Compilation of essays we got on the Causes of Water Pollution! Read this article to learn about: – Causes of Water Pollution: Essay, Paragraph, Article and Speech
Answer 1. Essay on the Causes of Water Pollution:
I. Water Pollution by Agriculture:
Agriculture has been a victim of water pollution in many instances, but sometimes. It is also responsible for polluting water. Water pollution caused by agriculture is mainly an outcome of fertilizers and agricultural chemicals such as insecticides and herbicides.
i. Water Pollution by Fertilizers:
Fertilizers given to crops are not always fully consumed, and part of it remains in the soil by being absorbed by soil colloid, and influence the quality of underground, river and sea waters when it is dissolved. Chemical fertilizers mainly consists of relatively simple compounds of nitrogen, phosphorus and potassium which are the nutritive elements of plants. Their runoff coefficients vary depending on the solubility of the fertilizer itself, the rate of absorption by plants, rate of absorption by the soil and rate of decomposition.
It is generally believed that the runoff co-efficient of nitrogen is 5.30%, and that of phosphorus is 0.5-5%. Especially, nitrogen having a high runoff co-efficient tends to cause the eutrophication of lakes and enclosed sea areas.
Fertilizers as the sources of water pollution are called “non-point sources” in contrast to “point-sources” such as sewage and industrial waste waters. The non- point sources are not only hard to eliminate, but also hard to measure their quantity. Organic fertilizers such as compost, farmyard manure, human waste and fish meal produce nitrogen and phosphorus when they are decomposed, and also become the sources of pollution. These organic fertilizers do not contain, in general, any toxic substances.
ii. Water Pollution by Agricultural Chemicals:
Agricultural chemicals comprise are considered as a source of peculiar pollution which cannot be overlooked. Agricultural chemicals comprise a variety of chemicals such as insecticides, sterilizers and weed killers, and have played important roles in the operation of modern agriculture, but they have also caused serious environmental pollution.
The characteristics of agricultural chemicals as water polluting substances lie in that:
(1) Almost all of them are special compounds not occurring at all in nature, and many of the behaviours and changes of such chemicals at the time when they are discharged into the natural environment are unknown;
(2) Many of their influences on the human body because of their inherent characteristic;
(3) When they are ingested into the human body, they tend to accumulate or concentrate in it;
(4) They are available in a variety of kinds, and new products are developed constantly;
(5) Some of them are extremely stable as chemicals, and remain in nature or in the human body for a long time thereby eventually afflicting the human body;
(6) It is common to all such chemicals to contain additives besides the main constituents, and the additives can contribute to affect the environment though they do not have a strong toxicity;
(7) Many of them require a special method of analysis.
Of the agricultural chemicals developed in the past, many of them are prohibited from being used because of their violent toxicity. Nevertheless, those remaining in the environment are still factors that contribute to environmental pollution.
In addition to above-mentioned pollutions, there are instances of water pollution caused by indirect effect of agricultural activities. For example, the change in the condition of the ground surface by reclamation of waste land, deforestation, supply of the soil to low land, and the alteration of the natural water system for irrigation purposes can be considered indirect causes of water pollution.
II. Water Pollution by Mining Industry:
In many countries, water pollution related to the mining industry can be traced back to olden times compared with those caused by other industries.
The characteristics of waste water from mining industries varies greatly depending on the kind of mine.
(i) Metal Mining Industry:
Many kinds of waste waters are discharged. For example, mine water, ore dressing water, waste water from smelters, etc. In general, it is strongly acid (Low pH), and contains metal irons, sulphuric acid and suspended solids of high concentrations.
(ii) Coal Mining Industry:
Waste water from coal mines mainly consists of mine water, coal dressing water, exudative water from coal-waste heap etc., and contains a large quantity of suspended solids. In general, the scales of operation of coal mines in much larger than that of other mining industries, and thus the coal mining industry exerts a large influence upon the natural environment.
(iii) Sulfur Mine:
In general, waste water from sulfur mines contains large quantities of sulfuric acid and iron and has a low pH value. Almost all sulfur mines are deserted; so the administration of deserted mines becomes a social and environmental problem.
(iv) Petroleum and Natural Gas Drilling Industries:
Different from other mining industries, these industries are very often located in plains. Waste water generally consists of welled up mine water and waste water incidental to the drilling operations. It contains large quantities of salt and organic matters such as mineral oil.
(v) Stone-Quarrying and Clay-Supply Industries:
These industries supply lime stones, building stones, porcelain clay etc. Waste water from the sites of these industries generally contains large quantities of suspended solids.
The characteristics of industrial pollution common to the above mentioned mining industries can be summarized as follows:
(a) In many instances, the development of a mine itself changes its natural environment artificially, and such a change first affects the quality of water of the environment even if any kind of waste water is not discharged from mining activities.
(b) In areas where mines can be developed, very often, even before the development of the mine, the quality of river water of underground water is different from that of other areas. For instance, river water or underground water in such areas contain special metals of high concentrations and is strongly acid.
Thus, it is rather difficult to measure the direct influence of mining activities on the quality of water. And also, geological features and the ways of land use are usually very peculiar in mining areas. These conditions should be taken into consideration prior to surveying the quality of water.
(iii) Mining activities generate large quantities of solid wastes in most cases, and such wastes from large heaps. Such wastes not only pollutes water by exudation of toxic substances, but also, the rapid generation of suspended solids in water when the heap is washed away by a heavy rainfall or a flood.
III. Water Pollution by Stockbreeding and Fisheries:
i. When cattle or horses are fed on a big pasture, there is little possibility of the livestock causing water pollution because their excreta are spread widely all over the pasture. However, when livestock is fed intensively in a limited area it causes a number of problems. In the case of the stockbreeding industry, the excreta and leftover feed on livestock are the sources of water pollution.
Water pollution caused by stockbreeding has the following characteristics:
(a) Degree of pollution varies largely depending on the location of the stockbreeding farm (whether in suburban or country area), system and scale of operation and the level of breeding technique.
(b) Composition and quantity of excreta of livestock varies depending on the type, quantity and methods of feeding and watering.
(c) Besides water pollution, the stockbreeding industry also generates an offensive odor, flies, noise and so on.
ii. Besides stockbreeding farms, waste water from slaughterhouses is a source of water pollution which should not be overlooked.
iii. In most instances, fisheries has been the victim of water pollution. But in recent years, as the number of fish farms increase, pollution of water areas surrounding fish farms caused by leftover feed and excreta of fish is becoming serious.
IV. Water Pollution by Urban Activity:
In a sense, the existence of human beings itself is a source of water pollution. In primitive ages, the purifying capacity of nature was much greater than the rate of water pollution caused by human living. But as time passed, men began to settle near water areas for the convenience of living; then they developed various industries which provided them with the foundation of civilized life.
