Question Paper: may 2018 EVS solved paper of Mumbai University part 3
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5A. Discuss briefly about green house effect

The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without its atmosphereIf a planet's atmosphere contains radiatively active gases (i.e., greenhouse gases) they will radiate energy in all directions. Part of this radiation is directed towards the surface, warming it. The intensity of the downward radiation – that is, the strength of the greenhouse effect – will depend on the atmosphere's temperature and on the amount of greenhouse gases that the atmosphere contains.Earth’s natural greenhouse effect is critical to supporting life. Human activities, mainly the burning of fossil fuels and clearing of forests, have strengthened the greenhouse effect and caused global warming

By their percentage contribution to the greenhouse effect on Earth the four major gases are:

• water vapor, 36–70%

• carbon dioxide, 9–26%

• methane, 4–9%

• ozone, 3–7%

Strengthening of the greenhouse effect through human activities is known as the enhanced greenhouse effect. The greenhouse effect, combined with increasing levels of greenhouse gases and the resulting global warming, is expected to have profound implications If global warming continues unchecked, it will cause significant climate change, a rise in sea levels, increasing ocean acidification, extreme weather events and other severe natural and societal impacts

5B- what are the main causes of soil degradation

Ans: Soil degradation has been defined as a process that leads to decline in the fertility or future productive capacity of soil as a result of human activity. It occurs whenever the natural balances in the landscape are changed by human activity through misuse or overuse of soil. Degraded soils which result in poor or no production are also called problem soils.

Causes of Soil Degradation:

  1. Nutrient disorder: Most of the Indian soils are deficient in nutrients and organic matter. Organic matter is rapidly decomposed and leached or eroded by heavy rains. In addition to these causes, intensive cultivation using high-yielding short-duration and fertilizer-responsive cultivars of crops has further accelerated the loss of plant nutrients which is much greater than what is supplemented through fertilizers.

  2. Water-logging: Soils become water-logged when the water balance of an area is disturbed because of excess recharge. Important sources of water are heavy rains, overland water flow towards basin, seepage from canals and distribution system and tidal flooding. Natural basins without outlet for water, low permeability of subsurface horizons, internal drainage, low intake rate of surface soils and obstructions to natural flow of rain water etc. are conditions cause water logging.

  3. Salinity: Salinity directly affects the productivity by making the soil unsuitable for crop growth. Indirectly it lowers productivity through its adverse effects on the availability of nutrients. The adverse effect of alkalinity on availability of nutrients is due to deflocculating effect of sodium ions. An area of about 21.7 million hectares of soil is rendered unproductive due to salinity and water-logging.

  4. Erosion: Soil erosion is the major cause of soil degradation. In the soil erosion, uppermost fertile layer of soil which contains essential nutrients is lost. Thus soil becomes deficient in essential minerals and this results in productivity loss. Deforestation or destruction of forests accompanied by reduced frequency of rainfall leads to soil erosion and causes damage to agriculture property. Deforestation causes fast degradation when the soil is steep sloppy or easily erodible. Destruction of natural vegetation cover is a major factor responsible for erosion of soils by water and wind.

  5. Biological degradation: The factors which affect soil micro flora and fauna also reduce the biological or microbial activity of soil adversely. These factors reduce the yield. It is well known that mono cropping (growing the same crop on the same land year after year) often leads to increasing attack of pests and diseases. The fatal nematodes threaten potato cultivation in the Nilgiris and, if not controlled they may pose threat to potato cultivation in that area. Excess use of pesticide reduces microbial activity and biomass.

  6. Other causes: Extension of cultivation to marginal land: Improper crop rotation: Fertilizer misuse: Overgrazing: Mining:

5C. what are the measures to control the global warming

  1. Use Fluorescent Light Bulbs: You should immediately change incandescent light bulbs and use fluorescent light bulbs, because these fluorescent bulbs consume only 25 % energy comparable incandescent bulbs.

