Environmental Studies Lecture Notes PDF

CHAPTER-1 MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL STUDIES AND NATURAL RESOURCES UNIT I MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL STUDIES Definition – Scope and importance – Need for public awareness NATURAL RESOURCES Renewab...

CHAPTER-1 MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL STUDIES AND NATURAL RESOURCES UNIT I MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL STUDIES Definition – Scope and importance – Need for public awareness NATURAL RESOURCES Renewable and Non-renewable resources- Natural resources and Associated problems- Forest resources:-Use and over – Exploitation – Deforestation – Case studies – Timber extraction – Mining – Dams and their ground water – Floods – Drought – Conflicts over water – Dams – Benefits and Problems – Mineral Resources:- Use Effects on Forests and Tribal People – Water Resources:- Use and Over-Utilization of Surface and Exploitation, Environmental Effects of Extracting and Using Mineral Resources, Case Studies – Food Resources: World Food Problems, Changes caused by Agriculture and Overgrazing, Effects of Modern Agriculture, Fertilizer- Pesticide Problems, Water Logging, salinity, Case Studies – Energy Resources:- Growing Energy Needs, Renewable and Non Renewable Energy Sources, Use of Alternate Energy Sources, Case Studies 1.1 MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL STUDIES 1.1.1 INTRODUCTION  The word environment is derived from the French word ‘environner’ which means to ‘encircle or surround’.  Thus our environment can be defined as “the Social, Cultural and Physical conditions that surround, affect and influence the survival, growth and development of people, animals and plants”  This broad definition includes the natural world and the technological environment as well as the cultural and social contexts that shape human lives.  It includes all factors (living and nonliving) that affect an individual organism or population at any point in the life cycle; set of circumstances surrounding a particular occurrence and all the things that surrounds us. Environmental Science 1 AITT & H&S  1.1.2 SEGMENTS OF ENVIRONMENT Environment consists of four segments. 1. Atmosphere- Blanket of gases surrounding the earth. 2. Hydrosphere- Various water bodies present on the earth. 3. Lithosphere- Contains various types of soils and rocks on the earth. 4. Biosphere- Composed of all living organisms and their interactions with the environment. 1.1.3 MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL STUDIES  The Environment studies is a multi-disciplinary science because it comprises various branches of studies like chemistry, physics, medical science, life science, agriculture, public health, sanitary engineering etc.  It is the science of physical phenomena in the environment. It studies about the sources, reactions, transport, effect and fate of physical and biological species in the air, water, soil and the effect of from human activity upon these.  As the environment is complex and actually made up of many different environments like natural, constructed and cultural environments, environmental studies is inter disciplinary in nature including the study of biology, geology, politics, policy studies, law, religion engineering, chemistry and economics to understand the humanity’s effects on the natural world.  This subject educates the students to appreciate the complexity of environmental issues and citizens and experts in many fields.  By studying environmental science, students may develop a breadth of the interdisciplinary and methodological knowledge in the environmental fields that enables them to facilitate the definition and solution of environmental problems. 1.1.4 SCOPE OF ENVIRONMENTAL STUDIES Environmental studies as a subject has a wide scope. It includes a large number of areas and aspects, which may be summarized as follows:  Natural resources- their conservation and management  Ecology and Biodiversity  Environmental pollution and control  Human population and environment  Social issues in relation to development and environment Environmental Science 2 AITT & H&S  These are the basic aspects of environmental studies which have a direct relevance to every section of society. Several career options have emerged in these fields that are broadly categorized as: (i) Research and development in environment: Skilled environmental scientists have an important role to play in examining various environmental problems in a scientific manner and carry out R&D activities for developing cleaner technologies and promoting sustainable development. (ii) Green advocacy: With increasing emphasis on implementing various Acts and Laws related to environment, need for environmental lawyers has emerged, who should be able to plead the cases related to water, air, forest, wildlife, pollution and control etc. (iii) Green marketing: While ensuring the quality of products with ISO mark, now there is an increasing emphasis on marketing goods that are environment friendly. Such products have ecomark or ISO 14000 certification. Environmental auditors and environmental managers would be in great demand in the coming years. (iv) Green media: Environmental awareness can be spread amongst masses through mass media like television, radio, newspaper, magazine, hoardings, advertisements etc., for which environmentally educated persons are required. (v) Environmental consultancy: Many non-government organizations, industries and government bodies are engaging environmental consultants for systematically studying and tackling environment related problems. 1.1.5 IMPORTANCE OF ENVIRONMENTAL STUDIES  The importance of environmental studies is that, the current trend of environmental degradation can be reversed if people of educated communities are organized, empowered and experts are involved in sustainable development.  Environmental factors greatly influence every organism and their activities. Environmental Science 3 AITT & H&S   At present a great number of environmental issues, have grown in size and complexity day by day, threatening the survival of mankind on earth. These issues are studied besides giving effective suggestions in the environment studies.  The environment studies enlighten us, about the importance of protection and conservation of our natural resources, indiscriminate release of pollution into the environment etc. Environment studies have become significant for the following reasons: 1. Environment Issues being of International Importance: It has been well recognized that environment issues like global warming, ozone depletion, acid rain, marine pollution and loss of biodiversity are not merely national issues but are global issues and hence must be tackled with international efforts and cooperation. 2. Problems Cropped in The Wake of Development: Development, in its wake gave birth to Urbanization, Industrial Growth, Transportation Systems, Agriculture and Housing etc. However, it has become phased out in the developed world. The North, to cleanse their own environment has, fact fully, managed to move ‘dirty’ factories to South. When the West developed, it did so perhaps in ignorance of the environmental impact of its activities. Evidently such a path is neither practicable nor desirable, even if developing world follows that. 3. Explosively Increase in Pollution: World census reflects that one in every seven persons in this plant lives in India. Evidently with 16 per cent of the world's population and only 2.4 per cent of its land area, there is a heavy pressure on the natural resources including land. Agricultural experts have recognized soils health problems like deficiency of micronutrients and organic matter, soil salinity and damage of soil structure. 4. Need for An Alternative Solution: It is essential, specially for developing countries to find alternative paths to an alternative goal. We need a goal as under: (1) A goal, which ultimately is the true goal of development an environmentally sound and sustainable development. (2) A goal common to all citizens of our earth. Environmental Science 4 AITT & H&S  (3) A goal distant from the developing world in the manner it is from the over- consuming wasteful societies of the “developed” world. 5. Need To Save Humanity From Extinction: It is incumbent upon us to save the humanity from extinction. Consequences to our activities cause destructing the environment and depleting the biosphere, in the name of development. 6. Need For Wise Planning of Development: Our survival and sustenance depend. Resources withdraw, processing and use of the product have all to be synchronized with the ecological cycles in any plan of development. Our actions should be planned ecologically for the sustenance of the environment and development. 1.1.6 NEED FOR PUBLIC AWARENESS 1. Growing Population: A population of over thousands of millions is growing at 2.11 per cent every year. Over 17 million people are added each year. It puts considerable pressure on its natural resources and reduces the gains of development. Hence, the greatest challenge before us is to limit the population growth. Although population control does automatically lead to development, yet the development leads to a decrease in population growth rates. 