UNIT 2
Natural Resources
What is a Natural Resource?
The term "Natural resources" was first coined and popularized by E.F....
b) Renewable Resources - the resources which can be renewed and reproduced
by physical, chemical or mechanical processes a...
Differentiate between Renewable and non–renewable
resources?
S. No. Renewable Resources Non-renewable Resources
1. A renew...
4. Conservation of flora & fauna:
• Forest offers a habitat to flora and fauna and, maintenance and
proper functioning of ...
for minimizing these soil movements, particularly shallow landslips
and slump.
Wind-rows and shelterbelts reduce the loss ...
plants. Herbal medicines are a common example of how plants are
utilized to prevent illness.
• Genetic resources for futur...
• Aesthetic, Spiritual and religious functions: Natural forests
contribute to the protection of human health by providing ...
deforestation on hills.
Grazing Land: In North –Western Himalayas, grazing by cattles,
sheeps, and goats is the most impor...
• Flooding: Trees are highly efficient in regulating water quantities,
and also serves as a cover against erosion and once...
• Non commercial farm forestry: Non commercial farm forestry
involves tree planting by farmers on their own land for their...
Write a short note on water resources?
Water is the liquid of life. Along with air, without which humans life cannot survi...
• Ground: Water that collects or flows beneath the Earth's surface, filling the
porous spaces in soil, sediment, and rocks...
Write a note on Floods.
Flood is the most common ecological hazard in India and worldwide. This is due to the
vast geograp...
o Increased agricultural production: They help in meeting irrigation
requirements on a gigantic scale. Dams and reservoirs...
o Socio-cultural Issue: In many cases, the construction of large dams have
negatively affected the cultural heritage by th...
India has a monsoonal climate and the average annual rainfall is 1,170 mm. It
varies from less than 150 mm/year in northwe...
Prospecting and exploration for precious metals, base metals, minerals and
diamonds begins with research to choose target ...
• Air, land and water pollution: Only minor pollution occurs during mineral
exploration but more intense air and water pol...
• Radiation hazards: Exposure to natural radiations emitted by some
radioactive minerals is a major source of health hazar...
7. Declining ecological conditions in agricultural regions:
Demographic and environmental pressures such as population gro...
cause of excess leakage and increase the risk of salinity and water logging in
irrigation areas.
As salts build up in sali...
needs and population grow the pressure on land and other natural resources
continue to increase. It is an important resour...
Define soil and write briefly on soil profile.
Answer: Soil can be defined as a composite mixture of inorganic material, o...
Soil Profile
Define landslides. Give various types of landslides and
with their causal factors
OR
How landslides are cause...
Explain the role of humans as a cause of landslides.
The Human activities/ anthropogenic activities can cause Landslides d...
 Agriculture: With the increase in population the extensive farming
systems, which were traditionally in harmony with the...
the degradation of natural vegetation cover, over-grazing results in a decrease
in the quality of rangelands.
• INDUSTRIAL...
• Contour strip cropping: This is cultivation of soil protecting crops in strips
alternating with erosion permitting crops...
Explain the advantages, disadvantages and ways of
utilization of solar energy.
Solar radiations are the earth’s prime ener...
2. If the solar heat is collected in a fluid, usually water or air, which is then
moved by pumps or fans for use, the sola...
the modular PV system allows designers to create solar power systems that
can meet a wide variety of electrical needs, no ...
2. It is sustainable source of energy (will last as long as sun last)
3. It is clean and does not pollute the air. Wind tu...
Schematic diagram showing hydropower generation
The dam creates a “head” or height from which water flows. A pipe (penstoc...
runoff volume, variability of flow and seasonality of the flow, directly affecting the
resource potential for hydropower g...
Positive impacts
• It is a predictable source of energy (compared with wind and solar), it is
independent of weather and c...
• The turbines are susceptible to bio-fouling i.e.; the growth of aquatic life on
or in the turbine. This can severely inh...
(2) Radioactive decay of elements such as uranium and thorium, and;
(3) Chemical reactions.
Fig. 2.13The Schematic structu...
Benefits
• Using geothermal resources can provide economic development
opportunities especially in rural areas.
• In addit...
• Once a potentially valuable source is found then, tapping the energy may
require an expansion of the power transmission ...
agricultural residues and municipal solid waste (MSW) treatment are used to
generate electricity, heat or both.
Various co...
can be blended in any proportion with petroleum-based diesel and propane as
products. This process involves reacting veget...
Explain the following Non-Renewable Energy sources?
a) Coal: Coal is the world’s most abundant and widely distributed foss...
called as crude oil. Petroleum means rock oil, (Petra – rock, elaion – oil, Greek
and oleum – oil, Latin), the name inheri...
Methane CH4 70-90%
Ethane C2H6
0-20%Propane C3H8
Butane C4H10
Carbon Dioxide CO2 0-8%
Oxygen O2 0-0.2%
Nitrogen N2 0-5%
Hy...
Fig. 2.17 Neutron Induced U235
Nuclear Fission Reaction
• Nuclear Fusion – A fusion reaction occurs when two hydrogen atom...
natural resources to achieve a long term sustainable availability of the natural
resources. We all must work together to c...
• By growing more trees near the houses the micro-climate can be
regulated which will cut off electricity consumption on a...
of 47

Natural resources and related aspects

The term "Natural resources" was first coined and popularized by E.F. Schumacher in the 1970's by his famous book “Small is Beautiful”. A natural resource can be defined as any substance that is present in nature independently of human industry and that is exploited in some or another way by humans. Forest, Water, Minerals, Food, Energy and Land are apparent examples because these are frequently utilized.
Published on: Mar 3, 2016
Published in: Environment      
Source: www.slideshare.net


Transcripts - Natural resources and related aspects

  • 1. UNIT 2 Natural Resources What is a Natural Resource? The term "Natural resources" was first coined and popularized by E.F. Schumacher in the 1970's by his famous book “Small is Beautiful”. A natural resource can be defined as any substance that is present in nature independently of human industry and that is exploited in some or another way by humans. Forest, Water, Minerals, Food, Energy and Land are apparent examples because these are frequently utilized. A flow–diagram to give the classification of Natural resources based on Exhaustibility in various categories. Also define them with suitable examples. Classification of natural resources Classification based on exhaustibility: a) Perpetual Resources – These are resources which exist irrespective of the amount of their usage. With sufficient technology, they provide a huge prospective for use, e.g. Sun, wind and water.
  • 2. b) Renewable Resources - the resources which can be renewed and reproduced by physical, chemical or mechanical processes are known as renewable or replenishable resources. These resources are able to increase their abundance through reproduction and utilization of simple substances. Examples of such resources are water, forests and wildlife, plants etc. we can further divide into continuous or flow and biological. Renewable Resources can be further classified as Living Renewable Resources and Non-Living Renewable Resources. Some examples of renewable resources though they do not have life cycle but can be recycled are wood and wood-products, pulp products, natural rubber, fibers (e.g. cotton, jute, animal wool, silk and synthetic fibers) and leather. • Living Renewable (biological) resources are those renewable resources which come from living (biotic) sources – like forests, plants. • Non-Living Renewable resources are those that renewable resources which come from non-living (abiotic) sources like land, water, air. Example, metals, minerals, wind, sun etc. c) Continuous/ Flow Renewable resources are resources which do not need regeneration. Similar to that of perpetual resources, example wind, tides etc. d) Non-Renewable Resources - this process takes place over a long geological time. Examples of such resources are minerals and fossil fuels. This may take millions of years in their formation. Some of the resources like metals are recyclable and some like fossils fuels cannot be recycled and as such they get exhausted with their use. Non-Renewable Resources can be further classified as Recyclable and Non- Recyclable resources: • Recyclable resources are those which can be processed to be used again and again. 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 (e.g. ores of aluminium, copper, mercury etc.) and deposits of fertilizer nutrients (e.g. phosphate sock and potassium and minerals used in their natural state like asbestos, clay, mica etc) • Non- Recyclable resources are those which once used perish, example coal. These are non-renewable resources, which cannot be recycled in any way. Examples of these are fossil fuels and uranium, which provide 90 per cent of our energy requirements. There are a few substances too which can be recycled a few times, before they completely perish or turn non-renewable resources.
  • 3. Differentiate between Renewable and non–renewable resources? S. No. Renewable Resources Non-renewable Resources 1. A renewable resource is one that naturally replaces itself at a rate near or equal to the rate at which you're using it. Non-renewable resource does not replace itself at the rate it is being used. 2. Renewable resources can be further divided in two types: Living Renewable Resources and Non- Living Renewable Resources Non-Renewable Resources can be further classified into two types: Recyclable and Non- Recyclable resources 3. Advantages: Renewable energy is beneficial because we do not have to worry about its depletion. Renewable energies such as wind and hydropower provides for cleaner, environmentally friendlier power sources. Advantages: Non-renewable resources are easy to use as these are relatively cheap to mine and to convert into energy 4. Disadvantages: Technologies to utilize renewable resources is very costly and do not give much efficiency. Disadvantages: The non- renewable resources are fast depleting and causing a lot of environmental pollution. 5. Example: Hydropower, Wind, Solar energy etc Example: Coal, Oil, Natural gas etc. Give the importance of Forest as resource. The Natural Forests are important due to following reasons: 1. Soil protection: • The forest vegetation protects the soil against water impact thus reducing the splash effect and dis–aggregation of the soil structure. • Forests that prevent landslides, mud flows, rock fall and avalanches from affecting roads, railways, cultivated areas and entire settlements. 2. Soil fertility: • Trees increase the soil's ability to absorb and retain water, produce nutrients for plants, maintain high levels of organic matter in the soil, and moderate soil temperatures. 3. Water conservation: • The foliage, rough bark and abundant litter of trees and forests decrease the speed of water dispersion and favors slow but total infiltration of rainwater. • Forests play a major role in the storage, purification and release of water to surface water bodies and subsurface aquifers.
