POLLUTION. Water Pollution Atmospheric Pollution The Atmosphere: Climate Change and Ozone Depletion

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1 POLLUTION Water Pollution Atmospheric Pollution The Atmosphere: Climate Change and Ozone Depletion

2 Water Pollution Background Sources Types Eutrophication Sewage Management and Treatment

3 Pollution = The presence of a substance in the environment that prevents the functioning of natural processes and produces undesirable environmental and health effects Pollutant = Any material that causes pollution Strategies to manage pollution 1. Identify materials causing the pollution 2. Identify source of the pollutants 3. Develop control strategies to prevent pollution 4. Develop alternatives to avoid pollution altogether

4 Sources of Pollution Point sources = Source of pollution with specific points of discharge Examples Factories Sewage systems Power Coal mines Oil wells Nonpoint sources = Sources of pollution that are harder to identify Examples Agricultural runoff Stormwater drainage Acid rain

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6 Types of Pollution 1. Chemical Pollutants 2. Pathogens 3. Organic Wastes 4. Sediments 5. Nutrients

7 1. Chemical Pollutants Inorganic chemicals Heavy metals Acids from mine drainage Acid precipitation Road salts Organic chemicals Petroleum products Pesticides Cleaning solvents and detergents Biomagnification = Pollutants become more concentrated by passing through several levels of the food web

8 2. Pathogens Pathogens = Disease-causing bacteria, viruses, and other parasitic organisms If wastes from carriers contaminate water, pathogens can infect others Methods for controlling waterborne diseases: 1. Purify and disinfect water 2. Sanitary collection and treatment of wastes 3. Sanitary standards around food 4. Public education in hygiene

9 Detritus = 3. Organic Wastes Dead organic matter, such as fallen leaves, twigs, and other plant/animal wastes As bacteria break down detritus, they use oxygen that is dissolved in water (DO) Lots of detritus = lots of oxygen getting used up This limits animal life

10 4. Sediments Erosion leads to more sediment in the water which disrupts the ecosystem 1. Muddy water reduces amount of light penetration and photosynthesis 2. Extra silt and sand removes attached aquatic organisms from rocks 3. Hiding and resting places get buried in sediment

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12 5. Nutrients Agricultural runoff is a primary source of nutrients Phosphorus Nitrogen Result: Excessive plant growth

13 Eutrophication Different Kinds of Aquatic Plants Phytoplankton = Lives suspended in water Found wherever light and nutrients are available Emergent vegetation = Rooted in sediment, grows with lower parts in water, but upper parts stick out of water Submerged aquatic vegetation (SAV)= Grows totally underwater so needs clear water that allows light penetration Get nutrients from sediment Not limited by water low in nutrients

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16 Balance between SAV and phytoplankton is changed when nutrient levels in water are changed Sequence of eutrophication 1. Nutrients added to water 2. Growth of phytoplankton 3. Death of SAV 4. Death of phytoplankton 5. Build up of detritus 6. Growth of bacteria 7. Dissolved oxygen gets used up 8. Suffocation of animals

17 Eutrophic = Body of water that is nutrient rich Supports growth of lots of phytoplankton Has little or no dissolved oxygen Organisms end up dying! Oligotrophic = Body of water that is nutrient poor Unable to support much phytoplankton Light penetrates deeply HEALTHY body of water! Note: Natural eutrophication is a normal process but can become a problem when accelerated by pollutants from humans

18 Combating Eutrophication Attack symptoms Herbicides Aeration Harvesting aquatic weeds Drawing water down Cut down on nitrogen and phosphorus in water Ban sale of phosphate detergents Issue and monitor permits for discharging pollutants Best management practices = Farm management practices that serve best to reduce soil and nutrient runoff

19 Sewage Management and Treatment Storm drains = Collect and drain runoff from precipitation Sanitary sewers = Receive wastewater from sinks, tubs, and toilets Raw sewage or sludge = Untreated organic matter that is removed from sewage water by letting it settle 99.9% water to 0.1% waste

20 Removing Pollutants from Sewage 1. Preliminary Treatment = Removal of debris and grit from wastewater using a course screen and grit-settling chamber 2. Primary Treatment = Water passes very slowly through large tank so that particulate organic material can settle out 3. Secondary or biological treatment = Removes most of remaining organic matter Organisms feed on it and oxidize it through respiration *Oxygen must be added to water*

21 4. Biological Nutrient Removal (BNR) = Removes nitrogen and phosphorus 5. Final Cleansing and Disinfection Usually using chlorine gas Note: Discharging this treated wastewater may improve water quality of the receiving body of water

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23 3 Ways to Treat Sludge 1. Anaerobic Digestion = Breakdown of organic material by microorganisms in the absence of oxygen 2. Composting = Letting organic wastes decompose in the presence of air Product = nutrient rich humus 3. Pasteurization = Heating organic material to kill pathogens *All 3 result in material that can be used for fertilizer*

24 Atmospheric Pollution Background Types of Pollutants Smog Acid Precipitation Impact of Air Pollutants Control Strategies

25 Background Air pollutants = Substances in the atmosphere that have harmful effects 3 factors determine level of air pollution 1. Amount of pollutants entering the air 2. Amount of space into which the pollutants can spread out 3. Mechanisms that remove pollutants from the air

26 Natural air pollutants = From volcanoes, fires, dust storms, and other natural processes There are natural cleansing agents that remove and recycle natural pollutants Hydroxyl radicals, sea salts, microorganisms in soil Anthropogenic pollutants = Traced back to human activities

