Chapter11

Till few decades ago, talks about "pollution", "energy crisis", birth control","conservation of energy" and so were looked upon as fashion. Today, however,all these issues ar,e of serious concern and are debated and discussed at everyinternational forum. Predictions are made that the human existence would beimpossible without proper management of the environment.

What is Environment? The word environment has been derived fromFrench word "environner" which means, "encircle" or "surround". The humanenvironment, thus, is the Earth we live on. It includes all the physical parts ofearth such as air, water, soil, minerals and all its biological inhabitants such as,animals, ,plants and microbes.

The modern man, with all its technical know how, is exploiting naturalresources at an alarming rate and in doing so he is adversely damaging theenvironment. Although he has made tremendous progress in the field ofmedicine, agriculture., forestry, aqua-culture, communications and a number ofscientific inventions has provided him maAy comforts of life, yet he is not happy.The answer is simple. These comforts have been achieved at the expense of hishealthy environment. Due to his numerous ecological malpractices,shortsightedness and greedy exploitation of natural resources, he is confrontedwith a number of serious environmental problems. Fig. 11.1 shows some of themajor environmental problems we face today.

There is a popular maxim that our all environmental problems and our allmiseries are due to three "P"s, namely, Population growth, Poverty and Pollution.The last two are directly related to first one. In simple words, it can be said thatthe root cause of our all problems is rapid growth of human population.

Air Pollution• global climatic change• ozone depletion• urban air pollu'tion• acid 'rain• outdoor pollutants• indoor pollutants• noise

Water Pollutionsedimentsnutrients overloadto~ic chemicalsinfectious agentsoxygen depletionpesticidesoil spillsexcess heat

Biodiversity Depletion• Habitat destruction

Habitat degradation• Extinction

Food Supply Problemsovergrazingfarmland loss & degradation

• wetland loss• . over-fishing• coastal pollution• soil waterlogging

water shortages• groundwater depletion• loss of biodiversity• poor nutrition

Waste Productssolid waste

• /hazardous wa\ste

Dr, Paul Ehrlich of Stanford University (1990) regards the humanpopulation explosion as a "Population Bomb" which is more catastrophic anddangerous than either cobalt bomb or atomic bomb,

It can be seen from Table 11,1 that not only has the world's populationcontinued to increase over the entire period, but it has done so at an everincreasing rate (each doubling of human population has taken less time),

Date Pooulation Estimate Doublinq Time5000 B.C. 50 million ?

800 B.C. 100 million 4,200 years200 B.C. 200 million 600 years

1200 AD. 400 million 1,400 years1700 AD. 800 million 500 years1900 AD. 1600 million 200 years1965 A.D. 3200 million 65 years2000 AD. 6100 million 35 years2030 B.C:. 12000 million 30 years

Before the invention of agriculture, the world's population was probablyfew millions. By 5000 B.C., there were only 50 million people. During middleages, human population were held in check by diseases, famine, naturalcatastrophes and wars. Human population began to 'increase rapidly after 1600A.D. It took all of the human history to reach one billion people in 1804, but lirt1emore than 150 years tb reach 3 billion in 1960. In 1987, the human populationwas 5 billion and to go from 5 to 6 billion, it took only 12 years. In another words,the number of human beings more than tripled during 20th century. Will it doagain in 21 st century? If it does, will it overshoot the carrying capacity of ourenvironment and experience a catastrophic die back.

Rate of Human Population GrowthEvery second on aVfHAQt! 4 or [j children are born

somewhere on this planet. In that same period, two otherpeople die. This difference between births and deaths means anet gain of 2.5 or more humans per second in world population.It has been estimated that we are growing a little less than10,000 per hour or 85 million persons are added every year.

Though world food productivity has increased steadilyover the years but it does not keep pace with the populationgrowth. The result is that millions have starved to death inrecent times and millions more are hungry today. If presentbirth rate is not checked, it is feared that the entire humanitywill starve to death.

How serious are our population growth and environmental problen,.?There is no simple answer to this problem and scientists have conflicting views IIi

this regard. It depends mostly on how you believe the world works and what rolethe human species can and should play on this planet. It also depends onwhether you have an pessimistic outlook about future the glass is halfempty or an optimistic view the glass is half full.

Most '~f the environmentalists believe that because of exponentialincrease of human population, many serious environmental prO.blems havearisen. These problems cry out for our immediate attention. Some of the mostpressing problems are:

1. Human population has grown at an alarming rate in this, cer)tury. Morethan 6 billion people now occupy the earth and we are adding 85·million each year. Most of the growth is taking place in poorercountries where resources and· services are already under heavy

\ stress.

2. We are depleting and degrading earth's capital at an alarming rate asour demands on earth's resources increase exponentially.

3. If the present rate of world population increase continued, there wouldbe one person for every square foot of earth's surface in less than 700years. It is impossible for us to stand elbow to elbow on this planet.One square foot of earth's surface cannot feed, clothe, and shelter aperson.

4. Because of degradation, land availability is shrinking. If the currentpopulation growth projections are correct, the current world average of0.27 ha cropland per person available will decline to 0.17 ha by theyear 2025. In Southeast Asia, croplands will be even scarcer i.e. 0.09ha per person.

5. Food shortages and famines already are too familiar in many placesof Africa and Asia and may increase in frequency and severity.

I Q. Define dieback.

6. Water deficiencies' and contamination of existing water suppliesthreaten to be critical environmental issues for agricultural productionas' well as for domestic and industrial uses. More than 1.5 billionpeople lack access to clean drinking water. Ground water is beingremoved faster than it can be recharged.

7. As we burn fossil fuels, we release carbondioxide and heat absorbinggasses that cause global warming and may bring sea level rises,catastrophic climatic changes, acid rains, and abnormal variations inpatterns of plant growth.

8. Destruction of tropical forests, cOral reefs and wetlands and otherbiological rich landscapes is causing enormous loss of species andbiological diversity. Many rare and endangered species arethreatened directly or indirectly by human activities. According to anestimate, 17,500 species are lost every year.

9. Urbanization in the developed countries has led to urban sprawl,which represent an inefficient use of land. Urbanization in lessdeveloped countries is often associated with dismal slums andpoverty.

10. Toxic air, water and soil pollutants along with mountains of solid andhazardous are becoming our major serious problems of study.

11. Long term exposures to various chemicals can disrupt the humannervous system, immune system and endocrine system.

12. Because of overgrazing, improper irrigation and soil erosiun,approximately 14 million acres.of land every year is turned into deseli.

In short, as a result of rapid population growth, our natural resources al'edepleting at a very faster rate. We are becoming more and more poor and thatpollution is also gradually touching hazardous level. Besides, the humanpopulation growth followed by poverty has led to increase in many social evils inour society. These include, drug abuse, looting, arson, kidnapping, linguistic riots,etllnic clashes, unemployment, dacoities, religious clashes and many others

: '2.'~ ::'lldrp re'duction in the population of a species when its numbers exceed ;he carrying r .",clr~ _:

The question is whether or not we would accept and practice effectivebirtll control measures in time. If not, history forcefully indicates that we willexperience a catastrophic mass extinction as of famine, some epidemic outbreakor war.

Some analysts however, contend that the world is not overpopulated andargue that population is rio threat. They believe that our planet could support 7 -12 billion people at a decent standard of living if land, food and wealth weredistributed more equally. Furthermore, they b~lieve our all problems can besolved with a combination of human ingenuity and technology as we havedone in the past. With modern technology, we can clean up pollution, find

. substitute for any resource that has become scarce, and kee~ expanding theearth's carrying capacity.

These analysts accuse most environmentalists of exaggerating theseriousness of problems we face and of failing to appreciate the progress' thathas been made both in improving the quality of life for the people and inprotecting the environment. \

1. A resource from popUlation growth leaves us better off than if theshortage had never arisen. For example, if firewood had not beenscarce, coal would not have been mined. If coal had not loomed, oilwells would not 'have been dug. Similarly oil and gas shortages haveforced us to search for some other energy sources, say, solar energy.

2. A large population means a large work force; more geniuses; more. ideas; about what to do. Along with every new feeding mouth comes apair of hands.

3. Annual worldwide population growth has declined from its peak of 2%in 1960 to 1.5% in 1995.

4. Average number of children per woman has dropped from about fivein 1950 to 3.1 in 1995.

5. Life expectancy has more than doubled.

6. Increased urbanization has helped in the protection of biodiversity.7. Food supply has been improving since World War II and there is no

scarcity. The problem is over consumption and wastage of food byrich countries. According to an estimate, 20 - 25% cooked food isthrown in garbage dumps daily by rich people. If food were dividedequally, there would be enough food for everyone to eat.