  • 4. 4. Conservation of flora & fauna: • Forest offers a habitat to flora and fauna and, maintenance and proper functioning of the forest ecological processes. 5. Micro-climate regulation: • Forests have positive effects for the local micro climate by producing shade, coolness, shelter and moisture. They especially influence the temperature in local urban areas (urban heat island effect). 6. Conservation of genetic resources: • Forest genetic resources play a fundamental role in scientific research and in the development of commercial products in a variety of sectors, including pharmaceuticals, biotechnology, and seed and crop industries. 7. Use of varieties for genetic breeding and biotechnology: • Forests are among the world's most important repositories of biological diversity. 8. Integrated watershed management: • Forests prevent or delay surface flow by interception, evaporation, transpiration and infiltration, thus help in watershed management. • Watersheds prevent floods and decrease the stream sedimentation. • Forests and forested watersheds provide water for household, farming, industrial and other needs in downstream areas. Explain the functions of Forest. The functions of Forests can be broadly classified into following categories: 1. Protective functions • Protection from intense radiation: Forest provides space, shade and shelter to animals and lower plants from the intense sun radiation. Trees are an essential part of many traditional agro–forestry systems. They offer shade for crops, animals and humans, make a favourable microclimate and supply feed for livestock • Protection of soil from wind and water erosion: The foliage and strong root system of trees of forests protect the soil from the corroding effects of wind and water. Surface erosion includes sheet, rill and small gully erosion, and is at a minimum in forests. Forests with under storey trees, shrubs and ground over, and forest floor debris protect soil from the impact of falling raindrops (soil dislodgement and splash erosion), overland flow of rainwater as a sheet, or channeling into rills and gullies. Mass wasting consists of landslips, slumps and debris flows (landslides) and, again, forests are the most effective vegetative cover
  • 5. for minimizing these soil movements, particularly shallow landslips and slump. Wind-rows and shelterbelts reduce the loss of nutrient rich topsoil and protect young plants from wind within their zone of influence. • Protection water resources from soil sedimentation: The product of erosion is sediment which deposit in stream channels or standing water bodies (such as ponds, lakes and reservoirs). Sediment can damage or kill precious aquatic life; harm water quality for drinking, domestic use or industry; reduce reservoir capacity for flood control, hydropower, irrigation or low flow augmentation; interfere with navigation; shorten the useful life of hydro-turbines or pumps; and build up river channel beds, aggravating flooding. • Prevention of drought and Floods: Forests shield water by reducing surface erosion and sedimentation. They control water yield and flow thus, moderate floods and improve rainfall. • Protection from Natural disasters: Forests ecosystems offer defense from extreme events such as hurricanes, tsunamis, high tides, floods, droughts, etc. For example, mangroves and coral reefs shield coastal areas from storm surge; vegetation cover on slope can help prevent erosion and mudslides. 2. Productive functions • Provides Food: For the majority of rural people, forest food adds variety to diets, improves palatability, and provides essential vitamins, minerals, protein and calories. Forest and farm tree resources serve to complement existing food resources and income. Forest fruits and nuts are the regular snack food, particularly for children. • Provides wood and Fuel wood: Of all the products derived from forests, timber and fuel wood is one of the most prominent. Contribution from forests to industries includes manufacture, furniture, village woodwork, harvesting, industrial, matches, particle board, sports goods, ply–wood, fibre board, boats, crates and boxes, railway ties, paper, pulp, chip board etc. Forests contribute fuel wood, which is the main source of household energy. • Provides Medicines: A large number of rural populations rely on traditional medicines harvested from the forests, for curing their ailments. Numerous medicines contain components made from
  • 6. plants. Herbal medicines are a common example of how plants are utilized to prevent illness. • Genetic resources for future utilization: The amazing rich natural diversity, characteristics of most forest species in the world, must be conserved for the future, in order to facilitate use of the best forest resources for timber, NTFP (Non–timber Forest produce) and services. Forest genetic resources may contribute the potential for adaptation for adapting to future climate changes. Moreover, conservation of genetic resources will be a prerequisite for future generations to be able to breed crop varieties and face new challenges. 3. Regulatory functions • Regulation of climate: The forests play a vital role in regional climate regulation by their interaction with water cycles and contribute significantly to continuous water supply in small- and large- scale water cycles. Planting trees in cities provides shade and increases the evaporation of water. This cools the microclimate and can reduce the costs of artificial air conditioning. • Regulation and purification of water: Forests ecosystems have strong water retention capacities. Forests regulate water flow and quality and store nutrients in soil. Natural wetlands can process and filter pollutants such as metals, viruses, oils, excess nutrients, and sediment. Forests retain water and slowly filter it through the ground. • Regulation of nutrients: Forests play an important role in nutrient regulation and circulation. Through the process of denitrification, for example, bacteria in wet forest soils convert nitrates — a nutrient that can lead to harmful algal blooms if too much of it enters bodies of water—into nitrogen gas, releasing it into the air instead of into local streams. • Absorption of pollutants: Forests perform the function of lowering the pollution levels. In addition to that they also act as noise and dust absorbers. They also help in reducing acid rain, absorbing carbon monoxide and in carbon sequestration. 4. Accessory functions • Habitat for diverse wildlife: Wildlife is an integral part of any healthy forest community. Natural Forests provide habitat to wild plants and animals and thereby contribute to the (in situ) conservation of biological and genetic diversity and the evolutionary development.
  • 7. • Aesthetic, Spiritual and religious functions: Natural forests contribute to the protection of human health by providing prospects for reflection, spiritual enhancement, cognitive progress, recreation and aesthetic experience. • Recreation and ecotourism: Forest and other recreational areas are important for our well-being, development and social relations. Most people derive a sense of calm and serenity from spending time in nature. Ecotourism has huge potential for alleviating poverty and improving human well-being for under developed countries. • Education: Forests can enrich and contribute to total quality of a children’s overall educational experience. It is also important for the young generation to know about the nature and significance of its preservation and management for the future. • Cultural heritage: It has been well documented that forests play a very important role in shaping human culture. For example sacred groves have an important place in the cultures of tribes residing forests. Define deforestation, and explain factors responsible for deforestation. Deforestation: The term deforestation refers to clearing or cutting down or destruction of natural forests for the various developmental activities. The factors responsible for deforestation are: Urban Construction: The Forests are removed to make way for the development of urban areas. Trees are cut down for lumber that is used for building materials, furniture, and paper products which creates a major impact on forest life. This results in loss of forest area and massive deforestation. Agriculture: • Expansion of agriculture: With growing population we need to feed more mouths. Natural Forests are cleared to give space for growing crops, building farms and other lands for agricultural purposes. • Shifting cultivation/Jhum cultivation/slash or Burn cultivation: Shifting cultivation or slash and burn is a farming system in which natural forest lands are cleared and used for the purpose of farming. They are utilized until the soil loses its fertility and then abandoned. This was mainly practiced by the tribal groups of North east India. • Extension of cultivation on hill slopes: The rampant expansion of farming on the hill slopes has been the major cause of
  • 8. deforestation on hills. Grazing Land: In North –Western Himalayas, grazing by cattles, sheeps, and goats is the most important cause of depletion of the vegetation cover and soil erosion. Most of the deforested land ended up as pasture to raise cattle in widespread grazing systems. Used for Fuel: Wood has been the primary fuel since ages. Wood fuels are still a major source of energy for people in developing countries Trees are cut down to be utilized as firewood or turned into charcoal ( by burning wood in a low-oxygen environment.), which are used for cooking and heating purposes. Dam construction: The Submergence of forest land in river valley projects as the dams require large reservoirs for water storage. The reservoir flooding leads to a loss of large area of natural forests. Illegal Logging/Timber extraction: The illegal timber extraction or illegal logging and corruption have been recognized as key drivers of forest degradation. Illegal logging exists because of the rising demand for timber, paper, and derivative products (including packaging). Forest Fires: Forest fires are one of the important natural threats leading to decline of natural forests. Forest fires can be natural as well as man–made. Natural fires are set off by lightning and dry conditions can cause forest loss whereas man–made fires are sometimes intentional (for clearing purposes) or accidental (escaped fires). Mining projects: In order to undertake mining projects, trees and vegetation are cleared and burned. The open pit mining requires clearing of natural forests and after the mining is finished the attempts of re– vegetation of the area are rarely successful. Briefly discuss the ill-effect of deforestation. The ill effects of deforestation can be categorized under two categories: A. LONG TERM EFFECTS • Climate change: Together with oceans our forests, are the largest carbon sink on this planet which help to regulate climate and temperature. • Loss of biodiversity: Collectively with forests numerous animals and plans that depend on them will also die. Rainforests for example are areas of the richest biodiversity on Earth, and if we continue to destroy them many animals and plants will become extinct. B. SHORT TERM EFFECTS
  • 9. • Flooding: Trees are highly efficient in regulating water quantities, and also serves as a cover against erosion and once they are removed, excess of surface run–off can lead to flooding downstream. • Soil erosion: As discussed above the loss of vegetation cover exposes the soil to erosion caused by wind and water. • Loss of watersheds: The loss of trees affect the hydrological cycle. When Forest Mountains are cleared, watersheds are degraded and this leads to the loss of sustained water supply for valley population. • Displacement of indigenous communities: The loss of natural forests lead to loss of local tribal communities and their traditional way of life. (a) Social Forestry: The rapid rate of deforestation in India has led to a large number of problems. With the loss of forest cover the satisfaction of basic requirements of forest products of the rural people, like fuel, fodder etc. have become more and more difficult. To supply the rural people with these necessities and to develop the rural eco-system social-forestry programmes were launched in India. The term social forestry first came to prominence in the 1976 report of the National Commission of Agriculture in India, in which it was used for a programme of activities to encourage those who depended on fuel wood and other forest products to produce their own supplies in order to lighten the burden on production forestry. Government of India has implemented the social forestry programme with the objectives to encourage the farmers to grow forest species (supplied to them free of cost) in their fields and along the boundaries to enhance their income, reduce soil erosion, conserve soil moisture, reduce pollution and to provide them wood for making farm implements and timber for construction of houses. The main driving force of social forestry is to decrease pressure on the traditional forest areas by developing plantation of fuel wood, fodder and grasses. The social forestry system has various components such as – • Agro–forestry: It involves the planting of trees and agricultural crops either on the same land or in close association in such. • Community forestry: The community forestry involves the raising of trees on public or community lands aimed at providing benefits to the community as a whole. • Commercial form forestry: Commercial farm forestry involves growing of trees in the fields in place of food and other agricultural crops.
