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1Rimmy Augustine. What is environmental chemistry? Study of Chemical species  Origin  Transport  Reactions  Effects  Fate 2Rimmy Augustine.

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Presentation on theme: "1Rimmy Augustine. What is environmental chemistry? Study of Chemical species  Origin  Transport  Reactions  Effects  Fate 2Rimmy Augustine."— Presentation transcript:

1 1Rimmy Augustine

2 What is environmental chemistry? Study of Chemical species  Origin  Transport  Reactions  Effects  Fate 2Rimmy Augustine

3 ENVIRONMENTAL POLLUTION What Does It Mean? Introduction of pollutants into the environment that causes undesirable changes and has harmful effects on plants, animals, and human beings MOST IMPORTANT ASPECT OF EN.CHEMISTRY 3Rimmy Augustine

4 Pollutants − Waste materials, which cause pollution 1.Biodegradable waste/pollutant − Breaks down easily Examples: food and garden waste, human waste, etc. 2.Non-biodegradable waste − Not easily degradable Examples: plastic, glass, heavy metals, etc. 4Rimmy Augustine


6 ATMOSPHERIC POLLUTION Atmosphere ? 6Rimmy Augustine

7 ATMOSPHERIC POLLUTION- types 1.Tropospheric pollution 2.Stratospheric pollution 7Rimmy Augustine

8 1.Tropospheric pollution a.Gaseous air pollutants  Oxides of sulphur  Oxides of nitrogen  Oxides of carbon  hydrocarbons b.Particulate pollutants Smoke Dust Mists Fumes 8Rimmy Augustine

9 Oxides of sulphur Example: SO 2 and SO 3 Formation:  burning S containing substances  Catalytic oxidation of SO 2 to form SO 3 9Rimmy Augustine

10 Harmful effects? Irritation to throat and eyes Asthma, bronchitis, respiratiory diseases Damage to plants,loss of chlorophyll, stiffness of flower buds Damage to buildings, (Taj Mahal) Sink/ control  Lime stone acts as a sink. It reacts with sulphuric acid  Remove sulphur from fuels  Use hydroelectric or nuclear power plants 10Rimmy Augustine

11 Oxides of nitrogen Example: NO(nitric oxide) and NO 2 (nitrogen dioxide) Formation:  during lightning strikes  Nitric oxide reacts with ozone 11Rimmy Augustine

12 Harmful effects? Irritant red haze in traffic Asthma, bronchitis, respiratory diseases Damage to plants, retard photosynthesis Harmful for fibres and metals Sink/ control  Gases get converted to nitric acid  Removed from atmosphere by acid rain 12Rimmy Augustine

13 Oxides of carbon Example: CO and CO 2 Formation: CO  incomplete combustion of carbon or fuel  Dissociation of CO 2 at high temperature  Conversion of methane Sink/ control  microorganisms present in soil convert CO to CO 2  Catalytic convertor fitted to exhaust pipes  Use CNG or LNG instead of petrol, diesel 13Rimmy Augustine

14 Harmful effects? Causes CO poisoning Form carboxy haemoglobin 300 time more stable than oxy haemoglobin Loses capacity to carry oxygen Leads to cardio vascular disorder Causes anoxia(acute oxygen starvation) 14Rimmy Augustine

15 Formation: CO 2  respiration  Burning of fuel  Decomposition of carbonate salts Sink/ control  green plants  Control burning substances 15Rimmy Augustine

16 Green house effect Atmosphere traps the sun’s heat near the earth’s surface and keeps it warm. It is called green house effect GLOBAL WARMING Carbon dioxide also trap heat. If the amount of carbon dioxide crosses the delicate proportion of 0.03 per cent, the natural green house balance may get disturbed and lead to global warming. Green house gases Carbon dioxide, methane, water vapour, nitrous oxide, CFCs, and ozone. ANIMATION 16Rimmy Augustine

17 Assignment  What is acid rain?  How is it caused?  What are its harmful effects?  How to control it TWO A 4 SIZE PAGES ANIMATION ACID RAIN 17Rimmy Augustine

18 PARTICULATE POLLUTANTS Small solid particles and liquid droplets suspended in air are collectively called as particulate pollutants A.Viable particulates B.Non viable particulates 18Rimmy Augustine

19 VIABLE PARTICULATES Viable particulates are minute living organisms that are dispersed in atmosphere. Bacteria, Fungi, moulds etc. 19Rimmy Augustine