8. If air, water and soil c n r ICindle ail he wastes we dump into thef!l,,why worr about pollution? Even if we do pollute an area, we caninvent a technology to clean it up.

9. Soil erosion is a serious problem but two modern soil savingtechniques, a) conservation tillage and h) no till cultivation .. ' ... cancut soil ero,sion by 65 - 85% respectively.

10. Proponents of pesticides say that their benefits far outweigh theilharmful effects as blown by environmentalists. Every dollar spent onpesticides saves food worth 5 dollars.

11. Despite greatly increased use of a variety of chemicals, pollutionaccounts for less than 1% human cancer.

12. Although tropical deforestation has increased, the total forest area oftemperate region has increased.

13. Global warming is too uncertain.14. Ozone depletion is a hoax.15. There is no statistical evidence for prediction of rapid loss of plants

and animal life. Again, the extinction of some species is no problem.16. Water does not pose a probJem of physical scarcity.17. Threats of air, water and soil pollution have been vastly overblown.

A growing number of people on the other hand, believe that both,optimistic and pessimistic views are wrong in some aspects. They contend tliatneither all is well today nor all will be rosy in future. A sustainable earth, decentliving and better future is guaranteed only if people, as individuals as enterprises,as volunteers, as government officers, will address the problems with musclesand mind.

How serious are our population growth and environmental problen I. ?

There is no simple answer to this problem and scientists have conflicting views 11'1

this regard. It depends mostly on how you believe the world works and what rolethe human species can and should play on this planet. It also depends onwhether you have an pessimistic outlook about future the glass is halfempty or an optimistic view the glass is half full.

Most '~f the erivironm~ntalists believe that because of exponentialincrease of human population, many serious environmental prOblems havearisen. These problems cry out for our immediate attention. Some of the mostpressing problems are:

1.' Human population has grown at an alarming rate in this_cef!tury. Morethan 6 billion people. now occupy the earth and we are adding 85million each year. Most of the growth is taking place in poorercountries where resources and services are already under heavy

\ stress., .

2. We are depleting and degrading earth's capital at an alarming rate asour demands on earth's resources increase exponentially.

3. If the present rate of world population increase continued, there wouldbe one person for every square foot of earth's surface in less than 700years. It is impossible for us to stand elbow to elbow on this planet.One square foot of earth's surface cannot feed, clothe, and shelter aperson.

4. Because of degradation, land availability is shrinking. If the currentpopulation growth projections are correct, the current world average of0.27 ha cropland per person available will decline to 0.17 ha by theyear 2025. In Southeast Asia, croplands will be even scarcer i.e. 0.09ha per person.

5. Food shortages and famines already are too familiar in many placesof Africa and Asia and may increase in frequency and severity.

I O. Define dieback.

6. Water deficiencies and contamination of existing water suppliesthreaten to be critical environmental issues for agricultural productionas· well as for domestic and industrial uses. More than 1.5 billionpeople lack access to clean drinking water. Ground water is beingremoved faster than it can be recharged.

7. As we burn fossil fuels, we release carbondioxide and heat absorbinggasses that cause globEd warming and may bring sea level rises,.catastrophic climatic changes, acid rains, and abnormal variations inpatterns of plant growth.

8. Destruction of tropical forests, coral reefs and wetlands and otherbiological rich landscapes is causing enormous loss of species andbiological diversity. Many rare and endangered species arethreatened directly or indirectly by human activities. According to anestimate, 17,500 species are lost every year.

9. Urbanization in the developed countries has led to urban spralNI,which represent an inefficient use of land. Urbanization in lessdeveloped countries is often associated with dismal slums andpoverty.

10, Toxic air, water and soil pollutants along with mountains of solid andhazardous are becoming our major serious problems of study.

11. Long term exposures to various chemicals can disrupt the humannervous system, immune system and endocrine system.

12. Because of overgrazing, improper irrigation and soil erosion,approximately 14 million acres of land every year is turned into deS8li.

In short, as a result of rapid population growth, our natural resources al'edepleting at a very faster rate. We are becoming more and more poor and thatpollution is also gradually touching hazardous level. Besides, the humanpopulation growth followed by poverty has led to increase in many social evils inour society. These include, drug abuse, looting, arson, kidnapping, linguistic riots,ethnic clashes, unemployment, dacoities, religious clashes and many others.

The question is whether or not we would accept and practice· effectivebirtl1 control measures in time. If not, history forcefully indicates that we willexperience a catastrophic mass extinction as of famine, some epidemic outbreakor war.

Some analysts however, contend that the world is not overpopulated andargue that population is rio threat. They believe that our planet could support 7 -12 billion people at a decent standard of living if land, food and wealth weredistributed more equally. Furthermore, they b~lieve our all problems can besolved with a combination of human ingenuity and technology as we havedone in the past. With modern technology, we can clean up pollution, find

. substitute for any resource that has become scarce, and kee;:> expanding theearth's carrying capacity.

These analysts accuse most environmentalists of exaggerating tileseriousness of problems we face and of failing to appreciate the progress thathas' been made both in improving the quality of life for the people and inprotecting the environment. \

1. A resource from population growth leaves us better off than if theshortage had never arisen. For example, if firewood had not beenscarce, coal would not have been mined. If coal had not loomed, oilwells would not 'have been dug. Similarly oil and gas shortages haveforced us to search for some other energy sources, say, solar energy.

2. A large population means a large work force; more geniuses; more. ideas; about what to do. Along with every new feeding mouth comes apair of hands.

3. Annual worldwide population growth has declined from its peak of 2%in 1960 to 1.5% in 1995.

4. Average number of children per woman has dropped from about fivein 1950 to 3.1 in 1995.

5. Life expectancy has more than doubled.

6. Increased urbanization has helped in the protection of biodiversity.7. Food supply has been improving since World War II and there is no

scarcity. The problem is over consumption and wastage of food byrich countries. According to an estimate, 20 - 25% cooked food isthrown in garbage dumps daily by rich people. If food were dividedequally, there would be enough food for everyone to eat.

8. If air, water and soil can helne 8 all tIle wastes we dump into thel" ..why worr about pollution? Even if we do pollute an area, we callinvent a technology to clean it up.

9. Soil erasion is a serious problem but two modern soil savingtechnique , a) conservation tillage and h) no till cultivation ... CClncut soil era.sion by 65 - 85% respectively.

10. Proponents of pesticides say that their benefits far outweigh thedharmful effects as blown by environmentalists. Every dollar spent onpesticides saves food worth 5 dollars.

11. Despite greatly increased use of a variety of chemicals, pollutionaccounts for less than 1% human cancer.

12. Although tropical deforestation has increased, the total forest area oftemperate region has increased.

13. Global warming is too uncertain.14. Ozone depletion is a hoax.15. There is no statistical evidence for prediction of rapid loss of plants

and animal life. Again, the extinction of some species is no problem.16. Water does not pose a problem of physical scarcity.17. Threats of air, water and soil pollution have been vastly overblown.

A growing number of people on the other hand, believe that both,optimistic and pessimistic views are wro'ng in some aspects. They contend thatneither all is well today nor all will be rosy in future. A sustainable earth, decentliving and better future is guaranteed only if people, as individuals as enterprises,as volunteers, as government officers, will address the problems with musclesand mind.

Poverty is defined as not being able to meet one's basic economic needs.The United Nations estimates that more than 1.5 billion people in world wide livein acute poverty and lack access to secure food supply, safe drinking water,education, health care, infrastructure (such as roads, markets, etc.) credits andjobs. At least 1/5 of world's population lack access to adequate sanitation leadingto spread of infectious diseases that debilitate the poor and prevent them fromworking effectively to improve their .conditions. of 1.5 billion, 1.2 billiondesperately poor people live in less developed countries.

Today, one of every five people on earth isdesperately poor too poor to grow or buy enoughfood to maintain health or to perform a job. The nextthree get by, while the fifth one lives in luxury. Each year40 million of 1.2 billion desperately poor people,. die fromhunger and malnutrition. Half of those who die arechildren under age of 5.

The poor peoples are caught in poverty trap by three forces local, nationaland global. The local forces are:

• lack of access to enough land and income to meet basic needs,• physical weakness and poor health decreases the ability to work and

plunges them deeper into poverty,• powerlessnElss subject the poor to being tricked in signing away the

little land or livestock they own, paying such high interest rates onloans that they lose their livestock and land,rapid population increase produced more workers than can beemployed and forces wages down as the poor compete each other forscarce work.

The local parts of poverty trap are reinforced by government politics atnational level. They include national budget that favour rich, urban and industrialover rural development and military over social expenditures.

~ . :=- \~\I, ~t is the averag~ growth rate of human population today?