  • 10. • Non commercial farm forestry: Non commercial farm forestry involves tree planting by farmers on their own land for their own use and not for sale. The land mainly used for this purpose includes margins of agricultural fields, wastelands and marginal lands which are not usually cultivated. (b) Agroforestry: Agroforestry is any sustainable land-use system that preserves or enhances total yields by combining food crops (annuals) with tree crops (perennials) and/or livestock on the same land, either simultaneously or sequentially, using management practices that suit the social and cultural characteristics of the local people and the economic and ecological conditions of the area. Types of Agro Forestry: There are different types of agro forestry which are characterized on the basis of their growth or combination with forestry. • Silvopasture agro forestry (It introduces forage crops into a forest for animals to graze) • Silvoarable agro forestry (It combines woods with traditional arable crops, particularly winter varieties that can thrive in deciduous forests) • Forest forming (In forest farming harvests high-yield crops, including specialty mushrooms such as shiitake, nuts, honey and forest fruits) • Forest gardening (It involves the cultivation of shrubs, flowers and perennial plants in a wooded setting) (a) Joint Forest management: The initiation of Joint Forest Management (JFM) programme can be traced to the Arabari, Midnapore district experiment initiated by forest officials in the state of West Bengal. This experiment provided a strong feedback for incorporation of the Joint Forest Management system in the National Forest Policy of 1988. The main objective of JFM was to develop procedures, methods and tools which involve villagers in the sustainable management of State Production Forests (SPF) and the village forests. As per the provisions of National Forest Policy 1988, the Government of India, outlined and conveyed to State Governments a framework for creating massive people’s movement through involvement of village committees for the protection, regeneration and development of degraded forest lands. Joint Forest Management (JFM) programme by the Government of India for involving the forest dwelling communities in the management of forests since 1990 has been implemented by most of the states in the country. In JFM villagers agree to assist the State Forest officials in the safeguarding of forest resources through protection from fire, grazing, and illegal harvesting in exchange for which they receive non-timber forest products (NTFP’s) and a share of the revenue from the sale of timber products.
  • 11. Write a short note on water resources? Water is the liquid of life. Along with air, without which humans life cannot survive, water is one of our most essential natural resource. Water comprises approximately 66% of the weight of an adult Human. Pure water is a colorless, odorless, and tasteless liquid. The depth and light give it a blue or bluish-green tint. Tastes and odors in water are due to dissolved gases, such as sulfur dioxide and chlorine, and minerals. The total amount of water in the world is almost constant. It is estimated to be 370,000 quadrillion gallons, 97% of which is the water in the oceans, which is salty and unfit for human consumption without an expensive treatment. The remaining 3% is known as fresh water, but 2% of that is the glacier ice trapped at the North and South Poles. Only 1% is available for drinking water. There are two main water supplies: • Surface: Surface water supply is the water from the lakes, reservoirs, rivers and streams. These water bodies are formed of water from direct rain, runoffs, and springs. A runoff is the part of rain water that does not infiltrate the ground or evaporate. It flows by gravity into the water body from the surrounding land. This drainage area is known as the watershed. World water resources
  • 12. • Ground: Water that collects or flows beneath the Earth's surface, filling the porous spaces in soil, sediment, and rocks. Groundwater originates from rain and from melting snow and ice and is the source of water for aquifers, springs, and wells. The upper surface of groundwater is the water table. Write a note on Drought. Drought is defined as a period in which a region has a deficit in its water supply. Due to continual shortage of water the conditions push towards the extreme dry lands. It is not easy to determine the time when it’s started or ends. Its impact often builds up slowly over a long period of time and may prolong from months to years even after the declaration of drought ends. Droughts result from severe water shortage due to lack of rains over long periods of time disturbing various human activities and lead to problems like crop production failure, depleted ground water level, depletion in water bodies like lakes/ rivers/ reservoirs, shortage of drinking water and, reduced feed availability for animals, famine etc. Droughts are responsible for millions of death due to food crisis in many part of the world every year. There are mainly three types of drought reported namely Hydrological drought, Agricultural drought and meteorological drought: • Hydrological drought is referred to the condition when precipitation is low than the usual rainfall for prolonged period. • Agricultural drought usually occurs when moisture content in soils is insufficient to maintain average crop yields. • Meteorological drought is a condition resulted from the global atmospheric disturbances. It is determined by amount of dryness and the duration of the drought. Causes: As we are aware drought is condition arises from scarcity in water supply, it can be caused by a several factors. The most important of all is the amount of rainfall in an area. Prolonged lack of rainfall dried out the areas and other factors falls into. The water vapour content is high in the low pressure zone but for any reason if there is dryness in the air or a high pressure zone is created, less moisture content is available to produce rainfall resulting into drought. According to some meteorologist it can also occurred as a negative impact of El Nino because it can shift the air masses above the ocean, often making wet places dry (drought prone) and dry places wet. Anthropogenic activities in catchment areas and watershed such as deforestation for agriculture, urbanisation, construction of roads and railway tracks etc. can also cause drought. Here, the removal of top soil results into the poor absorption of water during precipitation resulting in to lowering of ground water level finally leading to drought conditions.
  • 13. Write a note on Floods. Flood is the most common ecological hazard in India and worldwide. This is due to the vast geographical distribution of river floodplains and low-lying coastal areas. Flood is defined 'an overflowing of water onto normally dry land'. It also has a characteristic appearance of land cover with water which is usually dry in whole year. Occurrence of Floods depends on intensity and amount of precipitation, volume, timing, size and pre-conditions of rivers and their drainage basins. Presence of snow and ice, soil profile, moisture content of the soil, infrastructure and buildings and existence of embankment, dams, or reservoirs makes the river basin more fragile and prone to floods. Human intrusion into flood prone areas and lack of flood response mitigation plans amplify the damage potential. Generally floods are classified into Coastal floods, River floods, Flash floods, Groundwater floods and Sewer floods. A unique combination of climatic and geographic factors creates suitable conditions for the occurrence of floods. There are various factors from natural to man-made contributing in the occurrence of flood are given below: Effects: Floodwater can seriously disturb public and personal transport by blocking roads and railway lines, as well as communication links when telephone lines are damaged. It damages the property for e.g. houses and cars by forcefully washing them away or through direct contact with floodwater, which may be contaminated. Floods usually damage the normal functioning of the drainage systems in cities, accompanied by sewage spills, which pose a great threat and a grave concern for outbreak of serious health hazard, along with standing water and wet materials in the home. Microorganisms like bacteria mould and viruses, cause disease, trigger allergic reactions, and continue to damage materials long after a flood. Floods are responsible for soil erosion as top fertile layers are eroded by large amounts of fast flowing water, ruining crops, destroying agricultural land / buildings and drowning farm animals. Enlist the advantages and disadvantages of Construction of Dams. Dams have been used for thousands of years to regulate river flows and ensure adequate supply of water during dry periods. Their impacts come as advantages and disadvantages. The advantages of the Dams are: o Increased water availability for domestic and industrial purposes: Due to large variations in hydrological cycle, dams and reservoirs are required to be constructed to store water during periods of surplus water availability and conserve the same for utilization during lean periods when the water availability is scarce.
  • 14. o Increased agricultural production: They help in meeting irrigation requirements on a gigantic scale. Dams and reservoirs are most needed for meeting irrigation requirements of developing countries, large parts of which are arid zones. o Protection from floods and droughts: Floods in the rivers have been many a time playing havoc with the life and property of the people. Dams and reservoirs can be effectively used to control floods by regulating river water flows downstream the dam. o Generation of hydroelectric power: Energy plays a key role for socio- economic development of a country. Hydro power provides a cheap, clean and renewable source of energy. Hydro power is the most advanced and economically viable resource of renewable energy. o Navigation: Enhanced inland navigation is a result of comprehensive basin planning and development, utilizing dams, locks and reservoirs that are regulated to play a vital role in realizing large economic benefits of national importance. o Recreation: The reservoir made possible by constructing a dam presents a beautiful view of a lake. In the areas where natural surface water is scarce or non-existent, the reservoirs are a great source of recreation. Along with other objectives, recreational benefits such as boating, swimming, fishing etc linked with lakes are also given due consideration at the planning stage to achieve all the benefits of an ideal multipurpose project. The disadvantages associated with the construction of Dams are: o Resettlement and Rehabilitation of displaced population: The displacement caused by large scale irrigation and hydro-projects has been a reason for concern from past many years. Large scale water resource management initiatives rarely include an assessment of the displacement to be caused, or of the costs of rehabilitation. o Effects on forests: The environmental impacts associated with large scale dams often have major negative impacts on the forests. Human settlements and forests located in areas that are inundated have to be demolished and removed in order to increase navigability on the river. The loss of forests and agricultural lands leads to erosion and the buildup of sediment at the base of the river and reservoir. o Sedimentary issues: One of the primary problems with dams is the erosion of land. Dams hold back the sediment load normally found in a river flow, depriving the downstream of this.
  • 15. o Socio-cultural Issue: In many cases, the construction of large dams have negatively affected the cultural heritage by the submergence and destruction of cultural resources such as shrines, buildings, artifacts, burial sites, and sacred landscapes etc. o Safety aspects: The major issue associated with the safety of dams pertaining to the safety of the local community is the risk of dam failure. Dam failures are most likely to happen for one of five reasons. (a) Overtopping caused by water spilling over the top of a dam, (b) Structural failure of materials used in dam construction, (c) Cracking caused by movements like the natural settling of a dam, (d) Inadequate maintenance and up keep and (d) Piping—when seepage through a dam is not properly filtered and soil particles continue to progress and form sink holes in the dam. o Species Extinction: As fisheries become an increasingly important source of food supply, more attention is being paid to the harmful effects of dams on many fish and marine mammal populations. Discuss the reasons behind the conflicts over water. Climate change in combination with fast population growth and urbanization is putting an intense pressure on South Asia’s most precious resource: water. According to the Asian Development Bank, Per capita water availability in the region has decreased by 70 percent since 1950.The uneven distribution of water in space and time and a sturdy raise in the need of water utilization (which are not necessarily limited to areas having adequate water supplies) make water a scarce resource. The conflicts occur mostly over freshwater; since freshwater resources are necessary, yet limited, they are the center of water disputes arising out of need for potable water. As freshwater is a vital, yet unevenly distributed natural resource, its availability often impacts the living and economic conditions of a country or region. River water flows does not respect any administrative boundary. Most of the larger rivers in India meander through the administrative boundaries of the Indian federal system. The Transboundary Rivers have significant implications for water usage and policymaking, especially because while India has around 16% of the population and 2.45% of the land area of the world, it has only 4% of its water resources. In gross national terms the availability of water is comfortable. But this situation can easily change with increased demand due to changing patterns of economic growth and urbanization. Further, there is a large variation in terms of both spatial and temporal aspects. Spatially speaking with respect to water, the northern and eastern parts of the country are better endowed as compared to the western and southern. The less endowed regions with respect to water are located in arid parts in the states of Rajasthan, Gujarat, Maharashtra, Karnataka, Andhra Pradesh and Tamil Nadu that lie in one rain shadow region or the other.
