Environment

DEGRADATION OF NATURAL ENVIRONMENT  

the natural resources were over abundant as compared to human needs
natural resources are being exploited by humans to meet their needs

CONCEPT OF ENVIRONMENTAL DEGRADATION 

Increasing use of natural resources by rapidly increasing human population has resulted in overexploitation of natural resources .Exploitation is clearly seen in soil erosion, loss of biodiversity and pollution of land, air and water bodies.

RECKLESS EXPLOITATION  OF NATURAL RESOURCES LEADS TO ENVIRONMENTAL DEGRADATION

• In nature, there exists an ecological balance.
•  The interaction between abiotic and biotic components are so fine tuned that there exists an equilibrium in  nature

Some of the human activities that have led to environmental degradation are mentioned below-

1. Forests are natural resources but they have been cut down for use by humans for converting them into the cultivable fields, for building houses and for taking away logs for making shelters and furniture or fuel. The rate at which trees are cut far exceeds the rate at which trees grow, so forests are getting denuded.

2. Trees lose lot of water through transpiration. This helps in forming rain clouds. Cutting of trees and clearing of forest reduced rainfall in the area. Also removal of plants and trees leads to soil erosion.

3. Forests are natural habitats of wild life. Extinction of wild life species is on the rise because their natural habitats are being destroyed due to deforestation.

4. Non-renewable energy resources such as coal, natural gas and petroleum are being used up speedily, leading to their depletion.

5. Excessive burning of coal, wood, kerosene, petrol etc. release toxic gases such as  SO
 (sulphur dioxide), NOx (oxide of nitrogen),CO(carbon monoxide) and hydrocarbons in the air. These gases are also emitted by industries, power plants, automobiles and aircrafts. The toxic gases pollute air which adversely effects human health and plants.

6. Acid water from mines, toxic waste of industries, chemical fertilizers and pesticides from agricultural fields have polluted rivers and other water bodies.

7. The problem of soil pollution is increasing day by day in villages, cities and industrial areas due to faulty disposal of solid and liquid wastes generated from households and industries.

IMPACT OF POPULATION GROWTH ON ENVIRONMENT

Factors leading to rise in population

1. Improved agricultural practices have helped in increasing food production, hence food became available.

2. Progress in medicine prevented deaths due to injury and epidemic diseases.

3. Average longevity of humans has increased since heart, lung and kidney disorders as well as other diseases can now be diagnosed and treated through modern medical technology.

Impact of population growth on environment

For growing population, requirement for space, shelter, and commodities have exerted enormous pressure on the  environment.

1.Clearing land for cultivation to grow more food

•  Forests and natural grasslands have been converted to farmlands. 
•  Wetlands have been drained and arid lands have been irrigated. 
•  These changes have been made to grow more food and more raw materials. 
•  The natural resources have been depleted and the landscapes have undergone drastic changes. 
•  Forests have been cleaned over large for cultivation of agriculture crops. 
•  Many mangrove forests known to reduce erosion and stabilize shorelines have been cleared use for growing food crops to meet the needs of the growing population 

2.Water scarcity

• Water received as rainfall, flows into rivers, lakes and other water bodies. 
• Some of it seeps into the ground and reaches the ground water. 
• At certain depth of the soil, all the pore spaces between soil particles are saturated with water. This depth is called Water Table. 
• The water table may remain stable if the drawn from the ground water is replenished by the seepage of the rain water. 
•  But if water withdrawal exceeds beyond the rate of replenishment of the ground water table keep on receding and resulting in drying out of wells. 
• In many areas excessive withdrawal has depleted ground water resources causing acute water scarcity. 

3. Need for human settlements

•  Large population means growing more food and greater requirement for shelter.
• To make houses for so many, stones and other building materials have to be quarried more rocks have to be blown off and more water to be used.

4. Need for transport

• Elaborate network of transport is required to fulfill the growing need of teeming millions. 
• Various modes of transports have been developed which consume growing quantities of 
• fossil fuels such as coal, gas and petroleum, polluting the atmosphere.