2. Poverty: India has often been described a rich land with poor people. The poverty and environmental degradation are mixed with one another. The vast majority of our people are directly dependent on the nature resources of the country for their basic needs of food, fuel shelter and fodder. About 40% of our people are still below the poverty line. 3. Environment degradation has adversely affected the poor who depend upon the resources of their immediate surroundings. Thus, the challenge of poverty and the challenge of environment degradation are two facets of the same challenge. 4. Agricultural Growth: The people must be made familiar with the methods to sustain and increase agricultural growth without damaging the environment. High yielding varieties have caused soil salinity and damage to physical structure of soil. 5. Need to Increase Ground water: It is essential of rationalizing the use of groundwater. Factors like community wastes, industrial effluents, chemical Environmental Science 5 AITT & H&S  fertilizers and pesticides have polluted our surface water and affected quality of the groundwater. It is essential to restore the water quality of our rivers and other water bodies. Suitable strategies for conservation of water, provision of safe drinking water and keeping water bodies clean should be developed. 6. Development and Forests: Forests serve catchments for the rivers. With increasing demand of water, plan to harness the mighty river through large irrigation projects were made. Certainly, these would submerge forests; displace local people, damage flora and fauna. As such, the dams on the river Narmada, Bhagirathi and elsewhere have become areas of political and scientific debate. Forests in India have been shrinking for several centuries owing to pressures of agriculture and other uses. Vast areas that were once green, stand today as waste lands. These areas are to be brought back under vegetative cover. The tribal communities inhabiting forests, respects the trees, birds and animals give them sustenance. We must recognize the role of these people in restoring and conserving forests. The modern knowledge and skills of the forest department should be integrated with the traditional knowledge and experience of the local communities. The strategies for the joint management of forests should be evolved in a well planned way. 7. Degradation of Land: At present out of the total 329 mha of land, only 266 mha possess any potential for production. Of this, 143 mha is agricultural land nearly and 85 suffers from varying degrees of soil degradation. Of the remaining 123 mha, 40 are completely unproductive. The remaining 83 mha is classified as forest land, of which over half is denuded to various degrees. Nearly 406 million head of livestock have to be supported on 13 mha, or less than 4 per cent of the land classified as pasture land, most of which is overgrazed. Thus, out of 226 mha, about 175 mha or 66 per cent is degraded to varying degrees. Water and wind erosion causes further degradation of almost 150 mha This degradation is to be avoided. 8. Evil Consequences of Urbanization: Nearly 27% of Indians live in urban areas. Urbanization and industrialization has given birth to a great number of environmental problems. Over 30 percent of urban Indians live in slums. Out of Environmental Science 6 AITT & H&S  India’s 3,245 towns and cities, only 21 have partial or full sewerage and treatment facilities. Hence, coping with rapid urbanization is a major challenge. 9. Air and water Pollution: Majority of our industrial plants are using outdated and pollution causing technologies and makeshift facilities devoid of any provision of treating their wastes. A great number of cities and industrial areas have been identified as the worst in terms of air and water po llution. Acts are enforced in the country, but their implement is not so easy. The reason is their implementation needs great resources, technical expertise, political and social will. Again the people are to be made aware of these rules. Their support is indispensable to implement these rules. 1.1.7 INSTITUTIONS IN ENVIRONMENT Managing natural resources require efficient institutions at all levels i.e. local, national, regional and global. Among the large number of institutions that deal with environmental protection and conservation, a few well-known organization include government organizations like the BSI and ZSI, and NGOs like the BNHS, WWF-1, etc.  The Bombay Natural History Society (BNHS), Mumbai  World Wide fund for nature- India (WWF-1), New Delhi  Centre or science and environment (CSE), New Delhi  C.P.R Environmental Education Centre, Madras  Centre for Environment Education (CEE)  Bharati Vidyapeeth University, Institute of Environment Education & Research, Pune  The Salim Ali Center for Ornithology and Natural History (SACON)  Wild life Institute of India (WII), Dehradhun  Zoological survey of India (ZSI)  The madras Crocodile Bank Trust (MCBT)  Botanical Survey of India (BSI) Environmental Science 7 AITT & H&S  1.2 NATURAL RESOURCES 1.2.1 INTRODUCTION  Natural resources can be defined as ‘variety of goods and services provided by nature which are necessary for our day-to-day lives’.  Eg: Plants, animals and microbes (living or biotic part), Air, water, soil, minerals, climate and solar energy (non- living or abiotic part).  They are essential for the fulfillment of physiological, social, economical and cultural needs at the individual and community levels. 1.2.2 TYPES OF NATURAL RESOURCES They are of two types of resources namely Renewable and Non-Renewable Resources. 1. Renewable resources: The resources that can be replenished through rapid natural cycles are known as renewable resource. These resources are able to increase their abundance through reproduction and utilization of simple substances. Ex: Plants, (crops and forests) and animals.  Some examples of renewable resources though they do not have life cycle but can be recycled. Ex: Wood and wood-products, pulp products, natural rubber, fibers (e.g. Cotton, jute, animal wool, silk and synthetic fibers) and leather.  In addition to these resources, water and soil are also classified as renewable resources.  Solar energy although having a finite life, as a special case, is considered as a renewable resource in as much as solar stocks is inexhaustible on the human scale. 2. Non renewable resources: The resources that cannot be replenished through natural processes are known as non-renewable resources. These are available in limited amounts, which cannot be increased. These resources include fossil fuels (petrol, coal etc.), metals (iron, copper, gold, silver, lead, zinc etc.), minerals and salts (carbonates, phosphates, nitrates etc.).Once a non-renewable resource is consumed, it is gone forever. Environmental Science 8 AITT & H&S   Non-renewable resources can further be divided into two categories, viz. A) Recyclable and B) Non-recyclable A) Recyclable: These are non-renewable resources, which can be collected after they are used and can be recycled. These are mainly the non-energy mineral resources, which occur in the earth’s crust (Ex: Ores of aluminum, copper, mercury etc.) and deposits of fertilizer nutrients (e.g. Phosphate sock and potassium and minerals used in their natural state (asbestos, clay, mica etc.) B) Non-recyclable: These are non-renewable resources, which cannot be recycled in any way. Ex: Fossil fuels and uranium, which provide 90 per cent of our energy requirements 1.2.3 NATURAL RESOURCES AND ASSOCIATED PROBLEMS:  The main problem associated with natural resources is unequal consumption.  A major part of natural resources are consumed in the ‘developed’ world. The ‘developing nations’ also over use many resources because of their greater human population. However, the consumption of resources per capita (per individual) of the developed countries is up to 50 times greater than in most developing countries.  Advanced countries produce over 75% of global industrial waste and greenhouse gases.  Energy from fossil fuels consumed in relatively much greater quantities in developed countries. Their per capita consumption of food too is much greater as well as their waste. 1.2.4 FOREST RESOURCES A forest can be defined as a biotic community predominant of trees, shrubs or any other woody vegetation usually in a closed canopy. It is derived from latin word ‘foris’ means ‘outside’. India’s Forest Cover is 6,76,000 sq.km (20.55% of geographic area). Scientists estimate that India should ideally have 33% of its land under forests. Today we only have Environmental Science 9 AITT & H&S  about 12% thus we need not only to protect our existing forests but also to increase our forest cover. 1.2.4.1 FUNCTIONS OF FOREST 1. It performs very important function both to human and to nature. 2. They are habitats to millions of plants, animals and wild life. 3. They recycle rain water. 4. They remove pollutant from air. 5. They control water quality. 6. They moderate temperature and weather. 7. They influence soil condition and prevent soil erosion. 1.2.4.2 USES OF FOREST 1. Commercial uses 2. Ecological uses 1. Commercial uses: i. Wood – used as a fuel ii. Supply wood for various industries – Raw materials as pulp, paper, furniture timber etc. iii. Minor forest products – gum, dyes, resins iv. Many plants – Medicines v. Supply variety of animal products – honey. Ivory, horns etc. vi. Many forest lands are used for - Mining, grazing, for dams and recreation. 