biology-class-12-unit-15-chapter-06-ecology-environmental-issues-3-3-bbjtt847q-0

<h3 id="successenvironmental-issuessuccess"><Success>Environmental issues</Success></h3>
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<h3 id="lets-recap">Let’s recap!</h3>
<p><strong>In the last session we learnt about -</strong></p>
<ul>
<li>Solid waste and its management</li>
<li>Types of solid waste</li>
<li>Hospital waste</li>
<li>Electronic junk/waste</li>
<li>Remedy for Plastic waste - a case study</li>
<li>Green Revolution - Pros and cons</li>
</ul>
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<h3 id="successagro-chemicals-and-their-effectssuccess"><Success>Agro-chemicals and their effects</Success></h3>
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<ul>
<li>Use of certain agro-chemicals may lead to ecological damage</li>
<li>Excessive use of chemicals can lead to ground water contamination</li>
<li>Agro-chemicals when drained into the water bodies may lead to accelerated Eutrophication</li>
<li>Certain pesticides like DDT have been found to show the phenomenon of Biomagnification</li>
<li>Contamination of food products</li>
<li>The Bhopal gas tragedy which occurred was due to leakage of deadly MIC from Union Carbide that manufactured insecticides</li>
</ul>
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<h3 id="successcase-study-of-organic-farmingsuccess"><Success>Case study of organic farming</Success></h3>
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<ul>
<li>Ramesh Singh Dagar, a farmer in Sonipat, Haryana includes bee-keeping, dairy management, water harvesting, composting and agriculture in a chain of process which support each other</li>
<li>It is also an extremely economical and sustainable venture</li>
<li>There is no need to use chemical fertilizers for crops as cattle excreta (dung) is used as manure</li>
<li>Crop waste is used to create compost. This can be used for increasing soil fertility or generating natural gas for energy need of the farm
Dagar has also created the Haryana Kisan Welfare Club, with a membership of 5000+ farmers to spread information and help on the practice of Integrated farming</li>
</ul>
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<h3 id="successradioactive-wastesuccess"><Success>Radioactive waste</Success></h3>
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<ul>
<li>Nuclear energy was hailed as a non-polluting way for generating electricity</li>
<li>Later on, it was realised that the use of nuclear energy has two very serious inherent problems-</li>
<li>The first is accidental leakage</li>
<li>Safe disposal of radioactive waste</li>
<li>Nuclear radiation is extremely damaging to biological organisms</li>
<li>It causes mutations to occur at a very high rate. At high doses, it is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer</li>
<li>Nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution</li>
</ul>
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<h3 id="successthree-mile-islandsuccess"><Success>Three mile island</Success></h3>
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<ul>
<li>Three Mile Island accident was a partial nuclear meltdown that occurred on March 28, 1979, in reactor number 2 of Three Mile Island Nuclear Generating Station (TMI-2) in United States</li>
<li>In total approximately 2.5 megacuries of radioactive gases, and approximately 15 curies of lodine-131 was released into the environment</li>
<li>There were no injuries or adverse health effects from the Three Mile Island accident</li>
<li>The Three Mile Island accident caused concerns about the possibility of radiation-induced health effects, principally cancer, in the area surrounding the plant</li>
</ul>
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<h3 id="successfukushima-daiichi-nuclear-disastersuccess"><Success>Fukushima Daiichi nuclear disaster</Success></h3>
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<ul>
<li>The Fukushima Daiichi nuclear disaster was an energy accident at the Fukushima I Nuclear Power Plant in Fukushima, initiated primarily by the tsunami</li>
<li>Immediately after the earthquake, the active reactors automatically shut down their sustained fission reactions</li>
<li>It was found that the causes of the accident had been foreseeable, and that the plant operator, Tokyo Electric Power Company (TEPCO), had failed to meet basic safety requirements such as risk assessment, preparing for containing collateral damage, and developing evacuation plans</li>
<li>The Fukushimd disaster is the largest nuclear disaster since the 1986 Chernobyl disaster</li>