5. Need for various commodities

•  Articles of everyday use such as plastic vessels, mugs, buckets etc., agricultural implements, machinery, chemicals, cosmetics etc are manufactured in factories.  
•  The raw materials and fossil fuels and water needed to run industries for manufacturing these products lead to their depletion.  
• Rapid industrialization has also led to pollution from dumping of industrial effluents into rivers and other water bodies.  
• Rapid industrialization has caused much damage to the environment. 
• Mining activities have depleted stock of mineral resources particularly fossil fuels. 

6. Slum development

 Over populated areas result in congested roads and slum formation which lack basic
amenities like drinking water, drainage, waste disposal, lack of hygienic conditions and
filthy environment create potential conditions for public health problems including spread
of epidemic diseases.

 Discharge of untreated effluents and throwing of waste into water bodies have polluted
most of the lakes and rivers.

7. Pollution resulting from overpopulation

 Holy rivers Ganga, Yamuna and other are suffering from pollution due to discharge of effluents from industries, human settlements, bathing, washing of clothes and throwing of garbage into the river

DEFORESTATION AND ITS CONSEQUENCES

• Forests are found all over the world except the polar regions
• Forests covered one third of the land area.
• Forests are nature‟s major processors of solar energy
• Cutting of trees in forests is called deforestation 
• Deforestation has taken place for various purposes at an alarming rate in different parts of the world resulting in severe loss of wild plants and animals. 

Forests have been cleared for the various reasons-

1. Developmental activities
 a settled life, crop fields, building, roads, industries, schools, hospitals, railway and irrigation canals etc. became necessary developmental activities.
 Forests were cleared to meet the need for land needs for the above developmental activities.

2. For timber and wood
 Wood is used in buildings construction, making furniture and other articles for human use.
 Trees that yield wood grow in forests and were cut down for timber.
 Use of firewood for cooking and heating etc. also contribute to deforestation

3. For pastures
 Forests are cleared to grow grasses and converted into grassland for grazing by cattle.

4. Shifting cultivation

 Shifting cultivation is a system of crop cultivation involving cleaning of forest and burning the fallen trees to clear the land for raising crops.
 Crops are grown on the cleared area for few years and abandoned after few years as the land loses its fertility.
 Thereafter a new forest areas is cleared for cultivation and the same cycles is repeated


Consequences of deforestation

i. Soil erosion

• Trees intercepts rainfall and cutting of trees and removal of plants leads soil erosion. Plants roots hold the soil in place. 
• With loss of protecting cover of plants, top soil, that is rich in organic matter, is washed away and the soil looses its fertility.

ii. Landslides
Removal of trees from forests leads to soil erosion.
 Ultimately cause landslides in hilly areas. because roots of trees hold the soil in position;

iii. Silting
 The loss of trees from forests also causes silting of rivers and lakes as loose soil gets washed with rainwater and reaches water bodies;

iv. Loss of wild habitat
 Wild animals live in forests. Cutting forests means loss of their habitat which in turn renders them
endangered or even extinct.

v. Deforestation 
 Deforestation results in change of climate since trees make the surroundings humid. Loss of trees leads to loss of humidity.
 Also transpiration from plants makes rain clouds and so rainfall is reduced due to deforestation

vi. Loss of CO2 sink
 Pollutants released by industries take CO are taken up by trees. When forests are denuded. This CO sink is lost and CO collects in the environment

vii. Pollution
 When trees are cut to use for making furniture or paper, the sawmills and paper mills pollute water in which they dump the waste

viii. Loss of medicinal and other useful plants
 Unique medicinal plants grow in certain forests. They are lost due to deforestation.
  Aromatic herbs, rubber trees and other useful plants are also lost due to deforestation


ENVIRONMENTAL DEGRADATION FROM MINING

Loss of vegetation 
 Vegetation and soil are removed to get access to mineral deposits. The flora and fauna present in the area is lost

Depletion of minerals

•  Earth is full of metals and mineral resources. very important non-renewable natural resource. India is very rich mineral resources. In last two hundred years advancement in mining technology has progressively intensified mining of mineral resources.  
• Large amount of lead, aluminum, copper and iron ores have been used up. It is believed that in the next 20 years silver, tin,zinc and mercury will be depleted to an alarming level if their exploitation continues at the present rate. 