  • 16. India has a monsoonal climate and the average annual rainfall is 1,170 mm. It varies from less than 150 mm/year in northwestern Rajasthan to more than 10000 mm/year of rainfall in Meghalaya. Therefore, the storing and subsequent usage of water is of utmost importance. It is this imperative to store water that creates potential for conflicts over trans boundary rivers Indeed, the interstate water disputes in India have been on rise in recent years. The frequent repetition and long negotiations produce various kinds of insecurities and impact people's livelihoods. Table no. 2.1 some of the Rivers facing disputes over water in India River(s) States Involved Krishna Andhra Pradesh, Maharashtra, Tamil Nadu and Karnataka, Godavari Andhra Pradesh, Maharashtra, Madhya Pradesh and Orissa Yamuna Himachal Pradesh, Delhi, Haryana, Uttar Pradesh and Rajasthan Cauvery Tamil Nadu, Karnataka and Kerala Ravi-Beas Haryana, Jammu-Kashmir, Rajasthan and Punjab Bhakra-Nangal Haryana and Punjab Narmada Maharashtra, Madhya Pradesh, Gujarat and Rajasthan Define Minerals and what is the importance of minerals as a resource? Definition: Minerals can be defined as naturally occurring materials obtained from the earth. Some examples are coal, petroleum, natural gas, iron, copper, gold, etc. Some of them are also taken up by plants from the Earth's surface, and are transferred to humans through food. Give the steps of Mineral exploration. The following are the steps/stages of Mineral exploration and development: 1. PROSPECTING AND EXPLORATION
  • 17. Prospecting and exploration for precious metals, base metals, minerals and diamonds begins with research to choose target areas for exploration and taking samples from areas that look like they might have minerals. Exploration includes prospecting, mapping and surveying, either on the ground or from a plane or helicopter, where special equipment measures the magnetic or electrical properties of rocks on the surface and underground. 2. DISCOVERY AND ADVANCED EXPLORATION Discovery and advanced exploration happens when something of value is really found. At this stage, higher impact activities such as further ground geophysics, channel sampling, trenching and diamond drilling, take place. Very few discovered mineral deposits become producing mines. It may take between 10 to 15 years or more for a mine to be developed. The operation challenges such as limited infrastructure, including roads and power, as well as associated costs such as fuel, transportation, materials and labour, make it much more difficult to move beyond this stage. Most projects never get past this stage. 3. DEVELOPMENT/CONSTRUCTION Development/construction, is based on economics (is an area or deposit worth mining), and if shareholders approve. During this stage the land owner raises money in order to begin construction and develop a mine. 4. OPERATION AND PRODUCTION Operation and production is the actual mining, milling, and processing of the metal, ore or diamonds. The length of time a mine is in production (the mine life) depends on the amount (reserves) and quality (grade) of the mineral, metal or gems and whether the operation is still profitable. 5. RECLAMATION Reclamation of a site and protection of the environment starts at the beginning of the project. All existing and new mines must have closure and reclamation plans and are required to set aside in a trust, the total estimated reclamation costs. The goal is to protect the environment right from the beginning, to make sure the site is as productive as possible and safe for people and animals when the mine closes. Explain how the various steps of mineral exploration contribute to environmental pollution? Mineral resources are an important source of wealth for a nation but before they are harnessed, they have to pass through the stages of exploration, mining and processing. The three major steps of mineral exploration viz. exploration, mining and processing affects environment in the following ways:
  • 18. • Air, land and water pollution: Only minor pollution occurs during mineral exploration but more intense air and water pollution originate from the exploitation phase. In the oil-producing areas oil spillage of differing intensity resulting from burst pipelines, tanks, tankers, drilling operations, etc. causes water and land pollution with severe consequences on both aquatic and terrestrial life. • Damage of vegetation: Vegetation in form of natural forest or crop plantation is usually the first to suffer total or partial destruction during the exploration and exploitation of minerals in an area. The vegetation damage is more extensive at the time of mine development and mining operations and is more expensive when crop plantation is affected. • Ecological disturbance: Another adverse effect of mineral extraction and processing activities is the disturbance of the ecosystem with possible adverse consequences on the flora and fauna. For example, the deforestation of an area during the mine development may cause the removal of some plants and the migration of some animals that feed on such plants or depend on them for cover, from the affected area. Similarly, the noise generated in the course of blasting, quarrying and crushing can also frighten away part of the fauna in a mining locality. • Degradation of natural landscape: The most common negative result of mining minerals from the earth’s surface is the devastation of its natural landscape, generating open space in the ground and generating heaps of rock wastes that cannot be easily disposed off. • Geological hazards: Mining operations normally upset the equilibrium in the geological environment, which may trigger off certain geological hazards such as landslide, subsidence, flooding, erosion and tremors together with their secondary effects. • Social effects: Potential influx of people and significant community change represent challenges for the existing communities. The stoppage of mining activities imposed by depletion of the available reserves often leads to migration of people from the mining areas to other places. This may result in the formation of “ghost towns”, which are abandoned towns and previous bubbling mining communities. • Economic effects: The mining process results in increased training and skill development opportunities, which in–turn increases buying power and Creates positive role models.
  • 19. • Radiation hazards: Exposure to natural radiations emitted by some radioactive minerals is a major source of health hazards. The radiation intensity increases when the minerals are concentrated. What are the present world food problems? The current world food crisis is the result of the combined effects of competition for cropland from the growth in bio–fuels, low cereal stocks, high oil prices, speculation in food markets and extreme weather events. The causes of the world food problems are enlisted below following: 1. Natural catastrophes (drought, heavy rain and flooding, crop failures): Hurricanes, floods, land- or mudslides, volcanic eruptions, and sea surges directly influence food availability as well as in the survival of livestock. Standing crops may be completely destroyed, and seed stores and family food supply may be lost, especially if there is no warning period. 2. Environmental degradation (soil erosion and inadequate water resources): Environmental degradation due to unsustainable human practices and activities endangers the entire production platform of the planet. Land degradation and conversion of cropland for non-food production including bio–fuels, cotton and others are major threats that could shrink the available cropland. 3. Food supply-and-demand imbalances: The basic cause of food crisis can be attributed to supply-and demand imbalance. It is in-turn due to a “production crisis” coupled with increasing material demand and purchasing power in recent years. Specifically, these include the strong combination of effects arising from low food stocks and climate change and growing demand for some food products, linked with population and income growth, urbanization, and changing diets in urban centres. 4. Inadequate food reserves. Food inadequacy exists when people are undernourished as a result of the physical unavailability of food, their lack of social or economic access to adequate food, and/or inadequate food use. 5. Warfare and civil disturbances: The agriculture requires numerous things in order to thrive. Farmland must be productive and relatively undisturbed by human activities. A local workforce must be available for either traditional manual sowing and harvesting, or to operate modern equipment that accomplishes those tasks. There must be a market for the goods produced, whether it is a local farmer's market or the international commodities market. Warfare can have a shocking impact on all of these aspects. 6. Migration refugees: Population migration affects food production and the nutritional well-being of citizens. Migration may be seasonal or permanent, but either way it often causes the major burden on farming, while the demand for additional food to provide for the city dwellers continually increases.