The emergence of various industries coupled with the development of civilization has constantly increased the quantity of waste water containing pollutants. On the other hand, the increasing concentration of the population has also invited the concentration of pollution sources. As a result, the rate of environmental pollution has exceeded the rate of natural purification.
Municipal wastes such as waste water, human waste, household waste, waste gas and waste heat are the causes of water pollution.
The type of water pollution in a city varies largely depending on the characteristics of the city, life style of the inhabitants, degree of civilization, degree of development of sewage treatment plants or sewerage systems.
Although, it is very difficult to investigate these conditions in detail, they can be estimated by investigating the following:
(i) Population of the City:
This is the most essential datum to be obtained first.
(ii) Consumption of Water and Quantity of Waste Water:
Where a city water system is well established, it is relatively easy to obtain data concerning the consumption of water. For example, the consumption of city water in a modern civilized city is said to be about 500 liter/man/day. However, it is usually difficult to know the quantity of waste water even if it is only an estimate.
(iii) Condition of Sewage Treatment:
This can be measured in terms of the availability of age treatment plants and sewage works including their capacities and efficiency.
(iv) Condition of Municipal or Public Facilities and Private Facilities:
In a large city, there are a number of public facilities and various other facilities, and all these facilities can be the sources of water pollution, such as – (Public facilities) Government and municipal offices, schools, hospitals, public bath houses, public lavatories, markets, ports, power plants, city gas facilities, sewage treatment plants, etc.
(Non-public facilities) – Factories, stores, offices, gas stations, restaurants, bars, hotels, etc.
(v) Condition of Sewage:
Municipal sewage mainly consists of a mixture of human waste, household sewage and wastes from other facilities, and its condition varies depending on the characteristics of the city, degree of civilization, precipitation and the condition of road surface.
The quantity and condition of waste water resulting from human activity, mainly consisting of household waste water, generally vary depending on the time in a day; however, the “product of the concentration multiplied by the quantity” tends to remain within a relatively fixed range. Such a value is defined as “pollution loading amount”, and is used as the basic data for the sewage treatment planning.
The most conspicuous characteristics of municipal sewage are that the organic content (indicates as BOD) is extremely high; the contents of ammoniacal and organic nitrogen, phosphates and sulfides are considerably high; and normally, hazardous substances are not contained.
The modern sewage treatment technique is capable of removing organic pollutants very efficiently, but it is difficult economically to remove nitrogen and phosphorus contents efficiently with existing facilities. For example, only about 30% of the nitrogen and phosphorus contents can be removed through the currently employed two-step treatment method, which mainly applies the activated sludge method and the remainder of such contents causes the eutrophication of water areas.
Anyhow, all of the above mentioned techniques are possible where the municipal sewerage system and sewage treatment plants are well established, and the quantity and quality of waste water can be measured effectively. However, where sewage treatment plants are not available, or where waste water is discharged directly into the hydrosphere without passing a sewage treatment plant, it is almost impossible to measure the quality and quantity of waste water.
In case waste water is directly discharged into the hydrosphere, and if the pathogenic bacteria of an infectious disease are contained in the human waste, such bacteria would be discharged into the hydrosphere in active condition thereby eventually spreading the infectious disease through the water system. The degree of such a danger various depending on the quality of sanitation facilities of individual cities.
V. Water Pollution by Manufacturing Industry:
Characteristics of Water Pollution by Manufacturing Industry:
Of water pollutions with which human activities are concerned, the manufacturing industry is the largest in scale, and most diversified.
The characteristics of the water pollution of manufacturing industry can be summarized as follows:
i. Unlike the mining industry and agriculture, the discharging condition of waste water from manufacturing industries is relatively simple because it is rarely affected by complicated conditions of the natural environment. For example, waste water of the manufacturing industry is discharged concentratively from a fixed outlet, which is called “point source pollution”.
Besides, waste water from the manufacturing industry is generated as a result of the production activity which is 100% artificial, and thus the manufacturing industry can be considered as the source of water pollution which is most easy to catch and control in this point.
ii. Sources of water pollution from manufacturing industry are relatively easy to trace back through scientific method, but their control is not always easy because it involves complex social and political problems. Furthermore, tracing such point sources of pollution is not always easy because the interests of individual manufacturing companies can be affected by pollution control measures.
iii. In contrast to the relatively simple form of discharging process, the composition and quantity of waste water vary widely depending on the type and scale of individual factories, change from time to time, and its influence also takes a variety of forms.
iv.The influence of waste water on the environment varies depending on the geographical Iocation of the factory.
(i) In the case of an industrial conglomerate or large scale industrial complex – the influence of waste water on the environment is extremely large, but as far as such manufacturing facilities are concentrated in one area based on the results of careful environmental assessment, waste water from these facilities can be controlled in the most ideal form;
(ii) In case factories are located in commercial or residential areas of a city – the location of this type is primarily undesirable. Actually, however, there are a number of such cases because of historical reasons, or geographical advantages concerning the purchase of raw materials, transportation of products, or access to the labour market. In Japan, locations within easy access to the source of industrial water are decreasing in these areas.
As a result, factories that recycle water are increasing; small scale manufacturing companies establish cooperative associations and are promoting the construction of joint waste water treatment facilities.
(iii) Location of the manufacturing factory is whether mountainous area, plain, or costal region is also an important factor to be considered is assessing the influence of waste water on the environment. Especially, in the case of a water-consuming type of manufacturing industry, its location has to be decided depending on accessibility to an industrial water source.
On the other hand, the condition of the river or the sea into which waste water of the factory has to be discharged also has a great influence on the form and type of environmental pollution.
Characteristics of Waste Water of Main Industries:
The composition of industrial waste water is complex, and it varies largely according to the difference in the manufacturing process even among the same type of manufacturing factories. Furthermore, the manufacturing industry is constantly subject to the impact of technological innovations which occur at increasingly short intervals. For example, in Japan, the technique for recycling of waste water is making rapid progress.
Manufacturing companies were compelled to do so due to the increasingly strict pollution control requirements and the increasing shortage of industrial water. As a result, manufacturing companies are also compelled to alter conventional manufacturing processes. It is rather difficult to enumerate the characteristics of waste water of each industry.
General characteristics of waste water according to the type of manufacturing industry are as follows:
i. Food Processing Industry:
A common characteristic of waste water from all types of food processing industries is the high concentration of organic content. Another common characteristic is the high concentration of solid, semisolid and suspended solid contents in waste water discharged from raw material treatment processes. The quality and quantity of waste water vary depending largely on the season mainly due to the variation of raw materials to be processed.
