KONGU ENGINEERING COLLEGE �DEPARTMENT OF CHEMISTRY�Environmental Science(22MNT31) �(Mandatory Course)

Dr.A.Geetha

Associate Professor Department of Chemistry Kongu Engineering College

UNIT - I -

Environmental Studies and Natural Resources

Introduction to Environmental Science – uses, over-exploitation and conservation of forest, water, mineral, food, energy and land resources–case studies

Introduction to Environmental Science

Environment:

The term environment is derived from a French word

‘environner’ which means ‘surrounding’. It refers to an aggregate of all conditions that affect the existence, growth, and welfare of an organism or a group of organisms.

Definition: It can be defined as a sum total of all the living (biotic) and non-living

(Abiotic) elements and their effects that influence human life.

While all living or biotic elements are animals, plants, forests, fisheries, and birds, non-

living or abiotic elements include water, land, sunlight, rocks, and air.

Environmental Science:

“The systematic & scientific study of our environment and our role in it. This branch includes the knowledge of Pure Science & to some extent Social Sciences”.

Environmental Studies:

“The branch of Study concerned with environmental issues. It has a broader coverage than environmental science and includes the social aspects of the environment”.

Environmental Education:

Environmental education is a process that allows individuals to explore environmental issues, engage them in problem solving, and take action to improve the environment. As a result, individuals develop a deeper understanding of environmental issues and have the skills to make knowledgeable and responsible decisions.

Objectives of Environmental Education

Awareness: To help individuals and social groups to acquire basic awareness of and sensitivity towards the environment & its related problem.

Knowledge: To help individuals and social groups to acquire basic understanding of the environment, its associated problems and their responsible role towards the betterment of the environment.

Attitude: To help individuals and social groups to acquire social values, strong feeling of concern for the environment and the motivation for actively participating in its protection and improvement.

Skills: To help individuals and social groups to acquire the skills for solving

environmental problems.

Evaluation ability: To help individuals and social groups to evaluate environmental measures and education program in terms of ecological, political, economical, social, aesthetic and education factors.

Participation: To help individuals and social groups to develop a sense of responsibility and urgency regarding environmental problems to ensure appropriate action to solve those problems.

Importance of Environmental Studies

• Environmental Studies is useful in checking environmental pollution and related solutions.
• It helps in maintaining ecological balance.
• It helps to gain skills to assess the environmental impact of human activities. Environmental study will help to protect biodiversity.
• It gives us basic knowledge of environment and associated problems.
• It helps to achieve sustainable development .
• It helps to educate people regarding their duties towards the protection of environment.
• The knowledge of environmental science will be applied to the study of agriculture..

International Efforts for Environment

• Environmental issues received international attention about 35 years back in Stockholm Conference, held on 5^th June, 1972.
• Since then we celebrate World Environment Day on

5^th June.

• At the United Nations Conference on Environment and Development held at Rio de Jeneiro, in 1992, known popularly as Earth Summit.
• Ten years later, the World Summit on Sustainable Development, held at Johannesberg in 2002, highlighted the key issues of global environmental concern.
• Later, Conference on Climate Change was held at Copen Hagen in the year 2009 and is known as Copen Hagen Summit.

Need for Public Awareness

• Earth’s resources are dwindling and our environment is being increasingly degraded by human activities and hence something needs to be done.
• Government alone cannot perform all the clean-up functions.
• Individual/group efforts in their own every possible way has to be made to protect

our environment.

• Mass public awareness: newspapers, radio, television strongly influences public opinion on conserving our environment.

Methods for Public Awareness

• Environmental education
• Through mass & media
• Through organizing seminars & conferences
• Entertainment
• Science centers
• Involvement of youth
• Through print, broadcast and internet

Natural Resources

Life on this planet earth depends upon a variety of goods and services provided by the nature, which are known as Natural Resources.

(Or)

Natural resources are resources that exist without any actions of human kind.

(Or)

Any stock or reserve that can be drawn from nature is a natural resource.

Examples:

water, air, soil, minerals, coal, forests, crops and wildlife

Classification of Natural Resources:

The natural resources are of two kinds

1. Renewable Resources
2. Non-Renewable Resources

1. Renewable Resources

The resources which cannot be exhausted even after continuous utilization are termed as renewable resources.

Examples: Sun, Wind, and Tidal energy etc.

2. Non-Renewable Resources

The resources which cannot be immediately replaced once they are depleted are called Non-renewable resources.

Examples: Fossil fuels, such as coal, petroleum and natural gas etc.

Here we are going to discuss the following six Natural Resources

1. FOREST RESOURCE

The term “forest ”is derived from the latin word “foris” meaning outside. Originally ,it is uncultivated and uninhabited village boundary consisting of natural plants, i.e., trees and grasses .

• A forest is a biotic community with a predominance of trees; it is an important renewable resource.
• Forests restore oxygen in our atmosphere through photosynthesis and also provide solvents, medicines, fuels, and many other products that are important for our health and comfort.
• India is rich in forest resources with a great diversity of flora and fauna.

Direct (or) Commercial uses of forest

• They provide timber for house-building, ship-building, bridges, railway carriages, furniture's etc.
• They supply fire wood and charcoal for fuel in homes and in industries.
• They provide wood pulp for the paper and rayon industries.
• They provide honey for food and medicines.
• They provide bee wax for candles, medicines, shoe-making etc.
• They provide canes foe baskets, mats, chairs, ropes, walking sticks and umbrella handles.
• They provide sandal wood for carved boxes and small domestic articles .
• They provide tanning materials in the form of wood, barks, leaves, roots, and fruits for tanning hides and skin.