  • 20. 7. Declining ecological conditions in agricultural regions: Demographic and environmental pressures such as population growth, deforestation, and soil erosion, reduce the agricultural productivity of the land. As rural incomes are closely related to the productivity of the land, decreasing productivity increases poverty. Land scarcity and degradation threatens the ability of food production to keep pace with population growth. 8. Excessive population growth: Population growth directly affects needs and forces many farm families into marginal areas where conservation practices are essential. Such areas include cleared forest soils of fragile structure, steeply sloping lands and dry–land areas with limited rainfall. In addition, the increased demand for fuel–wood for cooking may leave marginal lands permanently denuded of soil cover and subject to erosion. Such loss of productivity in the resource base inevitably reduces food supplies and increases food insecurity and nutritional stress. 9. Pollution: To survive humans need food. Healthy food needs a healthy eco-system balance within an unpolluted air, water and soil system. Soil and water pollutants that adversely affect agriculture include sediment, out of place plant nutrients, inorganic salts and minerals, organic wastes, infectious agents, industrial and agricultural chemicals, and heat. Air pollutants cause injury to agricultural crops when present in high concentrations. Injury ranges from visible markings on the foliage, to reduced growth and yield, to premature death of the plant. 10. Loss of farmland to competing uses: Competing land uses are a significant risk to food security. It arises from demand for competing land uses such as biofuel cultivation; rural residential development; urban expansion; and abandonment. These competing land uses may also encroach on previously uncultivated land that has high potential for agricultural use. How excess of irrigation leads to soil salinity? Salinity from irrigation can occur over time wherever irrigation occurs; since almost all water (even natural rainfall) contains some dissolved salts. When the plants use the water, the salts are left behind in the soil and eventually begin to accumulate. Excess of irrigation, in the absence of leaching, can bring salts to the surface. The salts from the groundwater are raised by capillary action to the surface of the soil. Irrigation salinity occurs due to increased rates of seepage and groundwater recharge causing the water table to rise. Growing water tables can transport salts into the plant root zone which affects both plant development and soil structure. The salt remains behind in the soil when water is taken up by plants or lost to evaporation. Inefficient irrigation and drainage systems are a major
  • 21. cause of excess leakage and increase the risk of salinity and water logging in irrigation areas. As salts build up in saline release areas they can reach levels that affect plants in a following ways:  Under normal conditions, plants readily obtain water from the soil by osmosis (movement of water from a lower salt concentration outside the plant to a higher salt concentration in the plant). As soil salinity increases this balance shifts making it more difficult for plants to extract water.  Plant growth can be directly affected by high levels of toxic ions such as sodium and chloride. Excess sodium accumulation in leaves can cause leaf burn, necrotic (dead) patches and even defoliation.  An excess of some salts can cause an imbalance in the ideal ratio of salts in solution and reduce the ability of plants to take up nutrients.  Water logging aggravates the effect of salinity. Waterlogged plant roots are unable to exclude sodium and chloride due to the increased rates of transport of these ions, and concentrations in the plant shoot increase. Poor aeration also affects soil biology responsible for converting nutrients to their plant available form, causing nutrient deficiencies What is Bio–magnification? Explain. Biomagnification or bioamplification is the increase in non-biodegradable toxic compounds as we move up a food chain. The process of bio- accumulation and bio-magnification create exceedingly low quantities of pesticides or their toxic residues available to the living organism in a highly concentrated state. The symptoms of toxicity either appear in the animal accumulating the poisonous material or it makes the animal poisonous to other organisms which feed on it. The worst suffers are animals at the top of the trophic structure. It has many direct and latent effects on the health of living organisms. The following can be considered as the major once: - Health disorders due to presence of toxic chemicals like Mercury, DDT etc. - Genetic problems due to manipulation of genetic material. - Risk of destruction of any particular group of animals or birds. - Pollution of water reservoirs. - Effect on specific food chains in nature. Why soil is considered as a natural resource? Land is the primary natural resource that provides habitat and sustenance for living organisms, as well as being a major center of economic activities. As human
  • 22. needs and population grow the pressure on land and other natural resources continue to increase. It is an important resource due to the following reasons: • It is a store of natural resource (minerals, soil, plants etc.) wealth for individuals, groups, or a community. • It is the source for production of food, fibre, fuel or other biotic resources for human use. • It provides provision of biological habitats for plants, animals and micro organisms • It is responsible for regulation of the storage and flow of surface water and groundwater. • It acts as a depot of minerals and raw materials in nature. • It is important as a buffer, filter or modifier for chemical pollutants in the soil. • It provides physical space for settlements, industry and recreation • It acts as the storeroom and guards of evidence from the historical or pre- historical record (fossils, evidence of past climates, archaeological remains, etc.) • From the years unknown it has enabled or hampered movement of animals, plants and people between one area and another. Thus, resulting in the development of genetic variability. • It acts as a co-determinant in the global energy balance and the global hydrological cycle, which provides both a source and a sink for greenhouse gases. Explain the importance of soil as a natural resource. Soil is one of the world’s most valuable assets. It is essential to all life forms on this planet due to following reasons: 1. Soil act as a sieve to protect the quality of water, air and other resources. 2. Soil provide a physical medium, chemical environment and biological setting for water, nutrient, air and heat exchange for living organisms. 3. Soil control biological activity and molecular exchanges among solid, liquid and gaseous phases. This affects nutrient cycling, plant growth and decomposition of organic materials; 4. It offer mechanical support for living organisms and their structures, including most of our buildings, dams, pipelines and underground cables; and 5. Soils influence the water distribution to runoff, infiltration, storage or deep drainage. 6. They regulate water flow, which affects the movement of soluble materials such as nutrients or pollutants 7. Soils make it possible for plants to grow. Soils mediate the biological, chemical and physical processes that supply nutrients, water and other elements to growing plants. Soils are the water and nutrient storehouses on which most plants survive. 8. We eventually depend on soils for much of our food and fibre.
  • 23. Define soil and write briefly on soil profile. Answer: Soil can be defined as a composite mixture of inorganic material, organic material, microorganisms, water and air. The study of soils as naturally occurring phenomena is called pedology (from the Greek word pedon, meaning soil or earth). Soil profile: It is an exposure from the surface downward through a soil to its parent material. A general soil profile has following horizons: O – Organic horizon: Typically forms above the mineral soil due to the deposition of litter derived from dead plant and animal matter. These horizons are commonly observed in wetlands and forested areas – and are generally absent from grasslands and cropland soils. This horizon commonly contain >20% organic material by weight. A – Surface horizon: Typically the uppermost mineral horizon containing an accumulation of organic matter that imparts a dark brown/black color to the soil. The dark decomposed organic materials, which is called "humus". E – Eluvial horizon: This is the horizon designation for a horizon with a great deal of leaching or eluviation of clay, primary minerals (Fe and Al oxides). This horizon is typically lighter due to the uncoated mineral grains that make up this horizon. B – Subsurface horizon: The B horizon is typically a mineral subsurface horizon and is a zone of accumulation, called illuviation. Materials that commonly accumulate are clay, soluble salts, and/or iron. Minerals in the B horizon may be undergoing transformations such as chemical alteration of clay structure. C – Unconsolidated horizon: This is the designation for the horizon that contains unconsolidated mineral materials that are similar to the parent material. The interface between the bedrock surface (Parent material) and overlying sedimentary material is called the regolith and consists of broken, rubbly pieces of bedrock that are variably weathered and decomposed.
  • 24. Soil Profile Define landslides. Give various types of landslides and with their causal factors OR How landslides are caused? Give the factors responsible for landslide causal. Answer: A landslide occurs when part of a natural slope is not capable to hold its own weight. For example, soil matter on a smooth surface below, can become heavy by rainwater and slide downhill due to its increased weight. Thus, a landslide is a downhill or outward progress of soil, rock or vegetation, under the control of gravity. The speed of the movement may range from very slow to rapid. The mass of movement of material can devastate property along its path of movement and cause death to people and livestock. The basic causes of slope instability can be: • Weakness in the composition, material or geological structure of rock or soil formation. • External factors, which impact the ground water regimes like: oHeavy rainfall oMelting of Snow oAlteration in ground water level etc. • Earthquakes or volcanic activities may add to the instability resulting in landslides. • Creation of new site conditions such as changes to natural slope due to construction activities
  • 25. Explain the role of humans as a cause of landslides. The Human activities/ anthropogenic activities can cause Landslides due to the following reasons: Forest Cutting/ Deforestation: The denudation of the forest on mountain slope fields exposes the slope, and accelerates the processing of the weathering of the rock on the mountain slope. This contributes to the risk of landslides, also helps landslides to worsen further. In addition, overgrazing causes the soil on the slope to become trampled. Mining: Mining operations that use blasting techniques often cause other areas that are at the risk of sliding to slide due to vibrations under the soil. Irrational farming technologies: The wrong methods of irrigation for example, cultivating in a lengthwise direction down the slope, hastens the loss of material on the slopes that are eroded by weathering. These practices continue to worsen the mountain slopes and make these slopes the source regions of landslides. Road construction: The damage to the slope caused by road building and railway line construction also adds up to the chances of landslides in a hilly region. Agricultural or forestry activities: These activities may result in logging which change the amount of water which infiltrates the soil. Moreover, may cause increase in slope gradient or significant change in surface and ground water regimes adding to the instability of slopes. Explain the causes and effects of land degradation. The degradation of land may occur due to Natural causes as well as human activities, can be enlisted as following: • NATURAL CAUSES There is certain natural cause’s soil degradation such as running water, glaciers, wind etc. Erosion from these factors can create deserts over long time periods. • HUMAN CAUSES: They include the following activities:  Deforestation: Physically the process of deforestation includes repeated lopping, felling, removal of forest litter, browsing and trampling of livestock, fire, etc. It has been established that the increased demand for food, livestock and firewood for the increasing population is the direct cause of deforestation.
  • 26.  Agriculture: With the increase in population the extensive farming systems, which were traditionally in harmony with the environment, have become inappropriate. It has resulted in increasing numbers of the rural population being forced to farm on marginal and unsuitable land, which becomes quickly degraded. In addition to that more people move to urban areas, adding to congestion, pollution and often removing yet more prime agricultural land from production, ultimately leading to land degradation.  Economic activities: land degradation is a biophysical process driven by socioeconomic and political causes. Nutrient depletion as a form of land degradation has a severe economic impact at the global scale.  Developmental activities: The activities like road construction, railway line construction, housing, communication, transmission lines, etc. are also contributing to degradation of vegetation as well as of land in different parts of the world. Declining soil quality leads to diminishing economic growth in countries where wealth is largely agrarian. Write a note on desertification. Desertification is when land turns into desert. This means that little or no food can be grown in areas where people live and farm the land. Desertification is caused by the following factors: • DROUGHT: Drought affected semi-arid regions are considered one of the main causes of desertification encroachment. Drought can be caused by inadequate seasonal rainfall, a prolonged dry season or a series of sub- average rainy seasons. • EXTENSIVE CULTIVATION: A rapid increase in human and animal populations requires a corresponding expansion of cultivated areas; leading to land over-utilization and thus causing land degradation. • DEFORESTATION: The disappearance of many trees from rain-fed areas has contributed significantly to land degradation and the deterioration of soil fertility. Forests are constantly being cut down for fuel and negligible replanting is carried out. This absence of forests results in extensive wind erosion and the microclimate becomes increasingly arid. The dry season becomes more accentuated and precipitation decreases. • OVERGRAZING: In the past, nomadic herdsmen maintained the delicate balance between livestock numbers and the carrying capacity of pasture. But this balance has recently been disturbed, through the expansion of dry farming in traditional grazing lands and an increase in animal populations. Apart from
  • 27. the degradation of natural vegetation cover, over-grazing results in a decrease in the quality of rangelands. • INDUSTRIALIZATION / URBANISATION: Industries also require a large portion of agriculture land be it in coastal, urban or rural area. But it is more often observed if environment protection safeguards are not in place. The problem is more severe and complicated in developing world. So much so the area around industries is denuded of total vegetation in miles long stretches all around making land totally degraded to desertification Urbanisation is also encroaching upon agricultural lands causing immense damage to our natural resources. • SOIL AND WATER FACTORS: Life on earth depends on the layer of soil that is the source of nutrients for plants, crops, forests, animals and people. Without it, ultimately none can survive. Although topsoil takes a long time to build up, if mistreated it can vanish in just a few seasons due to erosion by wind and water. • CLIMATIC CONSIDERATIONS: Climate relates to climate variability, climate change, or drought. The frequently occurring drought have been a major cause of desertification, as during extended dry spells desertification becomes relatively more severe, widespread, and visible, and its rate of occurrence increases manifold. Explain the methods of soil conservation. Soil conservation methods are used to prevent the soil from getting eroded and preventing it from losing its fertility. Some of the important conservation methods include: Agronomic practices: Normally, the land will possess a vegetational cover so as to prevent erosion. The measures to be followed must be patterned along the nature's own methods of conservation. The following are some of the methods. • Contour farming: Crops are cultivated along the contour of the land. The plough marks will be on level and can hold the rain. Even in heavy rain, the runoff is checked by the plants growing along the contour. Tillage: contour tilling will prevent the excess run of water. • Mulching: Inter-culturing operations will kill weeds and soil mulches help the plants to be rooted firmly in the soil. • Crop rotations: Alternatively growing a cereal and a legume in the same field will not only increase the yield, but also increase the fertility of the soil. They also help in checking soil erosion. • Strip cropping: This is an agricultural practice of growing plants in suitable strips in the field. This is of the following types.
