UNIT VI lectures in surveying civil.pptx

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1. AIR POLLUTION: It is the presence of contaminants like dust, fumes, mist, smoke, odour or vapour in huge quantities which are injurious to human, plant or animal life or property which affects the comforts of life Sources: Stationary sources: Chimneys of different industries Mobile sources: Railway engine, vehicles, ships. Classification of air pollutants: Primary pollutants: NOx, SOx, CO, halogens Secondary sources: Ozone, PAN( Peroxy acetyl nitrate), Acid rain, smog.

2. Causes and sources: Rapid industrialization Urbanization Uncontrolled use of vehicles Deforestation Effects: Human being: Irritation in eyes, nose, throat and respiratory track. Respiratory disease such as asthma, bronchitis. Vegetation: bleaching of leaves. Premature aging

3. GREEN HOUSE EFFECT: The term green house effect indicates the heat trapping process caused due to CO 2 and the water vapour. They are transparent to incoming solar radiation but the re-emitted infrared radiation cannot penetrate through them. But the increasing rate of CO 2 causes more and more solar radiations to get entrapped. This results in increase of temperature of the earth’s surface. This process is called green house effect

4. Adverse effects of green house effect: It may cause increase in earth’s temperature at the rate of 0.2 to 0.5 °c per decade. It will result in melting of ice and general rise in sea level at the rate of 5 cm to 20 cm per decade. It may cause change in climatic conditions including precipitation. This may affect ecosystem and agricultural cycles.

5. ACID RAIN: It occurs due to excessive presence of acids in the precipitation. Industrialization, use of fossil fuels causes acid rain. The main gases responsible for acid rain are SO2 and NOx. The acid rain increases the acidity of water bodies and lakes. Adverse effects of acid rain: Decrease in Aquatic life Corrosion of monuments, statues, metals etc. Adverse effect on human nervous system, respiratory and digestive system Reduction in visibility.

6. Remedial measures: Process change: Adopt eco-friendly industrial and manufacturing process. Fuel change: use of cleaner fuels. Control at source: Trap the air pollutants at the exit point of the source. The gaseous pollutants are controlled by absorption, condensation process.

7. WATER POLLUTION: Foreign substances either from natural or manmade substances, contaminated with water supplies may be harmful to life due to toxicity, reduction in normal oxygen level of water, esthetically unsuitable and spread epidemic diseases. Sources: Domestic sewage Industrial waste water Pesticides and fertilizers Toxic metals Radioactive discharge