  2. Switch Off Electric Appliances: When electric appliances are not in your use, then plug them off, because they use some energy even in off position.

  3. Change Your Monitor with LCD: Try to get LCD instead of a monitor, because LCD takes about 56 percent energy than your monitor. Always keep your computer screen status off, when you are not working.

  4. Don’t Leave Fridge’s door open for a Long Time: You take or put things in your Fridge quickly, because if you keep open your fridge door for a minute, then its motor will remain operative for more than a half hour.

  5. Uses of Solar Energy: You should convert your heating system to the solar energy, in this way you can save electricity, money and your environment from global warming.

  6. Use Electric or Hybrid Car: You consider purchasing a hybrid or electric car, in place of gasoline car. Gasoline car covers 20 to 30 miles per gallon, whereas hybrid or eclectic gives you 130 to 140 mg.

  7. Plant Trees At Home: If you have placed at the front or back side of your home, trees shading, can make your home cold during summer. Since trees absorb carbon dioxide, so reduce the carbon dioxide in your surroundings.

  8. Save Clean Water : You should not waste clean water, because clean water has become less, experts see the water crisis in the future. We need more energy for the processing of clean water.

  9. Avoid Lighting at Day Time : The sun provides you light dawn to dusk; if you design your home with good planning you can save electricity cost.

  10. Make High Roofs: When you build your home, construct it with high ceiling, because it reduces the heat. Ceramic or soil material made roofs to comfort the temperature of the room.

  11. Get Your House Insulated: Your house must be properly insulated, use insulation in the lower floor, ceiling, over crawl spaces and walls.

  12. Reduce Trash At Home: You should reduce trash that gets produced in your house . You can achieve this goal by using recycled products and avoiding unnecessary garbage items.

  13. Reduce the Usage of Hot Water: You should try better to reduce the usage of hot water, install low-flow shower-heads in your bathroom; you will avoid contributing 350 pounds carbon dioxide yearly.

  14. Grow your Own Foods: Fresh vegetable is better than you buy from the grocery store. They will save you expense on gas & time.

6A. Discuss the role of 3R in sustainable development

Ans: The three R’s stands for: Reduce, Reuse and Recycle.

This rule is part of the waste hierarchy which is a process used to protect the environment and conserve resources through a priority approach. The aim is to get the most practical benefits from products and to generate the minimum amount of waste. This approach also triggers other positive externalities such as resource savings, pollution reduction, and avoidance of greenhouse gas emissions, development of sustainable technologies and creation of jobs.

Reduce

Waste reduction and waste prevention is all about reducing waste at the source. In terms of waste management, it is always the best option. Waste is often due to the inefficient use of resources or bad planning. For example, buying food we don’t need on impulse or because there’s a special offer and then wasting it.

Reuse

Reuse means using a product more than once, either for the same purpose (for example returnable glass milk bottles) or for a different purpose (such as old jam jars for food storage). Repairing products, selling them on or donating them to charity/community groups is also reusing! It is preferable to recycling because the item does not need to be re-processed before it can be used again which saves both money and reduces the environmental impact.

Recycle

Recycling is a way to manage waste materials once they have been generated if they can’t be reused. It prevents waste from being sent to landfill and makes waste into new goods or products. Effective recycling requires us to separate waste according to different materials so that they can be recycled efficiently. This can involve turning the old material into a new version of the same thing or into something completely different. For example, used glass bottles can be recycled into new bottles or they can be recycled road materials for use in construction projects.

6B How increasing population is exerting extra pressure on land and mineral resource discuss.

Competition for land between sectors and production systems is projected to intensify. It is expressed most accurately in the expansion of the use of land for arable and tree crops, shifting cultivation and grazing of livestock and its conservation under forest. Then there is the competition between crop and livestock production and, on a much smaller scale, between crop production or mangrove swamp preservation and aquaculture, there will be further pressures on the forest for timber and fuelwood extraction. Finally, increasing population and economic growth will contribute to further diversion of land to human settlements and infrastructure.