On top of these, global poverty traps added by .international monetaryagencies ard rich developed countries, such as,

• less developed countries owe 1.3 trillion dollars debt to banks of mostdeveloped countries,

• Sharp decline in the income of less developed countries that dependon'the export of their cash crops like coffee, sugar, cotton, rice, etc.

• because of rising trade barriers in rich countries; the less developedcountries lose each year 100 billion dollars, and

• Loss 'of investment capital in less developed countries becausewealthy people of these countries invest or deposit their moneyabroad where it is safe. from taxation.

Poverty is the primary cause of environmental degradation in LOCs (lessdeveloped countries). When their rural poor people are faced with starvation theyoverexploit their vital natural resources through excessive tree cutting, poorfarming and poor grazing practices that deforestation, soil erosion, flooding,spreading of desert and loss of biodiversity. The consequent degradat~Slr1of landresults in further impoverishment, desperation, misery and environmentaldegradation.

It is feared that 3 to 5 billion people could be living in absolute povertysometime between 2025 - 2075. And because of the degradation ofenvironment, there will be a population crash or dieback, with 2 - 5 billion peopledying prematurely.

Some observers contend that root cause of poverty and environmentaldegradation is not the "human population growth" but inequitable distribution ofwealth and power.

We are living in a world of "haves" and "have nots". A few of LIS live inincreasingly luxurious life while many others even lack the basic necessities oflife. According to World Bank estimates more than 1.3 billion people live in acutepoverty with an income of Jess than one dollar per day, These poorest of the poorpeople lack access to an adequate diet, housing, basic sanitation, clean water,education and health care.

2hl

About 20% of the world's population lives in 20 richest countries whereaverage per capita income is above 25000 dollars per year (North America,Canada, Japan, Singapore, Australia, New Zealand, UAE, Israel and WestEuropean countries). The other 80% of the world population live in middle or low-income countries. More than 3 billion people live in the poorest nations where percapita income is below 620 dollars per year. The ten poorest countries in theworld are Mozambique, Ethiopia, Tanzania, Congo, Malawi, Rwanda, Chad,Sierra Leon, Nepal and Niger, where per capita income is less than 200 dollarsper annum.

The MOCs (most developed countries) with 20% of the world's populationcommand about 80% of the world's wealth and use 80% of world's mineral andenergy resources. Whereas the LOCs with 80% population have only 20% of the.world's wealth and use only 20% of the mineral and energy resources. Table11.2 reflects the disparity in quality of life between poorest and richest countries.

The affluent life style enjoyed by rich countries Consume an inordinateshare of world's natural resources and produce a shocking high proportion ofpollutants and wastes. The USA witll less than 5% of the total world's populationconsumes about V4th of most commercially traded commodities (Table 11.2 and11.3).

Indicator Poorest RichestCountries Countries

GNP/Per capita 170 dollars 29,946 dollarsLife expectancy 47.4 years 77.9 yearsInfant mortality 114 5.7(per 1000 live birthsChild deaths 194 7.5(per 1000 children before age5) .Safe drinking water 42% 96%Female literacy 38% 97%Birth rate (per 1000 people) 45.2 11.4

Table 11.2 Average indicators of quality of life for the ten richestand ten poorest countries

I Q. How many people are homeless in the world? I

Consumes Produces Pollutants26% of all oil 50% of all toxic wastes24% of aluminum 20% of nitroqen oxide20% of copper 25% of SUlphur oxide19% of nickel I 22% of CFS13% of steel 26% of carbondioxide

Literally, pollution means "destruction of purity" or "to render unclean".Scientifically, pollution may be defined as "any undesirable change in thephysical, chemical or biological characteristics of our air, water and soii whichmayor will harmfully affect human health, plants, animats, our industrialprocesses, living conditions and cultural assets".

Pollution can also take the form of unwflnted energy emissions, such as,excessive .heat, noise or radiation. The sources of pollution may be classified asPoint sources and Non-point sources:

a. Point sources: Factories, power plants, sewage, coal mines, housechimneys, oil wells, etc are classified as point sources because theydischarge pollutants from a specific location (such as, ~~~:t::lUSlpipe;.drain pipe, chimney, sewer falls or ditches). These sources areidentifiable and can be monitored and regulated easily.

b. Non-point sources: In contrast, non-point sources are scatteredhaving no specific location. For example, run off fertilizers andpesticides from croplands into streams and lakes; pesticides sprayedinto the air or blown by wind; or a heavy rainfall may flush highconcentration of oil, rubber residues, chemicals etc., of city streetsinto a nearby water body. The irregular timing of rainfall makes non-point sources much more difficult to monitor, regulate and treat.

Pollution can have a number of unwanted effects. The important.ones aleas under:

1. Nuisance and aesthetic insult: Unpleasant smells and taste;reduced atmospheric visibility; noise; sites of garbage dumps etc.

2. Property damage: corrosion' and tarnishing of metals; surface. erosion, soiling and discoloration of buildings, monuments, statues,surface erosion of glass, ceramics and paints; embrittlement of paperand books; cracking of rubber goods; discoloration and fading ofleather goods and textiles.

3. Damage to plants: Decreases trees and crop production; damagefruits; sometimes plants are completely ruined.

4. Damage to animals: Harmful health effects on animals; large-scalemoralities; extinction of many species.

5. Damage to humans: Spread of infeCtious diseases; irritationallergies, headaches, and a variety of respiratory diseases; geneticdisorders; carcinogenic effects; large scale deaths.

6. Disruption of natural life-support systems: Climatic changes,global warming, decrease in biodiversity, decreased natural recyclingof chemicals, etc.

The substances, which cause pollution, are called pollutants. Pollutantsare the wastes, residues or bye products of industry, agriculture, transportation,mining or domestic processes. In short, pollutants are bye-products of man'saction. Pollutants are so many and of such variety in nature that neither ispossible to list them n_orto classify them.

Three factors de.termine how severe the effects of a pollutant will be,namely i) its chemical nature: how active and harmful it is to specific types ofliving organisms, ii) its concentration: the amount per volume unit of air, water,soil or body weight and iii) its persistence: how long it stays in air, water, soil, orin our bodies.

2ll-'t

On the basis of persistence, the pollutants may be divided into two types,Degradable and Non-degradable.

Degradable or Non-persistent pollutants are those that are broken downcompletely or reduced to acceptable levels by natural physical,' chemical orbiological processes. Such processes may take place over a span of minutes,hours or days. A material that decomposes in the environment as a result ofbiol09i9al action is said to be Biodegradable. For example, human sewage addedto river or the soil is biodegraded fairly quickly by bacteria as long as it is notheavily loaded.

The non-degradable or persistent pollutants are those, which are eithernot altered or are degraded at a very slow rate, often taking decades. These aremostly inorganic· salts (such as chlorides), metallic oxides, aluminum cans,chloroflourocarbons, phenolic compounds, plastics, spray propellants,hydrocarbons, DOT and a number of other synthetic chemicals. ·The method to'destroy them artificially either not known or they happen to be very costly.

\The important and common pollutants are:1. Deposited matter such as, soot, smoke, ash, tar, dust, grit, etc.2. Gases such as, carbon-monoxide, nitrogen oxides, carbondioxides,

chlorine, ozone, sulphurdioxide, iodine, etc.3. Metals like lead, zinc, mercury, iron, chromium, etc.4. Chemical compounds such as, aldehydes, arsines, hydrogen

fluorides, phosgenes, detergents.5. Photochemical pollutants like ethylene, peroxyacetyl nitrate.6. Industrial pollutants such as,' benzapyrenes, benzene, ether, acetic

acid and cyanide compounds.7. Agricultural pollutants such as, insecticides, fungicides, herbicides

and fertilizers.8. Sewage9. Noise10. Heat11. Oil spill12. Radiation pollutants include radiations from radioactive elements and

radioactive fallouts.

Generally pollution is classified either according to the environment as Airpollution, Water pollution, Soil pollution, etc., in which it occurs or according tothe nature of pollutant such as Lead pollution, Thermal pollution, Radioactivepollution, Oil pollution etc. by which pollution is caused.

In the following pages, we shall. discuss in brief the chief sources ofpollutants and pollution caused by them on environment basis.

Wherever we live, the air is contaminated to some degree. Smoke, haze,dust, odors, corrosive gases, noise, toxic compounds, and particulate matter arepresent. According to EPA, the total worldwide emissions of these pollutants arearound 2 billion metric tons per year. Worldwide, about 1.3 billion people (one infive) live in areas where air is unhealthy to breathe, causing between 0.3 - 0.7million premature deaths each year.

The WHO defines air pollution as "the presence of materials in the air insuch concentration which are harmful to man and his environment."

