POLLUTION. Water Pollution Air Pollution

Transcription

1 POLLUTION Water Pollution Air Pollution

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 plants 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 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 = Plants that live suspended in water Found wherever light and nutrients are available Emergent vegetation = Plants that are rooted in sediment, grow with lower parts in water, but upper parts stick out of water Submerged aquatic vegetation (SAV)= Plants that grow totally underwater so they need clear water that lets light through Get nutrients from sediment Not limited by water low in nutrients

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16 What happens when too many nutrients are added to water? Sequence of eutrophication 1. Phytoplankton grow 2. Phytoplankton block light 3. SAV die 4. Phytoplankton die (competition) 5. Detritus builds up 6. Bacteria grow (break down detritus) 7. Dissolved oxygen gets used up by bacteria 8. Animals suffocate and die

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 humans add too many nutrients too quickly (pollution!)

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 clumps of 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 Background Types of Pollutants Smog Acid Precipitation Impact of Air Pollutants Climate Change Ozone Destruction Control Strategies Air Pollution

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 Nature can t remove all of the pollution humans are creating fast enough

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

29 Impacts of smog Pollutants can build up to dangerous levels Can cause headaches, nausea, eye and throat irritation Affects trees and other vegetation also

30 Acid Precipitation Acid = Has a ph less than 7 Base = Has a ph greater than 7 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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32 Buffer, the Acid Slayer Buffer = Substance that will neutralize the ph of a solution Limestone is a natural buffer

33 Impact of Air Pollutants Effects on Human Health Those most sensitive to air pollution are Small children Asthmatics People with chronic lung or heart disease The elderly

34 Effects on Materials and Buildings 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

35 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

36 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 climate changes Examples Tree rings, ice cores

37 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

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

39 The Greenhouse Effect Greenhouse gases (GHGs) = Gases in atmosphere that absorb infrared energy and contribute to air temperature Create a heat blanket important in insulating Earth s surface Keep the surface of Earth warm and livable! Examples 1. CO 2 2. Water vapor 3. Methane 4. Nitrous oxide 5. Ozone 6. Chlorofluorocarbons and other halocarbons

40 More about 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 We need to be careful that pollution doesn t make it too warm!

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42 Ozone Destruction Importance of the Ozone Layer Ozone in the stratosphere (higher layer of the atmosphere) absorbs over 99% of UV radiation UV radiation damages protein and DNA Causes sunburn and skin cancer

43 The Hole in the Ozone Layer Ozone is broken down by pollutants such as CFCs Chlorofluorocarbons (CFCs) = Act as transport agents that continuously move chlorine atoms, which destroy ozone, into stratosphere Increase UV radiation Destruction of ozone layer is occurring worldwide Layer is getting thinner More UV radiation is getting through

44 Note: Ozone in the stratosphere protects us from harmful UV rays Ozone in the troposphere is a greenhouse gas Too much is considered pollution! Think: Good up high! Bad near by!

45 Control Strategies 1978 EPA banned use of CFCs in aerosol cans in US Limiting pollutants from motor vehicles Catalytic converter = Reduces amount of CO and hydrocarbons in a car s exhaust

46 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 Title IV of Clean Air Act Amendments 1 st law in US history to address acidprecipitation problem