Soil erosion

There is widespread evidence of erosion resulting in losses greatly in excess of 50 tonnes of soil per hectare per year, losses that may be five or more times the natural rate of soil formation.

Soil nutrient mining

The shortening of fallows and prolonged crop harvesting without adequate technological responses to replace the soil nutrients taken out by crops with organic or mineral fertilizer inputs, leguminous crops, nitrogen-fixing algae and so on is lowering the nutrient status of soils and the actual or potential crop yields. It consequently threatens the sustainability of agricultural production and also introduces an additional economic cost because the lack of balance lowers the technical efficiency of the mix of fertilizer nutrients.

Salinization of soils

This is primarily a problem of irrigated areas, but also occurs in hot dry zones where strong evaporation brings salts to the surface. In irrigated areas it is usually the consequence of bad design causing poor drainage, and/or inadequate maintenance and inefficient management leading to excessive application rates, and seepage from water courses. The end result is waterlogging, salinization, depressed crop yields and eventually, if corrective action is not taken, loss of land for agriculture. This leads to physical pressures on the finite resource base if land is permanently lost, which according to some estimates may vary in the range 0.2-1.5 million ha per year worldwide, while some 10 to 15 percent of irrigated land is to some extent degraded through waterlogging and salinization.

Desertification

Oil nutrient mining and the overcultivation of fragile soils does lead to dryland degradation and desertification.

Water contamination

The principal threats of agricultural origin are the following: rising salt concentrations in irrigated areas; fertilizer and pesticide contamination of surface and groundwater; and discharges of organic effluents from intensive livestock units and fish farms.

6.C what do you understand by landfilling? Explain briefly

Ans: A landfill, also called sanitary landfill, is a land disposal site for waste, which is designed to protect from environmental pollution and health risks. Landfills are built to concentrate the waste in compacted layers to reduce the volume and monitored for the control of liquid and gaseous effluent in order to protect the environment and human health. Besides municipal solid waste, faecal sludge can also be discharged into landfills. Well-constructed and maintained landfills are safer than open dumping sites, but even the best sanitary landfill will fill up and, after many years, probably start to leak. Therefore only waste, which cannot be reused further should be disposed of in landfills. To solve current waste problems, prevention of waste in the first place remains a priority. Separation of different types of wastes and reuse is much more sustainable.

A basic landfill is a pit with a protected bottom (to prevent contamination of groundwater) where trash is buried in layers, compacted and covered. Ideally, about 0.5 m of soil should cover the deposited refuse at the end of each day to prevent animals from digging up the waste, flies from breeding and to avoid that odour, waste (e.g. plastic bags) or pathogens are spread by the .The more advanced (“engineered”) landfills consist of a liner system at the bottom and the sides; a leachate removal system, which also includes a treatment of the leachate; groundwater monitoring, gas extraction (the gas is flared or used for energy production) and a cap system (see picture above). The capacity is planned and the site is chosen based on an environmental risk assessment study

Landfill leachates will cause environmental problems if not handled properly. One of the most promising methods of treating landfill leachate are constructed wetlands as they require little operation and maintenance Once the capacity of the landfill is reached, it has to be covered correctly and the bottom has to be controlled regularly to make sure no toxic effluent reaches groundwater sources. The cover should resist erosion by wind and water, promote vegetation and satisfy aesthetic, ecological, or end use criteria

Advantages

Effective disposal method if managed well

Sanitary disposal method if managed effectively

Energy production and fast degradation if designed as a bioreactor landfill

Disadvantages

Fills up quickly if waste is not reduced and reusable waste is not collected separately and recycled

A reasonably large area is required

Risk of groundwater contamination if not sealed correctly or the liner system is damaged

High costs for high-tech landfills

If not managed well, there is a risk of the landfill degenerating into an open dump

Once the landfill site is shut down O&M and monitoring must continue for the following 50 to 100 years

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