Air pollutants are products of both natural events and human activities.Natural sources of air pollution include,

• volcanic eruption that spews out ash, acid mist, hydrogen sulphideand other toxic gases,

• sea spray and organic decay are major source of sulphur compounds,• trees and bushes emit millions of tons of volatile organic compounds,• pollen grains, spores, viruses bacteria and other bits of organic

material in the air cause widespread sufferings, and• storms in arid regions raise dust clouds that transport millions of tons

of soil from one place to another ...

Pollution attributed to human activity result from,• automobile exhausts,• agriculture,• industrial processes,• electricity generating plants,• domestic cooking and heating, and• ionizing radiations

I Q. What is the population of Pakistan?

The air pollution is mainly caused by the particulate matter and gassesreleased by the burning of fossil fuels (such as coal, natural gas, petroleum) inthe automobiles, industry and domestic uses. The five major burning sources thatpour pollutants into the air are:

1. Automobiles: Cars, scooters, motorcycles, rickshaws are the mainsources of air pollution. 60% of air pollution is attributed to vehicle;,;today. According to an estimate, a combustion of 1000 gallons ofpetrol produces,

1500 kg90 - 180 kg9 - 35 kg8 kg8 kg1 kg0.1 kg

carbon-monoxideorganic vapoursnitrogenoxidealdehydessulphur compoundsorganic acidscarbon particles

\There are 550 million cars in the world that consumes one-third of ourtotal production of petroleum.

2. Electrical Power Plants: A number of electricity generating plantsare run by coal, gas, diesel or petrol. 1000 megawatt C,);.,I ;;1 "=",_! ;) -:.: ::~

emits about 275 kg of carbon monoxide. 1 , I,U 01 particulate matter, 5kg of sulphurdioxide and 7 kg of nitrous oxide.

3. Industria" Processes: About 1/5 of air pollution is caused by the fuelburned in metallurgical plants, oil refineries, paper and sugar mills,cotton and rubber manufacturing plants and so on.

4. Heating and Cooking Plants: Heating plants for homes, school,apartments, hotels, commercial buildings together form 4th largestsource of air pollution.

5. Transportation Industry: Rails, ships, airplanes,' buses, trucks,tractors, etc. produce same types of pollutants, as do cars.

267Following is an account of the important air pollutants that directly or

indirectly affect plants, animals and human" health adversely and also causeenormous economic loss.

A. Aerosols: An aerosol is an'y system of solid particles or liquid dropletssuspended ,in gaseous medium. For. convenience we generallydescribe aU atmospheric aerosol~as Particulate matter. This includesdust, ash, soot, lint, smoke, pollen spores, algal cells, asbestos fibersand various pesticides. . ,

The natural sources of aerosols, such as volcanic ash, forest andgrass fires, dust storms, se,a spray contribute 90% of emissions.Human contribution in ,the. formation of aerosols is only 10%.According to an estimate, 362 million metric tons of particulate matteris released into atmosphere per year due to human a~tivities.

The harmful effects of aerosols are: reduces visibility; leaves dirtydeposits on windows, painted surfaces, buildings, fabrics, etc;

\respirable particles cause a number 01 respiratory diseases; pollengrains cause irritation and allergies of various kinds.

B~ Smog: The fog deposited with smoke. and chemieal fumes form athick haze, the smog (fog + smoke = smog). There are two types ofsmog, Industrial and Photochemical.

a. Industrial smog: Industrial smog is grey. air and it b,uilds upmostly at night. It is most common in industrialized countries, ,which have cold wet winters like London, Chicago, New York.8uch cities burn enormous amount of fossil fuel for heating,travelling and in industrial plants. The burning of fuels releasestwo major classes of pollutants, particulate matter and oxides ofsulphur (such as 802 and 803). These substances may reachlethal limits when winds and rain do not disperse them. Forexample, as a result of smog, 1600 people died in Belgium in1930; in London 4000 people died on a single day on 5th

December 1952; in New York there were 1700 and 360 causalitiesin 1960 and 1963 respectively.

1.0. What is the current growth rate of human population in Pakistan? I

b. P~otocherriical smog: Photochemical smog is brown and begin~only during daylight. It occurs in cities with warm dry climates andwhere the main source of pollution is nitric oxide. Los Angeles,Denver, Sydney, Mexico are called as "brown air" cities. Nitricoxide reacts with oxygen in the air to form nitrogendioxide, themain source of brown haze. When exposed to sunlight,nitrogendioxide react with hydrocarbons (suspended in air) to formphotochemical oxidan·ts.

Nitrogen dioxide + hydrocarbons ultraviolet radiations PAN + Ozone

The main components of smog are thus PAN and ozone, both are·hazardous to living things. .

PAN (peroxyacetyl nitrate) causes eye watering; respiratorydistress; blocks "hill reaction" of photosynthesis; reduces nutrientsuptake by plants; damages leaves and stems.

Ozone irritates nose and throat at 0.5 ppm; at 1 ppm causesdryness of throat and headache; it is associated with a number oflung diseases; long exposures breakdown waxy coating that helpsplants prevent excessive water loss; causes leaves to turn yellowand drop off; damages crops; degrades rubber and fabrics.

C. Nitrogenoxide: The major sources of nitrogen oxides areautomobiles and electric power plants. In atmosphere, nitrogen oxideis reduced by ultraviolet radiations to nitrogen-monoxide andelemental' oxygen.

Atomic oxygen soon reacts with molecular oxygen to form ozone......... 0 + 02 ------------~---- 03

Ozone reacts with nitrogen-monoxide to form N02 and oxygen again,thus closing the cycle.

In the presence of sunlight, atomic oxygen from the photochemicalreduction of N02 also reacts with a number of hydrocarbons (such asmethane, ethane, toluene, etc.) to form reactive intermediates, calledRadicals. These radicals then combine with oxygen, hydrocarbons,and nitrogen-monoxide. As a result, nitrogen-dioxide is regenerated,nitric oxide disappears, ozone accumulates and a number ofsecondary pollutants are formed such as aldehyde:>, PAN, etc.Nitrogen-dioxide ,and secondary pollutants are hel mful both to manand plants. Nitrogen-dioxide is a pungent gas that ptOduces a brownhaze. Its role in the formation of smog has already been described. At13 ppm concentration it causes irritation of nose and throat while at 25ppm one feels pulmonary distress. It also reacts with atmosphericmoisture to form weak nitric acid, which is carried to soil and waterbodies as acid rain.

D. Carbon-monoxide: This is one of the most abundant and widelydistributed air pollutant. Besides smoking, it is also released by motorv~hicles, kerosene heaters, fireplaces, wood stoves, etc. It is highlyinjurious to human health. It readily combines withe-hemoglobin inblood to form carboxy-hemoglobin, whicll reduces o~ygen carryingcapacity and thus causes difficulty in breathing. At a concentration of10 ppm, it causes giddiness; slow down reflexes; headache andlassitude in less than ten minutes; such instances are very commonduring traffic jams. Higher concentration may even be fatal. This gasis one of the main cause of bronchial asthma which is very commonamong bus and truck drivers who remain exposed to this gas forlonger periods of time. The international permissible limit is 9 ppm.

E. Sulphur-dioxide: qxides of sulphur (802 and 803) are among themost dangerous air pollutants. These not only cause economic lossbut adversely affect human health. Coal burning factories, metalsmelting plants and electric power plants are the main sources ofsulphur-dioxide emission. Total yield is estimated to be 114 millionmetric tons per year. Nearly 70% of sulphur-dioxide comes from tilecombustion of coal.

270Once in the atmosphere, this gas does not stay long in gaseous statebut rapidly combines with moisture to form sulphuric acid. Thedroplets of sulphuric acid falls on the earth as acid rain (see nextsection). It irritates our respiratory epithelium and impairs normalbreathing; it causes cough, pharyngitis, headache and eye irritation.

F. Acid rain: When electric power plants, industrial plants andautomobiles burn coal and oil, they emit large alTlounts of sulphur-dioxide, suspended particulate matter and nitrogen oxide .. Dependingon climatic conditions, some of these emissions may remain air bornefor' a time as tiny particles. When they fall on earth and come incontact with objects in the enVironment, they ar' nic t be "dry aciddeposition" (e.g. sulphate and nitrate salts). Between 70 - 90% of theS02 and N02, however, dissolve in atmospheric moisture to form aweak solution of sulphuric or nitric acid. They fall to earth as wet "acidrain". In sensitive areas, the acid rain fall out increases the acidity ofwater bodies and spil. Not only do the acid rain causes injury to plantsand problems in public health, it also brings' about economic lossworth billions of dollars. It is estimated that damage from acid rain inUSA alone is 10 billion dollars per year. The harmful effects of aciddeposition are:

• High acidity can severely harm aquatic life in non-alkalinelakes. Because of excess acidity, some 16,000 lakes inNorway and Sweden contain no fish. In Canada, some 1,400lakes are almost fish-less due to acidity.

