Essay on Land Pollution!
Land is getting heavily polluted now-a-days by toxic materials and dangerous micro-organisms which enter the air, water and the food chain. The land pollution occurs mainly through centres: namely
(i) Production centre, and
(ii) Consumption centres.
The production centres may be further sub-divided into small scale production centre and large scale production centre or industrial production centre. The consumption centres contributing solid waste substance may be further divided into individual house, community centres, markets and municipal garbage centres.”
1. Sources of Land Pollution
2. Effects of Land Pollution
3. Effects of Agricultural Wastes
4. Effects of Pathogens in Soil
5. Effects of Hazardous Radioactive Pollutants
6. Disposal of Solid Waste
7. Management of Solid Wastes
(A) Sources of Land Pollution:
Land Pollution mainly results from the following sources:
(1) Industrial wastes
(2) Urban or commercial wastes,
(3) Agricultural wastes;
(4) Municipal wastes;
(5) Chemical and metallic pollutants;
(6) Biological reagents;
(7) Hazardous wastes or Radioactive pollutants; and
(8) Mining waste.
1. Pollution through Industrial Wastes:
The rapid growth of industries has resulted in the release of a tot of industrial waste on the land surface. The quantity of these wastes depends on the type of raw materials and chemicals used. It has been estimated that nearly 50% of the raw materials ultimately become waste products in the industries and about 20% of these wastes are extremely harmful.
The industrial wastes are mainly discharged from pulp and Paper mills, chemical industries, oil refineries, sugar factories, anneries, textiles, steel plant distilleries, fertilizer plants, pesticide industries, coal and mineral mining industries, metal processing industries, drugs, glass, petroleum and engineering industries etc.
Besides, thermal, atomic and electric power plants generate fly ash (un-burnt brownish black substance) which severely pollute air, water and land. The industrial wastes may be either organic or inorganic in nature. Also, these may be bio-degradable or non-bio-degradable.
The industrial pollutants affect and alter the chemical and biological characteristics of soil. The pollutants from soil enter into food chain, disturb the biochemical processes and finally induce serious hazards to living organisms.
According to Sabnis (1984), Mahim Bay in Mumbai is chronically polluted due to addition of 0.9 million tonnes of industrial wastes and 64 million tonnes of domestic sewage every year causing a serious threat to aquatic environment.
2. Pollution through Urban or Commercial Wastes:
Urban wastes include both commercial and domestic wastes consisting of dried sludge of sewage. The solid urban waste is commonly known as refuse. The refuse contains garbage and rubbish materials such as plastics, glasses, metallic canes, Fibres, rubbles, street sweepings, fuel residues, containers, abandoned vehicles and other discarded manufactured products.
Urban wastes are even more dangerous than the industrial waste because of their non-biodegradable nature. The leachates from dumping sites and disposal tanks of sewage mixed with industrial effluents and wastes become extremely toxic to living organsims. The leachates coming out of polluted soil contain partly decomposed organic material especially food remnants, vegetables, toxic hydrocarbons and pathogenic bacteria.
The maximum contribution to land pollution in India comes from urban areas, specifically from unplanned industrial progress in and around these areas. It is estimated that around 15 million tonnes of solid waste is dumped on land surfaces in India alone/ causing chronic pollution of land and water.
3. Pollution through agricultural wastes:
Agricultural wastes includes roots and stems of the crops, straw, hay, dung, food articles etc. These are also known as farm wastes. In addition to farm wastes, use of excessive fertilizers, pesticides, herbicides, weedicides and soil conditioning agents, induces land pollution to a greater extent. Although farm wastes are used and reused in a number of ways in developing countries, it has become headache in developed countries. USA alone produces about 18 million tonnes of agricultural wastes every year.
When the unused fertilizers are contaminated with other synthetic organic pollutants, the water present in the soil gets polluted. Although fertilizers are retained by the crops and soils, there are reports that if nitrate and phosphate concentration exceeds one part and thirty part per hundred per million parts of water respectively, there happens a number of health hazards and eutrophication, chocking the whole stretch of aquatic ecosystem.