  • 28. • Contour strip cropping: This is cultivation of soil protecting crops in strips alternating with erosion permitting crops. The strips should be across the slope. • Field strip cropping: Plants are cultivated in parallel strips across the slopes. Wind strip cropping: Crops are planted across the slopes to prevent soil loss. These may be legumes or grasses. •Agrostological measures: Cultivation of grass in a land which is heavily eroded is called an agrostological measure. This is of two types. In ley farming grass is cultivated in rotation with regular crops. This helps in soil protection as well as produce fodder to cattle. If a land is heavily eroded it is best to allow it to the growth of grasses for few years. This will help in the checking of erosion. • Dry farming method: This may be practised where rainfall is low, indefinite and variable. In dry farming methods only crops are grown that can sustain even a very low rainfall. The most important aspects of dry farming are conservation of soil moisture and fertility. Mechanical -Measures: The main aims of mechanical measures are to al- low for the absorption of run off, dividing the slope into short ones and protection against run off. A few of the mechanical measures are discussed below: • Basin listing: Small basins are formed along the contour with an implement called basin lister. These will hold water for some time. • Sub soiling: Soil is broken with a sub-soiler into fine grains to increase their absorptive capacity. • Contour terracing: Along the contour, series of ridges or bunds of mud are formed to check the run off. This is of four types. In channel terrace a shallow channel is dug and the mud is deposited along the lower edge of the canal. In broad base ridge terrace a canal is formed on the contour by excavating the mud. The canal is wide. If it is narrow it is called narrow based ridge terrace. In bench terracing a series of platforms are formed along the contour across the general slope of the plant. • Contour trenching: Several two feet by one foot trenches are formed across the slopes at suitable intervals. Tree seedlings are to be planted above the trench. • Terrace outlet: Outlets are to be constructed for the safe disposal of runoff water. • Gully control: Suitable water conservation measures are to be taken so as to prevent the formation of gullies. • Ponds: Construction of small ponds at suitable places to store water is a good practice. • Stream bank protection: Banks of channels or rivers usually cave in during floods. To prevent this, construction of stone or concrete protective walls should be undertaken. In addition to this, planting some useful tree species will also prevent stream bank erosion.
  • 29. Explain the advantages, disadvantages and ways of utilization of solar energy. Solar radiations are the earth’s prime energy source. It is the most abundant permanent energy resource on earth and it is available for use in its direct (solar radiation) and indirect (wind, biomass, hydro, ocean etc.) forms. The sun emits energy at a rate of 3.8x1023 kW. Of this total, only a tiny fraction, approximately 1.8x1014 kW is intercepted by the earth, which is located about 150 million km from the sun. About 60% of this amount or 1.08x1014 reaches the surface of the earth. The rest is reflected back into space and absorbed by the atmosphere. Even if only 0.1% of this energy could be converted at an efficiency of only 10% it would be four times the world's total generating capacity of about 3000 GW. Looking at it another way, the total annual solar radiation falling on the earth is more than 7500 times the world's total annual primary energy consumption of 450 EJ. Advantages 1. It is abundant: Solar energy is generally available everywhere, everyday, though the intensity varies with weather conditions and geographical locations. 2. It is environmentally friendly: No noise, heat or greenhouse gases. And hence will not deplete natural resources. 3. It is convenient to install: Solar panels can be retrofitted into existing building structures and fixtures. 4. Providing economically feasible energy: Solar home systems and PV- powered community grids can provide economically favorable electricity to many areas for which connection to a main grid is impractical, such as in remote, mountainous and delta regions. 5. Solar technologies can also improve the health and livelihood opportunities of world’s poor population Limitations 1. It is unpredictable and thus intermittent source of energy 2. High start-up costs 3. The land area requirements for centralized CSP and PV plants raise concerns about visual impacts. Utilization of solar energy 1. For solar energy systems, if the insulation is absorbed and utilized without significant mechanical pumping and blowing, the solar system is said to be passive.
  • 30. 2. If the solar heat is collected in a fluid, usually water or air, which is then moved by pumps or fans for use, the solar system is said to be active. 3. The sun’s energy can also be used to generate electricity, which may be used to operate solar batteries or may be transmitted along normal transmission lines. Solar Energy Applications The energy in solar radiation can be used directly or indirectly for all of our energy needs in daily life, including heating, cooling, lighting, electrical power, transportation and even environmental cleanup. There are several devices that are used to trap this tremendous store house of energy. They are solar collectors, solar thermal power plants, solar furnace, solar chimneys, solar ponds, solar photovoltaic cells etc. A few of them are briefly discussed below: Solar water heating system Solar water-heating systems used to produce hot water can be classified as passive or active solar water heaters. Passive solar water heaters are of two types (Figure 3.4). Integral collector- storage (ICS) or ‘batch’ systems include black tanks or tubes in an insulated glazed box. Cold water is preheated as it passes through the solar collector, with the heated water flowing to a standard backup water heater. The heated water is stored inside the collector itself. Active solar water heaters rely on electric pumps and controllers to circulate the carrier fluid through the collectors. Solar Photovoltaic system Photovoltaic cells convert sunlight directly into electricity without creating any air or water pollution. Photovoltaic cells are made of at least two layers of semiconductor material. One layer has a positive charge, the other negative. When light enters the cell, some of the photons from the light are absorbed by the semiconductor atoms, freeing electrons from the cell’s negative layer to flow through an external circuit and back into the positive layer. This flow of electrons produces electric current. To increase their utility, many number of individual photovoltaic cells are interconnected together in a sealed, weatherproof package called a module (Figure ). When two modules are wired together in series, their voltage is doubled while the current stays constant. When two modules are wired in parallel, their current is doubled while the voltage stays constant. To achieve the desired voltage and current, modules are wired in series and parallel into what is called a PV array. The flexibility of
  • 31. the modular PV system allows designers to create solar power systems that can meet a wide variety of electrical needs, no matter how large or small. Write a detailed note on wind as a source of energy. Wind energy is the kinetic energy associated with the movement of atmospheric air. Wind energy systems convert this kinetic energy to more useful forms of power. Wind turbines transform the energy in the wind into mechanical power which is further converted to electric power to generate electricity. Wind turbines can be used singly or in clusters called ‘wind farms’. Harnessing of Wind Energy All moving objects contain kinetic energy. The kinetic energy contained in wind can be transferred to other objects, such as boat sails, or transformed into electrical energy through wind turbine generators. Most wind turbines have the same basic parts: blades, shafts, gears, a generator, and a cable. These parts work together to convert the wind’s energy into electricity. 1. The wind blows and pushes against the blades on top of the tower, making them spin. 2. The turbine blades are connected to a low-speed drive shaft. When the blades spin, the shaft turns. The shaft is connected to a gearbox. The gears in the gearbox increase the speed of the spinning motion on a high- speed drive shaft. 3. The high-speed drive shaft is connected to a generator. As the shaft turns inside the generator, it produces electricity. 4. The electricity is sent through a cable down the turbine tower to a transmission line. Wind power plants, or wind farms, are clusters of wind turbines used to produce electricity. A wind farm usually has dozens of wind turbines scattered over a large area. Turbines are usually built in rows facing into the prevailing wind. Placing turbines too far apart wastes space. If turbines are too close together, they block each other’s wind. The site must have strong, steady winds. The best sites for wind farms are on hilltops, on the open plains, through mountain passes, and near the coasts of oceans or large lakes. The wind blows stronger and steadier over water than over land. There are no obstacles on the water to block the wind. There is a lot of wind energy available offshore. Offshore wind farms are built in the shallow waters off the coast of major lakes and oceans. Offshore turbines produce more electricity than turbines on land, but they cost more to build and operate. Benefits 1. The power source of wind is free of cost.
  • 32. 2. It is sustainable source of energy (will last as long as sun last) 3. It is clean and does not pollute the air. Wind turbines do not emit greenhouse gases or contribute to global warming. 4. It does not deplete resources 5. It is more cost-effective than other forms of renewable energy. As wind energy technology matures, construction and operating costs continue to drop, providing greater cost effectiveness. Challenges 1. It is intermittent and unpredictable. Wind turbine generator outputs are not controllable or predictable. Wind energy alone cannot be relied upon as the sole source of electricity. 2. Wind farms occupy large areas. Places with high population densities and land limitation often have difficulty finding the necessary space for wind farms. 3. Wind turbines can impose adverse impact on the environment Impact on migrating birds as they can get injured by turbines. Write a detailed note on hydropower as a source of energy. Hydropower is a renewable energy source where power is derived from the energy of water moving from higher to lower elevations. It is a proven, mature, predictable and typically price-competitive technology. Hydropower has among the best conversion efficiencies of all known energy sources (about 90% efficiency, water to wire). It requires relatively high initial investment, but has a long lifespan with very low operation and maintenance costs. The operation of hydropower reservoirs often reflects their multiple uses, for example, drinking water, irrigation, flood and drought control, and navigation, as well as energy supply. Hydropower provides some level of power generation in 159 countries. Five countries make up more than half of the world’s hydropower production: China, Canada, Brazil, the USA and Russia. Brazil and Canada are heavily dependent on this source, with a percentage share of total domestic electricity generation of 83.9% and 59%, respectively, whereas in Russia the share is 19.0% and in China 15.5%. Total potential of renewable power in India is 89774 MW which includes 15399 MW through Hydro energy generation. This potential is around 17.15 % of the total estimated potential. Hydropower generation In nature, energy cannot be created or destroyed, but its form can change. In generating electricity, no new energy is created. Actually one form of energy is converted to another form.