• it weakens or kills trees• it makes trees more susceptible to disease, insects and

drought• it leaches toxic metals such as copper and lead from water

pipes into drinking water'• it causes and aggravates many human respiratory diseases, it

causes irritation of mucous membrane and skin• it corrodes metallic structures of buildings• it damages buildings, statues, monuments, painted surfaces,

car finishes, etc.• it degrades leather goods, fabrics, rubber goods, etc.

271

G. vac or Hydrocarbons: VOC (volatile organic compounds) areorganic chemicals that exist as gases in the air. Plants are the largestVOC releasing source. An estimated 350 million metric tons ofIsoprene (C5H8) and 450 million metric tons' of terpenes (C10H15)are released each year. About 400 m.m.t. of methane are producedby natural wetlands and rice paddies. These volatile organiccompounds are generally oxidized to CO and C02 in atmosphere.VOC can cause mutations, reproductive problems or cancer. VOCal.so contributes to the formation of ozone near the ground.

H. Lead: Lead is mainly injected in atmosphere from automobile exhaustand is now widespread and important global contaminant. It iscommon practice these days to add in petrol or diesel "tetra-ethyllead" as an anti-knock agent which on combustion' releases leadparticles in atmosphere. Minor sources are metal smelting plants andagricultural areas where lead arsenate is used as. an spray. Onaverage, one vehicle releases about 1 kg of lead particles per year.piant roots take up lead from the soil and leaves take it up fromcontaminated air or from particulate matter that lands on the leafsurfaces. Once in or on plants lead enters the food chain. Roadsideplants along major highways and crossroads are foun~ to contain highconcentration of lead in their tissues and this has a s'ub-Iethal effecton health of plants. People who live near busy motorways or persons(such as, traffic policemen) who are exposed for long hours to heavytraffic have a higher lead content in their· blood than those fromelsewhere. A concentration of 0.2 - 0.4 ppm is considered normal buthigher concentrati.ons are responsible for anemia, kidney disordersand convulsions. In children 0.6 ppm level of lead may cause death.

I. Carbondioxide: Carbondioxide is a natural constituent of theatmosphere. It is not necessarily a pollutant. It produces advers~~effects only at very high levels. Today concentration of carbondioxidein atmosphere is 340 ppm and is rising at a rate of 18 ppm perdecade. Total emission of carbondioxide was estimated to be 1.5million tons but today we spew about 8 billion tons of carbondioxideevery year. Typically terrestrial ecosystems take up about 3 billiontons of this carbon every year while oceans take up another 2 billiontons. This leaves 3 billion to accumulate in the atmosphere. The mainsources of ccirbondioxide are fossil fuel burning, land clearing,respiration and industry.The continuos increase of carbondioxide, at an alarming rate in theatmosphere is causing "green-house effect" (see box below).

Global WarmingThe term "green-house effect" was first introduced by a Swedish

scientist. Svante Arrhenius in 1896. According to him there are certaingases In the atmosphere such as,

a. C02 mostly produced by fossil fuel burning,b. CFCs (trade name Freon), a refrigerant,c. Nitrous oxide from fertilizers and animal wastes,d. Methane from, biogas, bacterial decomposition and rice

paddies,e. Halons (haloparbons) from fire extinguishersCollectively referred as Green House Gases that act as heat

retaining blanket over the earth. The properties of these gases are suchthat they prevent infra red heat radiations from earth from escaping toouter space, and at the same time it disallows cool air from space, andhence causes rise in global temperatures (this is called green house effectbecause the glass of a green house allows sunlight to- pass through andthen traps the resulting heat inside the structure).

As the levels of carbon dioxide and other green house gasesincrease in atmosphere, they trap more and more heat causing globaltemperature to rise gradually, a phenomenon.. referred to as "GlobalWarming".

If nothing is done to control the level of green house gases, it ispredicted that earth's mean surface temper.ature will rise El C by 2050.

Ecologists predict that a rise in global temperature of El C by 2050will have disastrous effects. These may be summarized as follows:

1. Rise in sea level: Over the past 15 years, with a steady rise inglobal temperature of O.OEl C per annum, the polar ice caps haveshrunken by 6%. It is feared that with a rise in global temperaturesof El C by 2050, there will be a rise in sea level from 65 cm tb 1.5m (as a result of melting of glaciers and polar ice caps). Almost halfof the world population that lives in coastal regions will be flooded.Countries like Holland, Indonesia, Maldives, Bangladesh will bedrowned completely or partially.2. Loss of biodiversity: Many organisms that breed and live incoastal estuaries, swamps and marshes will be lost with flooding.3. Change in food production: This will happen due to shift intolerance ranges of plant species with respect to temperature(including food crops).4. Reduction in water supply: warming would also causereduction in water supplies in some areas. Lakes, streams,

aquifers could shrink or dry up altogether forcing entire human andanimal populations to migrate to areas with adequate watersupplies.5. Weather extremes: rapid climatic change (warming or cooling)over a few decades is likely to be disastrous for earth'secosystems.6. Threat to human health: Global warming also poses threats tohuman health. The spread of tropical climate from equator wouldbring malaria, encephalitis, yellow fever, and other insect boniediseases to formerly temperate zones.7. Refugee prob.1em: climatic change would lead to a growingnumber of environmental refugees. By 2050, global warming couldproduce 150 - 220 million environmental refugees. Most of therefugees would illegally migrate to tf)e countries causing muchresentment, social disorder and international political instabilities.8. Variability in weather pattern: Ecologists correlate globalwarming with serious and prolonged droughts; heavier rain andfloods; altered distribution of agriculture; change in location andstructure of forests; desertification of croplands and abnormalvariations in pattern of plant growth.

J. Ozone shield destruction: The protective layer of ozone instratosphere (see Fig. 6.2) is very important for us. The earth can notsupport life without it as it checks the ultraviolet radiations from sunwhich otherwise are lethal to living organisms. Scientists have found'that this protective layer is gradually depleting due to air pollution. 1I-Iemain source of ozone depletion are:

1. Chloroflourocarbons:' Written as CFCs (trade name isFreons). These compounds are used as propellants inpressurized aerosol cans and sprayers; as refrigerant inrefrigerators and air conditioners; in preparation of styrofoam(tha packing material).

2. Halons:. These are bromine compounds used in lireextinguishers.

n-l

3.' Nitrogenoxide: Released from biogas burning, breakdown ofnitrogen fertilizers and livestock wastes.

4. Supersonic flights of jets (release nitrogen-oxide).5. Space shuttles (that use sond fuels which on burning release

chlorine).

Pure ozone is a blue, explosive, poisonous gas.Very small amounts of ozone are produced in theatmosphere by the action of sunlight on oxygen. Thenatural concentration of ozone in our biosphere is 0.02ppm; in stratosphere it is about O. 1 ppm. It is unstablegas that breaks up quickly to form molecular oxygen.

Ozone depletion is a consequence of insoluble inert gases, mostly CFCsand halons, which release chlorine or bromine under the influence of short waveultraviolet radiations. The properties of chlorine, bromine and nitrogen oxide aresuch that they catalytically reduce ozone into molecular oxygen (one atoms 01chlorine destroys about 100,000 molecules of ozone before settling on earth'ssurface as chlorine later year). The reduction of ozone permits the penetralion otultraviolet radiations at earth's surface.

In 1974, chemist Dr. Sherwood Roland theorized that pollutants arelowering the average concentration of ozone in the stratosphere and therebyallowing more ultraviolet rays to enter our biosphere. He first reported big holesof about 50 square kilometers in the ozone layer abovp. Antctll;iica.

Ecologists predict that current rate of ozone depletion would cause,a. an increase in the incidence of human cancer, specially skin cancer,b. decrease yield of important food crops,c. suppression of human immune system,d. sharp increase in eye cataract cases,e. an increase in global warming,f. hasten the rate of smog formation, andg. the plants and animals living in top layers of oceans, particularly

phytoplankton, will begin to die.

I Ans: 340 million. -.J

K, Indoor air pollutants: Most of us spend 16 - 20 hours of our dayinside the building. In recent years, therefore, increasing concern hasbeen focused on the quality of air that we breathe in our homes,offices, schools, restaurants, clubs, etc. Indoor air carries pollutants

-from outdoors that are drawn in by fans or enter through windows, aswell as, pollutants that are generated within 'homes or bUildings.Because of this, indoor air is often more polluted than the outdoor air.As many as .150 indoor air pollutants have been recognized.

