Chemical_polution (1).pptx
- 2. What is pollution? • Pollution is the introduction of harmful substances or products into the environment • Main types of pollution – Water Pollution – Air Pollution – Soil Pollution – Biological – Nuclear
- 4. Causes of Water Pollution • Factors that contribute to water pollution can be categorized into two different groups – Point sources – Non-point sources • Point sources are the easiest to identify and control • Non point sources are ambiguously defined and harder to control
- 5. Point Sources • Some point sources of water pollution include – Factories – Sewage system – Power plants – Underground coalmines – Oil wells • Are direct sources of water pollution and can be reduced and monitored
- 6. Example of a point source
- 7. Non-point Sources • The term non-point source encompasses a large range of sources such as: – when rain or snow moves through the ground and picks up pollutants as it moves towards a major body of water – the runoff of fertilizers from farm animals and crop land – air pollutants getting washed or deposited to earth – storm water drainage from lawns, parking lots, and streets
- 9. Kinds of water pollutants • Inorganic Pollutants • Organic Pollutants • Biological Pollutants
- 10. Inorganic Pollutants • Pb in gasoline • Radionuclides • Phosphorus, nitrogen (Great Lakes) Inorganic Trace Contaminants- -Mercury—methyl Hg and dimethyl Hg in fish— Minamata Bay, Japan, 1950’s -Lead—toxicity has been known for a long time – Tetraethyl lead—anti-knock additive for gas, 1930- 1966
- 11. Phosphates and Nitrates • Phosphates—mostly a result of sewage outflow and phosphate detergents – Additional phosphate grows excess algae…oxygen depletion • Nitrates—sewage and fertilizers
- 12. Organic Pollutants • Three classes of compounds – Pesticides and Herbicides – Materials for common household and industrial use – Materials for industrial use
- 13. Pesticides • Chlorinated hydrocarbons – DDT, heptachlor, etc—2-15 years • Organophosphates – Malathion, methyl parathion—1-2 weeks • Carbamates – Carbaryl, maneb, aldicarb—days to weeks • Pyrethroids – Pemethrin, decamethrin—days to weeks
- 14. Herbicides • Triazines—e.g. atrazine, paraquat (interfere with photosynthesis) • Systemic—phenoxy compounds, N compounds, Alar, glyphosate (create excess growth hormones) • Soil sterilants trifluralin, dalapon (kill soil microorganisms)
- 15. Chemicals responsible for water pollution • Each year 700-800 new chemicals are produced • 55 million tons of hazardous chemical wastes are produced in the US each year • The 20 most abundant compounds in groundwater at industrial waste disposal sites include TCE, benzene, vinyl chloride…all are carcinogens, and also affect liver, brain, and nervous system • Polychlorinated biphenyls- Byproducts of plastic, lubricant, rubber & Paper Industry.