Materials contained in waste water can be divided roughly into carbohydrate, protein, fat and a mixture of them. In many instances, waste water contains oil, nitrogen and phosphorus. In the case of starch producing, sugar refining and brewing industries, the BOD level of waste water is especially high.
ii. Textile Industry:
There is much difference in the content of waste water between natural and chemical textile industries. Waste water from the wool industry contains high concentrations of BOD, fat and alkali. Waste water from dyeing discharges various pollutants such as dyes; auxiliary additives and other chemicals.
iii. Paper and Pulp Making Industries:
These are typical water consuming industries and the levels of COD and suspended solids in waste water are extremely high. Especially, waste water from the digesting process contains all components of wood except cellulose and has high COD and dense color, so that it is necessary to collect and treat most of the content to recover. A large quantity of waste paper fibre is also discharged as suspended solids together with the waste water.
iv. Petroleum Refining Industry:
The main component of pollutants is spilled oil; but waste water also contains hydrogen sulfide, other sulfides, ammonia, mercaptan, and phenols, etc.
v. Petrochemical Industry:
The waste water contains hydrocarbons, various organic compounds and catalysts, and its content varies largely depending on the type of product.
vi. Iron and Steel Making Industry:
This industry is also a water-consuming industry. Waste water from the cooling and cleaning processes for coke furnace gas contains ammonia, cyanide, phenols, etc. Besides, there is waste water from the dust collecting process of each furnace which contains suspended solids (coke dust and ore), and that from the pickling process which contains acid, iron and oil.
vii. Electroplating Industry:
Many of the raw materials and chemicals used in this industry contain toxic substances, and thus the waste water contains various heavy metals (cadmium, zinc, copper etc.), cyanide, hexavalent chromium, acids and alkalis.
viii. Leather Industry:
The level of BOD is high in waste water which comes from tannin used for tanning and raw skins. It also contains chromium used for tanning and lime for pretreatment, suspended solids and dyes.
ix. Steam and Nuclear Power Plants:
These power plants discharge large quantities of effluent water from the cooling process. In Japan, all the large power plants are located close to the sea, and these plants are using sea water for cooling. The temperature of waste cooling water is normally high, and such waste water can cause thermal pollution or the elevation of temperature to the vicinity of discharging outlet. No other pollution is considered.
VI. Water Pollution by Other Human Activities:
Aside from the various human activities, there are other types of human activities which also cause water pollution, and such activities sometimes become social problems as sources of environmental pollution.
These types of human activities are as follows:
i. Construction Work:
Construction works, especially those large-scale land development projects or forestry conservation and flood control projects aimed at preventing natural disasters, sometimes can cause water pollution. Water pollution caused by such construction projects can be divided into, those occurring incidental to the progress of construction works and those occurring due to the change in natural conditions as a result of the construction works.
The latter is more important than the former. Construction works for a dam, river improvement (including those for the alteration of basins), port facilities, creation and reclamation of land and gravel gathering from river-bed are enumerated as examples of the above-mentioned cases.
ii. Various Tertiary Industries:
Various tertiary industries can be considered to cause water pollution such as cleaning and laundry businesses, public bath houses, hotels, printing business, photographic film development businesses, hospitals, laboratories or research institutes, tourist businesses, transportation facilities and so forth.
An increase in the load of municipal waste water as a result of the increase in the load of municipal waste water as a result of the increase in the working population of cities also has become one of the factors directly related to water pollution. Of various transportations, ships, especially tankers which discharge waste cleaning water, have come to the fore as sources of water pollution in coastal regions.
iii. Errors, Accidents and Disasters:
Accidental damages to public sewage works or drainage of industrial effluent, as well as poor planning of sewage treatment plants, and erroneous operations of these facilities can also cause water pollution. Water pollution caused by accidents, pollution of the ocean due to oil resulting from the collision of tankers on the high seas has become an object of public attention in recent years.
Phosphorous and nitrogen compounds (phosphates, ammonium salts, nitrites and nitrates, etc.) are called nutrient salts which are essential to the growth of phytoplankton and algae participating in the primary production. However, if they are excessively supplied together with organic substances, the production activities become too vigorous due to over nutrition, ultimately changing the aquatic ecosystem. This phenomenon is called eutrophication.
Eutrophication of lakes is not an extraordinary phenomenon but one which occurs and slowly proceeds even in natural not polluted ecosystem. However, eutrophication in polluted sea and lakes progresses very quickly due to rapid increase of organic substances and nutrient salts, causing unusual growth of specific organisms and thus destroying the normal aquatic ecosystem.
This type of eutrophication is often observed in closed water areas, such as lakes and deeply recessed bays; the results is coloring and smelling of the drinking water taken from the lakes, lowered clarity of lake water, or the occurrence of the so called “red tide” in sea and lakes as a visible and conspicuous phenomenon. The red tide is caused by unusual propagation of certain kinds of planktons at such a terrific speed as to change the color of water.
Consequently, many environmental troubles occur such as death of fishes due to clogging of gills with planktons, oxygen deficiency over the polluted area, and generation of poisonous substances.
In Japan, this phenomenon has often been observed in the Inland Sea and other closed water areas. The true causes have not yet been determined exactly, but it is generally accepted that phosphorus and nitrogen compounds contained in urban and industrial waste waters and playing an important role.
Contamination of Bottom Sediments:
River, lake and sea bottoms are usually covered with a certain depth of muddy sediments. These sediments contain remains and excreta of aquatic organisms, other than the earth and sand carried over by river. Suspended solids in water tend to sediment remarkably in lakes, slow-flowing rivers, estuaries where the river stream is stagnated by tidal currents, and in closed sea areas.
Cases are also reported where some highly poisonous heavy metals and sparingly soluble organic substances, which had settled on the bottom of water and fixed as sediment over a long period, were dissolved again or raised under some conditions, causing serious hazards. A typical example is mercury in the bottom sediment of the Minamata Bay.
It was about twenty years ago when mercury caused the Minamata disease, but mercury hazard are still continuing Minamata disease, but mercury hazards are still continuing even after the discharge of mercury from industrial waste water completely stopped.
At the bottoms of lakes and closed sea areas with high organic loads, dissolved oxygen is consumed rapidly during the putrefaction of organic substances contained in the bottom mud. If vertical mixing of water is insufficient due to stratification, oxygen dissolved on the surface of water from the atmospheric air cannot reach the bottom. In addition, poor clarity of water weakens sufficient penetration of the sun beam and significantly suppresses photosynthetic reactions in the bottom water layer.
Under these conditions, the dissolved oxygen in the bottom water mass will decrease, ultimately leading to the zero-oxygen state. As a result, fishes in that area will be seriously affected and the surrounding ecosystem may be materially destroyed.