27 Types of Pollutants Primary pollutants = Pollutants released directly into atmosphere mainly as a result of burning fuels and wastes Examples Carbon monoxide (CO) Nitrogen oxides (NOx) Sulfur oxides (SOx) Lead (Pb) Radon (Rn) Secondary pollutants = Pollutants resulting from reactions of primary air pollutants in the atmosphere Examples Ozone (O 3 ) Sulfuric acids Nitric acids

28 Smog Industrial smog = Grayish mixture of moisture, soot, and sulfurous compounds Occurs in industrial areas and where coal is a primary energy source Photochemical smog = Brownish haze that typically forms over large cities with lots of automobile traffic

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30 Temperature inversion = A layer of warm air traps cooler air below it near the ground Prevents rising and dispersion of air pollutants Impacts of smog Pollutants can build up to dangerous levels Can cause headaches, nausea, eye and throat irritation Affects trees and other vegetation also

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32 Acid Precipitation Acid = Releases hydrogen ions (H + ) when dissolved in water Base = Releases hydroxide ions (OH-) when dissolved in water ph scale 0 (highly acidic ) 7 (neutral) 14 (highly basic) In the absence of pollution, rainfall is normally slightly acidic, with ph of 5.6 Acid precipitation = Acid rain, acid fog, acid snow, and other forms of precipitation that is more acidic than normal ph less than 5.6

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34 Buffer, the Acid Slayer Buffer = Substance that will maintain the ph of a solution by reacting with extra acid in the solution Limestone is a natural buffer

35 Impact of Air Pollutants Effects on Human Health Those most sensitive to air pollution are Small children Asthmatics People with chronic pulmonary or heart disease The elderly Acute effects Characterized by sharpness or severity Chronic effects Act over period of years to cause gradual deterioration of health Carcinogenic effects Increase risk of cancer

36 Effects on Materials and Aesthetics Walls and windows turn gray Paints and fabrics deteriorate more rapidly Rubber products become hard and crack Metal corrosion increases Limestone and marble buildings and monuments erode quickly Visibility decreases

37 Effects on the Environment Plants are even more sensitive to gaseous air pollutants than are humans Crop damage Forest damage Aquatic ecosystems become more acidic Kills organisms Upsets balance

38 Control Strategies Limiting pollutants from motor vehicles Catalytic converter = Reduces amount of CO and hydrocarbons in a car s exhaust Legislation Clean Air Act of 1970 (CAA) Calls for identifying and controlling most wide-spread pollutants Setting ambient standards = Determine certain levels of pollutants that should not be exceeded in order to maintain environmental and human health

39 Title IV of Clean Air Act Amendments 1 st law in US history to address aciddeposition problem Mandates reductions in both sulfur dioxide and nitrogen oxide levels

40 The Atmosphere: Climate Change and Ozone Depletion Climate Change Ocean Greenhouse Effect Ozone Depletion Importance of Ozone Layer Formation and Breakdown of Ozone Hole in the Ozone Layer Control Strategies

41 Climate Change Since 1855, global average temperature has increased 0.6ºC Proxies = Measurable records that provide data on factors such as temperature, ice cover, and precipitation Used to observe climatic changes Examples Tree rings, ice cores

42 The Ocean affects climate as well Conveyor system = Giant pattern of oceanic currents that moves water masses from the surface to the depths and back again Produces major effects on climate

43 Heinrich events = Melting icebergs from polar ice cap supply huge amounts of fresh water as they melt Effects: Lowers density of water Interrupts conveyor system Blocks northward movement of warmer, saltier water Changes climate Result of global warming

44 The Greenhouse Effect Greenhouse gases (GHGs) = Gases in atmosphere that absorb infrared energy and contribute to air temperature Heat blanket important in insulating Earth s surface Examples 1. CO 2 2. Water vapor 3. Methane 4. Nitrous oxide 5. Ozone 6. Chlorofluorocarbons and other halocarbons

45 1. Carbon dioxide Natural sources When there is more respiration (late fall through spring) CO 2 levels rise When there is more photosynthesis (late spring through early fall) CO 2 levels fall Other sources Burning of fossil fuels Burning of forest trees Recent years, steady rise in CO 2 levels Results in thicker insulating blanket

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47 2. Water Vapor Absorbs infrared energy Most abundant greenhouse gas 3. Methane (CH 4 ) Sources Wetlands Livestock Landfills Coal mines

48 4. Nitrous Oxide (N 2 O) Sources Agriculture, Burning of biomass, Fossil fuels 5. Ozone (O 3 ) Sources Automotive traffic, burning forests, agricultural wastes 6. CFCs and Other Halocarbons Sources all traced to human activities Used as refrigerants, pressurizing agent in aerosol cans, solvents, and fire retardants

49 Ozone Depletion Importance of the Ozone Layer UV radiation damages protein and DNA Over 99% of UV radiation is absorbed by ozone in stratosphere Note: Ozone in the troposphere is bad! Ozone in the stratosphere is good!

50 Formation and Breakdown of Ozone Ozone (O 3 ) forms in stratosphere when UV radiations act on oxygen (O 2 ) molecules Ozone is broken down by pollutants such as CFCs and other halogens Chlorofluorocarbons (CFCs) = Act as transport agents that continuously move chlorine atoms, which destroy ozone, into stratosphere Increase UV radiation

51 The Hole in the Ozone Layer Thinning in stratospheric ozone layer over the South Pole In 2003, it was about the size of North America Destruction of ozone layer is occurring worldwide

52 Control Strategies 1978 EPA banned use of CFCs in aerosol cans in US Montreal Protocol = 1987 agreement by large group of nations to cut back production of chlorofluorocarbons in order to protect ozone shield Most promising substitute for CFCs are HFCs Hydrofluorocarbons