2. Ecological uses: Forest provides number of environmental services. i. Production of oxygen: Photosynthesis produces large amount of oxygen which is essential for life. ii. Reducing global warming: Carbon dioxide is one of the main green house gas. It is absorbed by plants for photosynthesis. Therefore the problem of global warming caused by CO2 is reduced. iii. Soil conservation: Roots of trees bind the soil tightly and prevent soil erosion. They also act as wind breaks. iv. Regulation of hydrological cycle: Watershed in forest act like giant sponges and slowly release the water for recharge of spring. Environmental Science 10 AITT & H&S  v. Pollution moderators: Forest can absorb many toxic gases and noises and help in preventing air and noise pollution. vi. Wild life habitat: Forest is the home of millions of wild animals and plants. 12.4.3 REASON FOR DEFICIENCY OF FOREST: In India the minimum area of forest required to maintain good ecological balance is about 33% of total area. But at present it is only about 12%. So over exploitation of forest material occurs. 1.2.4.4 OVER EXPLOITATION OF FOREST: Due to over population, there is an increased demand for medicine, shelter, wood and fuel. Hence exploitation of forest materials is going on increasing. Cause of over exploitation: 1. Increasing agricultural production. 2. Increasing agricultural activities. 3. Increase in demand of wood resources. 1.2.4.5 DEFORESTATION: It is process of removal of forest resources due to natural or manmade activities (i.e.) destruction of forests. Causes of deforestation: 1. Developmental projects: Developmental projects causes deforestation through two ways.  Through submergence of forest area.  Destruction of forest area. Ex: big dams, hydro electric projects, road construction etc. 2. Mining operations: It reduces forest areas. Ex: Mica, coal, Manganese and lime stone. 3. Raw materials for industries: Wood is an important raw material for various purposes. Ex: Making boxes, furniture and paper etc. 4. Fuel requirement: Wood is the important fuel for rural and tribal population. Environmental Science 11 AITT & H&S  5. Shifting cultivation: Replacement of natural forest ecosystem for mono specific tree plantation. Ex: Teak 6. Forest fires: Forest fire destructs thousands of acres of forest. 7. Over grazing: Over grazing by cattle reduces the cultivation land Consequences of deforestation (or) impacts of deforestation: 1. Economic loss 2. Loss of biodiversity 3. Destructs the habitats of various species 4. Reduction in stream flow 5. Increases the rate of global warming 6. Disruption of weather patterns and global climate 7. Degradation of soil and acceleration of the rate of soil erosion. 8. Induces and accelerates mass movement / land slides. 9. Increases flood frequency, magnitude / severity. 10.Breaks the water cycle 11.Breaks the nutrient cycle 1.2.4.6 PREVENTIVE MEASURES (OR) AVOID OF DEFORESTATION (OR) METHODS OF CONSERVATION OF FORESTS 1. New plants of more or less of the same variety should be planted to replace the trees cut down for timber 2. Use of wood for fuel should be discouraged. 3. Forest pests can be controlled by spraying pesticides by using aero planes 4. Forest fire must be controlled by modern techniques. 5. Over grazing by cattle must be controlled. 6. Steps should be taken by the government to discourage the migration of people into the islands from mainland. 7. Education and awareness programmes must be conducted. 8. Strict implementation of law of Forest conservation Act. Case study: Environmental Science 12 AITT & H&S  Deforestation in the Himalayan region, involves clearing of natural forests and plantation of monoculture like Eucalyptus. Nutrient in the soil is poor; therefore soil losing their fertility, hence, Himalayan area facing the serious problem of desertification. 1.2.4.7 MAJOR ACTIVITIES IN FORESTS 1.2.4.7.1 TIMBER EXTRACTION Wood used for engineering purposes like building houses, making furniture is called timber. The products derived from timber have been important to many civilizations, and thus it has acquired value within these civilizations. Timber extraction results in deforestation and in the fragmentation of the last remaining forests. It harms valuable species of trees, birds and wild animals. In spite of this, it is sometimes necessary to extract timber, so as to meet the needs of a developing country. During the extraction of timber, cutting, felling and handling should be done selectively, carefully and in a planned manner, in order to save the remaining forests and biodiversity. Effects of Timber Extraction The major effects of timber extraction on forest and tribal people include: 1. Poor logging results in a degraded forest. 2. Floods may be intensified by cutting of trees or upstream watersheds. 3. Loss of biodiversity. 4. Climatic changes such as less rains. 5. New logging roads permit shifting cultivators to gain access to logged areas and cut the remaining trees. 6. It results in forest fragmentation which promotes loss of biodiversity because some species of plants and animals require large continuous areas of similar habitat to survive. 7. Exploitation of tribal people by the contractors. 8. Soil erosion especially on slopes occurs extensively. 9. Sedimentation of irrigation systems, floods may be intensified by cutting of trees on upstream. Case Study-Chipko Movement The world famous Chipko Movement, pioneered by Dasohli Gram Swarajya Mandal in Gopeshwar brought about a general awareness about conservation of forests. Environmental Science 13 AITT & H&S  The first Chipko Movement dates back to 1731, when a village woman named Amrita Bai led the Bishnoi women against the Maharajas men to prevent them from cutting trees. In this attempt to save the trees, she sacrificed her life along with the lives of her husband, three daughters and 363 people. The movement was given this name because the village women embraced or hugged the trees to stop them from being cut. In 1972, in Uttar Pradesh, the Chipko Movement was led by Bachnoi Devi of Advani who protected the hill forests from the contractors axe men. 1.2.4.7.2 DAMS Today there are more than 45,000 large dams around the world, which play an important role in communities and economies that harness these water resources for their economic development. Current estimates suggest some 30-40% of irrigated land worldwide relies on dams. Hydropower, another important the use of stored water, currently supplies 19% of the world’s total electric power supply and is used in over 150 countries. The world’s two most populous countries – China and India –have built around 57% of the world’s large dams. Dams problems Dams are the massive artificial structures built across the rivers to store water for much beneficial purpose. Dams are considered a “Temples of modern India”. Dams destruct vast area of forest area. India has more than 1600 large dams. Effects of dams on forest: 1. Thousands of hectares of forest will be cleared. 2. Killing of wild animals and destruction of aquatic life. 3. Spreading of water borne diseases. 4. Water logging increases the salinity of the soil. Ex: Narmadha Sagar project it has submerged 3.5 lakhs hectares of forest. Effects of dam on tribal people 1. Construction of big dams lead to the displacement of tribal people. 2. Displacement and cultural change affects the tribal people both mentally and physically. 3. They do not accommodate the modern food habits and life style. 4. Tribal people are ill treated by the modern society. Environmental Science 14 AITT & H&S  5. Many of the displaced people were not recognised and resettled or compensated. 6. Body condition of tribal people will not suit with new areas and hence they will be affected by many diseases. Case study- Sardar Sarovar Project: The World Bank’s withdrawal from the Sardar Sarovar Project in India in 1993 was a result of the demands of local people threatened with the loss of their livelihoods and homes in the submergence area. This dam in Gujarat on the Narmada has displaced thousands of tribal folk, whose lives and livelihoods were linked to the river, the forests and their agricultural lands. While they and the fishermen at the estuary, have lost their homeland, rich farmers downstream will get water for agriculture. The question is why should the local tribals be made homeless, displaced and relocated to benefit other people? Why should the less fortunate be made to bear the costs of development for better off farmers? It is a question of social and economic equity as well as the enormous environmental losses, including loss of the biological diversity of the inundated forests in the Narmada valley. 1.2.4.7.3 MINING The process of extracting mineral resources and fossil fuels like coal from the earth is called as mining. Types of mining 1. Surface mining: Mining of minerals from shallow deposits 2. Underground mining: Mining of minerals from deep deposits Steps involved in mining 1. Exploration 2. Development 3. Exploitation 4. Ore processing 5. Extraction and purification of minerals The extent of damage by underground mining is more than that of surface mining, which needs enormous amount of land area for its operation and management. Environmental Science 15 AITT & H&S  Effects of mining 1. Pollute soil, water and air. 2. Destruction of natural habitat. 