ĐĎॹá>ţ˙ TUţ˙˙˙S˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙ÜĽhcŕ e€–I'Ľ–F˘<˘<<Ł<Ł<Ł<Ł<ŁPŁPŁPŁPŁPŁPŁ ZŁPŁb¤1`¤`¤`¤`¤`¤`¤`¤`¤`¤b¤b¤b¤b¤b¤b¤“¤Xë¤<b¤<Ł`¤%&+`¤`¤`¤`¤b¤`¤<Ł<Ł`¤`¤`¤`¤`¤`¤<Ł`¤<Ł`¤`¤ƒ¨9ÄPŁPŁ<Ł<Ł<Ł<Ł`¤`¤`¤`¤Chapter 19 Water Pollution Learning Nature’s Ways to Purify sewage Arcata California – took land that was once a dump and converted it into a marsh – where the water acts as an inexpensive waste water treatment plant. Sewage first into settling ponds – then to marsh where bacteria and aquatic plants filter out other things – hope to send it to a salmon hatchery and make $ 19-1 Types and Sources of Water Pollution ( learn table 19-1) Definition – Any chemical, biological or physical change in water quality that has a harmful effect or makes water unfit for desired uses. Classes of Pollutants Disease causing agents pathogens (bacteria, viruses, protozoans, and parasitic worms ) diseases table 20-1 causes 80% of deaths in developing countries good indicator is number of coliform bacteria drinking water should be 0 colonies to 100ml swimming should be 200 colonies/100ml humans excrete 2 billion each day Oxygen demanding wastes organic wastes that bacteria feed on - need large amounts of oxygen measured by BOD – biological oxygen demand – where we measure the amount of dissolved oxygen needed by aerobic decomposers to break down organic material over a 5 day period in a certain volume of water at a certain temp (20o C) Water Soluble Inorganic Chemicals acids, salts, mercury, lead etc. Selenium – comes from irrigation run off and has caused the death of most fish and birds in Calif – Keterson wildlife refuge – authorities refused to recognize and demoted several until printed in Sports Illustrated. Inorganic Plant Nutrients nitrates and phosphates cause excessive growth of algae thus toxins and when they die use up Oxygen from other organisms lowers oxygen carrying capacity of blood – killing unborn and infants Organic Chemicals oil, gas plastics, pesticides, cleaning solvents, detergents nervous system damage, reproductive disorders, cancers Sediment or Organic matter soil from erosion reduces photosynthesis and fouls gills, clouds water, irritates gills of fish, carry pesticides, Radioactive materials – (nuclear) iodine, radon, uranium, cesium genetic mutations, birth defects, cancers, miscarriages, Heat absorbed by water used to cool industrial power plants Genetic pollution caused by non native species Detection of pollution Chemical Analysis Indicator species Computer models Sources of Water Pollution Point sources ditches, pipes of sewers – very specific Nonpoint sources souces that cannot be traced usually runoff from large areas of land or airshed 33%-64% of water pollution from non point difficult to control 19-2 + 3 Pollution of Streams and Lakes Pollution problems of streams Normally streams recover rapidly from pollution because they are moving and use dilution and bacterial decay Don’t work well if dammed up or overloaded Oxygen Sag curves – show have well a stream handles pollution Progress made in reducing stream pollution require cities to pull drinking water downstream instead of upstream would help tremendously Water cleanup laws enacted in 1970’s have increased number of waste water treatment plants – and decreased the pollution of disease causing and oxygen demand organisms Case study – Cuyahoga River in Ohio – once caught fire in 1959 and 1969 due to pollution. Today river used by boaters and anglers. Great Britain has also cleaned up the Thames river Bad News Large fish kills and contamination still occurs – by industry, sewage treatment plants and by non-point runoff of pesticides from cropland. Ex. Sandoz chemical plant in Switzerland caught fire and dumped chemicals into the Rhine river – killed life from Switzerland – Netherlands Becoming more of a problem in developing countries Pollution in Lakes Stratification can intensify pollution problems Because water is not moving and going somewhere dilution does not help much – in fact can be concentrated. Biological magnification also a problem Cultural Eutrophication – run off from surrounding lands increase plant nutrients and cause eutrophication plants take over and block out the light – then die and fall to the bottom as they are rotting they take up the oxygen asphyxiating other organisms Prevention advanced waste treatment ban or limit phosphates in detergents soil conservation and land use control Cures dredge bottom sediments to remove nutrients remove excess weeds pump air through the lakes Case Study – Great Lakes Contain 95% of surface freshwater in USA Even though it is big – very susceptible to pollution – because only 1% of the water leaves thru the St. Lawerence By 1960 suffering cultural eutrophication and genetic pollution – worst was Lake Erie because shallow Since 1972 clean up has occurred and Great Lakes have less levels of