According to public health experts, cigarettesmoke,' radon gas, asbestos fibers, andformaldehyde are the four most dangerous indoorair pollutants.

The main sources of indoor air pollutants are buildingmaterials (especially those that contain formaldehyde resins orasbestos); radon gas (incorporated in concrete blocks); householdchemicals used for cleaning (toilets, oven, floors, drains, etc);'disinfectants; detergents:, insecticides, house dust, etc. Molds andspores are probably the single great cause of allergic reactions.Cigarette smoking is another important indoor Cl:irpollutant. More thanfive million people die each year from emphysema, lung cancer andheart attack caused by smoking. In less developed countries of Africa,Asia and Latin America, more than 70% people are exposed to highlevel of indoor pollution. The main cause being the burning offirewood, coal, dried dung, and agricultural wastes for heating andcooking in un-vented stoves or poorly ventilated dwellings.

Water pollution may be defined as "addition of any organic or inorganicsubstance, which may alter the properties of water and render it unfit for aparticular use and adversely affects living organisms". Thus a waterbody may bepolluted and unfit for drinking purpose, while it is not polluted for irrigation andsome industrial use.

270

Since time immemorial, man is dumping every conceivable kind of wastedisposal in our lakes, rivers, and oceans but it is only during recent years thatvarious bodies of water are heavily polluted. Under natural processes most of thewater pollutant are rapidly decomposed, filtered out or diluted but when theyaccumulate in large quantities they create problems. Thus, pollution is a basicallyproblem of excess or overload a problem too much too fast. A substance,the~efqre, is not pollutant because it is toxic or poison; it is pollutant because it isan amount of toxin or poison that the ecosystem can not naturally handle it in anorma.l period of time.

Water, which is Vitally important for all living forms, is one of the mostpoorly managed resource on earth. We'waste it and pollute it. Water pollutionmay be divided into three categories namely, surface water, groundwater and the

,oceans.

A. Surface water pollution: The important pollutants' of surface waterare: .

1. Organic pollutants: Domestic sewage, agricultural run off,organic waste from' breweries, bakeries, milk dairies, sugar mills,hotels etc.

2. Chemical pollufants: Pesticides, detergents, heavy metals, acidmine wastes, oil dispersant and radioactive materials,

3. Thermal pollutants: Effluents from nuclear .reactors, steel mills,electric, power plants,etc.

4. Siltation: Sedimentation of .eroded soil.

Organic materials are a source of major pollution of water bodies, Thesepollutants originate mainly from domestic sewage, agricultural run otf, farmwastes, and industrial effluents. Domestic sewage is about 90% water and restconsists of human excreta, animal waste, kitchen refuse, organic compounds likecarbohydrates, urea, inorganic salts, such as, nitrates and phosphates of

,detergents. If organic waste is small in relation to the volume of water, it readilydecomposes but in excessive amount it poses many serious problems, forexample,

I Ans: 40%.

277i. Organic matter' which become oxidized by bacterial action in

water, lowers down the oxygen content of water body whiclladversely affects the living organisms. Due to high biologicaldemand of oxygen, the water may turn anoxia, producingdangerous gases like ammonia, hydrogen sulphide, methane,etc., which may ,kill most of the aquatic organisms and produceoffensive odors and taste.

ii.. Human refuse and farm waste contain pathogenic bacteria andviruses which are a serious threat to human health. About 80% ofworld diseases are water-borne. These include typhoid, cholera.poliomyelitis, 'dysentery, diarrhea, paratyphoid, etc. Sewagepollution also carries infections of filariasis, hookworm, guineaworm, thread worm and ascariasis diseases. Some 25 milliondeaths, mostly children each year maybe attributed to watercontamination.

iii. Sewage effluents and run off from agricultural fields posses richquantity of phosphorus and nitrogen nutrients which when enterstreams or lakes promote objectionable growth of algal bleJoms.Algal blooms, which float on the surface, spoil fishing, swimmingand recreational qualities of the water body. These when die notonly add organic matter to water body but sometimes releasetoxins which have lethal effects ori living organisms.

iv. Organic effluents often contain large quantities of suspendedmatter, which increases the turbidity of water. Consequently, thepenetration of sunlight responsible for photosynthetic activities ofplants is reduced.

v. Near agricultural centres or urban areas, the input nutrients toalake can be greatly accelerated by human activities, a processcalled as cultural eutrophication. It is caused mostly by nitrate andphosphate containing affluent from sewage treatment plants, runoff of fertilizers and animal wastes and accelerated erosion ofnutrient-rich topsoil.

vi. It increases the number of bacteria, which use the waste assubstrate.

Although natural chemical compounds have existed for billions of years,people have recently learned to make new chemical compounds, calledSynthetic chemicals. They are present in dyes, paints, food additives, drugs,cosmetics, pesticides, food additives, plastics, fertilizers, etc. In 1980, some70,000 synthetic chemicals were in use, and 2,000 new compounds are addedevery year. Some of the compounds are drugs that save millions of lives everyyear and others are poisonous. Some synthetic chemicals break up readily in tileenvironment by the action of sunlight, air, water or soil. Materials that decomposein the environment due to biological action is called biodegradable. While manyother compounds either stay for a long time in the environment (e.g. plastic) ordecompose very slowly (e.g. DOT) and are referred to as non-degradable. Someimportant chemical pollutants are as follows:

i. Pesticides: A pesticide is a· chemical that kills pest. A pest is anorganism that reduces the availability, quality or value of resources usefulto human beings. Pest competes for food with people, and some spreaddiseases. Of the millions of species of org;:misms only about 100 - 150species of plants, animals (mostly insects), fungi and microbes cause90% of all crop damage in the world. The specific pesticides areinsecticides (insect killers), herbicides (weed killers), fungicides (funguskillers), acricides (tick killers), avicides (bird killers), rodenticides (rodentkillers), and so on.

Commonly used pesticides are a) Inorganic oesticides (eq.mercury, arsenic powder), b) Natural O;gil::ic pesticides (e.g. rotenonenicotine, etc.) c) Fumigants (carbon-tetra chloride, methylene bromide, d)Chlorinated hydrocarbons (DOT, Aldrin, Lindane, etc.) e)Organophosphates (parathion, malathion, etc). f) Urethanes (e.g.aldicarboxyl, etc.) and g) microbial agents (e.g. bacteria such as Bacillus).

Proponents of pesticides believe that the benefits of pesticidesoutweigh their harmful effects. They point out following benefits:

a. Pesticides save lives. Insects and ticks serve as vectors intransmission of a number of dangerous diseases like malaria,sleeping sickness, plague, typhus, and so on. The pesticideshave successfully controlled these diseases.

b. They increase food supplies and lower food costs. It is thoughtthat plant .diseases, insects and bird rredation, andcompetition by weeds reduces crop yields worldwide by atleast 35%. Again post-harvest losses to rodents, insects, fungimay be as high as 20 - 30%. Without modern chemicalpesticides, these losses might be much higher. A commonlyquoted estimate is that farmer save fi\(e dollars for every dollarspent on pesticides.

Worldwide, about 2.5 mil/ion metric tons ofpesticides are used every year ... : .. an average of 0.5kg for each person on earth. About 90% of al/pesticides are used in agriculture, food storage andshipping.

While pesticides have brought us great economic and social benefits,they also cause a numb.er. of serious problems Extensive and indiscriminate useof DOT an'd other pesti'cides, all over the world, for the control of agricultural,forest and medicinal pests has become a matter of serious concern. When thewater run-off from agricultural fields and forests sprayed with insecticides enterinto any lake, pond or stream, it causes great damage to animal and plant life. Asmentioned earlier, most of the pesticides are non-dogradable, so they haveseriously contaminated the global ecosystems and entered food chains. Theadverse effects of pesticides are:

1. Living organisms and human health: Insecticides depressphotosynthetic ability of phytoplankton. DOT eoncentration of lessthan 0.2 ppb kills the commercial species of shrimps and crabs within20 days. Insecticides applied directly to water, for the control ofmosquitoes and black fly larvae, have caused great mortality of fishlarvae and aquatic invertebrates. The carnivores on the top-levelfood chain (for example, fish eating birds) are the ones that receivegreatest amount of DOT and other pesticides.Pesticides affect human health directly or indirectly. WHO estimatesthat each year about 3 million people are poisoned by pesticides and20,000 of·them die.'

2:-;0

About 3% of food bought from market have levels of residues ofpesticides. On average, each person is carrying in his fats 10 - 20ppm DDT, 0.1 - 0.3 ppm aldrin, and small amount of otherpesticides. Increasing concentration levels of tllese chemicals aresaid to affect hormonal balance and many of them cause cancer.