20 NON - VIABLE PARTICULATES 1. SMOKE: Solid carbon particles formed during combustion 2. DUST: Solid particles formed during crushing and grinding 3. MIST: Particles of spray liquid and condensation of vapours in the air 4. FUMES: vapours of certain material present in air 20Rimmy Augustine

21 HARMFUL EFFECTS OF PARTICULATES a.Particulates entering the lungs causes cancer, asthma, bronchitis etc b.Lead particulates causes retarded memory c.It retards photosynthesis in plants d.Leads to poor visibility in roads 21Rimmy Augustine

22 SMOG (Smoke + Fog) A.London smog/ Classical smog/reducing smog It killed many people in London Occurs in cool humid conditions Mixture of smoke, fog and sulphur dioxide Due to presence of Carbon it is reducing in nature 22Rimmy Augustine 1. LONDON SMOG

23 SMOG (Smoke + Fog) B. Photochemical smog /Los Angeles smog/Oxidising smog First observed in Los Angeles Occurs in warm dry and sunny climate In presence of sunlight NO 2 and hydrocarbons gets converted to harmful products like PAN, aldehyde, ketone, ozone and nitric oxide. Ozone and NO 2 are oxidising in nature HARMFUL EFFECTS  Powerful eye irritants  Causes headache chest pain cough  Extensive damage to plant life 23Rimmy Augustine ANIMATION

24 Los Angels photochemical smog 24Rimmy Augustine ANIMATION

25 CHEMISTRY OF PHOTOCHEMICAL SMOG 1. Sunlight breaks down NO 2 to NO and oxygen free radical 2. Ozone is produced by the reaction between O and O 2 3. Ozone forms more NO 2 by reaction with NO Ozone initiates other free radical mechanisms to form PAN(Peroxy acetyl nitrate,aldehyde and ketone O (g) + O 2(g)  O 3(g) CH4 (g) + O 3(g)  HCHO + CH 2 = CH-CHO + CH 3 COOONO 2 METHANAL ACROLEINPAN 25Rimmy Augustine

26 CONTROL OF PHOTOCHEMICAL SMOG  Catalytic converters in automobiles reduces NO 2 and hydrocarbon  Certain plants like Pinus, Juniparus and Vitis metabolise nitrogen oxides PINUS JUNIPERS Vitis (grape wines) 26Rimmy Augustine

27 GROUP A ( )/ ( )/( ) WATER POLLUTION  Major water pollutants  Causes (1) pathogens (2) organic wastes stress on BOD  International standards for drinking water GROUP B ( 616 – 630) /(661 – 675)/( ) SOIL POLLUTION  Major Pollutants  Causes  Pesticides  Industrial waste GROUP C ( 631 – 643) /( )/( ) Strategies to control environmental pollution  Waste management  Green chemistry 27Rimmy Augustine

28 28Rimmy Augustine Stratospheric Pollution Ozone hole

29 29Rimmy Augustine Ozone Layer

30 30Rimmy Augustine Ozone Layer importance

31 31Rimmy Augustine If no Ozone layer??????? More UV rays reaches earth Ageing of skin cataract Sun burn Skin cancer Evaporation of surface water Damage to phytoplankton and fishes

32 32Rimmy Augustine Ozone layer formation  UV rays split oxygen molecules into free oxygen atoms  Oxygen atoms combine with molecular oxygen to form ozone  Ozone further absorbs UV rays and split into dioxygen and an oxygen atom.  A dynamic equilibrium exists between production and decomposition of ozone O (g) + O 2(g)  O 3(g) uv O 3(g)  O 2(g) + O (g)

33 33Rimmy Augustine Ozone layer depletion  CFCs from different sources reach the stratosphere  Powerful UV rays break them down to free radicals  Chlorine radical react with ozone to form O 2 and chlorine monoxide  Chlorine monoxide produces more chlorine radicals by reacting with oxygen atoms  Process gets repeated leading to more break down of ozone ANIMATION



36 Rimmy Augustine36 OZONE HOLE OVER SOUTH POLE Summer climate: - sink for chlorine free radical / less ozone depletion Nitrogen dioxide combines with chlorine monoxide to form chlorine nitrate which is non reactive. Methane combines with chlorine free radical to form methyl free radical and HCl. Chain reaction stops. Winter climate:- Polar stratospheric clouds(PSC)/ an initiator for depletion A. In presence of PSC chlorine nitrate gets hydrolysed to hypochlorous acid. B. In presence of PSC chlorine nitrate gets hydrolysed to Cl 2.

37 Rimmy Augustine37 spring season:- Ozone depletion by chain reaction In sunlight HOCl and Cl 2 are photolysed to free radicals causing ozone depletion

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