The natural environment, particularly the land, is also under a stress due to different kinds of pesticides used to control pests. Mainly the chlorinated hydrocarbons (like DDT, BHC, aldrin, endrin, dieldrin etc.) and organo phosphates (like malathion, parathion, ethion, fenthion etc.) have tremendous effect on land pollution. The remnant of thse pesticides get absorbed by soil particles and coexist within biological system for a longer period of time.
In addition to fertilizers, pesticides and biocides, soil conditioners and fumigants (which contain several toxic metals like (As, Cd, Hg, Co etc.) are also added to the land system for increasing soil fertility and killing hazardous insects. These chemicals having long life time, accumulate on the soil and then enter to food chain through the growing crops, causing a number of health hazards.
4. Pollution through municipal wastes:
The municipal wastes include a number of solid wastes like papers, plastics, metal cans, glass bottles, aluminum foils, metal junks, garbage’s mostly coming from domestic uses etc. In addition, these also contain organic matters, compostable matter, ash stone, coal, straw, leaves, rotten vegetables, polythene bags, human excreta, animal wastes etc.
In developed countries, these are dumped either in underground pits or in sea. But in develop, ing countries like India, the municipal wastes are kept in certain dump land sites. When the municipal solid wastes are kept for a longer period of time these pollute the environment by foul smell and releasing a number of harmful gases.
The municipal waste substances are also classified in to:
(1) Non-combustible wastes;
(2) Highly combustible wastes,
(3) combustible wastes;
(4) Animal and vegetable trash etc.
5. Pollution through Chemical and Metallic Pollutants:
The industries like textiles, paints, dyes, soap and synthetic detergents, tanneries, drugs, batteries, cement, asbestos, rubber, petroleum, paper and pulp, sugar, steel, electroplating and metal industries release harmful effluents in soil and water creating hazards in living world. It is reported that synthetic chemicals and fertilizers are the source of trace metals such as As, Pb’ Cd, V, Mn, Hg, Mo, Si etc., which are added to the soil in one or other form.
When soil is found to be complexed with organic chemicals and toxic metals or its ions, these affect the soil texture, its fertility and stabilization of soil organic matter. Excess of sulphur in soil may be absorbed by plant leaves as SO2 injuring plant tissues.
The presence of high concentration of Mg, Fe, Zn and V, causes lethal effects on crop production. The metallic contaminants in soil are considered to be the indestructible poisons and then accumulation in plants and water may be highly dangerous because these inhibit the production of atmospheric oxygen reduce the rate of photosynthesis. Digested sewage sludge heavy application of manure to soil, causes chronic salt hazards to plants.
6. Pollution by Biological Agents:
The major source of land pollution by biological agents comes from the excreta of human beings, animals and birds. The sewage sludges contain a number of live viruses and viable intestinal worms which take shelter on lands and cause a number of diseases by attacking the living organisms.
The pathogenic organisms that pollute the soil may be divided into the following classes:
(a) Pathogenic organisms occurring naturally in contaminated soil:
The soil is residence of a number of bacteria, fungi, algae, protozoans, actinomycetes, nematodes, rotifiers etc. These modulate soil fertility and soil texture. Besides, these attack the different part of the plant, specially the roots, causing significant damage.
(b) Pathogenic organisms excreted by man:
Human excreta contain pathogens such as enteric bacteria and parasitic worms, which reside in soil. These organisms enter into human body either via food chain or by direct contact with contaminated soil. The sanitary habits of people help in the repetition of the cycle of infection with soil transmitted pathogens from man to soil and then from soil to man.
(c) Pathogenic organisms excreted by animals:
This class includes pathogenic bacteria and parasitic worms excreted from animals. These organisms are transmitted from animals to soil and then from soil to man.