• They provide corks for bottle-stoppers.
• They provide camphor for medicines.
• They provide rubber for rubber industries.
• They provide balata for the preparation of sea cables and machine belts.
• They provide edible fruits.
• They provide fibers.
• They provide grasses for the grazing of animals, thatching

Indirect (or) Ecological uses of forest

• Forests help in minimizing natural hazards.
• They help in reducing soil erosion and siltation of downstream water bodies.
• They help in reducing desertification and land degradation.
• They help in maintaining biodiversity by providing habitat to wild animals.
• They help in regulating hydrological cycle.

• They help in regulating the gases in atmosphere.
• They reduce global warming.
• They control floods during heavy rain by absorbing excess rain water.
• The thick roots of the trees absorb large quantity of water thus, forest help in the flow of rivers and streams.
• They offer hunting grounds.
• They improve the sanitary condition of a place.
• They are a source of revenue to the government.
• They facilitate human existence by providing O₂ to human beings and absorbing CO₂ by human beings.
• They provide employment to large number of people in different capacities as wood cutters, carriers etc.

Over Exploitation of Forest

Forest have been known to possess huge potential for human use and they have been exploited since early times for their vast potential. Exploitation of forests has taken place to meet human demands in the following ways

• Encroachment of forest land for agricultural use to meet the growing demands of foods.
• Expansion of cities to accommodate the growing population
• Construction of dams, canals, and highways
• Establishment of industrial areas
• Demand for firewood
• Mining activity
• Deforestation due to road construction
• About 78% of forest area is under heavy grazing

Deforestation

The term deforestation refers to the removal or reduction of forest cover.

• Causes of Deforestation
• Population explosion: Population explosion is the root cause of all the environmental problems, vast area of forests are cleared for human settlement
• Shifting Cultivation: It is a traditional agroforestry system in which felling and burning of forests followed by cultivation of crop for few years and abandon of cultivation allow forests for re-growth cause extreme damage to forest.

• Growing

food

demand: To meet the food

demand of rapidly growing population more and more forests are cleared off for agricultural purpose.

• Fire wood: Increasing demand of wood for fuel increases pressure on forests.

furniture, plywood, paper, match box etc results into tremendous pressure on forests.

• Infrastructure development: Massive destruction of forest occurs for various infrastructure development like, big dams, highways projects etc.

​

• Forest fires: Forest fires may be natural or man made cause a huge loss of forest. Over grazing: Overgrazing of land by cattle result into soil erosion, desertification.

​

• Natural forces: Floods, storms, heavy winds, snow, lightening are some of the natural forces.

• Effects of Deforestation
• Loss of natural habitat of wild animals and plants
• Increased intensity and frequency of floods
• In hilly areas it often leads landslides and also land degradation
• Loss of forest products
• Change in climatic conditions i.e., global warming is enhanced
• Siltation of rivers and lakes
• Loss of revenue
• Change in hydrological cycle and reduced rainfall
• Increased socio-economic problem in the long run
• Problems of soil erosion and loss of soil fertility increase

• Control of Deforestation
• Mining activities should be prohibited in areas declared as protected forests.
• Cutting of trees should be followed by massive plantation.
• The environmental laws and legal provisions should be strictly enforced.
• Public awareness should be created regarding medicinal and other economic and environmental significance of forests.

Case Study 1

Cherrapunji was famous because it received the largest volume of rainfall in the world. It still does but ironically, experiences acute water shortages. This is mainly the result of extensive deforestation (no trees to hold the water and the water run off to rivers. Because proper methods of conserving rainwater are not used. There has been extensive soil erosion. Only rain water harvesting can sort out the problems of the world's wettest town. Scientists point out the example of Jaisalmer, one of the driest towns in India in Rajasthan, with rainfall levels as little as 100 mm of water per year, where it was found that if you harvest water on just one hectare of land, you have captured as much as one million litres of water --enough to meet drinking and cooking water needs of 182 people at 15 litres per day for one year.

Case Study 2

Sardar Sarovar Dam

• The Sardar Sarovar Dam is a gravity dam on the Narmada river near Navagam, Gujarat in India.
• It is one of the largest water resources projects of India covering four major states - Maharashtra, Madhya Pradesh, Gujarat and Rajasthan.
• The project took form in 1979 as part of a development scheme to increase irrigation and produce hydroelectricity.
• Most importantly, This dam is one of India's most controversial project and its environmental impacts are widely debated.
• It is, in fact, designed as a concrete gravity dam,

having a height up to FRL 138.68 m.

Projected Benefits : Recreation 38% Flood control 18% Fire & farm ponds 17% Irrigation 11% Tailing & others 8% Undetermined 4% Hydroelectric 3% Debris control 1% Recreation Flood control Fire & farm ponds Irrigation Tailing & others Undetermined Hydroelectric Debris control

Environmental impacts of Sardar Sarovar dam project

1. Submergence causing loss of forest and agricultural land :

In order to minimize the adverse effects of submergence it becomes necessary

• To compensate and mitigate the losses due to deforestation.
• To reduce the dam height up to a minimum possible value.

After thoroughly examining, dam height was finally decided FRL 138.68 m by

constituted tribunal in 1979.

2. Loss of wild life :
• It was clarified that it will not cause any loss of flora and fauna.
• Also it will help to develop five sanctuaries.
3. Displacement of Tribals :
• Tribals, living in submergence zone, need to be displaced elsewhere.
• Nearly 2000-3000 families may opt rehabilitation in Gujarat, which is

manageable.