Other cases are also known where elution of phosphorus and nitrogen from bottom sediments in closed sea areas may be responsible for eutrophication and the resultant occurrence of red tide. Water bottoms often provide favourable spawning grounds for fishes; anaerobic conditions of bottom sediments destroy hatching in many cases.
A survey of bottom sediments provides the environmental information of the neighboring water area in the past ever a considerably long period. Thus, it is possible to obtain new findings on the progress of pollution not expected from water quality investigations.
Oil Pollution in Oceans:
Modern civilization relies in a large measure on petroleum in all aspects. A huge amount of crude oil is carried by supertankers on oceans throughout the world, stored in tanks at terminal stations, and processed into various petroleum products at petrochemical complexes. Many terminal stations and petrochemical complexes are located in coastal zones.
Probably, a considerable amount of oils is always flowing into the ocean, including slight leaks from various ground facilities, leakage from tankers during loading and unloading, and discharge of waste oil used on land. Besides, large scale oil spills due to maritime accidents have often occurred.
Oil spilt out to the sea tends to-spread on the sea surface as a thin layer. Volatile components gradually evaporate and some of them dissolve into water (benzene, for example, dissolves in seawater to a concentration of about 820 ppm at ordinary temperature). The oil membrane thus formed on the sea surface disturbs normal exchange of gases between the seawater and the atmospheric air, and also interrupts the penetration of sunbeams to retard the growth of planktons.
The oil gradually becomes thick as the volatile components; evaporate; the resultant viscous heavy oil is in or on the sea water, or gathers shellfishes and sand on the sea bottom to form oil balls, which drift over long distances and cast ashore. The spilt oil is degraded by some bacteria through very slowly. However, if it drifts faster than it decomposes, pollution will proceed. Heavy oil sometimes sticks to the bodies of seafowls and fishes; particularly, larvas are seriously damaged by oil deposition. Although not so critical, cases are often encountered when fishes cannot be used for food because of the smell of heavy oil.
Oxygen dissolved in water has been an important vital species which gets consumed by oxidation of organic matter/ reducing agent etc. It is regarded as an important water quality parameter. Its optimum value for good quality water has been 4.6 mg/litre of dissolved oxygen (DO) which is able to maintain aquatic life in a water body. If DO values are somewhat lower than this value, this indicates water pollution.
Biochemical Oxygen Demand (BOD):
It is a water quality parameter for organic matter in water, which is empirical in nature. It may be measured by the quantity of oxygen utilised by suitable aquatic micro-organisms during a five day period.
Biochemical oxygen demand (BOD) has been a standardized measurement of the amount of oxygen that would be required by micro-organisms to cause the decomposition of certain organic and inorganic matter in the water. The measurement is done under standardized conditions (e.g., at 20°C and five days to allow the decomposition to take place). The result is called the 5-day BOD and is expressed in milligrams of oxygen per litre of water.
BOD is not a pollutant but an indicator. It measures no particular substance but a family, any substance that micro-organisms can consume (using oxygen as they do) or any material attacked under the conditions of the test.
The substances decomposed in the test may be food used by the micro-organisms or certain chemicals that are readily attacked by oxygen, perhaps with the aid of enzymes released by the microorganisms. These chemicals include sulphites and sulphides (from paper mills), ferrous iron, and some easily oxidized compounds.
Many organics, however, make no contribution to the BOD but still render the water unfit for human use. BOD values of several hundred milligrams per litre characterize “strong” sewage. For “excellent” drinking water the 5 day BOD, on a monthly average, should be in the range of 0.75 — 1.5 milligrams/litre.
BOD values are important when they signify that the oxygen supply dissolved in the water will be so greatly reduced that desirable fish no longer can survive or when they signify that conditions for the propagation of dangerous bacteria exist.
Chemical Oxygen Demand:
It is an important water quality parameter. It is an index of the organic content of water oxygen demanding substances in water. The chemical oxygen demand (COD) has been a measure of the concentration in a water supply of substances that can get attacked by a strong chemical oxidizing agent in a standardized analysis. (Dichromate oxidation is commonly used).
The results of the analysis are usually expressed in terms of the amount of oxygen that would be needed (in principle, because oxygen is not itself used) to oxidize the contaminants to the same final products obtained with the standardized analysis. COD values do not get necessarily correlated with BOD values. Textile wastes, paper mill wastes, and other wastes with high levels of cellulose have COD values considerably higher than their BOD values as cellulose is not readily attacked in the BOD test.
Distillery and refinery wastes often have BODs higher than CODs unless the COD measurement is specially modified. In the nature of the two tests, the BOD of a given water supply is able to decrease faster than its COD.
Chemical oxygen demand (COD) has been found to be more scientific than the traditional empirical concept of Biological oxygen demand (BOD). The test is based on the chemical oxidation of material in water by K2Cr2O7 in H2SO4.
VII. Radioactive Materials:
Harmful radiation may result in water environments from the wastes of uranium and thorium mining and refining, from nuclear power plants; and from industrial, medical, and scientific utilization of radioactive material.
Many radioactive substances are lethal at relatively low concentrations and in minute amounts may be mutagenic.
Perhaps the greatest problem of radioactive pollution, as a result of uranium production, has been caused by the large quantities of “uranium tailings” produced. This finely divided solid material remains after useful materials have been leached out. Huge piles of these tailings are found in uranium producing areas.
These tailings create a radiation pollution problem as they contain radioactive decay products of uranium. Two of these radioactive materials are thorium-230 (2309Th) and radium-226 (22688Ra). Substances like these can be dissolved or eroded from piles of tailings by rainfall, and thus they can get mixed up into the general water supply.
Radium and thorium is chemically similar to calcium and so get absorbed by the bones when taken into the body. Some waters in the Colorado River Basin have had the concentration of 22688Ra increase to about double the maximum level permissible for human consumption.
An important source of radioisotopes is nuclear, weapons testing. The amount and variety of radioactive materials formed depends on the type of weapon tested. Some of the radio isotopes have a very short half-life and last only a few seconds or minutes, and some others may have a half-life of several hundred years. These materials reach the earth as radioactive fallout. Before the first test explosions were conducted, it was thought that fallout (dust and debris) would fall to earth quickly and at no great distance from the detonation site, thus the spread of radioactivity would be limited.
However these assumptions have proved wrong, especially in the case of large explosions. Radioactive particles can, remain suspended in the air long enough to circle the globe many times, dispersing as they go. It is true, however, that the main effects of atmospheric testing are found in the immediate vicinity of the detonation site. Because of concern about such fallout in 1963, of the Limited Nuclear Test Ban Treaty was signed. According to the U.S. and U.S.S R., it will limit testing of nuclear weapons to underground detonations.