3. Continuous removal of minerals leads to the formation of trench where water is logged which contaminates the ground water. 4. Vibrations cause earth quakes. 5. Produces noise pollution 6. Reduces shape and size of the forest. 7. Increased risk of landslides. 8. Spoils the aesthetic beauty. 1.2.5 WATER RESOURCES Water claims to be an important resource. An important use of water in our country is for irrigation. Besides, water is also required in large amounts for industrial and domestic consumption. 1.2.5.1 USES  Is essential for all forms of life.  Many uses of water include agricultural, industrial, household, recreational and environmental activities. Virtually, all of these human uses, require fresh water.  No plant or animal species can survive without water. If water in our body drops by 1% we feel thirst, if it drops by 10% we face death. 1.2.5.2 HYDROLOGICAL CYCLE: Water from various water bodies Evaporated by solar energy Enters in to the atmosphere as clouds Falls again on earth as rain or snow Ultimately returns to the ocean. Environmental Science 16 AITT & H&S  1.2.5.3 DISTRIBUTION OF WATER RESOURCES Fresh water resources Surface water Underground water Standing water bodies flowing water bodies 1.2.5.3.1 UNDERGROUND WATER Aquifer: Layers of highly permeable rock that can store water is called an aquifer. Layer of sand and gravels are good aquifers. Clay and crystalline rocks are not good aquifers. Effects of over utilization of water 1. Decrease of ground water: i. Increased usage decreases the ground water. ii. Insufficient rain fall iii. Building construction activities sealing the permeability of the soil. 2. Ground subsidence: If ground water withdrawal is greater than it’s recharge rate, then the sediments in the aquifers get compacted. As a result shrinkage of land surface takes place. Problems: a. Structural damages to the buildings b. Fracture in pipes. c. Reversing the flow of canals. 3. Lowering of water table: Over utilization of ground water in arid and semi arid regions for agriculture disturbs the state of equilibrium of the hydrological cycle. Problem: a. Lowering of water table b. Decrease the number of aquifers c. Change the speed and direction of water. 4. Intrusion of salt water: In coastal area over exploitation of ground water leads to the intrusion of salt water from sea. Therefore that water cannot be used for drinking and agriculture. Environmental Science 17 AITT & H&S  5. Over utilization of water causes earth quakes, landslides and famines. 6. Drying up of wells: Due to over utilization, ground water level decreases much faster than can be regenerated. It leads to drying up of dug well and bore wells. 7. Pollution of water: Near the agricultural land ground water decreases therefore water containing nitrogen enters into the ground and pollute the ground water. Problem: Water which contains excess nitrate content is not suitable for drinking. 1.2.5.3.2 REASONS FOR DECLINE OF GROUND WATER Population continues to rise at an unprecedented and unsustainable rate; many more areas are expected to experience this imbalance in the near future. 1. Population explosion: World population is > 6 billion and will continue to increase significantly during the next few decades - Enormous demands on the world’s limited freshwater supply. The total annual freshwater withdrawals today are estimated at 3800 cubic kilometers, twice as much as just 50 years ago (World Commission on Dams, 2000). 2. Overutilization of Surface and Groundwater: Occurs at various levels. Use of more water than really needed by human beings. Many agriculturists use more water than necessary to grow crops. Industries in order to maximize short-term economic gains, does not bother its liquid waste and releases it into streams, rivers and the sea. 3. Deforestation: Once hill slopes are removed of forest cover, the rainwater rushes down the rivers and is lost. Forest cover permits water to be held in the area permitting it to seep into the ground. This charges the underground stores of water in natural aquifers. This can be used in drought years if the stores have been filled during a good monsoon. This soil and water management and afforestation are long-term measures that reduce the impact of droughts. The destruction of forests influences the regulation of natural water cycle. The removal of dense and uniform cover over the hilly zones leads to occurrence of floods in drainage basins. Nations situated in tropical climates including India experience disastrous floods caused by the indiscriminate deforestation of the slopes above the valleys. 4. Hydropower generation: Large amount of water is used for generating power which otherwise used for human needs. 5. Dams - for Agriculture and Power Generation Environmental Science 18 AITT & H&S  6. Rain fall: The erratic and inadequate rainfall results in reduction in storage in subsurface reservoirs. The building construction activities are sealing the permeable zone, reducing the area for percolation of rainwater into subsurface and increase in surface runoff. 7. India’s increasing demand for water for intensive irrigated agriculture, for generating electricity, and for consumption in urban and industrial centers, has been met by creating large dams. Dams support 30 to 40% of this area. 1.2.5.4 FLOOD It is an over flow of water. It happens when the magnitude of flow of water exceeds the carrying capacity of the channel within its bank. 1.2.5.4.1 CAUSES OF FLOOD 1. Heavy rainfall, melting of snow and sudden release of water from dams. (Flash floods) 2. Reduction in the carrying capacity of the channel. 3. Deforestation, mining and over grazing increase the runoff from rains and the level of flood raises. 1.2.5.4.2 EFFECT OF FLOOD 1. Water spreads in the surrounding area and submerges them. 2. Cultivated land gets affected. 3. Extinction of civilization. 1.2.5.4.3 FLOOD MANAGEMENT 1. Floods can be controlled by dams. 2. Channel management control flood. 3. Flood hazards reduced by forecasting or flood warning. 4. Flood may also be reduced by reduction of run off by increasing infiltration through appropriate afforestation in the catchment area. 1.2.5.5 DROUGHT Drought is nothing but scarcity of water, which occurs due to 1. Inadequate rain fall 2. Late arrival of rain fall 3. Excessive withdrawal of ground water. Environmental Science 19 AITT & H&S  Lack of water for the needs of agriculture, livestock, industry or human population may be termed as a drought. Drought causes serious damages to plants, animals and human life. 1.2.5.5.1 CAUSES OF DROUGHT 1. When annual rain fall is below normal and less than evaporation, drought is created. 2. High population. 3. Intensive cropping pattern Ex: Maharashtra - There has been no recovery from drought for the last 30 years due to over exploitation of water by sugarcane crop. 1.2.5.5.2 EFFECTS OF DROUGHT 1. Drought causes hunger, malnutrition and scarcity of drinking water an also changes the quality of water. 2. Drought causes widespread crop failure leading to acute shortage of food and adversely affects human and live stock population. 3. Worst situation of drought causes desertification. 4. Raw materials of agro based industries are critically affected during drought time, hence industrial and commercial growth decreases. 5. Drought increases the degradation of natural resources. 6. Drought causes large migration of people and urbanization. 1.2.5.5.3 DROUGHT MANAGEMENT 1. Indigenous knowledge is essential. 2. Rain water harvesting system. 3. Construction of reservoirs to improve ground water level. 4. Modern irrigation technology (drip irrigation) very useful to conserve water. 5. Afforestration activities also improve the potential of water in the drought area. 6. Crop mixing and dry forming are the suitable methods which minimize the risk of crop failures in dry area. 1.2.5.6 DAMS Dams made significant contributions to human development and the benefits derived from them have been considerable. Large dams are designed to control floods and to help the drought prone areas, with supply of water. But large dams have proved to Environmental Science 20 AITT & H&S  cause severe environmental damage. Hence an attempt has been made to construct small dams. Multiple small dams have less impact on the environment. Benefits: Dams ensure a year round supply of water for domestic use and provide extra water for agriculture, industries and hydropower generation. Problems: They alter river flows, change nature’s flood control mechanisms such as wetlands and flood plains, and destroy the lives of local people and the habitats of wild plant and animal species, particularly is the case with mega dams. Some of the problems are mentioned below.  Dam construction and submersion leads to significant loss of farmland and forest and land submergence  Siltation of reservoirs, water logging and salination in surrounding lands reduces agricultural productivity  Serious impacts on ecosystems - significant and irreversible loss of species and ecosystems, deforestation and loss of biodiversity, affects aquaculture  Socio economic problems for example, displacement, rehabilitation and resettlement of tribal people.  