- 16. Air Pollution
- 17. Causes of Air Pollution • carbon dioxide -Deforestation and fossil fuel burning • Sulfur dioxide -burning of sulfur containing compounds of fossil fuels. • Chlorofluorocarbons (CFCs) reduces the amount of ozone. CFCs come from –the burning of plastic foam items –leaking refrigerator equipment –spray cans
- 18. • Hydrocarbons- from petrol engines • NOx- from burning of fossil fuels • Suspended particulate matter- by diesel engines, thermal power plants • Lead compounds- from petrol engines
- 19. Natural Air Pollutants • Natural air pollutants can include: – Smoke from wild fires – Methane released from live stock – Volcanic eruptions
- 21. Consequences of Air Pollution • CO2 is a good transmitter of sunlight, but it also partially restricts infrared radiation going back from the earth into space, which produces the so- called greenhouse effect that prevents a drastic cooling of the Earth during the night • Increasing the amount of CO2 in the atmosphere reinforces this effect and is expected to result in a warming of the Earth's surface • CO2 in atmosphereGLOBALWARMING
- 23. A smoggy city
- 24. Photochemical Smog • Sulfur dioxide, nitrogen oxides, ozone and peroxyacl nitrates (PANs), give rise to photo chemical smog, irritates eyes and lungs. • Chronic exposure of leaves and needles to air pollutants can also break down the waxy coating that helps prevent excessive water loss and damage from diseases, pests, drought and frost
- 25. Soil Pollution
- 26. Causes of Soil Pollution • Contamination of soil system by considerable quantity of chemicals or other substances resulting in reduction of its fertility. • Four Main causes of Soil pollution – Construction – Agriculture – Domestic waste – Industrial Waste
- 27. Chemicals causing soil pollution • Metallic pollutants- textiles, dyes, soaps, detergents, drugs, cement, rubber, paper, metal industries release Fe, Pb, Cu, Zn, Hg, Cd, CN, acids, alkalies etc. • Agro chemicals- Fertilizers, pesticides, insecticides, weedicides, rodenticides, fumigants release toxic chemicals like Pb, As, Cd, Hg, Co etc. • Radioactive Chemicals
- 28. Biological Pollution • Disturbance of the ecological balance by the accidental or deliberate introduction of a foreign organism, animal or plant species into an environment. • an individual organism (internal biological pollution by parasites or pathogens) • A population (by genetic change)
- 29. continued • a community • a habitat (by modification of physical-chemical conditions), • An ecosystem (by alteration of energy and organic material flow). • Biopollution may also cause decline in naturalness of nature conservation areas.
- 30. Biological Agents • Soil gets human, animal & bird excreta • Digested sewage sludge • Heavy applications of manure to soil Scale of Biologic Contaminant Problem: -Major cause of infant deaths in third world -Diarrhea kills 4-15 million children/year -Bacteria, viruses, parasites
- 31. Radiological & Nuclear pollution • Special form of physical pollution of air, water and soil with radioactive materials. • Radioactivity- Property of certain elements like Ra, Th, U etc to spontaneously emit alpha, beta & gamma rays by disintegration of atomic nuclei.
- 32. Sources • Nuclear explosions and detonations of nuclear weapons – U-235, Pu-239 for fission, H & Li for fusion. Fallouts contain Sr-90, Cs-137, I-131 • Defense weapon production- C-14, I-125, P-32 • Nuclear waste handling and disposal- high level & low level
- 33. Sources • Mining – radioactive gases like radon • Nuclear accidents • Medical X-Rays- from diagnostic X-rays & radiation therapy for cancer. • Nuclear reactors- U-235, U-238, Th-232
- 34. Effects of nuclear pollution • The effects vary from organism to organism and from level of radioactivity of nuclear isotopes. The radiations destroy the cells in human body and causes cancer. • A longer exposure to radioactive radiations can damage the DNA cells that results in cancer, genetic defects for the generations to come and even death.
- 35. continued • Kills foetus in the womb • Affects animals, some species preferentially accumulate specific radioactive materials- oysters deposit Zn-65, fish Fe-55, marine animals Sr-90.
- 36. Chemical Warfare agents • A chemical used in warfare is called a chemical warfare agent (CWA). • These agents may be in liquid, gas or solid form. Liquid agents are generally designed to evaporate quickly; such liquids are said to be volatile or have a high vapour pressure. • In July 1917, the Germans employed mustard gas. Mustard gas easily penetrates leather and fabric to inflict painful burns on the skin.
- 37. • Chemical warfare agents are divided - into lethal and incapacitating categories. A substance is classified as incapacitating if less than 1/100 of the lethal dose causes incapacitation, e.g., through nausea or visual problems. • Choking Agents (e.g., phosgene, chlorine) • Blister Agents (e.g., nitrogen mustard, Lewisite) • Nerve Agents (e.g., tabun, sarin, VX) • The most commonly used chemicals are four lung- destroying poisons: chlorine, chloropicrin, phosgene, and trichloromethyl chloroformate, along with a skin-blistering agent known as mustard gas, or bis (2- chloroethyl) sulfide.