Dumping of debris 

•  Extraction of minerals from the earth also produces significant amounts of over-burden or debris. Often it is much more as compared to the quantity of mineral obtained.  
•  The dug out loose waste material is dumped on the adjacent land. Dumping of mining waste not only occupies large land area but the waste dumps also become a source of soil erosion. 

Land subsidence

• Excessive mining specially underground mining may lead to land subsidence and may also cause landslides. The landscape too is spoilt. 
•  Unless care is taken, not only minerals will be alarmingly depleted but also a large land area, which could otherwise be used productively, is lost due to disposal of mining waste 

IMPACT OF INDUSTRIALIZATION ON ENVIRONMENT

•  Natural resources used as raw materials by industry are depleting rapidly. 
•  Industries generate lot of toxic gases, and liquid effluents leading to environmental degradation. 
•  Industries generate large amount of waste, which pile up in the environment. Disposal of waste not only needs land but also pollutes the environment and poses hazards to human health. 
• Industries use up a lot of fossil fuels as source of energy.  Accelerated consumption of fossils fuels is depleting their stock as they are limited and non-renewable. But burning of fossil fuels releases CO in the atmosphere leading to global warming 

IMPACT OF MODERNIZED AGRICULTURE ON ENVIRONMENT

Intensive agriculture unfortunately, may lead to serious damage to environment
 Forests have been cleared transformed into farmlands for growing food crops.

 Excessive irrigation and poor drainage causes water logging and kill plants.

Pollution by agrochemicals 
 Increased use of synthetic fertilizers causes to serious environmental problems.

 unused fertilizers from agricultural fields are carried away by run off waters into lakes and rivers causing pollution.

 even seep through the soil and pollute ground water.

 Excessive nutrients enrichment of water bodies leads to „eutrophication‟ (i.e. enrichment of water with nutrients particularly nitrates and phosphates triggers the explosive growth of green algae) may take place in water bodies and kill aquatic life

 Use of pesticides not only kills pests that destroy crop but may also kill many non pest organisms which may include even useful species of insects such as pollinators, birds and helpers in dispersal of plant seeds.

 Pesticides tend to accumulate and their concentration increases through the food chain and reach toxic levels in eggs, milk and other food items. (biomagnification)

 Agro- industrial wastes are generated. e.g. crop residues such as paddy, jawar, gram straws, cotton straws,sugarcane trash, and coconut shells etc. pile up causing environmental degradation.

 High yielding varieties (HYV) of food crops replaced various traditional crop varieties.

 Traditional agriculture was based on multicropping system, i.e. growing of food crops , fodder and firewood crops together.

 replaced by monoculture i.e growing of only one kind of crop (such as wheat etc) in a field of specific set of nutrients making soil unfit for growing other crops but is being considered again.



URBANISATION AND ENVIRONMENT

• More and more people are moving to cities from villages in search of jobs. 
• The rural-urban migration is also partly due to population growth and poverty in the villages. 
• Urbanization means permanent settlement of people in cities and this has resulted in degradation of the environment in various ways.
•  Industrialization opened up many new jobs 

Growth of cities lead to increasing demand of environmental resources leading to following changes -

Cultivated land was lost forever for building houses, industries, roads and other facilities.

A water supply system had to be developed to provide water for drinking and other domestic uses.
Growing urban population created increasing demand for potable water. As a result, availability of water become more and more scarce.