7. Hazardous Wastes (Radioactive Wastes):
In addition to chemical reagents, radioactive wastes cause serious environmental hazards. Radioactive substances produced from nuclear explosion, nuclear reaction and from nuclear testing laboratories, enters into the soil and accumulate there causing land pollution.
Radioactive waste contains several radio nuclides Such as Ceasium-137, Strontium-90, Todine-129 and Tsotopes or Radioactive elements. These wastes are highly dangerous and causes cancer in living organisms and also degrade genetic materials like DNA and RNA inducing mutation, nuclear reactors produce wastes containing Ruthenium-106, Iodine-131, Barium-14o Lanthanum-140 etc.
8. Pollution through Mineral Wastes:
During mining operations, huge quantities of wastes are dumped on land surface. For example, during mining of metal ores, huge quantities of earthen materials, rocks and other wastes are created. Similarly, during coal mining surficial crustal materials are removed to expose coal seam. Thus huge quantity of waste mining materials is created which not only occupy valuable land surface but also create nuisance due to the presence of toxic chemicals.
(B) Detrimental Effects of Land Pollution:
Land pollution is the result of urban technological revolution and exploitation of every bit of natural resources. A number of sources are contributing individually or together to land pollution. Now let us discuss the effect of land pollutants from different sources on man, animal and vegetation.
A. Effects of Industrial Pollutants:
1. Industrial wastes containing toxic metals (e.g., Hg, Pb, Cd, As, Cr, Cu, etc.) kill bacteria and beneficial micro-organisms in the soil. Heavy metals precipitate phosphatic compounds and catalyse their decomposition.
2. Industrial wastes containing soluble salts cause crop loss, soil loss, metallic corrosion etc. According to Food and Agriculture Organisation (FAO) 50% of the irrigated farms in the world are damaged by soluble salts.
3. Industrial effluents causing high acidity or high basicity of the soil cause severe agricultural crop damage.
4. The accumulation of wastes containing toxic pollutant like oils, greases, plastics, plasticizers, non-biodegradable matter etc. transfers pollutants into food chain causing a number of undesirable changes in living organisms.
5. Direct discharge of industrial effluents through sewage system causes poisoning of biological purification mechanism of sewage treatment inducing several soil borne and water- borne diseases.
6. When discarded plastic materials, textiles, packaging’s, synthetic fibres, waste paper etc. in soil are burnt, these emit highly toxic gases like HC1 fumes. SO2 , NOx etc.
7. Some industrial wastes also contain pathogenic bacteria, which cause significant health hazards. For example, the pathogen Anthrox bacilli are present in tannery waste.
B. Effects of Urban Wastes:
1. The dumped urban wastes along highways and other places in cities spread several chronic diseases posing a serious threat to human health.
2. The dumping of waste including building materials sludge, dead animal skeleton and thrown away garbage at public places causes a lot of problems in daily life.
3. Solid wastes result in offensive odour and cause clogging of ground water filters.
4. Sewage is an excellent medium for the growth of pathogenic bacteria, viruses and protozoa.
5- Due to inadequate sewage disposal, refuse gets mixed with solid particles of land. Such type of mixing, damages crop and decreases crop production and soil fertility.
C. Effects of Agricultural Wastes:
(i) Effects of Fertilizers:
The presence of excess of MPK fertilizers declines protein contents of corn, maize, gram and wheat crops and also favours the degradation of carbohydrates and proteins.
2. The fertilizers inhibit the synthesis of vitamin-C and carotene in vegetables and fruits.
3. The excessive use of nitrogenous fertilizers in land leads to accumulation of nitrate in the soil which subsequently enters into human body through food chain. In human body nitrates are converted into nitrous compounds which are capable of inducing stomach cancer.
4. The vegetables and fruits obtained from highly fertilized lands are prone to pest, insects and diseases.
5. The cereal crops like maize, jawar and pearl millet, grown on alkaline soil absorb higher quantity of fluorides and are reponsible for fluorosis.