  • 33. Schematic diagram showing hydropower generation The dam creates a “head” or height from which water flows. A pipe (penstock) carries the water from the reservoir to the turbine. The fast-moving water pushes the turbine blades. The waters force on the turbine blades turns the rotor, the moving part of the electric generator. When coils of wire on the rotor sweep past the generator’s stationary coil (stator), electricity is produced. Most of the dams are constructed for multiple purposes like providing irrigation, flood control and generation of power. But apart from the functions constructions of large dams leads to some serious environmental and social costs. NOTE: For Advantages and disadvantages of Dam construction please refer water resources Limitations of hydro energy utilization 1. The initial capital investment is very high. Construction work takes very long time leading to cost and time overruns. 2. Valuable agriculture and forest lands are lost. 3. It causes water logging in the low lying areas and soil salinity. 4. Changes in river flow (runoff) related to changes in local climate, particularly in precipitation and temperature in the catchment area. This may lead to changes in
  • 34. runoff volume, variability of flow and seasonality of the flow, directly affecting the resource potential for hydropower generation. 5. Changes in extreme events (floods and droughts) may increase the cost and risk for the hydropower projects. 6. Effects of sediment-induced wear of turbines in power plants : • Generation loss due to abrasions which results in reduction in turbine efficiency; • Increase in frequency of repair and maintenance; • Increase in generation losses due to downtime; • Loss of reservoir storage • Reduction in lifetime of the turbine; and • Reduction in regularity of power generation. 7. Loss of Biodiversity 8. Release of Green House gases (GHG’s) thereby increasing carbon footprint. 9. Social Impacts: Relocation of communities living within or nearby the reservoir or the construction sites, compensation for downstream communities, public health issues and water conflicts etc. Write a detailed note on Tidal power as a source of energy. Tidal Energy is a renewable energy resource of enormous potential. The gravitational pull of the sun and the moon, along with the earth’s rotation, causes tides. All coastal areas experience high and low tide. If the difference between high and low tides is more than 16 feet, the differences can be used to produce electricity. The tidal movement of water represents a great deal of energy which is then captured to generate electricity. Tidal power converts the energy of tides into electricity utilizing the rise and fall of the ocean tides. Tidal generators act in much the same way as do wind turbines; however the higher density of water (832 times that of air) means that a single generator can provide significant power at velocities much lower than those associated with the wind power generators.
  • 35. Positive impacts • It is a predictable source of energy (compared with wind and solar), it is independent of weather and climate change • It is more efficient than wind energy due to high density of water • It will decrease reliance on coal driven electricity so less cause CO2 emissions. • The Changing technology will allow quicker construction of turbines, which in turn increases likelihood of investment with a shorter return. • Once constructed, very little cost is required to run and maintain. Negative impacts • It is an intermittent energy production based around tides creates unreliable energy source generating energy for only 6-12 hours in each 24 hour period. • Its High construction costs are disadvantageous
  • 36. • The turbines are susceptible to bio-fouling i.e.; the growth of aquatic life on or in the turbine. This can severely inhibit the efficiency of energy production and is both costly and difficult to remove. • The turbines are also prone to damage from ocean debris. In the Bay of Fundy, project developers are particularly concerned with ice floes the size of small apartments, and cobblestones the size of watermelons constantly being tossed across the Bay's terrain by the power of the Bay's water flows. • Barrages can disrupt natural migratory routes for marine animals • Barrages can also disrupt normal boating pathways • The Turbines can kill up to 15% of fish in area, although technology has advanced to the point that the turbines are moving slow enough to decrease fist mortality. Write a short note on Ocean Thermal Energy Conversion (OTEC) as a source of energy. The oceans has a vast & largely untapped source of energy in the form of fluid flow (current, waves and tides known as hydrokinetic) thermal and salinity gradients. The oceans collect and store huge quantities of solar radiations in the form of heat. Most of the heat is stored on the surface of the sea water while the temperature of deep waters is very low.. Using this temperature difference, which is of the order of 20ºC, it is theoretically possible to convert the heat into electricity. Many low boiling liquids like ammonia nad Freon, butane etc. can be used for extracting the heat and converting it to electricity with a theoretical efficiency of 1-3%. Fig.2.13 A Schematic diagram for OTEC Write a note on Geothermal Energy. The Geothermal resources consist of thermal energy from the Earth’s interior stored in both rock and trapped steam or liquid water. Heat passes from the crust by: (1) Natural cooling and friction from the core;
  • 37. (2) Radioactive decay of elements such as uranium and thorium, and; (3) Chemical reactions. Fig. 2.13The Schematic structure of Earth’s interior Geothermal Electric Power The core (at about 4000 miles from the surface) is thought to be a molten alloy of iron and nickel; it may also be a solid due to the very high pressure. In any case, it is very hot (close to 200,000 °C). The heat associated with such a high temperature is conducted to the surface and from there it is radiated into space. Generation can be done in following ways: 1. Natural hydrothermal circulation. In this, water percolates to deep aquifers to be heated to dry steam, vapour/liquid mixtures or hot water. Emissions of each type can be observed in nature. If pressure increases by steam formation at deep levels, spectacular geysers may occur, as at the Geysers near Sacramento in California and in the Wairakei area near Rotorua in New Zealand. Note, however, that liquid water is ejected, and not steam. 2 Hot igneous systems. These are associated with heat from semi-molten magma that solidifies to lava. The first power plant using this source was the 3MWe station in Hawaii, completed in 1982. 3 Dry rock fracturing. Poorly conducting dry rock, e.g. granite, stores heat over millions of years with a subsequent increase in temperature. Artificial fracturing from boreholes enables water to be pumped through the rock to extract the heat. The world's largest plant that produces electricity from geothermal energy (1650 MW) is located at The Geysers, near San Francisco in California. Smaller plants are in operation in Lardarello, Italy (400 MW), Cerro Prieto in Mexico (645 MW).
  • 38. Benefits • Using geothermal resources can provide economic development opportunities especially in rural areas. • In addition to generating electricity, the heat in geothermal fluids can be used directly for many applications such as: aquaculture, greenhouses, industrial and agricultural processes, resorts and spas, space and district heating, and cooling. • Provide reliable electricity at a stable price since the power source is free of cost. • Renewable energy resources like geothermal can help to diversify the mix of fuels they rely on for power and protect customers from volatile electricity prices. • Generate electricity in a manner that produces minimal environmental impacts and emissions Schematic diagram for Geothermal Power generation Challenges • Detecting, leasing and siting potentially productive geothermal reservoirs are very difficult. • Exploration and drilling activities are expensive and risky. Drilling costs alone can account for as much as one-third to one-half of the total cost of a project.
  • 39. • Once a potentially valuable source is found then, tapping the energy may require an expansion of the power transmission system, which can also be expensive. • Water Use: Geothermal plants use 5 gallons of freshwater per megawatt hour, while binary air-cooled plants use no fresh water. This compares with 361 gallons per megawatt hour used by natural gas facilities. • Water Quality: Geothermal fluids used for electricity are injected back into geothermal reservoirs using wells with thick casing to prevent cross- contamination of brines with groundwater systems. They are not released into surface waterways. At The Geysers facility, 11 million gallons of treated wastewater from Santa Rosa are pumped daily for injection into the geothermal reservoir. Injection reduces surface water pollution and increases geothermal reservoir resilience. • Land Use: Geothermal power plants can be designed to .blend-in. to their surrounding more so than fossil fired plants, and can be located on multiple- use lands that incorporate farming, skiing, and hunting. Over 30 years, the period of time commonly used to compare the life cycle impacts from different power sources; a geothermal facility uses 404 square meters of land per gigawatt hour, while a coal facility uses 3632 square meters per gigawatt hour. • Subsidence: Subsidence, or the slow, downward sinking of land, may be linked to geothermal reservoir pressure decline. • Induced Seismicity: While earthquake activity, or seismicity, is a natural phenomenon, geothermal production and injection operations have at times resulted in low-magnitude events known as .micro earthquakes. Explain how biomass can be utilized as source of Energy. Biomass is organic material which has stored sunlight in the form of chemical energy. Bioenergy is embedded in complex ways in global biomass systems for food, fodder and fibre production and for forest products as well as in wastes and residue management. Biomass is categorized with varying degrees of energy efficiency in various sectors: • Low-efficiency traditional biomass such as wood, straws, dung and other manures are used for cooking, lighting and space heating, generally by the poorer populations in developing countries. This biomass is mostly combusted, creating serious negative impacts on health and living conditions. • High-efficiency modern bioenergy uses more convenient solids, liquids and gases as secondary energy carriers to generate heat, electricity, combined heat and power (CHP), and transport fuels for various sectors. Liquid biofuels include ethanol and biodiesel for global road transport and some industrial uses. Biomass derived gases, primarily methane, from anaerobic digestion of
  • 40. agricultural residues and municipal solid waste (MSW) treatment are used to generate electricity, heat or both. Various conversion technologies are adopted to convert feedstock into electricity, heat, bio fuels including biodiesel and ethanol, namely: (I) Thermo–chemical processes Biomass combustion It is a process where carbon and hydrogen in the fuel react with excess oxygen to form CO2 and water and release heat. Pyrolysis It is the thermal decomposition of biomass occurring in the absence of oxygen (anaerobic environment) that produces a solid (charcoal), a liquid (pyrolysis oil or bio-oil) and a gas product. The relative amounts of the three co-products depend on the operating temperature and the residence time used in the process. High heating rates of the biomass feedstocks at moderate temperatures (450°C to 550°C) result in oxygenated oils as the major products (70 to 80%), with the remainder split between a biochar and gases. Biomass Gasification Biomass Gasification occurs when a partial oxidation of biomass happens upon heating. This produces a combustible gas mixture (called producer gas or fuel gas) rich in CO and hydrogen (H2) that has an energy content of 5 to 20 MJ/Nm3 (depending on the type of biomass and whether gasification is conducted with air, oxygen or through indirect heating). This energy content is roughly 10 to 45% of the heating value of natural gas. Fuel gas can then be upgraded to a higher- quality gas mixture called biomass synthesis gas or syngas. (II) Chemical processes Transesterification: Transesterification is the process through which alcohols (often methanol) react in the presence of a catalyst (acid or base) with triglycerides contained in vegetable oils or animal fats to form an alkyl ester of fatty acids and a glycerine by-product. Vegetable oil is extracted from the seeds, usually with mechanical crushing or chemical solvents prior to transesterification. The fatty acid alkyl esters are typically referred to as ‘biodiesel’ and can be blended with petroleum-based diesel fuel. The protein-rich residue, also known as cake, is typically sold as animal feed or fertilizer, but may also be used to synthesize higher-value chemicals. Hydrogenation: The hydrogenation of vegetable oil, animal fats or recycled oils in the presence of a catalyst yields a renewable diesel fuel—hydrocarbons that
  • 41. can be blended in any proportion with petroleum-based diesel and propane as products. This process involves reacting vegetable oil or animal fats with H2 (typically sourced from an oil refinery) in the presence of a catalyst. (III) Biochemical processes Biochemical processes use a variety of microorganisms to perform reactions under milder conditions and typically with greater specificity compared to thermochemical processes. Anaerobic digestion: It involves the breakdown of organic matter in agricultural feedstocks such as animal dung, human excreta, leafy plant materials, urban solid and liquid wastes, or food processing waste streams by a consortium of microorganisms in the absence of oxygen to produce biogas, a mixture of methane (50 to 70%) and CO2. In this process, the organic fraction of the waste is segregated and fed into a closed container (biogas digester). Fig 2.15 A Fixed dome Biogas plant In the digester, the segregated biomass undergoes biodegradation in the presence of methanogenic bacteria under anaerobic conditions, producing methane-rich biogas and effluent. The biogas can be used either for cooking and heating or for generating motive power or power through dual-fuel or gas engines, low-pressure gas turbines, or steam turbines. The biogas can also be upgraded through enrichment to a higher heat content bio–methane (85 to 90% methane) gas and injected in the natural gas grid.