phosphates, decreased levels of coliform bacteria, DDT In 1991 US feels that the great lakes is an environmental Hot spot ( one of 27 and should be cleaned up), No $ provided In spite of industry opposition Environmentalist urge ban use of Cl in pulp and paper industries all new incenerators in the area discharge into the lakes 70 toxic chemicals Concern – levels still rising Toxic chemicals carried by air currents from TX and CA. PCB built up in food chains Zebra Mussel In 1986 brought to Detroit by ship emptying bilge – no predator Out compete native species, clog irrigation pipes, grow on ships, foul beaches – have spread to most of US Damage has cost $10 billion Good news for number of aquatic plants – because consumes algae, making water clearer, so plants increase photosynthesis Quagga Mussel In 1991 came from Russia May be worse than Zebra mussel because can tolerate wider range of conditions. EX . colonize Chesapeake & FL Case Study : Protecting Lake Baikal Largest Freshwater lake located in Siberia – most biologically rich lake – watershed comes from taiga Environmental battle started in 1960 to prevent paper plants – concern of waste water and deforestation – So allow the tree – pulp operation and then send pulp elsewhere for further treatment. Now foreign interest in timber and lake reserves. Hope to be a model of sustainable development of watersheds. Heat Pollution – thermal pollution Power plants use energy from coal or nuclear to heat water to turn turbines for electricity Cheapest way is to pull water from surface and return it. bad – many fish die being pulled on to screens over intake pipes Thermal temp change – decreased Oxygen Disrupt spawning and young fish Thermal Shock from fluctuating temp Some call it Thermal Enrichment increase commercial fishing season reduces winter ice cover an extend growing season if used as irrigation water in frost prone areas can grow oysters and other warm water organisms in aquaculture areas Heat nearby buildings and greenhouses ( however because of pollution of power plants usually not near housing) Ways to reduce or control thermal water pollution use and waste less energy limit the amount of heated water returned return the heated water away from shore zone transfer heat from water to atmosphere – through cooling towers discharge heated water into shallow ponds or canals and then reuse it 19-5 – Ocean Pollution How much can they tolerate Oceans are the ultimate sink Dilute, disperse and degrade large amounts of sewage, oil, industrial waste Marine life much more resilient than any other group It may be safer to put hazardous waste in deep oceans Pollutants affect on coast Coast has most of the global population Most polluted coast off developing countries ex. Bangladesh, Thailand, etc. But also 85% of the sewage goes to Mediterranean Sea US – 35% of sewage goes to oceans – black mayonnaise covers the bottoms of some bays – mixture of feces, industrial waste and oil. Especially in California Also agricultural runoff cause algal blooms and oxygen depletion Case Study: The Chesapeake Bay largest estuary in United States – in trouble because of human pop. Very shallow – receives waste from 9 major rivers and 141 smaller streams and creeks Since 1983 – a cooperative program – CHESAPEAKE BAY PROGRAM – has taken many governmental , industries, environmental, and recreational groups and $700 million impressive cleanup has occurred Major problem now is non native invasive. What pollutants are dumped into the ocean Dredge spoils – materials scraped from bottom of harbors, channels and dumped in 110 sites off the Atlantic – often laden with toxic materials. Sewage Sludge – dumped from waste water treatment plants – not allowed in US since 1992 – however Mexico still does and currents carry the waste to Calif. Beaches In 50 countries - merchant fleets no longer dump sewage into oceans. This wastes kill millions of sea life London Dumping Convention of 1972 – 100 countries agreed not to dump high level radiation into the ocean. However Soviet Union has be dumping low level radiation into the artic sea. Effects of oil on Ocean Ecosystems Oil from crude petroleum and refined petroleum sometimes enter the ocean through accidents or on purpose Accidents like Valdez get a lot of attention but actually US oil companies leak /spill/waste as much as 17 Valdez in the Mediterranean alone. Kills larval forms – but evaporates quickly in warm seas Some form tar like globs that float on surface and coat fur and feathers Other oil sinks to the bottom and kills benthic organisms Most sea life recovers after 3 years – takes longer in cold temp, Considered low risk ecological problem How can oil spills be Cleaned up Mechanical means Floating booms to contain the oil Skimmer boats that vacuum up the oil Absorbent bags or feather pillows to soak up oil Chemical Means coagulating methods dispersing agents Fire Natural means – action of wind and waves emulsifies the oil and bacteria break it down. These methods only breakdown part of the oil and some do as much harm – reason why P2 (pollution prevention) – is so important. Case Study: The Exon Valdez In Alaska – 1989 - a tanker hit submerged rocks and spilled oil – caused a spill the length of NJ – SC Environmentalist wanted oil to come by pipeline instead of tanker because of dangers Alyeska (company of oil exporters from alaska) did not want the pipeline it was too expensive – also was not prepared for the disaster – too little too late. Cleanup actually did more harm than good – the areas cleaned killed more than areas not cleaned At fault – alcoholic captiain – drunk – fatigued crew Clean up cost $8.5 billion would have been prevented by $22.5 million double hull – now required on all tankers P2 important because only 15% of spilled oil can be recovered Solutions – Protecting Coastal Waters Key – reduce the flow of pollution from land to streams to oceans Prevention separate sewage and storm run off in coastal urban areas discourage ocean dumping of sluge and toxics protect ecologically fragile and valuable areas from development, oil drilling and shipping Double hulls for all oil tankers by 2002 Recycle used oil Cleanup improve oil cleanup require at least secondary treatment of coastal sewage 19-6 Solutions – Surface Water Pollution Non point sources leading source in agriculture use none or moderate slow release fertilizers on steep sloping land Plant buffer zones of trees - Sometimes called SMZ – stream management zone Apply pesticides only when needed Reforest critical watersheds Point Sources – Legal approach Federal Water Pollution Control Act (1972) renamed CLEAN WATER ACT (1977) – make all US surface waters safe for fishing and swimming by 1983 – some progress – didn’t make the goal. Areas tested have increased from 36%(1972) - 62% in 1992. $85 billion by government and $500 billion by industry spent – mainly on end pipe controls Environmentalist want act strengthened by control non point sources of pollution phase out certain toxic discharges provide and integrated water and air shed permit states to take over some parts expand private citizens ability to bring lawsuits against polluters Some oppose want act weaken because too restrictive and costly want to be compensated for land/water they cannot make a profit from – takings rights more local discretion of which water test to do US house proposed weakening act in 1995 but bill did not pass the Senate Point Sources – Technological Sources Septic Tanks – in 25% of all US homes mostly rural or suburban homes with suitable soils. tank that catches solids and allow bacteria to work on them – settle to the bottom Water drains from top of the tank and goes to drain field – a system of perforated pipes on be of gravel Must not be placed too close together, or in too wet of soil and should be pumped out every 3 – 5 years to prevent the settling tank from overflow Urban areas use Sewage treatment plants primary treatment – mechanical process that screens out debris – uses screens and polymers to remove suspended solids Secondary treatment – biological process -Aerobic bacteria are bubbled in and remove 90% of oxygen demanding waste Then goes to a sedimentation tank where most of the suspended solids and bacteria (bugs) sink and are removed -–this is what is called sludge Sludge is usually incinerated and dumped into oceans, landfills or applied to land as fertilizers. Water is usually chlorinated too – some concern because if mixes with hydrocarbons – have chlorinated hydrocarbons in drinking water – some estimate that 7 – 10% cancers could be due to chlorinated drinking water No radioactive isotopes or pesticides removed in this stage As a result of Clean Water Act most cities now have Secondary water treatment plants – not all – 34 East coast cities only do primary treatment – any one want to swim? Advanced Sewage Treatment chemical and physical processes that remove specific pollutants. Usually expensive to build and operate Used in Finland, West Germany, Switzerland, Sweden Other ways to purify water – as described at beginning of the chapter 19-5 Groundwater Pollution and prevention Groundwater pollution – serious problem Out of sight pollution Low risk ecological problem – that can be high risk if ground water is drinking water. Laws protecting ground water are weak or non-existant Ground water can not cleanse itself because it is slow and not turbulent – pollution can not be diluted and dispersed Takes hundreds to thousands of years to cleanse of degradable wasted because cold temp slow decomposition Many wells – as many as 9% may be contaminated with nitrates – Good news- a small company in Germany has developed an enzyme that can convert nitrates to nitrogen gas Many aquifers are polluted – all in NJ FL – 92% of drinking water is ground water