(ii) Effect of pesticides:
1. The pesticides present in the soil sometimes appear in fruits and vegetable and make them unusable.
2. Entry of polychlorinated biphenyl (PCB) into human body causes deformities in foetus, nervous disorders, liver and stomach cancer.
3. When vegetables contaminated with 0.5 gm or more PCB is consumed, there is the possibility of eye damage, darkening of skin and severe ache.
4. Pesticides, due to their non-biodegradable nature, are known to seep gradually through the soil into ground water and thereby contaminate the entire public water supply system.
5. Herbicides and chlorinated pesticides affect soil texture and function thereby disturbing the natural eco-system.
6. Organophosphate pesticides cause extreme muscular weakness, tremors and diziness in poisoned animals.
7. The excessive use has also resulted in defoliation of forests adversely affecting flora and fauna.
D. Effects of Pathogens in Soil:
1. Pathogenic bacteria in soil act as carrier of a number of chronic diseases like cholera, typhoid, dysentery, etc. from soil to man and vice versa.
2 Few pathogenic bacteria are Mycobacterium, Leptospira, Pasteurella and Tuberculosis. These cause diseases like amoebic dysentery, cholera, typhoid, polio, hepatitis etc.
3. Leptospires (the virus causing leptospirosis) are brought to the soil surface by the excretion of faecal matter or urine of the patients. These have longer life time in soil (few weeks). When a healthy person comes in contact with infected soil, the virus enters into the body through macerated skin or mucous membrane to cause leptospirosis.
4. Q Fever is caused by rickettsia coxiella burneti which is present in dust and soil.
5. Antibiosis micro-organisms in soil produce antagonistic effect through metabolic products which may inhibit the growth or cause killing of symbiotic bacteria.
6. Certain fungi and actinomycetes present in soil cause most serious subcutaneous and systemic mycoses. The spores of these enter the human body either through respiration or through wounds.
7. Algae poison present in soil is considered to be most virulent poison which produces cirrhosis of liver.
E. Effects of Hazardous Radioactive Pollutants:
1. Since radioactive wastes are produced in huge quantities and these have high activation energies, these cause a number of hazards to public health system.
2. The accumulated radioactive wastes enter into food chain by coming into aquatic system and finally enter into living organisms. The accumulation of radioactive substances causes the disruption of physiological process and metabolic change.
3. Introduction of radioactive substances into human body through food causes diseases of digestive track.
4. It is reported that nuclear explosion at a higher altitude; introduces radioactive wastes into biological cycle and these are distributed in biota present in that region. A brust close to ground makes all the elements of soil as potential induced radioactivity.
5. The presence of radioactive wastes affects soil quality and soil fertility.
Disposal of Solid Waste:
The concentration of solid wastes (which include industrial wastes, agricultural wastes, municipal wastes, radioactive wastes, mining wastes etc.) and their removal from natural eco-system in which these would biodegrade naturally have resulted in accumulation of huge quantities of refuse.
The term solid waste sometimes includes liquid wastes also. Waste products in natural system are broken by decomposers and converted to a form to be used by other organisms in the eco-system. However, rapid urbanization, agricultural modernization and industrialization have resulted in a number of complex inorganic and organic byproducts which are non-biodegradable or persistent resulting in the disruption of natural eco-system.
For example, chemicals from wastes of one organism incorporates into another organism’s tissue. These often combine with other compounds in the environment to produce more harmful toxin. According to Berry (1979), improper disposal of solid wastes create conditions for a wide range of diseases such as cholera, typhoid, hepatitis, conjunctivitis, entamoebiasis, poliomyelitis, round worms, hook worms, and many more. So, disposal of solid wastes needs special attention of environmental scientists.
Some waste disposal strategies adopted by different countries are as follows:
(i) Open dumping on to land surface near pond, river, lake and ocean without prior treatment. This process of disposal is now-a-days discouraged due to a lot of side effects.