4. Submergence of old monuments:
• No protected archaeological monument lies in submergence area.
• Only few temples, like Shoolpaneshwar Mahadev at village Supan, are likely to be affected.
5. Water-logging and Salinity problem:
• The problem of waterlogging and soil salinity is little serious here.
• It is so because the command areas of the projects have largely black soils, which have very good water retention capacity.
6. Seismic effect of the reservoir :
• By survey, it was concluded that formation of reservoir in this area may cause earthquake to occur but not of destructing dimensions.
• So the dams have been designed to withstand earthquake shocks of magnitude 6.5 (Richter scale).
7. Health aspects :
• No risk of malaria & Schistosomiasis like diseases by irrigation facilities for 17 years

2.Water resources

Introduction

Water is, literally the source of life on earth.

Water is an Unique Resource

Water is characterized by certain unique features which make it a marvelous resource:

• It exists as a liquid over a wide range of temperature i.e.from 0^◦C to 100^◦C.
• It has the highest specific heat, due to which it warms up and cools down very slowly without causing shocks of temperature jerks to the aquatic life.
• It has a high latent heat of vaporization.
• It is an excellent solvent for several nutrients.
• It has an anomalous expansion behaviour.
• Due to high surface tension and cohesion it can easily rise through great heights.

Water use and Overutilization

• Due to its unique properties water is of multiple uses for all living organisms.
• Water is absolutely essential for life. Water is used for drinking, irrigation, transportation, washing and waste disposal for industries and used as a coolant for thermal power plants.
• Water shapes the Earth’s surface and regulates our climate.
• More than 99% of Earth’s water in its natural state is unavailable or unsuitable for beneficial human use.
• Thus, the amount of freshwater for which all the people, animals and plants on Earth compete is even less than 1% of the total.
• With increasing population pressure and rapid development, the demands for water have increased tremendously. On a global average 70 % of water is used for agriculture and 25 % of water is used in industrial sector.

1. Surface water sources:

SOURCES OF FRESH WATER:

1. Natural Lakes and Ponds
2. Artificial Impounding Reservoirs
3. Rivers and Streams
4. Sea water

2. Ground water sources:

After glaciers, ice caps and snowfields, ground water is the next largest fresh water reservoir.

Till some time back ground water was considered to be very pure. However, of late, even

groundwater aquifers have been found to be contaminated.

A layer of sediment or rock that is highly permeable and contains water is called an aquifer. Aquifers may be of two types :

Unconfined aquifers which are overlaid by permeable earth materials and they are recharged by water seeping down from above in the form of rainfall and snow melt.

Confined aquifers which are sandwiched between two impermeable layers of rock or sediments and are recharged only in those areas where the aquifer intersects the land surface.

Effects of Groundwater usage

1. Subsidence :

When groundwater withdrawal is more than its recharge rate, the sediments in the aquifer get compacted, a phenomenon known as ground subsidence. Huge economic losses may occur due to this phenomenon because it results in the sinking of overlying land surface. The common problems associated with it include structural damage in buildings, fracture in pipes, reversing the flow of sewers and canals and tidal flooding.

2. Water logging:

When excessive irrigation is done with brackish water it raises the water table gradually leading to water-logging and salinity problems.

3. Lowering of water table:

Mining of groundwater is done extensively in arid and semi-arid regions for irrigating crop fields. However, it is not advisable to do excessive mining as it would cause a sharp decline in future agricultural production, due to lowering of water table.

4. Water pollution :

Discharge and dumping of wastes very often seeps down into groundwater causing pollution problems.

Floods

Heavy rainfall often causes floods in the low-lying coastal areas. Prolonged downpour can also cause the over-flowing of lakes and rivers resulting into floods.

Deforestation, overgrazing, mining, rapid industrialization, global warming etc have contributed largely to a sharp rise in the incidence of floods, which otherwise is a natural disaster.

Droughts

When annual rainfall is below normal and less than evaporation, drought conditions are created. Drought is a meteorological phenomenon, but due to several anthropogenic causes like over grazing, deforestation, mining etc. there is spreading of the deserts tending to convert more areas to drought affected areas.

Big Dams benefits and problems�Big dams are often regarded as a symbol of national development.

Environmental impacts of Sardar Sarovar dam project

1. Submergence causing loss of forest and agricultural land
2. Loss of wild life
3. Displacement of Tribals
4. Submergence of old monuments
5. Water logging and salinity problem
6. Seismic effects of the reservoir

3. Mineral Resources

Minerals are naturally occurring, inorganic, crystalline solids having a definite chemical composition and characteristic physical properties.