 Industries, that were set up to provide the necessary goods for urban folk, generated industrial waste, leading to the pollution of the environment. In cities, black smoke emitted from industries, buses, truck etc. cause air pollution

Large amount of garbage is generated and not disposed properly. As a result garbage remains scattered and unattended. Domestic and industrial effluents are drained into rivers and lakes. High noise levels are a common feature of urban environment.

An incessant influx of people into cities and shortage of housing result in development of slums and squatter areas. Inadequate facilities and lack of basic amenities in slums leads to unhygienic condition and social distortion and crime


ENVIRONMENTAL BACKLASH

 Floods, drought, acid rain, oil spills are of common occurrence and they are largely due to the carelessness and callousness of humans towards the environment.

 Loss of wildlife and their habitat , disappearance of some of species such as cheetah from the country; Bhopal gas tragedy are examples of the environmental retort.

At the global level, the problem of „global warming‟ and „ozone layer depletion‟ poses serious threat to human health and well-being

Local environmental backlash

(i) Salination of irrigated soils 

Over irrigation resulted in salt accumulation in the soil as water is lost from evaporation but the salts dissolved in water remains in the soil and accumulate progressively making the soil saline and unfit for cultivation and infertile.

(ii) Eutrophication 

•  Eutrophication of a water body occurs when plant nutrients such as nitrates and phosphates are released by the action of aerobic bacteria on organic wastes entering a water body. 
•  nutrients promote growth of algae (algal bloom). 
• Algae consume all the oxygen and aquatic organism die due to lack of oxygen. 

(iii) The Minamata disease 

• Plastic, caustic soda, fungicide and pesticide manufacturing factories release mercury along with other effluents in the water body nearby. 
•  Mercury enters food chain through bacteria –algae-fish and finally the humans. 
•  Fish died due to consumption of Hg. 
• Those who ate these fish were affected by mercury poisoning which proved fatal in certain cases. 
•  The high concentration of Hg in water and in tissues of fish resulted from formation of soluble mono methyl mercury and volatile dimethyl mercury by the action of anaerobic bacteria.

(iv)Extinction of wild life species mercury 

•  The numbers of tigers and lions have dwindled, the great Indian bustard is endangered and the list of the animals and plants threatened to extinction is long and growing. 
• The Kalu River near Mumbai is severely polluted by industrial waste and the Bombay duck, a favorite edible fish which was once common in this river has been lost forever. 
• Tigers and lions are being killed for sport and by poachers. 

Regional Environmental backlash

(i) Floods 

•  a natural disaster and India is a flood prone country. 
•  occur almost every year during the period monsoon, continuous heavy rainfall brings huge quantities of water into rivers which overflow and cause flood.  
•  The habitations close to the river get flooded resulting in loss of human life and property. This means heavy economic losses.  
• The flood affected areas suffer from quite shortage of potable water often outbreak of epidemic diseases.

(ii) Drought

 Failure of monsoon and absence of rain leads to drought.
 Rise in the average global temperature due to global warming will increase water use and may create water shortage.
 Global warming may reduce as much as 10% precipitation and creating water scarcity leading to drought conditions.
 Shortage of water would adversely affect agriculture, industries and plants communities.
 Animals that are unable to move to greener pastures will perish; humans will suffer from health problems.

(iii) Acid rain 

 Moisture laden air rises to higher altitudes and condenses to fall as rain or snow
 Pure rain has a pH of 5.6 but in areas where industries burn oil and coal emit SO
 (sulphur dioxide)into the atmosphere and motor vehicles release NOx (compound of nitrogen) into air, the rain becomes more acidic reaching pH of 2.
 This is because SO2 and NOx dissolve in water vapour present in the atmosphere and forms H2O
 When acidic snow melts acid rain drops reaches water bodies and making them acidic. Acidic water kills aquatic fauna and flora.
 Acidic rain is toxic to trees and corrodes buildings, marble structures and archaeological monuments.