Fragmentation and physical transformation of rivers  Displacement of people - People living in the catchment area, lose property and livelihood  Impacts on lives, livelihoods, cultures and spiritual existence of indigenous and tribal people  Dislodging animal populations  Disruption of fish movement and navigational activities  Emission of green house gases due to rotting of vegetation  Natural disasters – reservoirs induced seismicity, flash floods etc and biological hazards due to large-scale impounding of water – increase exposure to vectorbrone diseases, such as malaria, schistosomiasis, filariasis. 1.2.5.7 SUSTAINABLE WATER MANAGEMENT  Building several small reservoirs instead of few mega projects  Developing small catchment dams and protecting wetlands Environmental Science 21 AITT & H&S   Soil management, micro-catchment development and afforestation permits recharging of underground aquifer, thus reducing the need for large dams  Treating and recycling municipal waste water for agricultural use.  Preventing leakages form dams and canals and loss in municipal pipes  Effective rainwater harvesting in urban environments  Water conservation measures in agriculture, such as using drip irrigation, control of growing water intensive cash crops ; control of water logging.  Pricing water at its real value makes people use it mo re responsibility and efficiently and reduces wastage  In deforested areas where land has been degraded, appropriate soil management practices, making bunds along the hill-slopes and making nalla plugs can help retain moisture and make it possible to revegetate degraded areas  Use waste water for activities that does not need fresh water – Recycling  Adopt mini water harvesting models for domestic usage.  Protect existing tanks  Develop systematic water management and adopt strict water auditing  “Save water Campaigns” for public awareness on water scarcity  Through rainwater harvesting, community based participatory initiatives and holistic watershed management.  Responsible water usage can only be achieved by empowering local communities and creating local accountability.  The government should develop policies that protect water resources, promote sustainable watershed management and invest in technologies that will increase efficiency in irrigation, industrial usage and improve water harvesting techniques. 1.2.5.8 WATER CONFLICTS 1. Conflict through use: Unequal distribution of water led to interstate and international disputes. National conflicts: a. Sharing of cauvery water between Karnataka and TamilNadu. b. Sharing of Krishna water between Karnataka and Andrapradesh c. Siruvani – TamilNadu and Kerala Environmental Science 22 AITT & H&S  International conflicts: Indus – India and Pakistan & Colorado river – Mexico and USA 1.2.6 MINERAL RESOURCES Naturally occurring inorganic crystalline solids with uniform chemical composition are called as minerals. 1.2.6.1 USES AND EXPLOITATION OF MINERALS 1. Development of industrial plants and machinery. - Fe, Al & Cu 2. Construction work – Fe, Al &Ni 3. Generation of energy - coal, lignite, uranium 4. Designing defense equipments like weapons and o rnaments 5. Agricultural purposes – fertilizers and fungicides – Zn & Mn 6. Jewellery –Au, Ag & Pt 7. Making alloys for various purposes 8. Communication purposes – telephone, wires, cables and electronic devices 9. Medicinal purposes, particularly in ayurvedic system 1.2.6.2 ENVIRONMENTAL DAMAGES CAUSED BY MINING ACTIVITIES 1. Devegetation:  Topsoil and vegetation get removed  Deforestation leads to several ecological losses  Land scape gets badly affected 2. Ground water contamination: Mining pollutes ground water; sulphur is converted into sulphuric acid which enters into the soil. 3. Surface water pollution: Radioactive wastes and other acidic impurities affect the surface water, which kills many aquatic animals. 4. Air pollution: Smelting and roasting are done to purify the metal which emits air pollutants and damage the nearby vegetation. It causes many health problems. 5. Subsidence of land: Mainly underground mining results in cracks in houses, tilting of buildings and bending of rail tracks. Environmental Science 23 AITT & H&S  1.2.6.3 EFFECTS OF OVER EXPLOITATION OF MINERALS 1. Rapid depletion of mineral deposits 2. Wastage 3. Environmental pollution 4. Needs heavy energy requirements. 1.2.6.4 MANAGEMENT OF MINERAL RESOURCES 1. The efficient use and protection of mineral resources. 2. Modernization of mining industries 3. Search for new deposit 4. Reuse and recycling of the metals. 5. Environmental impacts can be minimized by adopting eco friendly mining technology. 1.2.6.5 CASE STUDIES-MINING AND QUARRYING IN UDAIPUR 200 open cast mining and quarrying in Udaipur. But 100 mines are illegal. 150 tons of explosives are used per month. It pollutes air, soil and water. It affects irrigation and wild life. 1.2.7 FOOD RESOURCES Food is an essential requirement for survival of life. Main components are carbohydrates, fats, proteins, minerals and vitamins. 1.2.7.1 TYPES OF FOOD SUPPLY 1. Crop plants: Grains mostly constitute about 76% of the world’s food. Ex: Rice, Wheat and Maize 2. Range lands: Produces 17% of world’s food from trees and grazing animals. Ex: Fruits, milk and meat 3. Ocean: Fisheries – 7% of world’s food Environmental Science 24 AITT & H&S  1.2.7.2 WORLD FOOD PROBLEM 1. In the earth’s surface, 79% is water out of total area. 21% land (forest, desert, mountain and barren land). Less % cultivated land, at the same time population explosion is high therefore world food problem arises. 2. Environmental degradation like soil erosion, water logging, water pollution, salinity affects agricultural land. 3. Urbanization affects agricultural land. Hence production of rice, wheat, corn and other vegetable is difficult. 1.2.7.3 TYPES OF NUTRITION 1. Nutritious nutrition: To maintain good health and disease resistance, we need large amount of carbohydrate, proteins, fats and smaller amount of micronutrients such as vitamins and minerals such as Fe, Ca and iodine. Food and agricultural organization (FAO) of United Nations estimated that on an average, the minimum calorie intake on a global state is 2500 calories/day. 2. Under nutrition: People who cannot buy enough food to meet their basic energy needs suffer from under nutrition. They receive less than 90% of this minimum dietary calorie. Effect of under nutrition: Suffer from mental retardation and infectious diseases. 3. Mal nutrition: Besides minimum calorie intake we also need proteins, minerals, vitamins, iron and iodine. Deficiency leads to malnutrition resulting in several diseases. Effect of mal nutrition: S.No Deficiency of nutrients Effects 1 Protein Growth 2 Iron Anemia 3 Iodine Goiter 4 Vitamin – A Blindness India 3 rd largest producer of crops, nearly 300 million Indians are still under nourished. World food summit 1996: The world food summit, 1996 has set the goal to reduce the number of under nourished and mal nourished people to just half by 2015. Environmental Science 25 AITT & H&S  1.2.7.4 OVER GRAZING It is a process of eating the forest vegetation without giving a chance to regenerate. 1.2.7.4.1 EFFECTS OF OVER GRAZING 1. Land degradation  Over grazing removing the cover of vegetation  Exposed soil gets compacted  Soil moisture reduces.  Desertification - OG leads to poor, dry and compacted soil.  Land cannot be used for further cultivation. 2. Soil erosion: When the grasses are removed the soil becomes loose and gets eroded by the action of wind and rain fall. 3. Loss of useful species: OG affects the plant population and their regenerating capacity. OG replace the plant of high nutritive value with plant of low nutritive value. 1.2.7.5 AGRICULTURE Agriculture is an art, science and industry of managing the growth of plants animals for human use. It includes cultivation of the soil, growing and harvesting crops, breeding and raising livestock, dairying and forestry. 1.2.7.5.1 TYPES OF AGRICULTURE 1. Traditional agriculture 2. Modern (or) industrialised agriculture 1. Traditional agriculture Small plot, simple tools, surface water, organic fertilizer and a mixture of crops constitute traditional agriculture. They produce enough food to feed their family and to sell it for their income. 2. Modern agriculture Hybrid seeds of single crop variety, high tech equipments, lot of fertilisers, pesticides and water to produce large amount of single crops. 1.2.7.5.2 EFFECTS OF MODERN AGRICULTURE 1. Problems in using fertilizers Environmental Science 26 AITT & H&S  a. Excess of fertilizers causes micronutrient imbalance. (e.g) Punjab and Haryana deficiency of nutrient zinc in the soil affect the productivity of the soil. b. Blue baby syndrome (nitrate pollution): Nitrate present in the fertilizer causes blue baby syndrome, when the amount exceeds the limit leads to death. c. Eutrophication: Nitrogen and phosphorus in the crop fields washed out by runoff water in the water bodies, which increases the nourishment of the lakes called eutrophication. Hence algal species increases rapidly. Life time of the species is less and they decompose easily and pollute the water which affects the aquatic life. 2. Problems in using pesticides 1. Death of non target organism. 2. Producing new pest – super pest 3. Bio magnification – Most of the pesticides are non bio degradable, keep on concentrating in the food chain and it is harmful to human beings. 