environmental studies pollution chapter -1

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This is the presentation prepared to teach Environmental Studies to UnderGraduate students.

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ENViRONMENTAL POLLUTiON

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Environmental Pollution Can be defined as any undesirable change in the physical, chemical or biological characteristics of any component of the environment (air, water, soil), which causes harmful effects on various forms of life or property.

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Classification of pollutants:- Degradable or Non-persistent pollutants: Ex: domestic Sewage, discarded vegetables etc., Slowly-degradable or persistent pollutants: Ex: DDT(pesticides) and most plastics Non-degradable pollutants: Ex: Toxic elements like lead or mercury and nuclear wastes Structure of the Atmosphere: Troposphere Stratosphere Mesosphere Thermosphere

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Air Pollution is an atmospheric condition in which certain substances like gases , particulate matter , radioactive substances etc are present in concentrations which can cause undesirable effects on human environment. -Average Human-being requires 12-20 kg of air each day, which is nearly 12-15 times greater than the amount of food we eat. Classification of Air Pollutants Primary Pollutants CO, CO2, NO2, SO2, volatile organic compounds(hydrocarbons), and suspended, particulate matter Secondary Pollutants sulfuric acid, nitric acid, carbonic acid …

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Sources of Air Pollutants Natural Sources : These are volcanic , eruptions , forest fires , pollen grains of flowers , spores , sea salt sprays etc. Man-made Sources : These include thermal power plants , vehicular emissions , fossil fuel burning , agricultural activities etc. Effects of air pollution on human health : Lower respiratory system of human beings Fig:

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Some Important Air Pollutants: Carbon monoxide (co): colorless, odorless and toxic gas -- By-product of incomplete burnt fuels. -- combines with haemoglobin and reduces the oxygen carrying capacity of blood to brain, heart and other organs. At high levels causes coma, irreversible brain cell damage and death Carbon dioxide (CO2): industrial and vehicular exhausts, respiration -- Green house gas causes Global warming Sulfur oxides: sulfur containing fossil fuels -- causes respiratory diseases, asthma, bronchitis, emphysema and cardiovascular diseases and formation of H2S O4 Nitrogen oxides: vehicular exhausts; -- causes asthma, bronchitis, pneumonia and irritates lungs involves in the production of ozone(O3) , PAN , HNO3 etc., Hydrocarbons: fuels and oils containing carbon and hydrogen atoms -- causes eye irritation, coughing and drowsiness Particulate matter: Aerosol, Mist, Dust, Smoke, Fume, Fog, Smog PAN, Photochemical smog and Asbestos -- carcinogenic (cancer causing) agents, lungs damage, asthma Lead: vehicular exhausts -- weakens central nervous system, causes coma, irreversible brain damage, uncontrollable mental disturbances & death.

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Control of Air Pollution Minimize activities which cause pollution like transportation and energy production. Modification of process Using appropriate eqipment (cyclone filters, bag houses, electrostatic precipitators,scrubbers etc.,) Using low sulphur coal in industries. Using mass transport system , bicycles etc. Using non-conventional sources of energy. Planting more trees. Reduction of pollution at source.

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Marine Pollution Causes: Rivers, which bring pollutants from their drainage basins Catchment areas Offshore oil production Oil spills and tanker operations

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Effects of marine pollution: Phytoplankton, zooplankton, algal species, coral reefs, fish, species of invertebrates, birds and mammals are affected by oil pollution. Oil in the sea water affects sensitive flora and fauna. Control of marine pollution Toxic pollutants from industries and sewage treatment plants should not be discharged in coastal waters. Run off from non-point sources should be prevented to reach coastal areas. Sewer overflows should be prevented. Dumping of toxic, hazardous wastes and sewage sludge should be banned. Development activities on coastal areas should be minimized. Oil ballast should not be dumped into sea. Ecologically sensitive coastal areas should be protected by not allowing drilling.

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Noise Pollution Sources : Various modes of transportation , industrial operations , construction activities and celebrations . Effects of Noise: Interfaces with man’s communication : In a noisy area communication is severely affected. Hearing damage : Depends on intensity and duration of sound level.(TTS & NIPTS) Physiological and psychological changes : Affects the functioning of various systems of the body.

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Noise level in dB (A) Leq Noise standards recommended by Central Pollution Control Board committee

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Safe limit for exposure to various noise levels

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Control of Noise Pollution Reduce noise at the source Block the path of noise Increase the path length Protect the recipient Reduction in sources of noise by vehicles. Noise making machines should be kept in containers with sound absorbing media. Proper oiling reduces the noise from the machinery. Use of sound absorbing silencers. Planting more trees having broad leaves. Through law : Unnecessary horn blowing should be restricted.

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Water Pollution defined as alteration in physical , chemical or biological characteristics of water making it unsuitable for designated use in its natural state.

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Sources of water pollution Major point sources are industries , power plants , underground coal mines, offshore oil wells etc. Non-point sources are overflowing small drains , rain water sweeping roads and fields ,surface run-off from agricultural fields etc. Ground water pollution- Septic tanks, industries, deep well injection, mining etc. are mainly responsible and are irreversible. Surface water pollution- Sewage, industrial effluents, synthetic detergents, agro-chemicals, oil, waste heat are the major sources.