Distribution of mineral resources in India:

Coal and Lignite : West Bengal, Jharkhand, Orissa, MP, AP

Uranium : Jharkhand, AP, Meghalaya, Rajasthan

Aluminium : Jharkhand, West Bengal, Maharashtra, MP, Tamil Nadu

Iron : Jharkhand, Orissa, Madhya Pradesh, Andhra Pradesh, Tamil Nadu, Karnataka, Maharashtra and Goa

Copper : Rajasthan, Bihar, Jharkhand, Karnataka, Madhya Pradesh, West Bengal, Andhra Pradesh and Uttarakhand

Classification of Minerals:

Based on the properties, minerals are basically of two types :

1. Non-metallic minerals - Graphite, diamond, quartz, feldspar
2. Metallic minerals - bauxite, laterite, haematite Based on the usage, minerals are classifies into two types :
3. Critical minerals are essential for the economy of a nation – iron, aluminium, copper, gold
4. Strategic minerals are those required for the defense of a country – Manganese, cobalt, platinum, chromium

Uses and Exploitation of mineral resources:

• Development of industrial plants and machinery
• Generation of energy(Ex- coal, uranium)
• Construction
• Defense equipments
• Transportation
• Communication- wires, cables, electronic devices
• Medicinal system- particularly in Ayurvedic- Ex- Sulphur pyrites
• Agriculture- as fertilizers, seed dressings and fungicides. Ex- zineb (contain Zn)

maneb (contain Mn )

• Jewellery for example, gold, diamond

Environmental impacts of mineral extraction

Mining:

Mining is done to extract minerals from deep deposits in soil.

Types of mining :

1. Surface mining

Surface mines are mining operations to extract deposits of mineral resources that are close to the surface.

• Open-pit mining in which machines dig holes and remove the ores. Ex- Copper, iron, gravel, limestone, marble.
• Dredging in which chained buckets and draglines are used which scrap up the minerals from under-water mineral deposits.
• Strip mining in which the ore is stripped off by using bulldozers, power shovels and stripping wheels.

Ex- phosphate rocks

ii.Sub-surface mining

Sub-surface mining is used for the extraction valuable minerals from the earth.

The environmental damage caused by mining activities are as follows:

1. Devegetation and defacing of landscape-The topsoil as well as the vegetation are removed from the mining area to get access to the deposit.
2. Land subsidence- This is mainly associated with underground mining.
3. Groundwater contamination – Mining disturbs the natural hydrological processes and also pollutes the groundwater
4. Surface water pollution – The acid mine drainage often contaminates the nearby streams and lakes.
5. Air pollution- Smelting leads to the emission of soot, arsenic, cadmium and lead to the atmosphere.
6. Occupational health hazards- due to constant exposure miners working in different types of mines suffer from asbestosis, silicosis, black lung disease etc.

Remedial measures:

• Adopt eco-friendly mining technology
• Use microbial leaching technique. The bacterium Thiobacillus ferroxidans has been successfully and economically used for extracting gold embedded in iron sulphide ore.
• Restoration of mined areas by re-vegetating them with appropriate plant species.
• Prevention of toxic drainage discharge and conforming to the standards of air emissions are essential for minimizing environmental impacts of mining.

Case study

4.FOOD RESOURCES

Food is an essential requirement for the human survival. Each person has minimum food requirement. The main components of food are carbohydrates, fats, proteins, minerals and vitamins.

Types of Food Supply:

1. Croplands mostly produce grains and provide about 76% of the

world’s foods.

Example: Rice, wheat, maize, barley, sugarcane, potato.

2. Rangelands produce meat, mostly from grazing livestock and supply.

Example: Meat, milk, fruits etc

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3. Oceanic fisheries supply about 7% of the world’s food. Example: Fish, prawn, crab, etc.

World Food Problems

• The food supplied from the existence of less percentage of the land is not enough to feed all the people.
• The problem of population explosion has made it worse.

• The world population increases and cultivable land area

decreases. Therefore the world food problem arises.

• Environmental degradation like soil erosion, water logging, water pollution, salinity affect agricultural lands
• Urbanization in developing countries deteriorates the agricultural

lands.

• The food grains like rice, wheat, corn and the vegetable like potato are the major food for the people all over the world, the food problem arises.
• Human activity which degrade most of the earth’s net primary productivity which supports all life.

World Scenario :

• During the last 50 years world grain production has increased almost three times. But, at the same time, population growth increased at such a rate in LDCs [Less Developed Countries].
• Every year 40 million people [50% of children (1-5year)] die of undernourishment and malnutrition. This means that every year our food problem is killing as many people as were killed by the atomic bomb dropped on Hiroshima during World War-II.
• In countries like North America and Europe the daily average calorie intake is about 3500 cals, which is nearly one – third more than that required for healthy living.
• In Ethiopia, Sudan and Somalia the food production is very low due to drought, war and governmental mismanagement.
• These startling statistical figures more than emphasize the need to increase our food production, equitably distribute it and also to control population growth.

Indian Scenario:

• Although India is the third largest producer of stable crops, an estimated 300 million Indians are still undernourished. India has only half as much land as USA, but it has nearly three times population to feed. Our food problems are directly related to population.
• The world Food Summit, 1996 has set the target to reduce the number of undernourished to just half by 2015, which still means 410 million undernourished people on the earth.

UNDER NUTRITION AND MALNUTRITION

• Macronutrients: Carbohydrates, Proteins, Fats.
• Micronutrients: Vitamins A,C,E, Minerals such as iron, calcium and iodine.
• The food and Agriculture Organization (FAO) of United Nations estimated that on an average the minimum caloric intake on a global scale is 2,500 calories/day. People receiving less than 90% these minimum dietary calories are called undernourished and if it is less than 80% they are said to be seriously undernourished.

• Besides the minimum calorific intake we also need proteins, minerals etc. Deficiency or lack of nutrition often lead to malnutrition resulting in several diseases as shown in the following table.

Overgrazing and Agriculture

Overgrazing:

• It is a process of eating away the forest vegetation without giving it a chance to regenerator.

Impacts of overgrazing: Land degradation:

• Overgrazing removes the cover of vegetation over the soil and the exposed soil gets compacted.
• So the roots of the plant cannot go much deep into the soil and the

adequate soil moisture is not available.