The purpose of underground detonations, carried out in the U.S. at the Nevada test site, is to limit the amount of atmospheric fallout, and in majority of cases this is achieved. Occasionally accidental releases of radiation reach the atmosphere due to “venting” at the explosion site. When this happens, radioactive gases are forced up through the hole used to place the explosives.
The leakage may take place through channels left the control and monitoring cables, natural cracks or fissures in the rock, fractures formed by the blast, or combinations of these. Sometimes venting occurs when the materials used to fill the hole are simply blown out. Leakage may immediately take place after the explosion or later, when rock and earth fall into the cavity formed by the explosion and leave a channel for gas venting.
In only 12 of 190 tests conducted at the Nevada site from 1961 through 1969 venting were reported different amount of radiation are released. It is released near ground level and so poses no world-wide fallout problems, but it may result in very serious local hazards.
Atmospheric fallout, irrespective of the source, can have far reaching effects and can be conveyed to man in a number of ways. The effects of radioisotopes on man can be illustrated. Strontium-90 (9038Sr) a component of radioactive fallout which has a half-life of 28 years, is chemically similar to calcium. Calcium is absorbed from the soil by plants and passed on to animals, where it is used in the formation of bones and teeth.
Man gets calcium from both plant and animal sources like milk, vegetables, and cereal grains Strontium is produced it from these sources and, due to chemical similarities to calcium it is also deposited in bones and teeth. The marrow of bones is the main site of blood-cell formation. The presence of radioactive strontium-90 in the surrounding bone tissue seriously curtails this which may result in production anemia or more serious disorders.
Cesium-137 (13755Cs) which is chemically similar to potassium is a common constituent of all living cells. Cesium from fallout passes to man through contaminated meat and dairy products or contaminated grains and leafy vegetables. Cesium contamination of foods results in the same effects as strontium contamination. The soft parts of the body, specially the muscles, are badly affected by the presence of cesium.
More and more of nuclear energy is being produced so as to meet the ever increasing demand for electrical power. Nuclear generators are better as compared to more commonly used types. Because, nuclear energy is cheaper to use than that from conventional sources such as fossil fuels or falling water. Moreover, nuclear generators do not produce any SO2 or particulate pollutants commonly produced by fossil-fuel burning generators.
Nuclear power plants are different from conventional electricity generating facilities. In the conventionally fueled power plant, fossil fuel is burnt to produce heat while in a nuclear plant the heat is generated by a nuclear reaction. In both the heat produces steam which turns a generator and produces electricity.
Four types of pollutants that are formed by nuclear generating plants are as under:
(a) Low Level Radioactive Liquid Wastes:
Radioactive isotopes are produced when impurities in the primary coolant water and corrosion products from coolant pipes are bombarded with neutrons from the core area. This can be avoided to some degree by using demineralized coolant water.
The secondary cooling system takes away huge amounts of heat from the reactors and mixes it into natural water supplies. A variety of research laboratories, including medical and biochemical facilities, release radioactive wastes into the air and sewer systems. It is not now feasible to collect and dispose of these materials. Nor is it feasible to collect and bury the large amounts of radioisotope-containing liquids, solids, and gases forward by laboratory uses other than research, like diagnostics or treatment.
Presently, the amounts of radioactive waste discharged from such laboratory sources poses no threat to natural communities of plants, animals, and man.
(c) Liquid and Gaseous Wastes from Fuel Elements:
Complete sealing of the fuel in steel or zirconium containers is apparently impossible to attain or sustain. Minute cracks allow fission products to escape into the primary coolant. This further complicates the disposal problem of low level wastes.
(d) Fission Products:
Within 1-3 years, fission products (the ashes of nuclear fuels) accumulate to the point that they absorb sufficient neutrons to slow or stop the chain reaction. Then the extremely radioactive fuel elements are removed and shipped in special containers to a fuel reprocessing plant. In these plants the fission products are separated from the remaining usable fuel. The fuel is returned to the reactor where it is used and the waste fission products are stored, in liquid form, in huge underground stainless steel tank. Hundreds of millions of gallons of these high level wastes are now in storage.
Vast amounts of water find use for cooling purposes by steam-electric power plants (and other industries to a lesser extent). Cooling water is discharged at a raised temperature, and some rivers may have their temperatures so high (even up to 40°C) that fish life completely gets eliminated and the river becomes useless for assimilation or pollution further cooling.
Increasing the water temperature of a system is harmful since it generally alters the chemical, physical and biological characteristics of that system. In addition to the possibility of decreasing or eliminating various aquatic forms, it may also stimulate spawning at a time of year when food supplies are limited. This leads to starvation of the newly spawned individuals in the population.
High temperatures also decrease the density and viscosity of water, causing an increased settling rate of suspended solids. Evaporation rate is increased and, in marine systems, this may lead to localized areas of abnormally high salinity.
Heat is not ordinarily thought of as a pollutant by many people, at least not in the same sense as a corrosive chemical. However, the addition of excess heat to a body of water brings about adverse effects as numerous as many of the chemical pollutants. This serious problem of thermal pollution originates primarily with the practice of using water as a coolant in many industrial processes.
Most water used for this purpose gets returned, with the added heat, to the original sources. At present, about 70% of the water diverted, to industrial use serves as a cooling medium.
Used coolant water frequently may be having a temperature 20°F higher than the river or stream to which it gets returned. This added heat raises the temperature of the natural waters, with the results that – (a) the amount of dissolved oxygen in the water gets decreased; (b) the rates of chemical reactions have been increased; (c) false temperature cues have been given to aquatic life; and (d) lethal temperature limits may be exceeded.
The decreasing ability of water to contain dissolved oxygen as the temperature increases is shown graphically in Fig 3.2.
The addition of heated water to a cooler, body of water may accelerate the lowering of DO levels due to density differences between the two. The less dense warm water tends to form a layer on top of the cooler, denser water. This occurs particularly when the body of cool receiving water is deep. The resulting blanket of “hot” water cannot dissolve as much atmospheric oxygen as the underlying cold water, which is denied contact with the atmosphere. Normal biological reduction of the DO level of the atmospherically un-replenished lower layer may give rise to anaerobic conditions.
Another effect of this stratification may show up downstream from a dam when the oxygen deficient lower level get discharged through the lower gates of a dam. Serious effects on downstream fish life may result. Also, the ability of the stream below the dam to assimilate oxygen demanding wastes will get curtailed.
In thermally polluted water, fish need more oxygen due to an increased respiration rate. However, the available oxygen in such water gets decreased. Thus, thermal pollution affects fish in a double-barreled fashion.
Other reactions are also influenced. Trout eggs hatch in 165 days when incubated at 37°F. When water temperatures have been 54°F, only 32 days are needed and no hatching takes place at water temperatures in excess of 59°F. Such a result can be disastrous to fish populations.