</ul>
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<h3 id="successdisposal-of-nuclear-wastesuccess"><Success>Disposal of nuclear waste</Success></h3>
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<ul>
<li>The primary harm from nuclear waste comes from radiation, which can cause health problems in humans and other living organisms and degrade the quality of surrounding air, water and soil</li>
<li>Nuclear fuel remains dangerously radioactive for thousands of years after it is no longer useful in a commercial reactor</li>
<li>Low-level radioactive waste, such as contaminated gloves, can be disposed of in landfill sites</li>
<li>Higher level waste, which may be dangerously radioactive, is more difficult to dispose of</li>
<li>It can be reprocessed to extract nuclear fuel or encased in glass and left deep underground about $500 \mathrm{~m}$ below earth’s surface</li>
</ul>
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<h3 id="successcauses-of-global-warmingsuccess"><Success>Causes of global warming</Success></h3>
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<p><strong>Human activities</strong></p>
<ul>
<li><strong>Nitrous oxide</strong>
<ul>
<li>Atutomobile exhausts, fertilizers, livestock wastes</li>
</ul>
</li>
<li><strong>Methane</strong>
<ul>
<li>Landfills, paddy, fields, livestock ranches</li>
</ul>
</li>
<li><strong>CFC’s</strong>
<ul>
<li>Use of aerosol cans, Refrigerants, AC’s Plastic foams etc</li>
</ul>
</li>
<li><strong>Carbon dioxide</strong>
<ul>
<li>Burning of fossil fules in industries, Automobiles and thermal power plants</li>
</ul>
</li>
</ul>
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<h3 id="successglobal-warming--effectssuccess"><Success>Global warming- effects</Success></h3>
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<ul>
<li>Rise in temperature is leading to deleterious changes in the environment</li>
<li>Odd climatic changes e.g. EI Nino effect</li>
<li>Melting of polar ice caps and Himalayan snow caps</li>
<li>Rise in sea level and submergence of island and coastal areas</li>
<li>The total spectrum of changes that global warming can bring is under active research</li>
</ul>
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<h3 id="successcontrol-of-global-warmingsuccess"><Success>Control of global warming</Success></h3>
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<ul>
<li>Cutting down use of fossil fuels</li>
<li>Improving efficiency of energy usage</li>
<li>Use of clean fuels and renewable source of energy</li>
<li>Reducing Deforestation</li>
<li>Planting trees and slowing down the growth of human population</li>
<li>International initiatives are taken to reduce the emission of greenhouse gases into the atmosphere</li>
</ul>
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<h3 id="successinternational-efforts--kyoto-protocolsuccess"><Success>International efforts- Kyoto protocol</Success></h3>
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<ul>
<li>The Kyoto Protocol is an international treaty which extends the 1992 United Nations Framework Convention on Climate Change (UNFCCC).</li>
<li>It commits State Parties to decrease greenhouse gas emissions, based on the fact that (a) global warming exists and (b) human-made $\mathrm{CO}_2$ emissions is its cause</li>
<li>The Kyoto Protocol was adopted in Kyoto, Japan, on 11 December 1997 and entered into force on 16 February 2005.</li>
<li>There are currently 192 parties to the Protocol</li>
<li>The Protocol is based on the principle of common but differentiated responsibilities</li>
<li>Copenhagen Accord endorses the continuation of Kyoto protocol which ended in 2012</li>
</ul>
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<h3 id="successozone-layer-depletionsuccess"><Success>Ozone layer depletion</Success></h3>
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<h3 id="successozone-holesuccess"><Success>Ozone hole</Success></h3>
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<ul>
<li>CFC’s have permanent and continuing affects on Ozone layer.</li>
<li>The depletion of ozone is particularly marked over the Antarctic region.</li>
<li>This has resulted in formation of a large area of thinned ozone layer, commonly called as Ozone Hole.</li>
</ul>
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<h3 id="successmontreal-protocolsuccess"><Success>Montreal protocol</Success></h3>
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<ul>
<li>Montreal protocol is an international treaty which was signed at Montreal (Canada) in 1987</li>