4. Risk of cancer: a. It directly acts as carcinogen b. It indirectly supports immune system. 3. Water logging: Land where water stand for most of the year. Causes of water logging: 1. Excessive water supply 2. Heavy rain 3. Poor drainage Remedy: 1. Preventing excessive irrigation 2. Subsurface drainage technology 3. Bio drainage like trees like Eucalyptus 1.2.7.6 CASE STUDY- PESTICIDES IN INDIA In Delhi the accumulation of pesticide in the body of mother causes premature delivery and low birth weight infant. Environmental Science 27 AITT & H&S  Pesticides in Pepsi and Coca Cola India has reported that Pepsi and coca cola companies are selling soft drinks with pesticide content 30-40 times higher than EU limits. This damages the nervous system,. 1.2.8 ENERGY RESOURCES 1.2.8.1 ENERGY DISTRIBUTION IN THE WORLD  Developed countries like USA and Canada constitute only 5% of the world’s population but consume 25% of the world’s available energy.  Energy consumed by a person in a developed country for a single day is equal to energy consumed by a single person in a poor country for one year.  Developed country GNP increases and energy consumption increases. In the poor country GNP and energy consumption are less. 1.2.8.2 TYPES OF ENERGY RESOURCES: 1. Renewable energy resource (or)Non conventional energy resources 2. Non renewable energy resources (or) Conventional energy resources 1.2.8.2.1 RENEWABLE ENERGY SOURCES: Energy which can be regenerated. Merits of renewable energy resources 1. Unlimited supply 2. Provides energy security. 3. Fits into sustainable development concept. 4. Reliable and the devices are modular in size. 5. Decentralized energy production. Types of renewable energy resources 1. Solar energy: Nuclear fusion reaction of sun produces enormous amount of energy. Several techniques are available for collecting, storing and using solar energy. a. Solar cell (or) Photovoltaic cell (or) PV cell:  Solar cell consists of p- type semi conductor (Si doped with B) and n-type semi conductor (Si doped with P). P-type forms top layer and n-type forms bottom layer.  Solar rays fall on the top layer, the electrons from valence band promoted to the conduction band which crosses the p-n junction into n-type semi Environmental Science 28 AITT & H&S  conductor. Potential difference between the two layers is created which causes flow of electrons. Uses: It is used in calculators, electronic watches, street light, water pumps etc. b. Solar battery: Large number of solar cells connected in series is called solar battery. It is used in remote areas where continuous power supply is a problem. c. Solar water heater: It consists of insulated box painted with black paint with glass lid. Inside the box black painted copper coil is present. Cold water is allowed to flow, it is heated up and flows out into a storage tank from which water is supplied through pipes. 2. Wind energy: Moving air is called wind. The energy recovered from the force of the wind is called wind energy It’s speed is high. a. Wind mills: When a blowing wind strikes the blade of the wind mill, it rotates continuously. And rotational motion of the blade drives number of machines like water pump, flour mills and electric generators. b. Wind farms: When a large number of mills are installed and joined together in a definite pattern – it forms wind farm. It produces large amount of electricity. Condition: Minimum speed for wind generator is 15 Km/hr Advantages: 1. It does not cause air pollution 2. Very cheap Environmental Science 29 AITT & H&S  3. Ocean energy: Tidal energy (or) Tidal power: Ocean tides are due to gravitational force of sun and moon which produce enormous amount of energy. High tides – rise of water in the ocean. Low tides – fall of water in the ocean. Tidal energy can be used by constructing a tidal barrage. During high tides sea water enters into the reservoirs and rotates the turbine, produce electricity. During low tides water from reservoir enters into the sea rotate the turbine produce electricity. Ocean thermal energy: Temperature difference between surface water and deeper level water in ocean generates electricity. The energy available due to the difference in temperature of water is called ocean thermal energy. Condition: Temperature difference should be 200C. Process: Ammonia is converted into vapours on the surface of warm water, it increases the vapour pressure which rotate the turbine and generates electricity. Deeper level cold water is pumped to cool and condense the vapour in to liquid. 3. Geo thermal energy: Temperature of the earth increases at a of 20 –750C per/km when we move down the earth. The energy ut ilised from the high temperature present inside the earth is called geothermal energy. Natural geysers: Hot water or steam comes out of the ground through cracks naturally is called natural geysers. Artificial geysers: Artificially a drill hole up to the hot region and by sending a pipe into it. The hot water or steam is used to rotate the turbine and generate electricity. 4. Bio mass energy: Bio mass: Organic matter produced by plants or animals used as source of energy Bio gas: Mixture of methane, carbondioxide and hydrogen sulphide. Methane is the major constituent. It is obtained by anerobic fermentation of animal dung (or) plant wastes in the presence of water. Environmental Science 30 AITT & H&S  Bio fuels: Fuels obtained by the fermentation of biomass. Ex: Ethanol, methanol Ethanol: Produced from sugar cane. Calorific value is less. Methanol: Obtained from ethanol Calorific value too less. Gasohol: Mixture of ethanol and gasoline India trial is going on to use gasohol in cars and buses. Hydrogen fuel: Hydrogen produced by pyrolysis, photolysis and electrolysis of water. It has high calorific value. Non polluting one because the combustion product is water. Disadvantages: 1. Hydrogen is highly inflammable and explosive. 2. Safe handling is required. 3. Difficult to store and transport. 1.2.8.2.2 NON RENEWABLE ENERGY SOURCES: Energy which cannot be regenerated is called as non-renewable. 1. Coal: It is a solid fossil fuel. Disadvantages: 1. When coal is burnt large amount of CO2 is released which causes global warming. 2. S, N produces toxic gases during burning. 2. Petroleum: Crude oil is a liquid consists of more than hundreds of hydrocarbons and small amount of impurities. The petroleum can be refined by fractional distillation. In the world level 25% of oil reserves are in Saudi Arabia. At present rate of usage, the world crude oil reserves are expected to get exhausted in just 40 years. Environmental Science 31 AITT & H&S  3. Liquefied petroleum gas (LPG): Petroleum gases obtained during FD and cracking can be easily converted into liquid under high pressure as LPG. It is colorless and odorless gas, but during cylindering mercaptans are added to detect leakage. 4. Natural gas: These are found above oil in oil wells. It is a mixture of methane and other hydrocarbons. Calorific value is high. There are two types. Dry gas and wet gas. 5. Nuclear energy: Dr.H.Bhabha is a father of nuclear power development in India. 10 nuclear reactors are present in India. It produces 2% of India’s electricity. Nuclear energy can be produced by two types of reactions. Nuclear fission and nuclear fusion. Nuclear fission; It is a nuclear change in which heavier nucleus split into lighter nuclei on bombardment of fast moving neutrons. Large amount of energy is released through chain reaction. Ex: Uranium with fast moving neutron gives barium and krypton in addition to three neutrons; in the second stage it gives nine neutrons and so on. This process of propagation of the reaction by multiplication is called chain reaction. Nuclear fission: It is a nuclear change in which lighter nucleus is combined together at extremely high temperature (1 billion 0C) to form heavier nucleus and a large amount of energy is released. Ex: Isotopes of hydrogen combine to form helium molecule. 1.2.8.9 CASE STUDY Wind energy in India: India generating 1200 MW electricity using the wind energy. Largest wind farm situated near Kanyakumari in Tamilnadu. It produces 380 MW electricity. Hydrogen fuel car: General motor company of china discovered a experimental car ( fuel H2) can produce no emission only water droplets and vapors come out of the exhaust pipe. This car will be commercially available by 2010. Environmental Science 32 AITT & H&S  CHAPTER-2 ECOSYSTEMS AND BIODIVERSITY Concepts of an Ecosystem – Structure and Function of an Ecosystem – Producers, Consumers and Decomposers – Energy Flow in the Ecosystem – Ecological Succession – Food Chains, Food Webs and Ecological Pyramids – Introduction, Types, Characteristic Features, Structure and Function of the (A) Forest Ecosystem (B) Grassland Ecosystem (C) Desert Ecosystem (D) Aquatic Ecosystems (Ponds, Streams, Lakes, Rivers, Oceans, Estuaries) BIODIVERSITY Introduction to Biodiversity – Definition: Genetic, Species and Ecosystem Diversity – Biogeographical Classification of India – Value of Biodiversity: Consumptive Use, Productive Use, Social, Ethical, Aesthetic and Option Values – Biodiversity at Global, National and Local Levels – India as a Mega- Diversity Nation – Hot-Spots of Biodiversity – Threats to Biodiversity: Habitat Loss, Poaching of Wildlife, Man-Wildlife Conflicts – endangered and Endemic Species of India – Conservation of Biodiversity: In-Situ and Ex-Situ conservation of Biodiversity. Field Study of Common Plants, Insects and Birds. 