The life cycle and natural processes of many aquatic organisms have been closely and delicately geared to water temperature. Fish often migrate, spawn, and are otherwise distributed in response to water temperature cues. Shellfish, such as oysters, spawn within a few hours after their environment reaches a critical temperature. These normal life patterns of aquatic organisms can get completely disrupted by artificial changes in water temperatures.
Fish have been found to vary widely in their water temperature preferences. An indication of this has been the commonly used classification of fish as either cold or warm water species. An upper lethal, temperature limit exists for each species. It is known that temperatures well below the lethal value can bring about stress in organisms; hence the much lower recommended values. Lethal limits can be exceeded, in some examples under conditions of warm water waste discharge.
Another factor to be considered in addition to the temperature change has been the rapidity with which the change occurs. Fish are able to acclimate themselves to moderate temperature changes (below lethal levels) if the change has been not a sudden one. Normally a moderate temperature change over a 30-40 hour period could be handled by the fish. For instance, 95% of the eggs of largemouth bass perish when suddenly transferred from water at 65-70°F into water at 85°F. However, if similar eggs are kept in water and the temperature gradually increased to 85°F over a 30-40 hour time period, 80% of the eggs survive.
An additional threat to aquatic life has been created by the common practice of chlorinating coolant water prior to use. This is carried out to prevent bacterial growths that clog pipes- The chlorine affects organisms in the area receiving the used water until dilution occurs. The chlorine has been able to kill microorganisms important in some food chains and may in this way exert a negative influence on fish populations.
A problem of thermal population not related to aquatic life has been the reduced cooling capability of warmed waters. It is important because nuclear reactor power sources need about 50% more cooling water for a given temperature increase than similar power plants using fossil fuels, and it appears that nuclear plants will find use extensively in the future.
Different solutions to the thermal pollution problem have been postulated and some have been already in use. Several industries have incorporated cooling towers into their operations to remove heat from cooling water before returning it to the natural water supply. Two types of towers, wet and dry, have been used.
Water is run over baffles in a thin layer in the wet tower. Cool air, entering at the bottom, circulates upward and removes heat from the water. In dry towers, air is forced over water containing pipes by huge fans. Heat gets exchanged by radiation and convection from the pipes.
The use of cooling ponds or lakes has been another alternative. These ponds could act as ice-free wintering areas for waterfowl in northern locations or as a means of extending the range (northward) of certain fish. Both of these have been positive results of thermal pollution.
Answer 2. Paragraph on the Causes of Water Pollution:
i. Sewage and Wastewater:
Domestic households, industrial and agricultural practices produce wastewater that can cause pollution of many lakes and rivers.
(i) Sewage is the term used for wastewater that often contains feces, urine and laundry waste.
(ii) There are billions of people on Earth, so treating sewage is a big priority.
(iii) Sewage disposal is a major problem in developing countries as many people in these areas don’t have access to sanitary conditions and clean water.
(iv) Untreated sewage water in such areas can contaminate the environment and cause diseases such as diarrhea.
(v) Sewage in developed countries is carried away from the home quickly and hygienically through sewage pipes.
(vi) Sewage is treated in water treatment plants and the waste is often disposed into the sea. Sewage is mainly biodegradable and most of it is broken down in the environment.
(vii) In developed countries, sewage often causes problems when people flush chemical and pharmaceutical substances down the toilet. When people are ill, sewage often carries harmful viruses and bacteria into the environment causing health problems.
ii. Marine Dumping of Industrial Waste:
Dumping of litter in the sea can cause huge problems. Litter items can get caught in marine animals and may result in death.
Different items take different lengths of time to degrade in water:
(i) Cardboard- Takes 2 weeks to degrade.
(ii) Newspaper- Takes 6 weeks to degrade.
(iii) Photodegradable packaging- Takes 6 weeks to degrade.
(iv) Foam- Takes 50 years to degrade.
(v) Styrofoam- Takes 80 years to degrade.
(vi) Aluminum- Takes 200 years to degrade.
(vii) Plastic packaging- Takes 400 years to degrade.
(viii) Glass- It takes so long to degrade that we don’t know the exact time.
iii. Radioactive Waste Dumping:
Nuclear waste is produced from industrial, medical and scientific processes that use radioactive material. Nuclear waste can have detrimental effects on marine habitats.
Nuclear waste comes from a number of sources:
1. Operations conducted by nuclear power stations produce radioactive waste. Nuclear-fuel reprocessing plants in northern Europe are the biggest sources of man-made nuclear waste in the surrounding ocean. Radioactive traces from these plants have been found as far away as Greenland.
2. Mining and refining of uranium and thorium are also causes of marine nuclear waste.
3. Waste is also produced in the nuclear fuel cycle which is used in many industrial, medical and scientific processes.
iv. Oil Spills:
Oceans are polluted by oil on a daily basis from oil spills, routine shipping, run-offs and dumping. Oil spills make up about 12% of the oil that enters the ocean. The rest come from shipping travel, drains and dumping. An oil spill from a tanker is a severe problem because there is such a huge quantity of oil being spilt into one place.
Oil spills because a much localized problem but can be catastrophic to local marine wildlife such as fish, birds and sea otters. Oil cannot dissolve in water and forms a thick sludge in the water. This suffocates fish, gets caught in the feathers of marine birds stopping them from flying and blocks light from photosynthetic aquatic plants.
v. Underground Storage Tanks (UST’s) Leaks:
A tank or piping network that has at least 10 percent of its volume underground is known as an underground storage tank They often store substances such as petroleum, that are harmful to the surrounding environment should it become contaminated. Many UST’s constructed before 1980 are made from steel pipes that are directly exposed to the environment. Over time the steel corrodes and causes leakages, affecting surrounding soil and groundwater.
vi. Atmospheric Deposition:
Atmospheric deposition is the pollution of water caused by air pollution.
1. In the atmosphere, water particles mix with carbon dioxide sulfur dioxide and nitrogen oxides, this forms a weak acid.
2. Air pollution means that water vapor absorbs more of these gases and becomes even more acidic.
3. When it rains die water is polluted with these gases, this is called acid rain.
4. When acid rain pollutes marine habitats such as rivers and lakes, aquatic life is harmed.
vii. Global Warming:
An increase in water temperature can result in the death of many aquatic organisms and disrupt many marine habitats. For example, a rise in water temperatures causes coral bleaching of reefs around the world. This is when the coral expels the microorganisms of which it is dependent on. This can result in great damage to coral reefs and subsequently, all the marine life that depends on it.