(iv) Oil spills 

 Sometimes there is accidental spill of crude oil and petroleum products into the sea by oil tankers and ships.
 A thin layer of oil covers sea surface depriving marine organisms of oxygen. F
 loating oil slicks kill marine life and severely affect ocean ecosystem


Global backlash

(i) Biodiversity loss 

 Dwindled forests the natural habitat of various plants and animals has vanished and so have vanished forever many valuable trees and animals.
 Some are on the verge of extinction while others are on the borderline.

(ii) Global warming and green house effect 

 Green house is a glass chamber in which heat or solar radiations is trapped and plants grown in its closed warm environment.

 Industrialization and urbanization have led to emission of large quantities of carbon dioxide into
atmosphere from burning of fossil fuels.

 Increased CO2 concentration in the atmosphere does not allow heat radiations given out by earth, to escape into the outer space.

 Increased atmospheric concentration of CO2 has raised the average global temperature causing global warming.

 Consequences of global warming include melting of snow caps and rising of sea level, rising temperature of the earth will cause polar ice caps to melt leading rise in sea level. Excessive heat expands water. Sea level rise cause flooding of coastal cities and damage coastal ecosystems like marshes and swamps.

 Global warming may change rainfall pattern; lead to early maturation of crops and reduce grain size and yield of crop.

(iii) Collapse of marine fisheries

 acid rain has toxic effect on ecosytem.
 Global warming has driven marine fish towards cooler northern parts of the earth.
 Others are swimming to reach the cool deeper realms of ocean.
 The temperature of northern sea, it is estimated, to have increased by 1 degree centigrade
in the last twenty-five years, several
species of fish and other marine animals have permanently moved to cooler northern regions.
 Smaller fish are able to move faster to cooler areas away and the elevated temperature is taking its toll no larger fish, some of which are likely to become extinct.
 This change in behaviour of fish has led to collapse of marine fisheries and loss of livelihood for many -many fisher folk.
 Other reasons for collapse of marine fisheries is the dumping of massive amount waste into the sea.
 The waste dumped with the sea include sewage and garbage generated by people living in coastal areas and industrial waste from industries.
 Run off from agricultural fields carrying fertlilzers and pesticides are brought by rivers to the sea. Fertilizers cause “eutrophication.” Oil spills and oil slicks also kill marine life.

(iv) Ozone layer depletion

• The ozone layer in earth‟s atmosphere prevents harmful UV radiations of sun from reaching earth‟s surface.
• CFCs(Chloroflorocarbons) used in refrigeration, air conditioning, cleaning solvents, fire extinguishers and aerosols have damaged the ozone layer or ozone shield particularly over Artic and Antarctic. 
• 30-40% reduction in the ozone layer may cause sunburn, fast ageing of skin, skin cancer, cataract, cancer of retina, genetic disorders, and reduced productivity in sea and forests. 

ENVIRONMENTAL DEGRADATION: A THREAT TO SURVIVAL

 Primitive humans struggled with nature for their survival as you have read in the earlier lessons.
 As human beings became more civilized and through the progress of science and technology they created various luxuries of comfortable living.
 But population explosion coupled with human greed for progressive prosperity and comfort has exploited and degraded the environment mercilessly to such a large extent that human survival itself is now threatened.
 Contaminated food, water and air is taking its toll on human health.
 Toxic chemicals and harmful radiations have the potential of causing serious problems of human health.
 Asthma, pulmonary fibrosis, pneumoconiosis are caused due to air pollution.
 Long exposure to pollutants in the working place such as mines, textile mills, poultry, crackers, sand blasting and chemical industries cause respiratory diseases.
 Carcinogenic chemicals and ionizing radiations in the environment have been responsible for cancer.
 The enormously large population means reduced job opportunities, unemployment and related stress.
 Stress may also due to job pressure, money problems, uncomfortable living and dislike for work or workplace. 
 Asthma, ulcers, diabetes, hypertension, depression, schizophrenia are stress related diseases and increasing rapidly.
 Degraded quality of life and continuous health problems lead to mental problems. Environmental health and well being are the most valuable possessions of humans. These are fast getting lost due to the fast deterioration of the environment