  • 42. Explain the following Non-Renewable Energy sources? a) Coal: Coal is the world’s most abundant and widely distributed fossil fuel. It is a global industry that makes a significant economic contribution to the global economy. Coal is mined commercially in more than 50 countries and used in more than 70. Annual world coal consumption is about 5,800 million tons, of which about 75% is used for electricity production. This consumption is projected to nearly double by the year 2030 to meet the challenge of sustainable development and a growing demand for energy. The total estimated reserve of coal in India was around 286 billion tones in 2011. Coal deposits are mainly confined to eastern and south central parts of the country. The states of Jharkhand, Orissa, Chhattisgarh, West Bengal, Andhra Pradesh, Maharashtra and Madhya Pradesh account for more than 99% of the total coal reserves in the country. Coal is a variety of solid, combustible, sedimentary, organic rocks that are composed mainly of carbon and varying amounts of other components such as hydrogen, oxygen, sulphur and moisture. Coal is formed from vegetation that has been consolidated between other rock strata and altered by the combined effects of pressure and heat over millions of years. The four types of coal mined today are: (a) Anthracite (b) Bituminous (c) Sub–bituminous, (d) Lignite. By rank, anthracite and bituminous coal account for 53% of the estimated recoverable coal reserves (on a tonnage basis), sub-bituminous coal accounts for 30%, and lignite accounts for 17%. • Lignite: Lignite makes the largest contribution in the world’s coal reserves. It’s a soft, brownish-black coal that forms the lowest level of the coal family. • Subbituminous: Next up the scale is sub–bituminous coal, a dull black coal. It gives off a little more energy (heat) than lignite when it burns. • Bituminous: Still more energy is packed into bituminous coal, sometimes called “soft coal.” • Anthracite: Anthracite is a hard, compact variety of mineral coal that has a high lustre. It has the highest carbon count and contains the fewest impurities of all coals. Anthracite is the highest of the metamorphic rank, in which the carbon content is between 92% and 98%, burns with a short, blue, and smokeless flame and gives off a great amount of heat. b) Petroleum: Petroleum is oily, flammable, thick dark brown or greenish liquid that occurs naturally in deposits, usually beneath the surface of the earth; it is also
  • 43. called as crude oil. Petroleum means rock oil, (Petra – rock, elaion – oil, Greek and oleum – oil, Latin), the name inherited for its discovery from the sedimentary rocks. It is used mostly for producing fuel oil, which is the primary energy source today. Petroleum is also the raw material for many chemical products, including solvents, fertilizers, pesticides and plastics. Alkali metal H2O Temp. & pressure CaCO3 ======> CaC2 ======> HC=CH ======> Petroleum Petroleum is a combination of gaseous, liquid and solid mixtures of many alkanes. It consists principally of a mixture of hydrocarbons, with traces of various nitrogenous and sulfurous compounds. Gaseous petroleum consists of lighter hydrocarbons with abundant methane content and is termed as ‘natural gas’. Table2. : Composition of Petroleum Natural Gas: Natural gas is a vital component of the world's supply of energy. It is one of the cleanest, safest, and most useful of all energy sources. Natural gas consists of hydrocarbons that remain in the gas phase (not condensable into liquids) at standard temperature and Pressure (STP). It occurs along with petroleum crude as well as independently. It is also produced in large amounts during oil refining process. It can be used as a source of energy for domestic, industrial use and for power generation. It is also used as a raw material for petrochemical i9ndustries and fertilizer plants. Table: 2. 2 Typical composition of Natural Gas Element Percent composition Carbon 83.0 – 87.0 Hydrogen 10.0 –14.0 Nitrogen 0.1– 2.0 Sulphur 0.05 – 6.0 Oxygen 0.05 – 1.5
  • 44. Methane CH4 70-90% Ethane C2H6 0-20%Propane C3H8 Butane C4H10 Carbon Dioxide CO2 0-8% Oxygen O2 0-0.2% Nitrogen N2 0-5% Hydrogen Supphide H2S 0-5% Rare Gases A, He, Ne, Xe trace Natural Gas Products Natural gas and its constituent hydrocarbons are marketed in the form of different products, such as lean natural gas, wet natural gas (liquefied natural gas (LPG)) compressed natural gas (CNG), natural gas liquids (NFL), liquefied petroleum gas (LPG), natural gasoline, natural gas condensate, ethane, propane, ethane-propane fraction and butanes. c) Nuclear Energy: Nuclear energy is the energy trapped inside each atom. It is a clean, safe, reliable and competitive energy source. It is the only source of energy that can replace a significant part of the fossil fuels (coal, oil and gas) which massively pollute the atmosphere and contribute to the greenhouse effect. Nuclear power is the cleanest form of mass energy generation, producing no greenhouse gases like CO2, SO2 and ash. Therefore the growth of nuclear energy in developing and populous countries is a matter of great benefit for mankind in view of its potential to protect the earth from irreversible environmental damage. Nuclear energy can be harnessed through two reactions: • Nuclear Fission – When a neutron collides with a larger isotope, it causes the isotope to break apart and results in the powerful release of energy. When a nucleus fissions, it splits into several smaller fragments, including two or three neutrons. The neutrons released in fission may produce an additional fission in another nucleus. This nucleus in turn produces neutrons, and the process repeats, causing a chain reaction producing large amounts of energy. The process may be controlled as in nuclear power plants, or it may be uncontrolled, like in nuclear weapons.
  • 45. Fig. 2.17 Neutron Induced U235 Nuclear Fission Reaction • Nuclear Fusion – A fusion reaction occurs when two hydrogen atoms combine to produce one helium atom. This reaction takes place continuously in the sun which generates solar energy. Fig. 2.18 Nuclear Fusion Reaction Write a note on role of an individual in conservation of natural resources. Answer: As we all are aware that natural resources are exhausting rapidly. So, it is the responsibility of each and every individual to participate in conservation of
  • 46. natural resources to achieve a long term sustainable availability of the natural resources. We all must work together to conserve the available natural resources for future generation. So, it is duty of all individuals to conserve natural resources. Conservation of forest resources can be achieved by: • Usage of non-timber products should be minimized. • Plant more trees and protect them. • Over grazing must be controlled. • Use of papers and fuel wood should be minimized. • Developmental works like dam, road and industrial constructions in forest areas should be controlled. Conservation of water resources can be achieved by: • The utilization of water should be minimum amount for all domestic purposes. • The leakage of water in pipes and toilets should be checked and repaired immediately to control unnecessary wastage. • The water from kitchen and other house hold activities should be reused for washing off the courtyards, drive ways, etc.., • Rainwater harvesting system should be promoted and adopted by every household. Conservation of Food resources can be achieved by: • The conservation of natural resources can be achieved by adopting vegetarian food habits as growing of vegetables consumes less natural resources in comparison to non-vegetarian produce from farm animals. • The promotion of utilization of locally available fruits and vegetable also helps in conservation of natural resources that may be utilized for their packaging, preservation and transport. • Fresh food items should be consumed instead of packaged one as they cause less wastage of resources. • The food cooked at home should not be thrown out in the bin, instead of that it could be given away to the needy people around the locality. Conservation of Energy resources can be achieved by: • The lights, fans and other appliances should be switched off when not in use, this will contribute towards the saving of coal on which the thermal power plants run. • The solar heater could be used for cooking your food on sunny days, which will reduce the LPG consumption.
  • 47. • By growing more trees near the houses the micro-climate can be regulated which will cut off electricity consumption on air conditioners and coolers. • The use of pressure cooker also helps to reduce the consumption of LPG a non-renewable resource. Conservation of soil resources can be achieved by: • By growing different types of plants, herbs, trees and grasses in open areas, helps to bind the soil and prevent soil erosion. • The usage of fertilizer and pesticides should be controlled. • The natural manure should be used to fertilize the crops instead of fertilizers. • While constructing the house the uprooting of the trees should be minimal. • The mixed cropping, should be promoted it will ensure that some specific soil nutrients will not get depleted. • Only required amount of the food should be cooked.

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