• Thus overgrazing leads to organically poor, dry, compacted soil which cannot be used for further cultivation.

Soil erosion:

• Due to overgrazing by livestock, the cover of vegetation gets removed from the soil. The roots of the grass are very good binders of the soil.
• When the grasses are removed, the soil becomes loose and gets eroded by the action of wind and rainfall.

Loss of useful species:

• Overgrazing affects the soil composition of plant

population and their generation capacity.

• The grassland consists of grasses and forbs with high

nutritive value.

• When the livestock grazes the grasses heavily, the root stocks which carry the food reserve get destroyed. The other secondary species will appear in their places which

are less nutritive in nature. Some livestock keep on

overgrazing these species also.

• It reduces grass cover, which will have impact on global warming.

• Finally it causes deforestation

Agriculture

• Agriculture is an art, science and industry of managing the growth of plants and animals for human use.
• Agriculture society slowly took shape during the “Neolithic period” (i.e., new stone age) about 10,000 B.C. the early agriculturists’ practiced “Slash and burn cultivation” or “shifting cultivation” or “Swidden”. This starts with the clearing of small plots in tropical forests by cutting and burning the vegetation.
• Agriculture includes cultivation of the soil, growing and harvesting

crops, breeding and raising livestock, dairying and forestry.

Types of Agriculture

• The two major types of agricultural systems are
1. Traditional agriculture,
2. Modern agriculture (or) Industrialized agriculture

1. Traditional agriculture:

• It involves a small plot, simple tools, surface water, organic fertilizers

and a mix of crops. They produce enough food to feed their families

and to sell it for their income.

Effects or impacts of traditional agriculture

Deforestation: Cutting and burning of trees in forests to clear the land for cultivation results in loss of forest cover.

Soil erosion: Clearing of forest cover exposes the soil to wind, rain and storms, thereby resulting in loss of top fertile layer soil.

Loss of nutrients: During cutting and burning of trees, the organic matter in the soil gets destroyed and most of the nutrients are taken up by the crops within a short period. Thus the soil becomes poor in nutrient, which makes the farmers shift to another area.

2. Modern agriculture:

• It makes use of hybrid seeds of single crop variety, high-tech equipments, lot of fertilizers, pesticides and water to produce large amount of single crops.

1. Problems in using Fertilizer

1. Micronutrient imbalance:

Most of the chemical fertilizers used in modern agriculture contain nitrogen, phosphorous and potassium (N, P, and K) which are macronutrients. When excess of the fertilizer are used in the fields, it causes micronutrient imbalance.

Example: Excess use of the fertilizer in Punjab and Haryana has caused deficiency of the micronutrient zinc in the soil, which affects the productivity of the soil.

2. Blue baby syndrome (nitrate pollution):

When the nitrogenous fertilizers are applied in the fields, they leach deep into the soil and contaminate the ground water. The nitrate concentration in the water gets increased. When the nitrate concentration exceeds 25 mg/L, they cause serious health problem called “Blue baby syndrome”. This disease affects infants and lead to death.

3. Eutrophication:

A large proportion of N and P fertilizers used in crop fields is washed off by the runoff water and reaches the water bodies causing over nourishment of the lakes. This process is known as Eutrophication.

Due to eutrophication lakes get attacked by algal blooms. These algal species use up the nutrients rapidly and grow very fast. Since the life time of the algal species are less they die quickly and pollute the water,which in turn affect the aquatic life.

2. Problems in using pesticides

In order to improve the crop yield, lot of pesticides used in the agriculture.

• First generation pesticides:

Sulphur, arsenic, lead and Mercury are used to kill the pests.

• Second generation pesticides:

DDT (Dichloro diphenyl trichloromethane) is used to kill pests.

Although these pesticides protect our crops from huge losses due to pests, they produce number of side-effects.

• Death of non-target organisms:

Many insecticides not only kill the target species, but also kill the several non-target species which are useful to us.

• Producing new pests:

Some pest species usually survive even after the pesticide spray which generates highly resistant generations. They are immune to all types of pesticides and are

called superpests.

• Bio-magnification:

Many of the pesticides are non-biodegradable and keep on concentrating in the food chain. This process is called bio-magnification. These pesticides in a bio-magnified form are harmful to the human beings.

• Risk of cancer:

Pesticides enhance the risks of cancer in two ways

• It directly acts as carcinogens.
• It indirectly suppresses the immune system.

are hazardous, so they

Desired qualities of an ideal pesticide

• An ideal pesticide must kill only the target species
• It must be a biodegradable
• It should not produce new pests
• It should not produce any toxic pesticide vapour.
• Excessive synthetic pesticide should not be used.
• Chlorinated pesticides and organophosphate pesticides should not be used.

3. Water logging

Water logging is the land where water stand for most of the year

Problems in water logging:

During water-logged conditions, pore-voids in the soil get filled with water and the soil-air gets depleted. In such a condition the roots of the plants do not get adequate air for respiration. So, mechanical strength of the soil decreases and crop yield falls.

Causes:

Excessive water supply to the croplands.