2.1 ECOSYSTEMS 2.1.1INTRODUCTION: ECOLOGY:  The term was first coined by Hons Reiter and Haekel in 1869.  The term ecology (Okekologie) is originated from two Greek words Oikos (eco) – means “house” (or) place of living and “ology” means “the science of (or) the study of. Hence, ecology is the branch of science that deals with the study of the pattern of relations between the organism and their environment. (OR)  Ecology is the study of interactions among organisms (or) group of organisms with their environment. (OR)  Ecology is the study of ecosystems. ECO SYSTEM:  In 1935, the British ecologist A.G.Tansley coined the term “eco system”. Environmental Science 33 AITT & H&S   The term “eco system” is made up of two Greek words. “Eco” means ecological sphere (or) house (or) place of living (or) surroundings (or) Environment, w here living organism does exist while “system” means “group of organisms joined in regular and interdependent manner. Hence,  A group of organisms interacting among themselves and with environment is known as ecosystem. (OR)  A system of interaction of organisms with their surroundings (i.e., environment) is called as “ecosystem”. Examples: Pond, lake, ocean, forest and desert…. Etc are some of the examples of the ecosystems. 2.1.2 FUNDAMENTAL CHARACTERISTICS OF ECOLOGY STRUCTURE:  Living /Biotic  Non-Living /Abiotitic PROCESS:  Energy flow  Cycling of matter CHANGE:  Dynamic (Not static)  Succession etc. FUNCTION:  Food chain  Food web  Ecological pyramids  Energy Flow  Cycling of matter 2.1.3 CHARACTERISTICS OF ECOSYSTEM  Eco system is the basic functional unit of ecology.  It contains both biotic and abiotic components. Environmental Science 34 AITT & H&S   The function of ecosystem is related to the cycling of matter (materials) and flow of energy.  The amount of energy needed to maintain an ecosystem depends on its structure.  Ecosystem passes from a less complex state to more complex state, which is called as “ecological succession”. 2.1.4 CLASSIFICATION OF ECOSYSTEM:  The ecosystem can be generally classified into two types: 1. Natural Ecosystem 2. Artificial Eco system 1. NATURAL ECOSYSTEM:  A natural ecosystem is developed and governed by nature.  These are capable of operating and maintaining themselves without any major interference by man.  The following are the two types of natural ecosystem based on their habitat. 1. Terrestrial Ecosystem. 2. Aquatic Ecosystem. 1) Terrestrial Ecosystem:  This ecosystem is related to land. Examples: Grassland ecosystem. Forest ecosystem, and Desert ecosystem etc. 2) Aquatic Ecosystem:  This ecosystem is related to water, it is further sub divided into two types based on salt content. i. Fresh Water Ecosystem: a. Running Water Ecosystems Examples: Rivers, streams (small narrow rivers) b. Standing Water Ecosystems Examples: Pond, lake & well, etc ii. Marine Ecosystem: Examples: seas and sea shores Environmental Science 35 AITT & H&S  2. MAN MADE (OR) ARTIFICIAL ECOSYSTEM: An artificial ecosystem is created and maintained by man for his different needs. Examples: Reservoirs, Artificial lakes and gardens, etc. 2.1.5 STRUCTURE (OR) COMPONENTS OF AN ECOSYSTEM:  The term structure refers to various components. So, the structure of an ecosystem explains the relationship between the abiotic (non-living) and the biotic (living) components.  Each and every ecosystem has two major components are: 1. Biotic (living) components. 2. Abiotic (Non-living) components. Biotic Components Eco System Abiotic Components Fig: Components Of Ecosystem 1. Biotic Components: The living component of an ecosystem is called “Biotic component”. Examples: Plants (Producers) Environmental Science 36 AITT & H&S  Animals (Consumers) and Micro Organisms (Decomposers)  The biotic components of an ecosystem are classified into three types based on how they get their food. A. Producers (Autotrophs) : Plants B. Consumers (Heterotrophs) : Animals C. Decomposers (Saprotrophs) : Micro organisms. A. Producers (or) Autotrophs (Auto=self, troph=feeder)  Self food producing organisms are known as autotrophs. Examples: All green plants and trees.  Producers synthesize their food themselves through photosynthesis. Hence they are also called “Photo autotrophs”. (photo = light) B. Consumers (or) Heterotrophs (Hetero = other, troph = feeder:  Consumers are organisms, which cannot prepare their own food and depend directly (or) indirectly on the producers. Examples: Plant Eating Species: Insects, rabbit, goat, deer, cow, etc. Animals Eating Species: Fish, lions, tigers, etc.  Depending upon the food habits the consumers are divided into four types. i. Herbivores (or) Primary Consumers (Plant Eaters) ii. Carnivores (or) Secondary Consumers (Meat Eaters) iii. Omnivores (or) Tertiary Consumers (With plant & meat eaters) iv. Detritivores (dead organism eaters) i. Herbivores: (Herbi = the green plant & Vorare = to devour)  Animals that eat only plants are called Herbivores.  They directly depend on the plants for their food. So they are called Plant eaters. Examples: Insects, goat, deer, cow, horse, etc. ii. Carnivores: (Carne = flesh meat & Vorare = to devour)  Animals that eat other animals are called carnivores. Environmental Science 37 AITT & H&S   They directly depend on the herbivores for their food. Examples: Frog, cat, snake & foxes, etc. iii. Omnivores: (Omni = whole comes from “ohm” & Vorare = to devour)  Animals that eat both plants and animals are called omnivores.  They depend on both herbivores and carnivores for their food. Examples: humans, tigers, lions, rats and fox etc. iv. Detritivores: (Detritifeeder)  Animals that eat dead organisms and waste of living are called detritivores. Examples: beetles, termites, ants, crabs, earthworms, etc. C. Decomposers (or) Saptrotrophs: (Sapros = Rotten, trophos = feeder)  Decomposers attack the dead bodies of producers and consumers and decompose them into simple compounds. During the decomposition inorganic nutrients are released.  The organisms which break down the complex compounds into simple products are called decomposers (or) reducers. Examples: micro-organisms such as bacteria and fungi, etc. 2. Abiotic Components:  The non-living component of an ecosystem is called “abiotic component”  These non-living components enter the body of living organism, take part in metabolic activities and then return to the environment. The abiotic component of the ecosystems divided into three portions. 1. Climate factors : Solar radiation, temperature, wind, water current, rainfall, etc. 2. Physical factors : light, fire, soil, air, etc. 3. Chemical factors : Organic and Inorganic substances. Chemical Factors Organic Substances Inorganic Substances Environmental Science 38 AITT & H&S  2.1.6 FUNCTION OF AN ECOSYSTEM:  The function of an ecosystem is related to the cycling of materials (matter) and flow of energy. 2.6.1 Types of functions:  Functions of an ecosystem are of three types: 1. Primary Function: The producers (plants) can make their food themselves through photosynthesis. This process is called primary function of eco system. Examples: All green plants and trees. 2. Secondary Function: The consumers (animals and humans) cannot make their own food. They are always depending upon the producers for their energy. This is called secondary function of eco system. 3. Tertiary Function: Decomposers attack the dead bodies of consumers and producers and decompose them into simpler compounds. During the decomposition inorganic nutrients are released. Examples: Micro organisms like bacteria and fungi, etc. The functioning of an ecosystem may be understood by studying the following terms: A. Food chains B. Food webs C. Food pyramids (or) Energy pyramids D. Energy and material flow. A. Food Chain:  Anything which we eat to live is called food.  Food contains energy.  Food can be transferred from one organism to the other.  The process of transfer of food (energy) from one organism to a series of organisms is called as “food chain”.  A food chain always starts with a plant life and end with animal life. Thus, a food chain is a picture (or) model that shows the flow of energy from autotrophs (producers) to series of organisms in an environment, as shown in the following figure. Environmental Science 39 AITT & H&S  Producers Herbivores Carnivores Omnivores Decomposer SUN Figure: Schematic representation of food chain.  Infact, all the food chains starts with the sun. The sun provides energy for plants.  The producers (plants) can make their food themselves with the help of the sunlight, chlorophyll, water and air. The consumers, including animals and humans, cannot make their own food. They are always depending upon the producers for their energy.  Decomposers are the micro-organisms that break down the dead animals and plants and release nutrients that become part of the soil, which are re-used by new plants, back to the starting point of the food chain. Types of food chain: Three basic types of food chains are found in a typical eco system. They are: 1. Grazing food chains. 2. Detritus food chains. 3. Parasitic food chains. 1. Grazing food chains:  Grazing food chain starts with green plants (producers) and goes to decomposer food chain (or) detritus food chain through herbivores and carnivores.  