The rise in the Earth’s water temperature is caused by global warming:
1. Global warming is a process where the average global temperature increases due to the greenhouse effect.
2. The burning of fossil fuel releases greenhouse gasses, such as carbon dioxide, into the atmosphere.
3. This causes heat from the sun to get ‘trapped’ in the Earth’s atmosphere and consequently the global temperature rises.
Eutrophication occurs when the environment becomes enriched with nutrient (e.g. N, P, K, etc.) This can be a problem in marine habitats such as lakes as it can cause algal blooms.
1. Fertilizers are often used in fanning, sometimes these fertilizers run-off into nearby water causing an increase in nutrient levels.
2. This causes phytoplankton to grow and reproduce more rapidly, resulting in algal blooms.
3. This bloom of algae disrupts normal ecosystem functioning and causes many problems.
4. The algae may use up all the oxygen in the water, leaving none for other marine life. This results in the death of many aquatic organisms such as fish, which need the oxygen in the water to live.
5. The bloom of algae may also block sunlight from photosynthetic marine plants under the water surface.
6. Some algae even produce toxins that are harmful to higher forms of life. This can cause problems along the food chain and affect any animal that feeds on them.
There are many causes for water pollution but two general categories exist– direct and indirect contaminant sources.
Direct sources include effluent outfalls from factories, refineries, waste treatment plants, etc., that emit fluids of varying quality directly into urban water supplies. In the United States and other countries, these practices are regulated, although this does not mean that pollutants cannot be found in these waters.
Indirect sources include contaminants that enter the water supply from soils/groundwater systems and from the atmosphere via rain water. Soils and ground waters contain the residue of human agricultural practices (fertilizers, pesticides, etc.) and improperly disposed of industrial wastes. Atmospheric contaminants are also derived from human activities such as gaseous emissions from automobiles, factories and even bakeries.
Many causes of pollution including sewage and fertilizers contain nutrients such as nitrates and phosphates. In excess levels, nutrients over-stimulate the growth of aquatic plants and algae. Excessive growth of these types of organisms consequently clogs our waterways, use up dissolved oxygen as they decompose, and block light to deeper waters. This, in turn, proves very harmful to aquatic organisms as it affects the respiration ability or fish and other invertebrates that reside in water.
Pollution is also caused when silt and other suspended solids, such as soil, wash off plowed fields, construction and logging sites, urban areas and eroded river banks when it rains. Under natural conditions, lakes, rivers, and other water bodies undergo eutrophication, an aging process that slowly fills in the water body with sediment and organic matter. When these sediments enter various bodies of water, fish respiration becomes impaired, plant productivity and water depth become reduced, and aquatic organisms and their environments become suffocated.
Pollution in the form of organic material enters waterways in many different forms as sewage, as leaves and grass clippings, or as run-off from livestock feedlots and pastures. When natural bacteria and protozoan in the water break down this organic types of fish and bottom-dwelling animals cannot survive when levels of dissolved oxygen drop below two to five parts per million. When this occurs, it kills aquatic organisms in large numbers which leads to disruptions in the food chain.
Pathogens are another type of pollution that prove very harmful. They can cause many illnesses that range from typhoid and dysentery to minor respiratory and skin diseases. Pathogens include such organisms as bacteria, viruses, and protozoans.
These pollutants enter waterways through untreated sewage, storm drains, septic tanks, run-off from farms, and particularly boats that dump sewage. Though microscopic, these pollutants have a tremendous effect evidenced by their ability to cause sickness.
The term ‘pesticide’ is a composite term that includes all chemicals that are used to kill or control pests. In agriculture, this includes herbicides, insecticides, fungicides, nematocides and rodenticides.
Agricultural use of pesticides is a subset of the larger spectrum of industrial chemicals used in modern society. The American Chemical Society database indicated that there were some 13 million chemicals identified in 1993 with some 5,00,000 new compounds being added annually. In the Great Lakes of North America, for example, the International Joint Commission has estimated that there are more than 200 chemicals of concern in water and sediments of the Great Lakes ecosystem.
Because the environmental burden of toxic chemicals includes both agricultural and non-agricultural compounds, it is difficult to separate the ecological and human health effects of pesticides from those of industrial compounds that are intentionally or accidentally released into the environment. However, there is overwhelming evidence that agricultural use of pesticides has a major impact on water quality and leads to serious environmental consequences.
The impact on water quality by pesticides is associated with the following factors:
i. Active ingredient in the pesticide formulation.
ii. Contaminants that exist as impurities in the active ingredient.
iii. Additives that are mixed with the active ingredient (wetting agents, diluents or solvents, extenders, adhesives, buffers, preservatives and emulsifiers).
iv. Degradation that is formed during chemical, microbial or photochemical degradation of the active ingredient.
Monitoring data for pesticides are generally poor in much of the world and especially in developing countries. Many developing countries have difficulty carrying out organic chemical analysis due to problems of inadequate facilities, impure reagents, and financial constraints. New techniques using immunoassay procedures for presence/absence of specific pesticides may reduce costs and increase reliability. Immunoassay tests are available for triazines, acid amides, carbamates, 2, 4-D/phenoxy acid, paraquot and aldrin.
Data on pesticide residues in fish for liphophilic compounds and determination of exposure and/ or impact of fish to dipophobic pesticides through liver and/or bile analysis is mainly restricted to research programmes. Hence, it is often difficult to determine the presence, pathways and fate of the range of pesticides that are now used in large parts of the world. In contrast, the eco-systemic impacts from older, organochlorine pesticides such as DDT, became readily apparent and has resulted in the banning of these compounds in many parts of the world for agricultural purposes.
Table 24.1 indicates why older pesticides, together with other hydrophobic carcinogens such as PAHs and PCBs, are poorly monitored when using water samples. As an example, the range of concentration of suspended solids in rivers is often between 100 and 1000 mg 1–1 except during major run-off events when concentrations can greatly exceed these values. Tropical rivers that are unimpacted by development have very low suspended sediment concentrations, but increasingly these are a rarity due to agricultural expansion and deforestation in tropical countries.
As an example, approx. 67% of DDT is transported in association with suspended matter at sediment concentration as low as 100 mg 1–1, and increases to 93% at 1000 mg 1–1 of suspended sediment. Given the analytical problems of inadequate detection levels and poor quality control in many laboratories of the developing countries, plus the fact that recovery rates (part of the analytical procedure) can vary from 50-150% for organic compounds, it follows that monitoring data from water samples are usually a poor indication of the level of pesticide pollution for compounds that are primarily associated with the solid phase.
The number NDs (Non-detectable) in many databases is almost certainly an artifact of the wrong sampling medium (water) and, in some cases, inadequate analytical facilities and procedures. Clearly, this makes pesticides assessment in water difficult in large parts of the world. Experience suggests that sediment-associated pesticide levels are often much higher than recorded, and NDs are often quite misleading. Some water quality agencies now use multimedia (water + sediment + biota) sampling in order to more accurately characterize pesticides in the aquatic environment.