Heavy rain

Poor drainage

Remedy:

Preventing excessive irrigation, sub-surface drainage technology and bio-drainage by trees like Eucalyptus tree are some method of preventing water-logging

4. Salinity

The water, not absorbed by the soil, undergoes evaporation leaving behind a thin layer of dissolved salts in the topsoil. The process of

accumulation

characterized

of salts is called salinity. The saline soils are

by the

accumulation of soluble salts like sodium

chloride, calcium chloride, magnesium chloride, sodium sulphate, sodium bicarbonate and sodium carbonate. The pH of the water exceeds 8.0 (alkalinity)

Problems in salinity:

Most of the water, used for irrigation comes only from canal or ground, which contain dissolved salts. Under dry climates, the water gets evaporated leaving behind the salt in the upper portion of the soil. Due to salinity the soil becomes alkaline and crop yield decreases.

Remedy:

The salt deposit is removed by flushing them out by applying more good quality water to such soils.

Using sub-surface drainage system the salt water is flushed out

slowly.

CASE STUDY

1. Water logging and salinity in Haryana and Rajasthan

Introduction of canal irrigation in Haryana state resulted in rise in water-table followed by water-logging and salinity in many agricultural lands causing huge economic losses as a result of decrease in crop productivity. Similarly Rajasthan has also suffered badly due to the biggest irrigation project, “Indira Gandhi Canal Project” which converts a big area into water soaked waste land.

2. Pesticides in Delhi

It has been reported in Delhi, that the high accumulation of pesticides and DDT in the

body of mothers causes premature deliveries or low birth weight or death of many children’s.

3. Pesticide in Pepsi and Coca-Cola

Food centre for Science and Environment (CSE) India has reported that Pepsi and Coca-cola companies are selling soft drinks with pesticide content 30-40 times higher than EU guidelines permit. It also said that the total average pesticide content in all Pepsi products were 0.0180 mg/L, while in coco-cola products 0.0150 mg/L, which are 30-40 times higher than European Union limits. This damages the nervous system. The centre said the reason for high pesticide content in India is due to the use of ground water in soft

drinks and bottled water industries.

5. ENERGY RESOURCES

Energy consumption of a nation is usually considered as an index of its development. This is because almost all the developmental activities are directly or indirectly dependent upon energy.

Energy may be defined as any property which can be produced from or converted into work.

GROWING ENERGY NEEDS:

1.Development in different sectors depends largely upon energy. Agriculture, industry, mining,

transportation, lighting, cooling and heating in buildings all need energy.

2. With the demands of growing population the world is facing further energy deficit
3. Our life style is changing very fast and from a simple way of life we are shifting to a luxurious life style.
4. The number of electric devices, private cars and scooters has multiplied many in the last years and all of them consume energy.
5. Developed countries like U.S.A. and Canada constitute about 5% of the world’s population but consume ¼ of global energy resources.
6. An average person in USA consumes 300 GJ [Giga Joules, equal to 60 barrels of oils) per year. By contrast as average man in a poor country like Bhutan, Nepal or Ethiopia consumes less than 1 GJ in a year.
7. So a person in a rich country consumes almost as much energy in a single day as one person does in a whole year in a poor country. This clearly shows that our life-style and standard of living are closely

related to energy needs.

Classification of Energy Resources

A source of energy is one that can provide adequate amount of energy in a usable from over a long period of time. There sources can be two types.

1. Renewable Resources which can be generated continuously in nature and are in

exhaustible.

Example: Wood, solar, wind energy, tidal energy, hydropower, biomass energy, bio-fuels, geo-thermal energy and hydrogen.

They are also known as non-conventional sources of energy and they can be used

again and in an endless manner.

2. Non-renewable Resources which have accumulated in nature over a long span of

time and cannot be quickly replenished when exhausted.

Example: Coal, petroleum, natural gas and nuclear fuels like uranium and thorium.

1. SOLAR ENERGY

Sun is the ultimate source of energy directly or indirectly for all other forms of energy. The nuclear fusion reactions occurring inside the sun release enormous quantities of energy in the form of light and heat.

The solar energy received by the near earth space is approximately

1.4KJ/second/m2 known as solar constant.

Some important solar energy harvesting devices are discussed here.

(i) Solar heat collectors:

• Solar radiant energy can be converted into thermal energy by solar

collectors.

• These can be passive or active in nature.
• Passive heat collectors are natural materials like stones, bricks etc. or material like glass which absorb heat during the day time and release it slowly at night.
• Active solar collectors pump a heat absorbing medium (air or water) through a small collector, which is normally placed on the top of the building.

(ii) Solar cells

• They are also known as photovoltaic cells or PV cells. Solar cells are made of thin wafers of semi conductor materials like silicon and gallium.
• When solar radiations fall on them, a potential difference is produced

which causes flow of electrons and produces electricity.

• The potential difference produced by a single PV cell of 4 cm2 size is about 0.4 – 0.5 volts and produces a current of 60 milli amperes.
• The groups of solar cells joined together in a definite pattern form a

solar panel which can harness a large amount of solar energy.

(iii) Solar cooker

• Solar cookers make use of solar heat by reflecting the solar radiations using a mirror directly on to a glass sheet which covers the black insulated box within which the raw food is kept as shown in figure.
• Now, spherical reflector [concave or parabolic reflector] is used instead of plane mirror in the solar cooker

4. Solar water heater

It consists of insulated box painted black from inside and having a glass lid to receive and store solar heat. Inside the box it has black painted copper coil through which cold water is made to flow in which gets heated and flows out into a storage tank.

5. Solar furnace

Here thousands of small plane

concave reflectors,

all of which collect the solar heat

mirrors are arranged on

and

produce as high a temperature as 3000˚ C.

(vi)Solar power plant

Solar energy is harnessed on a large scale by using concave reflectors which cause boiling of water to produce steam. The steam turbine drives a generator to produce electricity. A solar power plant [50 KW capacity] has been installed at Gurgaon, Haryana.