2. Destruction of non-target species: Pesticides, very often, killbeneficial species (for example, honey bees and a number of insectpollinators are killed by spray). Similarly, killing of harmless speciescauses reduction in biodiversity.

3. Resistance among pests: The development of resistant strain isanother unexpected consequence of widespread use of insecticides.By 1964, more than 500 major insect pest species have acquiredgenetic resistance to one or more insecticides, and at least 20 insectspecies are now immune to all widely used insecticides.

4. Persistence in the environment: Only about 1 -5% of insecticidesapplied to crops reach the target species. 90- 99% Of chemicals endup in soil, air, surface water, ground water, bottom sediment, food,and non-tal'get species. Estimates show that today, more than onemillion tons of DDT is present in the soil.

ii. Detergents: The term detergent is~ applied to washing products.Detergents, when released with domestic sewage contribute towards theeutrophication of the water body. The detergent.~ are mainly composed ofcomplex phosphates which when breakdown release a large amount ofphosphorus in the aquatic ecosystem. It has been estimated thatdetergents account for as much as 60% of phosphorus content of sewageeffluent in some developed countries. In a natural body of water,excessive amount of phosphorus stimulates the growth of floating plantsand algae even when the .nitrogen supply is exhausted. The species,which grow in abundance are generally the blue green algae which aremostly unsuitable as food for fishes and other organisms. Again,' whenthe algae die, they sink to the bottom and in the process of decompositioncause oxygen deficiency. Some species produce toxins when they die.They also emit unpleasant odor, foul beaches and make resort facilitiesoffensive and depressing. Detergents also cause damage to gills ~ndremove protective mucus from gill filaments, skin and intestine of fish.

I Ans: 33 %. I

Industrial wastes or' effluents of industries such' as, petro-chemicalcomplexes, sugar mills, tanneries, synthetic material plants of fibers plastic andrubber, etc. when released in water cause serious damage. These effluentscontain salts of copper, zinc, lead, cadmium, nickel, mercury, etc. and all of thesechemicals are toxic to animals at various levels and may cause death or sub-·Iethal pathology of liver, kidney, reproductive and respiratocy systems. The toxiceffects of most metallic compounds lead to the coagulation of mucus secretion ofgills and protoplasm. Arsenic compounds immediately kill the fish and otheranimals. Concentration of aluminum salts higher than 0.5 ppm is lethal, similmlythat of iron, if more than 0.2 ppm, and lead more than 0.3 ppm. Mercury is highlytoxic to both humans and animals and aquatic life. Like other toxic heavy metalslike lead and cadmium, it accumulates in the bodies of organisms gradually andacts as an accumulated poison.

In Japan, illness and even deaths occurred in 1950 among fisherrnerl whoingested fish, crabs and prawns contaminated with methyl mercury released fromindustries in water. The mercury poisoning produced a crippling disease called

- Minamata disease. The toxic and pathological effects on man of heavy metalswater pollutants have been tabulated in Table 11.4.

Metal Patholoqical Effects on Man1. Mercury Abdominal pain; headache; diarrhea2. Lead Anemia; vomiting; loss of appetite; convulsions; damage to liver and

kidney4. Arsenic Disturbed peripheral circulation; mental disorder; liver cirrhosis; lung

cancer; kidney damage; gastric ulcer5. Cadmium Diarrhea; bone deformation; kidney damage; testicular atrophy;

hypertension; stunted growth6. Copper Hypertension; uremia; sporadic fever7. Barium Excessive salivation; vomiting; colic pain; paralysis; diarrohoea8. Zinc Vomiting; .renal damage;. cramps9. Selenium Damage of liver, kidney, and spleen, fever, nervousness; blindness

and even death10. Chromium Nephritis; gastric ulcer; cancer11. Cobalt Diarrohea; low blood pressure; lung irritation; bone deformities;

paralysis

Today most of the rivers and streams of the world are heavily polluted i)yindustrial wastes. Rhine is probably the most heavily polluted river of Europe. InPoland, Vistula, the largest river has been declared unfit both for drinking alidindustrial use.

4. Acid Mine WasteMost kind of mining processes of man have side effects of serious natLJre

in our' ecosystems. Acid and wastewater from mines of copper, coal, iron, etc.greatly reduce the pH and release toxins when drained in a water hodi'. Aconcentration of sulphuric acid (13 mg/liter) Or acetic acid (340 mg/liter) mayprove fatal to many groups of fishes.

5. Radioactive SubstancesRadioactive pollution poses a serious threat to the future of man and the

whole biosphere. It mainly results from bomb testing fallout, nuclear weapontesting, fuel processing plants, nuclear reactors and other radiation sources.Many radioisotopes occur naturally in rocks and soil containing radioactiveelements while a great majority result from fission products. Wastes from nuclei::Hreactors, or fall o~t or leakage from atomic power plants add such isotopes {awater reservoirs or rivers. Radioactive isotopes ~become accumulated throughcontaminated food, water or air, or they effect directly when surface becomesexposed. These enter tile food chain spreading to organisms concel'ned in chain.Forexample, strontium - 90 is absorbed by grass, ingested by grazing animalsand it can then be passed on to human beinqs through milk.

Of more than 450 radio-isotopes, only few are of serious concern thatenter food chain. Cesium is known to accumulate in the body muscles, stro tiumin bones, and iodine in thyroid. Instances have occurred where due to radiation

. fishes have become sterile or developed malformation of body. Theradioisotopes can also produce mutation in the genetic material, which wouldhave serious consequences for later generations.

6. Oil DispersionOil is mainly a problem of marine ecosystem but petrol and oil pollutants

sometimes enter surface waters. Typically they are run-off from streets (duringrain), leaks from pipe line, or discharge from industries, often at a small scale, uutoccasionally refinery effluents affect big rivers.

"In big lakes and rivers, motor bpats, steamers etc, also discharge an vilYmixture in water. The oil, which floats on the surface of water, prevents thedissolution of oxygen. Oil pollution r)ot only releases obnoxious vapours or smellbut makes water unfit for drinking and recreational purposes,

7. Thermal PollutionVarious industrial processes such as iron factories, steel mills, electric

power plants, nuclear reactors use water for cooling and resultant warm waterhas often been discharged in nearby streams, rivers or lakes. This causes.thermal pollution or Calefaction. A sudden rise in temperature by 10° C willdQuble the rate of many chemical reactions and will produce distinct changes inaquatic biota. A body of water at 30° - 35° C is essentially a "biological desert",

The sudden discharge of boiling water in a lake or river, may affectaquatic organisms in several ways, such as, i) organisms may be killed directly

, ,

when water temperature exceeds their tolerance limits, ii) solution rate of salt isaccelerated, iii) respiration and growth rates of ma~y organisms are 'adverselyaffected, iv) oxygen regime may be seriously affected, v) organisms may becomesusceptible to infection, and vi) species not generally found in unheated watersmay thrive and multiply in large numbers e.g. tubificid worms.

8. SiltationSiltation of lakes and streams due to soil erosion is one of the most

serious, damaging and widespread pollution. Most of the soil erosion arises fromhill degradation during' the rainy season, due to deforestation, intensiveagriculture, mining operations road building projects and extensive housebuilding schemes (that leave large dumps of sand and debris). Natural erosion ofsoil by wind and wa.ter and consequently siltation of water body is going pn formillions of years as a slow process but man made silting has become five foldduring past 40 years. Siltation not only affects the aquatic organisms but changesthe character of water body completely. Some of the important changes causedby siltatiolJ are:

a. Excessive siltation over a long period of time completely destroys an"open water body". As silt and organic debris build up, a clear anddeep lake or reservoir decrease in depth. With continued decrease itbecomes eutrophic followed by a marsh and eventually turn into a dryland or forest.

2S-l

b. Eroded soil gets deposited on riverbed, raising their level and leads todevastating floods.

c. The heavy load of particulate matter cut down the primary productivityby decreasing the depth of light peneJration.

d. High turbidity due to· silt, kills fish by clogging their delicate gillfilaments.

e. Silt and sand particles when settle down on gravel or rubble bottom,particularly in streams, destroy the spawning ground of many speciesof fish or prevent reproduction of fish by smothering E;lggs laid downon the bottom.

f. Due to rapid siltation, the life of our multipurpose dams (in which wehave invested billions of dollars) is. feared to have reduced very much.For example, Tarbela dam may not last for more than 25 years assiltation is going at the rate of 10 cm per year.

B. Ground Water Pollution: The pollution of groundwater from human. sources presents special problems that are different from the pollutionof surface water such as, li;lkes, streams, or rivers. There are followingreasons for this difference:'

a. Most ground water move quite sl.owly through their zones;contaminants are not effectively diluted or dispersed as in the case ofsurface waters, which are turbulent.

b. The cold temperature of grou/ndwater slows down decompositionreactions.

c. Groundwater has much smaller. population of decomposing bacteriacompared to surface waters. _

d. Groundwaters do not have access to air that is available to surfacewaters. Therefore, the oxidation that can purify or decontaminatedsurface water does not occur in deep aquifers.