(ii) Treating the solid wastes and allowing them for natural decomposition and recycling in a specially made oxidation pond or sanitary landfills.
(iii) Treating the solid wastes by incineration or in a chemo mechanical regeneration system.
(iv) Public education to minimise creation of waste and government encouragement for safe reuse and recycling of waste.
(A) Open dumping:
Although open dumping of solid wastes is the usual practice of most of the industries and municipalities, now-a-days both developed and developing countries are discouraging such waste disposal practices. This is due to the fact that the process is not at all an environment friendly practice since its biological environment with flies, insects, rats, hogs, vermin differ from those of a natural eco-system, and is not controlled by any regulatory mechanism.
The organisms that multiply in open dumps, becomes very good carrier of many diseases. Sometimes it is seen that municipal waste is subjected to open dumpling followed by open burning. This should be prohibited because open burning produces a lot of dangerous gases like SO2, NOx, PAN etc.
(B) Natural treatment:
In this method, the solid, wastes are subjected to natural treatment on specific sites or areas through landfills. A sanitary land fill provide a safe and effective means of waste disposal. This method is more ecofriendly than open dumping process and it is also quite economical.
A well-engineered landfill is lined by some non-porous barrier of clay, granite or any synthetic source. The sides of the land fill are slopping into centre. There is a drain which serves as an outlet for the percolating polluted water. The trash is covered with nearly six inches of fresh soil at the end of everyday as waste is added, to exclude air, odour of decomposition and action of disease carrying flies, rats or vermin.
Landfills should be located at the sites where rain water leaching through the refuse will not pollute the ground water. Sanitary ‘sandflies allow inexpensive biodegradation without pollution and diseases.
(C) Mechanical treatment (Incineration):
Some specific solid Pastes may be subjected to recycling by cost expensive mechanical treatments. One of such type of waste disposal is incineration of waste. The resultant ash produced is disposed to a sanitary landfill. Incineration involves burning of waste inside a furnace at high temperature (900-1400°C).
The furnace heats the boilers and the steam evolved is sold to industry for running turbines to produce electricity. Europeans countries like Denmark, Sweden, Netherlands, Switzerland etc. have adopted this methodology for getting electricity from steam that comes out of incineration of about 60% of their solid wastes. Incinerators operate efficiently if constant furnace temperatures are maintained. One limitation of this method is that it causes environmental air pollution which can be avoided by suitable air pollution control technique.
Minimisation of Solid Waste Level:
The level of solid waste in the environment can be minimised possibly through the following approaches:
(i) Creation of waste prevention attitude and approach which emphasises changes in life style in our patterns of production and consumption.
(ii) Formulation of National plans for minimization of waste. This can be done by the recycling and reuse of some of the wastes.
(iii) Waste control programmes should be developed by the Government in co-operation with local municipalities and administration, business establishments, non-gov- emmental organizations and consumer bodies.
(iv) Industries should be encouraged with education, regulation and funds to redesign products to reduce wastes.
(v) Government should formulate necessary guidelines towards the safe reuse of recycled wastes and encourage bussiness sectors to market recycled and reuseable products.
(vi) Government should give patronage and financial assistance to small scale and cottage based low cost recycling industries for the construction of waste disposal facil1‘ ties, for use of treated waste water for irrigation, production of compost and extraction of energy.
Management of Solid Wastes:
The soil or land on which the human beings are depending for their food and shelter is getting polluted largely by solid wastes from homes, industries, and agricultural farms. So environmental scientists are highly concerned about the disposal of solid wastes which is highly expensive. To make the disposal of waste economical, emphasis has been given on management of solid wastes i.e., recycling and re-use of waste materials.
The management of solid wastes involves basically three fundamental steps:
(1) Collection of Wastes;
(2) Disposal of solid waste; and
(3) Recovery of resources.