2. WIND ENERGY

The high speed winds have lot of energy in them as kinetic energy due to their motion. The wind energy is harnessed by making use of wind mills. The blades of wind mill rotate due to the force of the striking wind. The rotational motion of the blades drives a number of machines like water pumps, flour mills and electric generators

“Wind farms” consisting of arrays of 50 to several thousand wind mills, are now producing power in a number of places around the world. These farms are ideally located in coasted regions, open grasslands or hilly regions, where the winds are strong and steady.

The minimum wind speed required for satisfactory working of a wind generator is 15 Km/hr. the wind power potential of our country is estimated to be about 20, 000 MW, while at present we are generating about 1020MW. The largest wind farm of our country is near Kanyakumari in Tamilnadu generating 380MW electricity.

3. HYDROPOWER

The water flowing in a river is collected by constructing a big dam where the water is stored and allowed to fall from a height. The blades of the turbine located at the bottom of the dam move with the fast moving water which in turn rotates the generator and produces electricity. The minimum height of the water falls should be 10 meters.

The hydropower potential of India is estimated to be about 4 x 1011 KW – hours. Till now we have utilized only a little more than 11% of this potential.

4. TIDAL ENERGY

Ocean tides produced by gravitational forces of sun and moon contain enormous amounts of energy. The “high tide” and “low tide” refer to the rise and fall of water in oceans. The difference of several meters is required between the height of high and low tide to spin the turbines.

The tidal mill at La Rance, France is one of the first modern tidal power mill. In India Gulf of Cambay, Gulf of Kutch and the sunderbans deltas are the tidal power

5. OCEAN THERMAL ENERGY (OTE)

The energy available due to the difference in temperature of water at the surface of the oceans and at deeper levels is called Ocean Thermal Energy. The difference of 20˚ C or more is required between surface water and deeper water of ocean for operating OTEC [Ocean Thermal Energy conversion] power plants.

The warm surface water of Ocean is used to boil a low boiling liquid like ammonia. The high pressure vapours of the liquid formed by boiling are then used to turn the turbine of a generator and produce electricity. The colder water from the deeper ocean is pumped to cool and condense the vapours into liquid. Suitable sites for this system is limited OTEC plants are costly and maintenance cost is high.

6. GEOTHERMAL ENERGY

The energy harnessed from the hot rocks present inside the earth is called geothermal energy. High temperature, high pressure steam fields exist below the earth’s surface in many places. This heat comes from the fission of radioactive material naturally present in the

rocks.

7. BIOMASS ENERGY

Biomass is the organic matter produced by the plants or animals which include wood, crop residues, cattle dung, manure, agricultural waste etc., Biomass is obtained through the process of photosynthesis. Biomass energy is considered to another form of indirect use of solar energy.

8. BIOGAS ENERGY
1. Biogas is a mixture of gases such as methane, carbon dioxide, hydrogen and hydrogen sulphide etc. It contains about 65% of methane gas.
2. Biogas is obtained by anaerobic fermentation of wastes like animal dung or plant wastes in the presence of water. Anaerobic means in the absence of oxygen.
3. India has the largest cattle population in the world [240 million] and has tremendous potential for biogas production. At present there are more than 330, 000 biogas plants in the country. It has been estimated that 150, 000 biogas plants will save 600, 000

^{tones of wood equivalent per year}

9. BIOFUELS

• Biomass can be fermented to alcohols like ethanol and methanol which can be used as fuels.
• Ethanol – Produced from carbohydrate rich substance like sugar cane.
• Methanol – Produced from wood.
• For example: Gasohol is a common fuel used in Brazil and Zimbabwe for running cars and buses. Gasohol is a mixture of ethanol and gasoline.

​

10. HYDROGEN AS A FUEL

As hydrogen burns in air, it combines with oxygen to form water and a large amount of energy [150KJ/gm] is released. Due to its high, rather the highest calorific value, hydrogen can serve as an excellent fuel.

H₂ + O₂ H₂O + 150 KJ/gm

(i)

(ii)

(iii)

Hydrogen is generated by using the following methods.

By heating the water (i.e. Thermal dissociation) (at 3000º K or above) (Or) By passing electricity through water [i.e. electrolysis of water] (Or)

By photolysis of water (i.e. breakdown of water in the presence of sunlight to

release hydrogen)

NON-RENEWABLE ENERGY SOURCES

These are the fossil fuels like coal, petroleum, natural gas and nuclear fuels. The fossil fuels were formed by the decomposition of the remains of plants and animals buried under the

1. COAL

The coal was formed 255 – 350 million years ago in the hot, damp regions of the earth during carboniferous age. There are three types of coal, namely,

• Anthracite (hard coal)
• Bituminous (soft coal) and
• Lignite (brown coal)

At present rate of usage, the coal reserves are likely to last for about 200 years and if its use increases by 2% per year, then it will last for another 65 years.

India has about 5% of world’s coal and Indian coal is not very

good in terms of heat capacity.

2. PETROLEUM

• It is the lifeline of global economy. There are 13 countries in the world having 67% of petroleum reserves. About ¼ th of the oil reserves are in Saudi Arabia.
• At the present rate of usage, the world’s crude oil reserves are estimated

to get exhausted in just 40 years.