It has two types : a. Terrestrial food chain and b. Aquatic food chain a. Terrestrial food chain: Food chain on land is called terrestrial food chain. Example: Grassland food chain Forest land food chain Desert land food chain Grass land food chain Grasses Grasshoppers Frog Snake Eagles Forest food chain Environmental Science 40 AITT & H&S  Green plants Deer Tiger (or) lion b. Aquatic food chain : This food chain is slightly different from terrestrial food chain. It is seen in aquatic (water) eco system. Food chain in water is called “Aquatic food chain”. Example: Marine food chain Example: Ocean Fresh water food chain Example: Pond, lake, streams, etc. Food chain in a pond Phytoplankton Zoo Plankton Small fish Large fish Man Marine Food chain: Sea Weeds Small fish Large fish Sharks and other animals Figure: Food chain Grazing food chain Detritus food chain Parasite food chain Terrestrial food chain Aquatic food chain Marine food chain Fresh water food chain Standing water food chain Running water food chain Environmental Science 41 AITT & H&S  2. Detritus’ food chain: Detritus food chain starts with dead organic matter (plants and animals) and goes to decomposer through consumers. Detritus food chains, independent of solar energy, but they depend on influx of dead organic matter. Example: Dead Plants Soil mitts Algae Crabs Small fish Large fish 3. Parasitic food chain: Parasitic food chain operates in many ecosystems. In this food chain either consumer (or) producer is parasitized and the food passes to smaller organisms. A parasitic food chain involves host parasite hyper parasites’ links. Example: Trees Fruit eating birds Lice & Bugs Bacteria Fungi B. Food Web:  Web means “network” such as spider’s web, World Wide Web (WWW) etc.  So, food web is a network of food chains.  In a food web many food chains are inter connected, where different types of organisms are connected at different tropic levels, so that there are a number of options of eating and being eaten at each tropic level. Thus, there is a inter connecting of various food chains are called food webs and as shown in following figure. Bird(Eagle) Snake Fish Insect Frog Grass Grasshopper Environmental Science 42 AITT & H&S  Figure: Food Web Sparrow Hawk Snake Insect Mouse Cat Lizard Grain Grass This food web shows many linear food chains. These linear food chains are inter connected with other food chains operating in the eco system to form a food web. The grazing food chains are as follows:  Grains Mouse Cat  Grains Mouse Hawk  Grains Mouse Snake Hawk  Grains Insect Sparrow Hawk  Grass Insect Lizard Snake Hawk  Grass Insect Sparrow Snake Hawk The above food web is a simple one. Much more complex food webs do exist in nature. C. Ecological Pyramids:  The concept of ecological pyramids was first developed by British ecologist Charles Elton in 1927.  Ecological pyramids are the diagrammatic representation of tropic structures in which the tropic levels (i.e., tiers) are depicted in successive stages.  An ecological pyramid is shown in the following figure. Environmental Science 43 AITT & H&S  Apex Tertiary Consumers (Omnivores) Decrease in number (or) Biomass (or) Energy Secondary Consumers (Carnivores) Primary Consumers (Herbivores) Producers Base Figure: Formation of an Ecological Pyramid  In ecological pyramids, tropic levels are shown in the following manner: i. The producers represent first tropic level in the ecological pyramid. ii. The herbivores (or) primary consumers represent second tropic level in the ecological pyramid. iii. The carnivores (or) secondary consumers represent third tropic level in the ecological pyramid. iv. The omnivores (or) tertiary consumers represent fourth tropic level in the ecological pyramid.  On the basis of the number of organisms, the biomass of organisms and energy flow in organist population. Three types of ecological pyramids are: 1. Pyramid of numbers. 2. Pyramid of biomass 3. Pyramid of energy. Environmental Science 44 AITT & H&S  1. Pyramid of numbers:  It shows the number of individual organisms present in each tropic level.  It is expressed in numbers per unit area.  Depending upon the type of ecosystem, we have three types of pyramid of numbers. a. Upright pyramid of numbers. b. Partly upright pyramid of numbers. c. Inverted pyramid of numbers. 1. Upright Pyramid of numbers:  The number of individual organisms gradually decreases from lower tropic level to higher tropic level is called “upright pyramid of numbers”. Example: A grassland ecosystem and a pond ecosystem show an upright pyramid of numbers.  The producers in the grass lands are grasses, which are small in size and large in numbers. So, producers occupy lower tropic level (1 s t tropic level).  The primary consumers (herbivores) are rats, which occupy the II tropic level. Since the numbers of rats are lower when compared to the grasses, the size of which is lower.  The secondary consumers (carnivores) are snakes, which occupy the III tropic level. Since the numbers of snakes are lower when compared to the rats, the size of which is lower.  The tertiary consumers (omnivores) are eagles, which occupy the IV tropic level. The number and size of the last tropic level is lowest.  Similarly, in the case of pond ecosystem, producers, herbivores and carnivores are decreases from lower tropic level to the higher tropic level. Thus, these pyramids are upright.  Therefore, the numbers of individual organisms permit area, decreases from lower tropic level to higher tropic level as shown in figure. Environmental Science 45 AITT & H&S  Apex Large Tertiary Consumers Fish Distance in Number Secondary Consumers Small Fish Primary Consumers Zoo Plankton Ex: Protozoa In Number Producers Phytoplankton (Algae) Base Large Fish Tertiary Consumers Small Fish Secondary Consumers Zoo Plankton Ex: Protozoa Primary Consumers Phytoplankton (Algae) Producers Figure: Pyramid of numbers in an aquatic (pond) ecosystem Environmental Science 46 AITT & H&S  2. Partially Upright Pyramid Of Numbers:  A forest eco system is an example of partially upright pyramid.  In a forest eco system, big trees are the producers, which are less number. So, these producers occupy the lower tropic level which is narrow base.  The primary consumers (herbivores) are birds, insects, which occupy the II tropic level. Since the number of birds, insects and other species are higher when compared to the trees, the size of which is broader.  The secondary consumers (Carnivores) are fox, snakes, lizards, which occupy the third tropic level. Since the number of fox, snakes are lower when compared to the birds, insects the size of which is lower.  The tertiary consumers (omnivores) are lion, tiger, which occupy the IV tropic level. Since the number of lion, tiger are lower when compared to the fox and snakes the size of which is very (or) narrow lower. So the pyramid is narrow on both sides and broader in the middle and hence it is called partially upright of number as shown in figure. Tertiary Consumers Lion, Tiger Snakes, Secondary Consumers Foxes Insects, Birds Primary Consumers Trees Producers Environmental Science 47 AITT & H&S  Lion, Tiger Tertiary Consumers Snakes, Foxes Secondary Consumers Insects, Birds Primary Consumers Trees Producers Figure: Pyramid of numbers in the forest ecosystem 3. Inverted Pyramid Of Numbers: The number of individual organisms gradually increases from lower tropic level to higher tropic level, is known as “inverted pyramid of numbers”. Example: Parasitic food chain shows as inverted pyramid of number as shown in the following figure. Hyper parasites-Fleas, Microbes Tertiary Consumers Parasites, Lice & Bugs Secondary Consumers Birds Primary Consumers Trees Producers 2. Pyramid of Biomass:  It represents the total amount of biomass (mass (or) weight of biological material (or) organism) present in each tropic level.  It is expressed in gram per unit area. Environmental Science 48 AITT & H&S   Depending upon the type of ecosystem, we have two types of pyramid of biomass. i. Upright pyramid of biomass. ii. Inverted pyramid of biomass. i. Upright Pyramid Of Biomass:  The pyramid of biomass gradually decreases from the produce level (or) first tropic level to consumer level (higher tropic level) is called “upright pyramid of biomass”  A forest ecosystem showed an upright pyramid of biomass.  In this ecosystem, the biomass decreases from the producer level to consumer levels (as shown in figure) Apex Lion- Tertiary Consumers 10kgs Distance in Number Snakes, Secondary Consumers fox- 100kgs Insects, Birds- Primary Consumers 1000kgs In Number Trees-10000kgs Producers Base Environmental Science 49 AITT & H&S  Lion, Tiger Tertiary Consumers Snakes, Foxes Secondary Consumers Insects, Birds Primary Consumers Trees Producers ii. Inverted pyramid of biomass:  The pyramid of biomass gradually increases from producer level to consumer level are called as Inverted pyramid of biomass.  Example: The pond ecosystem shows an inverted pyramid of biomass.  In this, ecosystem, the biomass increases from producer level to consumer levels as shown in the following figure. Big fish Tertiary Consumers Small fish Secondary Consumers Insect s Primary Consumers Algae Producers Environmental Science 50 AITT & H&S  Big fish Tertiary Consumers Small fish Secondary Consumers Insects Primary Consumers Algae