biology-class-12-unit-15-chapter-05-ecology-environmental-issues-2-3-zsatfakdzyy

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<h3 id="successlets-check-our-understandingsuccess"><Success>Lets check our understanding</Success></h3>
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<p><strong>Question 1.</strong> This element is added to paints mainly to speed up drying and increase durability, but due to its toxic effects it has been banned in many countries. Most homes built before the year 1960 contained this element in its paint. Which element is this?</p>
<p>A. Mercury<br>
B. Lead<br>
C. Earth pigment<br>
D. Clay</p>
<p><strong>Point to remember -</strong> Lead released into the environment makes its way into the air, soils, and water. Lead can remain in the environment as dust indefinitely. The lead in fuels contribute to air pollution, especially in urban areas.</p>
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<h3 id="successlets-check-our-understandingsuccess-6"><Success>Lets check our understanding</Success></h3>
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<p><strong>c. Groundwater depletion and ways for its replenishment</strong></p>
<ul>
<li><strong>Groundwater</strong> (or <strong>ground water</strong>) is the water present beneath earth’s surface in soil pore spaces and in the fractures of rock formations</li>
<li><strong>water table</strong>, also called <strong>groundwater table</strong>, upper level of an underground surface in which the soil or rocks are permanently saturated with <strong>water</strong></li>
<li>Groundwater is becoming scarce in many parts of the world due to
<ul>
<li>Excessive pumping of water before it can be replenished</li>
<li>Deforestation</li>
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</li>
<li>Replenishment can be done by rainwater harvesting and reforestation</li>
</ul>
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<h3 id="successcontrol-of-noise-pollutionsuccess"><Success>Control of noise pollution</Success></h3>
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<ul>
<li>Use of sound absorbent materials or by muffling noise</li>
<li>Constructing sound proof buildings</li>
<li>Use of silencers in automobile engines and machines</li>
<li>Being sensitive to others problem. For example- keeping the volume of your devices low or using ear phones to enjoy music.</li>
<li>Stringent following of laws laid down in relation to noise -
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<li>Delimitation of horn-free zones around hospitals and schools</li>
<li>Permissible sound levels of crackers and of loudspeakers</li>
<li>Timings after which loudspeakers, D.J. can not be played</li>
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</li>
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<h3 id="successsolid-wastessuccess"><Success>Solid wastes</Success></h3>
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<ul>
<li>Solid waste means any garbage, refuse, sludge from a wastewater treatment plant and other discarded materials including solid, liquid, semi solid, or contained gaseous material, resulting from industrial, commercial, mining and agricultural operations etc</li>
<li>In short, everything that goes out in trash</li>
<li>Municipal solid wastes $\rightarrow$ wastes from homes, offices, stores, schools, hospitals etc.</li>
<li>Municipal solid waste comprises of paper, food waste, plastics, glass, metals, rubber, leather, textile etc.</li>
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<h3 id="successsolid-waste-managementsuccess"><Success>Solid waste management</Success></h3>
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<ul>
<li>Burning reduces the volume of the wastes although it is not burnt to completion</li>
<li>Open dumps serve as breeding ground for rats and flies</li>
<li>Sanitary landfills were adopted as the substitute for open-burning dumps</li>
<li>There are 3 landfill sites namely Bhalswa land fill site, Ghazipur sanitary land fill site, Okhla sanitary land fill site in Delhi</li>
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<h3 id="successsolid-waste-managementsuccess-1"><Success>Solid waste management</Success></h3>
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<ul>
<li>In a sanitary landfill, wastes are dumped in a trench or depression after compaction, and covered with dirt everyday.</li>
<li>Are landfills a good solution?</li>
<li>The amount of garbage generated has increased so much that these sites are getting filled too</li>
<li>Their is a danger of seepage of chemicals from these landfills polluting the underground water resources</li>
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<h3 id="successhow-can-we-effectively-reduce-our-garbagesuccess"><Success>How can we effectively reduce our garbage?</Success></h3>
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<li>What can be reused or recycled should be separated out</li>
<li>Biodegradable wastes can be put into deep pits in the ground and be left for natural breakdown as they can be easily degraded by microbes</li>
<li>Non-biodegradable waste can not be decomposed easily by the micro-organisms and so remains in the environment for long</li>
<li>To reduce the garbage should be our prime goal, instead we are increasing the use of non bio-degradable products, especially plastic</li>
<li>State government across the country are trying to push for reduction in use of plastics and use of eco-friendly packaging</li>
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