effects. Because the compounds poorly soluble in water appear rare in the non-biological environment, they are easily ignored. However, their biomagnification and negative effects can be serious though the compound may be present in traces.
After decades of discussion, DDT still remains controversial as far as its actual effects on human health are concerned. However, many countries like U.K., U.S.A., Sweden Germany and Denmark had banned the use of DDT and other organochlorine pesticides.
According to World Health Organization (WHO), the level of DDT in human milk in India is the highest in the world. Monitoring of contamination of dairy milk within the country reveals that the residual level is the highest in Delhi, followed by Gujarat, Punjab, U.P. Haryana, Maharashtra, Bihar, Andhra Pradesh and Karnataka.
x. Handigod Syndrome:
The indiscriminate use of pesticides in agriculture and public health operations has increased the scope of disruption of ecological balance as many of the “non-target” organisms that are important links of food chain perish in the process thus adversely affecting the secondary and tertiary productivity of fresh water ecosystems. The tragic incident occurred in Karnataka. The incident has been reported in Cochin area in 1955 and Sitapur-Hardoi (U.P.) area in 1977.
Among various chlorinated insecticides viz. DDT, lindane, dieldrin, aldrin, endrin, endosulfan and chlordane examined for their toxicity in fish, endrin has been found to be highly toxic and endosulfan the least toxic. In catfish, endrin was reported to be 70,000 times more toxic than carbaryl.
The leather industry occupies an important place in the National economy of every country. India occupies a predominant position in the world production of hides and skins. Tanneries in Tamil Nadu alone fetch the exchequer over Rs. 1,400 crore through exports but bring multifaceted environmental problems.
Tannery effluents contain vegetable tannins and non-tannins which cause chemical oxygen demand. They also contain high amounts of proteins. These proteins are biodegradable and exert high BOD where water from tanneries contain about 46% proteins, 10% fatty acids, 4% tannins, 20% inorganic volatile solids and about 21% total dissolved volatile solids.
Chlorides, trivalent chromium, nitrogen, phosphorus, sulphate, ammonium salts, lime etc. are the inorganic pollutants present in significant quantities. For each kg salted hide 35 litres of water is required. The discharge of untreated waste waters in a nearby water body may affect the physical, chemical and biological characteristic of water.
High oxygen demand, high pH, excessive alkalinity, suspended matter, sulphides are injurious to fish and other aquatic organisms. The chrome process involves 250 chemicals including cadmium, arsenic and chromium. Chromium in particular is used in large quantities.
Tanneries make the ground water unfit for drinking, and irrigation. Groundwater of a few districts viz. Pallavaram, Chrampet, Ambut, Ranipet, Pernabet and Vaniyambadi in Tamil Nadu have been affected by tanneries. A 100 km stretch of river Polar in T.N. receives the effluents of about 300 tanneries. Therefore, subsurface water of river Polar have been badly polluted. Another river Vaniyambadi faces similar problems.
A tannery waste can contaminate the groundwater in a radius of 8 kms. The effluent from vegetable tanning is coloured which makes the water turbid. Turbidity reduces light penetration, thereby reducing the photosynthetic activity of aquatic plants. Pathogenic micro-organisms such as, Bacillus anthrasis may increase in these waters and may be transmitted to human beings.
As many as 139 organic chemicals, heavy metals (Zn, Pb, Cr, Cu, Hg, Me, Ba) and their salts, acids and alkalies are used in the manufacture of dyes. Most of these compounds, besides small quantities of intermediate compounds along with final products are discharged into waste waters causing serious pollution problems.
Total dye-stuff production in the organized sector alone was 187440 tonnes during 1982-83. Beside this a large number of small units are in operation in India. The estimated demand for dyes for 1983-84 was 36,100 tonnes. The use of dyes has enormously increased during the last decade. The main intermediate used are benzoic acid, nitrobenzene, chlorobenzene and aniline all ranked as highly toxic and suspected carcinogens.
Heavy metals such as mercury, lead, cadmium and zinc are dangerous pollutants and are often deposited with natural sediment in water systems. Then they are incorporated in plants, food crops and animals. Heavy metal poisoning occurs when this water is used for agricultural and human consumption.
xiii. Organic Compounds:
Artificial organic compounds are used primarily in industrial processes, pest control, pharmaceuticals, food additives and other consumer products. Many of them escape into the environment and spread widely throughout the biosphere and can be found in many species. Their presence in non-target marine organisms far from the sources of their production confirms their presence in water bodies.
The dissolved organic matter (DOM), suspended organic matter (SOM) and bottom organic matter (BOM) cause a steep rise in BOD, killing off zooplankton and fish. SOM is more hazardous to the fish as the organic matter gathers round each silt particle and this silt organic mass clogs the gills of fish causing asphyxiation. The water polluted by organic compounds is unfit for human consumption.
Answer # 8. Effects of Water Pollution:
The main effect of pollution is to deplete through the excessive organic load the Dissolved Oxygen (D.O.) content of receiving water to a point that the stream becomes incapable of exercising the self- purification process. The de-oxygenation may be to such an extent that practically all the fish and other aquatic life may be destroyed.
The water pollution may further lead to stream insanitation by causing suspended solids to deposit on the stream bed causing silting, the organic matter undergoing putrefaction with the solid matter buoyed up by gas rising to the top and resulting in floating masses of evil smelling and unsightly sludge.
The use of polluted water downstream by human beings for their daily requirement would mean taking an unsafe and unwholesome water which may cause the sporadic outbreak of waterborne diseases. A vast population of our country resides along the banks of the rivers and many bathing ghats located thereon receive water polluted by the industrial wastes discharged into the rivers on the upstream side, so that the use of such water for bathing and recreational purposes cannot be considered good. The polluted waters are also difficult to be treated and it is found that the treatment plants have to incur increased costs in handling such waters.
Some of the effects of water pollution:
1. The oil that is spilled or spread in oceans can get washed up on nearby beaches by the wave action. Oil spills can devastate the plant and animal species and change the entire ecosystem in the coastal areas, sea coasts and beaches, and severely affect tourism as well as the life of the people living in the coastal areas. The people who bear the cost of the spill, a small coastal community, are not the people who caused the problem, but those who operate the oil tankers amidst the oceans.
2. Sewage contamination is another example of how pollution can affect us all. Sewage discharged into coastal waters can wash up on beaches and cause a health hazard. People who bathe or surf in the water can fall sick due to an array of diseases caused by the ingestion of Enterobacteriaceae, such as Escherichia, Salmonella, Proteus, Citrobacter, Enterobacter and Klebsiella, if they swallow polluted water.
Sewage and wastewater contamination can poison the fish communities and shellfish that inhabit near the shore. People who eat poisoned fish and shellfish risk are thus exposed to an acute illness called ‘paralytic shellfish poisoning’. Same diseases can afflict the people living in hinterland where too the sewage water and wastewaters pollute the terrestrial water resources. Shellfish is no longer caught along many shores because it is simply too polluted with sewage or toxic chemical wastes that have discharged from the land nearby.