• Crude petroleum is a complex mixture of alkane hydrocarbons. Hence it has to be purified and refined by the process of fractional distillation, during this process different constituent separate out at different temperatures. We get a large variety of products from this namely, petroleum gas, Kerosene, petrol, diesel, fuel oil, lubricating oil, paraffin wax, asphalt, plastic etc.
• Liquefied petroleum gas (LPG): The main component of LPG is butane, the other being propane and ethane. The petroleum gas is easily converted to liquid form under pressure as LPG. It is odourless, but the LPG in our domestic gas cylinders gives a foul smell. This is due to ethylmercaptan (C₂H₅SH), a foul smelling gas, added to LPG to detect the gas leakage.

3. NATURAL GAS

• It is mainly composed of methane (95%) with small amounts of propane and ethane. Natural gas is the cleanest fossil fuel
• It can be easily transported through pipelines. It has a high calorific value of about 50 KJ/gm and burns without any smoke. Currently, the amount of natural gas deposits in the world are of the order of 80, 450 g.m-3
• It is used as a fuel in thermal power plants. It is used as a source of hydrogen gas in fertilizer industry and as a source of carbon in type industry
• Compressed natural gas (CNG): It is used as an alternative to petrol and diesel for transport of vehicles. Delhi has totally switched over to CNG. CNG use has greatly reduced vehicular pollution in the city.
• Synthetic natural gas (SNG): It is a mixture of CO and H2. Low grade coal is initially transformed into synthetic gas by gasification followed by catalytic conversion to methane.

4. NUCLEAR ENERGY:

Nuclear power produces around 11% of the world’s energy needs.

Nuclear energy can be generated by two types of reactions.

(i) Nuclear fission: It is the nuclear change in which nucleus of certain isotopes with large mass numbers are split into lighter nuclei on bombardment by neutrons and a large amount of energy is released through the chain reaction as shown in below.

In conventional nuclear fission reactors, the splitting of uranium–235

nuclei releases heat, which produces high-pressure steam to spin

turbines and thus generate electricity.

(ii) Nuclear fusion: Here two isotopes of a light element are forced together at extremely high temperatures (1 billion º C) until they fuse to form a heavier nucleus releasing enormous energy in the process.

Nuclear fusion is much more difficult to initiate than nuclear fission, but once started it releases for more energy per unit of fuel than does fission. Fusion of hydrogen nuclei to form helium nuclei is the source of energy in the sun and stars.

6. LAND RESOURCES

Land as a resource

• Land is the most important and valuable resources for mankind as it provides food fiber, wood, medicine and other biological materials needed for food.
• Soil is the mixture of inorganic materials (rocks and minerals) and organic minerals (dead animals and plants)
• Top soil is classified as a renewable resource, because it is continuously regenerated by natural process at a very slow rate.
• But if the rate of erosion is faster than the rate of renewal, then the soil becomes a non-

renewable resource.

Uses

• Land provides food, wood, minerals, etc., for us.
• Land nurtures the plants and animals that provide our food and shelter.
• Land is used as watershed or reservoir.
• Land acts as a dust bin for most of the wastes created by the modern society.
• Land is used for construction of buildings, industries etc.

Land degradation

• Land degradation is the process of deterioration of soil or loss of fertility of the soil

Effects:

• The soil texture and soil structure are deteriorated.
• Loss of soil fertility, due to loss of invaluable nutrients.
• Increase in water logging, salinity, alkalinity and acidity problems.
• Loss of economic social and biodiversity.

Causes:

• Population
• Urbanization
• Fertilizers and pesticides
• Damage of top soil
• Water logging, soil erosion, salination and contamination of the soil with industrial wastes all cause land degradation.

Soil Erosion

It is a process of removal of superficial layer of the soil from one place to another.

​

Types of soil erosion

Normal erosion

Caused by gradual removal of top soil by the natural process

Rate of erosion is slower

Accelerated erosion

Caused by man-made activities

Rate of erosion is faster

Effects:

• Soil fertility is lost
• The soil loss its ability to hold water and sediments
• Sediment runoff can pollute water and kill aquatic life

action.

Causes:

• The soil erosion is affected by water in the form of rain, run-off, rapid flow, wave
• Wind carry away the fine particles of soil and creates soil erosion

• Overgrazing, mining and deforestation cause soil erosion. About 35% of the world soil

soil erosion is due to the

erosion is due to overgrazing and 30% of the world deforestation.

• Landslides cause soil erosion.

• Construction of dams, buildings, roads removes the protective vegetal cover and leads to soil erosion.

Control of soil erosion (or) soil conservation practices

Conservational till farming:

In tradition method, the land is ploughed and soil is broken up and leveled to make a planting surface. This disturbs the soil and makes it susceptible to erosion. However, no-till-farming machines make slits in the unploughed soil and inject seeds, fertilizers and water in the slit. So the seed germinates and the crop grows.

Contour farming:

It involves planting crops in rows across the contour of gently sloped land. Each row acts as a small dam to hold soil and to slow water run-off.

Terracing:

It involves conservation of steep slopes into a series of broad terraces which run across the contour. This retains water for crops and reduces soil erosion by controlling run off.

Alley cropping (or) Agro forestry:

It involves planting crops in strips or alleys between rows of trees of shrubs that can provide fruits and fuel wood. Even when the crop is harvested, the soil will not be eroded because trees and shrubs still remain on the soil and hold the soil particles.

Wind breaks or shelter belts:

The trees are planted in long rows along the boundary of cultivated lands which block the wind and reduce the soil erosion. Wind breaks help in retaining soil moisture, supply of some wood for fuel and provide habitat for birds.