1. Collection of Wastes:
The collection of wastes is the first step in the management of solid wastes. In rural areas of India, there is no proper arrangement for the collection and disposal of domestic wastes and sewage and hence, these spread on the ground within the village land outside the village.
The dumps of domestic garbage remain at their places for several days and thus pollute the environment by foul smell and releasing harmful gases. In cities and towns, domestic wastes are thrown in specially enclosed masonry structures on the road side, in the corners of buildings, behind the boundary wall etc. The heaps of municipal garbage’s are further spread by stray cattle, pigs, rats, rodents and poor people, who collect some reusable items such as iron and aluminum junks, papers, plastics etc.
The solid wastes are collected by municipal personals and carried by trucks and lorries to dump site. The collection and clearance of municipal wastes from various collection sites are not performed regularly in most of the cities.
The collection of solid wastes should be done by municipal personnel at least twice a day from the market and business areas and at least once a day from residential localities. Wastes are also collected with the help of pneumatic pipes.
More number of transfer stations may be constructed at different place of a city so that the waste could be taken away to the nearest stations for ultimate disposal after cramming. In developed countries, there are quick and efficient machines for the collection and disposal of solid waste. It is estimated that about 80% of the total cost of solid waste management is spent for collection of waste only.
2. Disposal of Wastes:
Disposal of solid waste involves:
(i) Sorting of waste substances;
(ii) Dumping of non-combustible substances into suitable dumpsites; and
(iii) Incineration of combustible substances.
Depending upon the nature of solid wastes, these are divided in to the following categories:
(a) Compostable Organic matter;
(b) Non-combustible Solid Wastes;
(c) Highly combustible wastes; (e.g. paper, card boards, plastics, rubbers etc.);
(d) Combustible wastes (e.g. wood scrap, cartons, floor sweepings);
(e) Animal and vegetable wastes and reusable wastes.
Landfill operation is usually adopted by most of the countries as one of the possible ways of waste disposal. This operation involves the depositing of solid waste, compacting and covering it with soil. The solid wastes containing vegetables, plant leaves, animal and human wastes etc. are biodegradable and hence, these are subjected to composting either through open window composting method or through mechanical composting method to get useful organic manure.
Thus, composting plays dual role:
(i) Proper disposal of solid waste, and
(ii) Production of organic manure. According to J. n. Singh and D. N. Singh (1988), a town with one lakh population can produce 20,000 tonnes of garbage and 8,000 tonnes of night soil which can be converted into 18,000 tonnes of compost.
The solid wastes such as metals and metallic containers etc. which are noncombustible are dumped and compacted in garbage disposal sites such as land fills, depressed ground or even in open wasteland. The combustible solid wastes are subjected to burning in specially designed (incinerators such as Multiple Hearth Furnace (MHF) and Fluidized Bed Furnace (FBF)). The combustible solid wastes are also subjected to pyrolysis (a process of thermal breakage or destructive distillation in an oxygen free atmosphere) to get gases like hydrogen, methane (CH4), ethane (C2H6), acetylene (C 2H2), CO2, CO, ethane (C2H4) etc. and liquids like light oil, water soluble distillate, tar and solid charcoal.
3. Recovery of Resources:
A number of useful products can be obtained from the solid wastes. Some important examples are discussed below:
(i) Converting Waste into Biogas:
The production of biogas from cow dung, Cattle dung and numerous organic wastes is done by the action of large varieties of micro-organisms in a synchoronised manner in a biogas unit. The main constituent of biogas is methane which can be used for energy production. The digested slurry obtained from biogas units can be used as enriched manure in agriculture, pisciculture and mushroom cultivation etc.
By linking pour-flush toilets with biogas units, human waste for manure purposes can be used. The Ministry of Mon-conventional Energy Sources (MNES) is providing, either central subsidy or turn-key job fee for constructing a toilet and attaching it with biogas unit.
(iii) Meeting energy demands:
Burning of biogases provide a lot of thermal energy which may be used in a number of ways to solve acute energy crisis of modern society.