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Effects of Water Pollution Oxygen demanding wastes (BOD) Nitrogen and Phosphorous compounds(nutrients) Pathogens Toxic compounds Example for biomagnification of DDT in aquatic food chain: Component DDT concentration(ppm) Birds 10.00 Needle Fish 1.00 Minnows 0.10 Zooplankton 0.01 Water 0.000001

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Control of Water Pollution Judicious use of agrochemicals like pesticides and fertilizers which reduces their surface run-off and leaching. Use of nitrogen fixing plants to supplement the use of fertilizers. Adopting integrated pest management to reduce reliance on pesticides. Prevent run-off of manure. Separate drainage of sewage and rain water should be provided to prevent overflow. Planting trees would reduce pollution by sediments and will also prevent soil erosion. Root Zone Process --Thermax

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Fig: Flow diagram of sewage(wastewater) treatment plant

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Thermal Pollution Defined as presence of waste heat in the water which can cause undesirable changes in the natural environment.

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Sources of thermal pollution : Thermal power plants, nuclear power plants, refineries, steel mills etc. Effects of thermal pollution The dissolved oxygen content of water is decreased. High temperature becomes a barrier for oxygen penetration into deep cold waters. Toxicity of pesticides, detergents and chemicals in the effluents increases with increase in temperature. The composition of flora and fauna changes. The fish & other organisms adapted to a particular temperature range can be killed by the abrupt change in water temperature Metabolic activities of aquatic organisms increase at high temperature and require more oxygen. Discharge of heated water near the shores can disturb spawning and kills young fishes. Fish migration is affected due to formation of various thermal zones.

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Control of Thermal Pollution Methods: Cooling ponds: Water from condensers is stored in ponds where natural evaporation cools the water which can then be discharged in nearby water vapour. Spray ponds: Here the water is sprayed through nozzles where fine droplets are formed. Cooling towers: Wet cooling tower: Cool air entering from sides takes away the heat and cools the water. Large amount of water is lost through evaporation. Dry cooling tower: There is no water loss in this method but installation and operation cost of dry cooling tower is many times higher than wet cooling tower.

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Soil Pollution Sources of soil pollution: Dumping of various types of materials especially domestic and industrial wastes causes soil pollution. Domestic wastes include garbage, rubbish material like glass, plastics, metallic cans, paper, fibres, cloth rags, paints etc. Industrial wastes include paper and pulp mills, tanneries, textile mills, steel industries, refineries, pesticides and fertilizer industries, pharmaceutical industries thermal and nuclear power plants , mining industries etc. Radioactive Substances: Improper disposal of nuclear wastes can cause radioactive substances to remain in the soil for a long time & causes mutations

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Pesticides The pesticides used in agriculture have chemicals that last long in the environment. In addition to killing the pests, they also effect some beneficial organisms like the earthworm in the soil. Organisms like earthworm are vital to the decomposition of materials and formation of soil. Acid Rains The acid rains can change the pH of the soil making it unsuitable for cultivation. Deforestration and soil erosion Soil Erosion occurs when the weathered soil particles are dislodged and carried away by wind or water. Deforestation, agricultural development, temperature extremes, precipitation including acid rain, and human activities contribute to this erosion. Humans speed up this process by construction, mining, cutting of timber, over cropping and overgrazing. It results in floods and cause soil erosion Salinization and Water Logging Indiscriminate and intensive use of over irrigation coupled with imbalanced use of fertilizers and poor drainage has caused salinity and water logging. Night Soil Human excreta mixed with soil is called night soil. Open latrines in the villages and some parts of cities are the source of this pollution.

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Effects of soil pollution Various types of chemicals like acids, alkalis, pesticides, insecticides, fungicides, heavy metals causes Ground Water & Soil Pollution. Decomposing organic matter in soil also produces toxic vapours. Nitrogen and phosphorous from the fertilizers in soil cause eutrophication. Control of soil pollution Effluents should be properly treated before discharging them on the soil. Solid wastes should be properly collected and disposed off. Recovery of useful products should be done from the wastes(3 R’s). Biodegradable organic waste should be used for generation of biogas. Cattle dung should be used for methane generation. Microbial degradation of biodegradable substances can be approached for reducing soil pollution. Reducing chemical fertilizer and pesticide use and shifting to the application of bio-fertilizers and manures. Using Integrated Pest Management. Crop rotation or mixed cropping can improve the fertility of the land. Control of land loss and soil degradation can be attempted through restoring forest and grass cover to check wastelands, soil erosion and floods. Ban on use of plastic bags (below 20 microns thickness) - which are major cause of pollution in cities

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Nuclear Hazards Sources of radioactivity Natural: Cosmic rays from outer space, radioactive radon-222, soil, rocks, air, water and food. Anthropogenic: Nuclear power plants, nuclear accidents, X-rays, diagnostic kits, test laboratories etc., Effects of Radiations Genetic damage is caused by radiations, which affects genes and chromosomes. Somatic damage includes burns, miscarriages, eye cataract and cancer of bone, thyroid, breast, lungs and skin Control of Nuclear Pollution Siting of nuclear power plants should be carefully done. Proper disposal of wastes from laboratory should be done Uranium and Thorium mining and refineries must be carefully maintained. In-door pollution should be minimized.

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Role Of An Individual In Prevention Of Pollution Prevention can be done by some suggestions as given: Lay greater emphasis on pollution prevention than pollution control. Use ecofriendly products. Cut down the use of CFCs as they destroy the ozone layer. Use CFC free refrigerators. Do not use polystyrene cups that have CFC molecules in them. Improve energy efficiency, which reduces the amount of waste energy. Saving electricity. Reduce the production of wastes. Use mass transport system. Decrease the use of automobiles. Do not put pesticides, paints or other harmful chemicals into ground water. Use only minimum required amount of water for various activities. Use rechargeable batteries, which will reduce metal pollution. Plant more trees, as they absorb many toxic gases and can purify the air by releasing oxygen. Check pollution growth so that demand of material is under control.

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The End by Venakteswar Reddy M