Another problem is that analytical detection levels in routine monitoring for certain pesticides may be too high to determine presence/absence for protection of human health. Gilliom (1984) noted that the US Geological Survey’s Pesticide Monitoring Network (in 1984) had a detection limit of 0.05 (µg1–1 for DDT, yet the aquatic life criterion is 0.0002 µg1–1 both much less than the routine detection limit of the programme.
Non-detectable (ND) values, therefore, are not evidence that the chemical is not present in concentrations that may be injurious to aquatic life and to human health protection from pesticides in developing countries, must be extremely serious. Additionally, detection limits are only one of many analytical problems faced by environmental chemists when analyzing for organic contaminants.
The aquatic environment with its water quality is considered the main factor controlling the state of health and disease in both man and animal. Now-a-days, the increasing use of the waste chemical and agricultural drainage systems represents the most dangerous chemical pollution.
The most important heavy metals from the point of view of water pollution are Zn, Cu, Pb, Cd, Hg, Ni and Cr. Some of these metals (e.g., Cu, Ni, Cr and Zn) are essential trace metals to living organisms, but become toxic at higher concentrations. Others, such as Pb and Cd have no known biological function but are toxic elements.
Metals have many sources from which they can flow into the water body.
These sources are:
Metals are found throughout the earth, in rocks, soil and introduce into water body through natural processes, weathering and erosion.
Industrial processes, particularly those concerned with the mining and processing of metal ores, the finishing and plating of metals and the manufacture of metal objects. Metallic compounds which are widely used in other industries as pigments in paint and dye manufacture; in the manufacture of leather, rubber, textiles, paint, paper and chromium factories which are built close to water for shipping.
Domestic wastewater contains substantial quantities of metals. The prevalence of heavy metals in domestic formulations, such as cosmetic or cleansing agents, is frequently overlooked.
Agricultural discharge contains residues of pesticides and fertilizers which contains metals.
Acid rains containing trace metals as well as SPM input to the water body will cause the pollution of water with metals.
Answer 4. Speech on the Causes of Water Pollution:
There are numerous causes of water pollution and are discussed here:
i. Industrial Waste:
Industries produce huge amount of waste which contains toxic chemicals and pollutants such as lead, mercury, sulphur, asbestos, nitrates and many other harmful chemicals which are drained in the fresh water which goes into rivers, canals and afterward into sea. This may lead to Eutrophication, change the temperature of water and cause serious hazard to organisms living in water.
ii. Sewage and Waste Water:
The sewage and waste water that is produced by each household is chemically treated and released into sea with fresh water. The sewage water carries harmful bacteria and chemicals that cause serious health problems. Pathogens are known as a common water pollutant. The sewers of cities house several pathogens and hence, diseases.
Microorganisms in water are known to be causes of some very deadly diseases and become the breeding grounds for other creatures that act like carriers. These carriers impose these diseases through various forms of contact with an individual. Malaria is a very familiar example of this process.
When untreated sewage is thrown into rivers, it causes diseases like typhoid, dysentery and cholera. Algae grow uncontrollably, using the oxygen in the water and causing the death of all the water organisms. Harmful bacteria flourish in untreated sewage. When drinking and swimming water becomes contaminated, the disease-causing bacteria spread rapidly, making many people ill.
Sewage must be treated so that it can be recycled into the environment. Local government agencies monitor effluent levels in dams, rivers and also, the sea around our country. When they find that the levels have exceeded legal allowance, investigations are conducted and the culprits are fined or operations closed down.
iii. Leakage from Sewer Lines:
A small leakage from the sewer lines can contaminate the underground water and make it unfit for drinking. Also, if not repaired on time, the leaking water can come on to the surface and become a breeding ground for insects and mosquitoes.
iv. Burning of Fossil Fuels:
When fossil fuels like coal and oil are burnt considerable amount of ash is produced in the atmosphere. These particles which contain toxic chemicals are mixed with water vapours present in air and result in acid rain. Carbon dioxide released from burning of fossil fuels result in global warming.
v. Marine Dumping:
In some countries, garbage like paper, aluminum, rubber, glass, plastic, food, etc. are collected and deposited into the sea which not only cause water pollution but also harm animals living in the sea.
vi. Mining Activities:
During the process of mining, elements which are extracted in the raw form contain harmful chemicals and can enhance the quantity of toxic elements when mixed up with water which result in several health problems. In addition, mining activities produce some metal waste and sulphides from the rocks which also pollute water.
vii. Accidental Oil Leakage:
Since oil is immiscible with water, therefore accidental oil spill cause a problem for local marine wildlife such as fish, birds and other marine life and beaches. Pollution due to oil occurs due to leakage from ships, oil tankers, pipelines etc.
viii. Chemical Fertilizers and Pesticides:
Chemical fertilizers and pesticides are used by farmers for protecting crops from insects and pests. But, when these chemicals are mixed with water, they are harmful for plants and animals. In addition, when it rains, these chemicals mixes up with rainwater and flow down into rivers and canals and cause serious damage to aquatic animals.
ix. Animal Waste:
The waste generated by animals is washed away into the rivers by rain and gets mixed with other harmful chemicals and cause various water borne diseases such as diarrhea, cholera, jaundice, typhoid and dysentery.
x. Urban Development:
Due to increase in population, the demand for housing, food and clothing has also increased. As more cities and towns are developed, they have resulted in soil erosion due to deforestation, increase use of fertilizers for more food production, increase in construction activities, inadequate sewer treatment, landfills, increase in chemicals from industries to produce more materials and hence, more pollution.
xi. Leakage from the Landfills:
Landfills are giant pile of garbage that produces unpleasant smell and can be seen across the city. When it rains, the landfills may leak and the leaking landfills can pollute the underground water with large variety of contaminants.
xii. Underground Storage Leakage:
Transportation of coal and other petroleum products through underground pipes is well known. Accidentals leakage may happen anytime and may cause damage to environment and result in soil erosion.
xiii. Radioactive Waste:
Nuclear energy is produced using nuclear fission or fusion. The element that is used in production of nuclear energy is Uranium which is highly toxic chemical. The nuclear waste that is produced by radioactive material needs to be disposed of to prevent any nuclear accident. Nuclear waste can have serious environmental hazards if not disposed of properly. At high enough concentrations, it can kill and in lower concentrations, it can cause cancers and other illnesses.
xiv. Global Warming:
An increase in earth’s temperature due to greenhouse effect results in global warming. It increases the water temperature and result in death of aquatic animals and marine species which afterward results in water pollution.