The groundwaters, once contaminated, can not cleanse itself; and thereis no practical way to clean it up. The natural process of self-purifying is too slowand may take hundred to thousands of years. The main sources of groundwaterpollution are:

a. Defective or improperly sited septic tanksb. Faulty landfills

forests

32%

rangeland

and pastures

26%

,1. Solid Waste: The "solid waste" may be defined as any unwanted ordiscarded material that is not liquid or a gas. Virtually all our activitiesgenerate waste. We create waste when we extract and process rawmaterials, fuels, food, and when we use services. When products wearout, or outlive their utility or damaged we simply throw them out.Solid waste is one of the major pollution problef!ls, particularly of bigcities. Its accumulation on city streets attract rats and flies; stimulatesgrowth of bacteria; rotting of organic matter produces bad smell; becomesbreeding ground for rodents, cockroaches, and other insects and causeshindrance to traffic. Its collection and disposal is a huge task.USA with only 4.6% of the world's total population produces 33% of solidwastes. A total of 11 billion metric tons of solid waste is produced eachyear and six billion dollars are spent on its collection and disposal. Thesolid waste consists of 50% from agriculture + 34% from mining + 14%from industries + 1.5% - 2% from municipality ..In Karachi (Pakistan), a city of 10 million people and having more than500 industrial units, 10,000 metric tones of solid waste is produced daily(i.e. on average per person 1 kg of solid waste is produced). Only 60% ofit is collected by municipal corporation while the rest disperses at its ownin streets and open spaces.

Plastic shopping bags are also a great nuisance. More than 40 millionbags are thrown out in our atmosphere daily. These may be seen clingingto hedges, trees, electric poles, and other structures and thus the qualityof surroundings is badly affected. These bags create problem in cities aw'tOlilns with open drainage systems. Being non-degradable, the drains " _clogged or choked very often.

The municipal waste from homes an, iJusilless make upto1.5% of the total solid waste pro due cI rn USA. The estimated 168million metric tons of municipal waste comprises of 18 billion diapers;2 billion disposable razors; 1.6 billion ball points; 26 billion bottles; 15million tons glass; 35 million ton wood fibers; 500 million cigarettelighters; 14 billion catalogues; 2.5 billion plastic bottles; 38 billionpieces of junk mail; 8 million computers; 7 million automobiles besidekitchen refuse and many other rubbish material.

2. Deforestation: About 1/3 of the world's land surface is covered withforests, which constitute the most important natural resource. The modernman gets fuel, timber, fodder, pulp,. raw materials for syAthetic fibers,medicines from the forest. For man, forests have been a source ofrecreation and civilization. Besides, these forests regulate earth'stemperature, the water cycle, control floods, check soil erosion, maintainfertility of the soil and help in balancing the level of oxygen andcarbondioxide in the atmosphere. According to one calculation, onetypical tree du.ring its lifetime provides ecological benefits (as describedabove) worth 19,625 dollars. Wherfilas if it is cut and sold, the same treeis worth 590 dollars.Today, extensive deforestation is occurring, particularly, in less developedcountries. Deforestation may be defined as "removal of trees from aforested area without adequate replanting". Forests are being cutruthlessly for firewood, fodder, timber, agricultural needs, river valleyprojects, industrial purposes and for the construction of highways,buildings, dams, etc. It has been estimated that every minute 100 acres offorest is destroyed. Between 1950 and 1980, South East Asia has nearlylost 2/3 of its forests; Central America 40%; th.e Philippines 70%; Brazil12% and Africa 50%.

I Ails: Agriculture 85%; industry 8%; domestic use 7%.

Extensive deforestation results in soil erosion, lowering of groundwaterlevel; decline in annual precipitation; occurrence of floods, loss of soilfertility, reduction in wildlife, and greater incidence of diseases because ofloss of organisms which helped in controlling the various vectors.

In Pakistan, forests occupy 4.74 million hectares, which comes out to lJG

5.4 % of the total land area. It must be noted that for a healtllyenvironment, a country should have at least a forest cover 20 - 25% of itstotal Ia:nd area. As a result of ruthless exploitation of forests, 1% of tileland area of Pakistan is being laid bare every year.

3. Overgrazing: Overgrazing is another serious hazard" afflicting OUIgrasslands, pastures, forests and mountains. Overgrazing occurs whentoo many grazing animals feed too long and exceed the carrying capacityof a grassland area. It destroys the little vegetation cover and enhanceswind and water erosion of the soil. Selectiveness of most grazers leavebehind undesirable plants. The soil becomes compact, nutrients depleteand its water holding capacity is reduced.

, \4. Soil erosion: The top layer of soil is of vital importance since it is themain source for the entry of nutrients into plants. Soil, as most peoplethink, is not a dirt or dead matter but a healthy soil beside mixture of rockmaterials, contain a variety of living organisms like bacteria, fungi,protozoans, worms, and inst;lcts which decompose organic. matter andincrease the' fertility of the soil. This fertile top layer of soil, which varies indepth form 15 to 30 cm in different agricultural areas, is termed as"feeding zone of plant".The loss of topsoil is called "soil erosion". Water and wind are the twomain forces causing soil erosion. The naturai process of soil erosion isgoing on for the past millions of years. Today, however, due to humanactivities, the rate of soil erosion has increased many folds. Soil erosionis, thus, one of the world's critical problem and if not solved, will seriouslyreduce agricUltural and forestry production and degrade the quality of ouraquatic ecosystems (by siltation). It must be pointed out here, that onaverage, it takes about 500 years for an inch (2.54 cm) of the top layersoil to develop.

World is losing about 7% of its topsoil from potential croplands eachdecade. With every spell of shower about 0.1 cm soil is eroded. Atpresent, 0.27 hectare area of farmland is available per person w!lereas by2025 only 0.17 hectare will be available per person. In Southeast Asia,cropland will be even scarcer (i.e. 0.9 hectare per person).Man himself has destroyed much of the productive land. The rapidlyexpanding population demands more and more food. ·To meet thedemand, intensive agriculture is being practiced. This has led to soilerosion, increase in salinity, depletion of organic matter, water loggingand pollution of soil, air and water through extensive use of fertilizer's,pesticides, overgrazing, deforestation, poor drainage system and pooragricultural practices.

Noise may be defined as "unwanted sound" and the noise pollutionmeans the unwanted sound dumped into th'e atmosphere, which has adverseeffects. High intensity sounds are produced by different 'rnachines of mills,factories; different kinds of autos; aeroplanes; jets; loudspeakers; pop musIc'radio; television; social gatherings; and so on. Sound intensity is measured on ascale of values called "decibel" (abbreviated as dB) one decibel is equivalent to1/10 of sound produced by a call bell). Table 11.5 shows typical sources ofsound from 0 - 180 dB.

Human ear can afford a maximum noise of 50 decibel. Some people feeldiscomfort with sound of 85 decibel. An occasional loud sound is no problem, butif one is exposed for long periods to a loud noise, say at 150 decibel, theeardrum might rupture beyond repair. The threshold of pain has been placed atbetween 130 and 150. . .

Studies have shown that noise has physiological and psychologicaleffects on human health. Sensory hair cells of "organ of Corti" of inner ear maybe permanently damaged if subjected to repeated high intensity soundOccupational noise such as, that produced by bulldozers, jackhammers, die~t:dtrucks is deafening millions of workers. gradually. Further, noise is found toincrease cholesterol level and blood pressure. It also causes headaches,hypertension, peptic ulcer, and anxiety and shortens the temper. It can causepeople to become nervous and tense, irritable and frustrated, particularly wlleilone is at sleep.

Thus, noise is not only annoying but injurious to health also.

Sound Sound Sources Perceived· .Level Loudness

180 dB,

Rocket engine Painful150 dB Jet plane take off . Painful130 dB Maximum recorded pop music Painful120·dB Thunderclap; textile loom; auto-horn; rivetter Uncomfortable100 dB Jet fly over; newspaper press Uncomfortable

90 dB Motor cycle; rickshaw; food. blender; diesel Very loudtruck

80 dB Garbaqe disposal Very loud70 dB Vacuum cleaner Loud60 dB Ordinary conversation Moderately loud50 dB Light traffic noise Moderately loud40 dB Bedroom noise Quite30 dB Library; soft whisper Quiet20 dB Broadcasting studio Very quiet10 dB Rustling leaves Very quieto dB Barely audible

Table 11.5: Sound levels and human responses\