<li>It is a protocol to the Vienna Convention for the protection of ozone layer</li>
<li>In recognition of the deleterious affects of ozone depletion, it intended to control the emission of ozone depleting substances</li>
<li>On February 11, 1992, the United States, responding to recent scientific findings, announced that the phaseout of the production of CFCS, halons, carbon tetrachloride, and methyl chloroform would be accelerated and that these substances would be phased out by December 31, 1995</li>
</ul>
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<h3 id="successforests-our-lifelinesuccess"><Success>Forests-our lifeline!</Success></h3>
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<ul>
<li>Forests cover 31% of total land area in the world</li>
<li>Forests are home to 80% of terrestrial biodiversity</li>
<li>Forests provide a home to more than 300 million people worldwide</li>
<li>Forests contribute to the livelihoods of 1.6 billion people</li>
<li>Forsets products account for an catimated $ 330 billion of total global trade</li>
</ul>
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<h3 id="successbenefits-of-forestssuccess"><Success>Benefits of forests</Success></h3>
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<ul>
<li><span style="color:red">Climate Change Mitigates</span> Forests play a key role in out battle against climate change-storing carbon and sucking in carbon dioxide form the atmosphere and locking it into their biomass</li>
<li><span style="color:red"> Fresh Water</span> More than three quarters of the world’s accossible fresh water comes from forested catchments. Water quality declines with decrease ini forest condition and cover</li>
<li><span style="color:red">Wildelife and Biodiversity</span> Forest flora & constitute the most biologically diverse ecosystems onland. Some of world’s most threatened and endangered species, crucial to sustaining the ecosystems, live in these forests</li>
</ul>
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<h3 id="successeffects-of-deforestationsuccess"><Success>Effects of deforestation</Success></h3>
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<ul>
<li>Ecological Imbalance</li>
<li>Habitat destruction</li>
<li>Species extinction and loss of biodiversity</li>
<li>Disturbance in hydrologic and nutrient cycle</li>
<li>Soil erosion and desertification</li>
<li>Increase in global warming</li>
<li>Trees can hold a lot of carbon in their biomass and forests act as carbon sink.</li>
<li>In absence of trees, carbon dioxide concentration in the atmosphere increases contributing to global warming.</li>
<li>Occurances of floods and famines</li>
<li>Frequency of calamities and catastrophes may increase due ta deforestation</li>
</ul>
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<h3 id="successcontrolling-deforestationsuccess"><Success>Controlling deforestation</Success></h3>
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<ul>
<li>Reforestation is the process of restoring a forest that once existed but was removed at some point of time in the past</li>
<li>However, it can be accelerated by planting trees with due consideration to Biodiversity that earlier existed in that area.</li>
<li>Forest laws should be strengthened to curb felling of trees on large scale</li>
<li>Afforestation is the establishment of a forest or stand of trees in an area where there was no previous tree cover</li>
<li>The concept of Managed forests should be encouraged</li>
<li>It believes that for every tree harvested, several more are planted or regenerated in their place</li>
</ul>
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<h3 id="successcase-study-of-jodhpur-in-rajasthansuccess"><Success>Case study of Jodhpur in Rajasthan</Success></h3>
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<ul>
<li>In 17314, the king of Jodhpur in Rajasthan asked one of his ministers to arrange wood for constructing a new palace</li>
<li>The ministers and workers went to a forest near a village, inhabited by Bishnois, to cut down the trees</li>
<li>The Bishnoi community is known for its peaceful co-existence with nature</li>
<li>The efforts to cut down trees by the king’s men was thwarted by the Bishnois</li>
<li>The tree species for which the Bishnois showed resistance was the tree of “Khejadi* or Khejri</li>
<li>It enriches soil nitrogen and provides fodder, and during draught and famine, the bark of this tree is mixed with flour for human consumption</li>
</ul>
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