Contamination comes mainly from leaking tanks and leaking land fills. Cleaning ground water involves pumping to surface, cleaning it and pumping it back – very $$$$ - P2 very imp. Solutions – protect ground water monitor aquifers near landfills and underground tanks require leak detection systems for new and old tanks Require liability insurance for hazardous liquid tanks Banning disposal of hazardous waste by deep injection wells and in landfills Store hazardous liquids in above ground tanks with leak detection systems – and collect each leak 19-7 Drinking Water Quality Is water safe to drink? In most developed countries – yes – developing – no 1980 UN recommended – spending $300 billion to supply the world with clean drinking water and adequate sanitation by 1990. $1.5 billion /year was actually spent – not there yet – Trying to find cheap ways to purify water ex. Solar power UV lamp zaps water as it passes thru the tap – kills germs Horseradish and peroxide rids water of phenols Slime of blue green algae that remove chemical toxins. How is drinking water purified very similar to waste water treatment – settling – then run through sand filters and activated charcoal before it is disinfected. How is Drinking Water Quality Protected Safe Drinking Water At of 1974 – requires EPA to establish national drinking water standards – called maximum contaminant levels Privately owned wells do not have to meet these standards – because of the cost to test – over $1000 per well Have had problems in municipal water programs with cyptosporium ( caused 104 deaths in Milwaukee in 1993) and Giardia Some want Safe Drinking Water Act weakened eliminate national test of drinking water eliminate the requirement of media notification allow states to violate a standard if the state feels it is too costly eliminate the requirement that systems remove cancer causing contaminants Some want the Safe Drinking Act strengthened Combine water systems – reduce administrative cost Strengthen the public notification systems Ball all lead in new plumbing ( now 10% qualifies as lead free) Is Bottled Water the Answer? No – many is dirtier than tap water Only way to know is look for IBWA seal – cost companies $2,500/year to test for 200 chemical and biological contaminants Home Water Purification Systems Type Price Pros Cons Activated Carbon Filters$35 – 2,500Removes chlorine, organic chem and radon –Does not remove biological pathogens – can be breeding ground – if not changed or cleanedReverse Osmosis$600 – 1,000Removes particulates by forcing water through semipermeable membranesProduces 4 gallons of waste for every one gall produced – does not remove toxic chem and some pathogensDistillation$200 – 700Removes most everything except volatile chem and radon$ to operate, uses lots of energy, produces flat tasting waterUV light$300Kills pathogensDoes not remove other pollutantsWater Softeners$1,000Remove dissolved minerals – Does not remove pathogens and toxic substances best to use machines that use a variety of methods – EPA does not approve any machines – does register them Solutions Integrated approach to managing water resources through out each watershed and air shed. Shift emphasis from water pollution clean up to pollution prevention source reduction reuse waste water instead of discharging recycling pollutants Ą¤Đ/Ľŕ=Ś§¨ Š Şe)g),,Â<Ä<‚E›E§E,F-FřFůF‡GˆGÇGČG+H,HĽHŻH•I–I°Iýúýúýúýöýöööööýóýńu^cUVcchcDyz¸CYqĆýýý×ÔýŽˆb<% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h3% ¤˜ţ3 4˙€¤-¤3 Ćó"Ou—°öŰÚ´ŽŽŽhBÚ% h˜ţ3 4€h.h% h˜ţ3 4€h.h% ¤˜ţ3 4˙€¤-¤% h˜ţ3 4€h.h% h˜ţ3 4€h.hŰýů ,  Ó Ú´Žh´ŽB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hÓ ĺ " Y t † č ) c Ú´´Ž´hB99Đ˜ţĐ% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h c i   ˛ Ď ć ř Ú´Ž´hB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€ h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hř  5 C l } š Ú´ŽhBÚB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hš Í ÷ 4 R ż Ú´Ž„^8% h˜ţ3 4€h.h% h˜ţ3 4€h.h †zţ3†% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hż ę )TąYÝÚ´ŽhÚ´B% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hĽ2ex¨<Ú´ŽhB´Žh% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h<;F_…Ź˛Ţň &Ú´ŽŽŽhŽŽŽB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% ¤˜ţ3 4˙€¤-¤% h˜ţ3 4€h.h% h˜ţ3 4€h.h &OÂ(¤Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hX€ĄÍë#?LÚ´ŽhB´Žh% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hLŒ÷Œšł!EŤnÚÚÚÚ´ÚڎhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% ¤˜ţ3 4˙€¤-¤ n ÝŢ]—Ú´ą‹e?% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h3% h˜ţ3 4€h.h% h˜ţ3 4€h.h—Ř˙Cd‡ ę/Ú´ŽhBÚ´Žh% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h /žĐęAÚ´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hAČßúcÚ´ą‹e?% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h3% h˜ţ3 4€h.h% h˜ţ3 4€h.hc˜Îé ] ’ /!Ú´ŽhBÚ´% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h/!p!!Ô!)"ë"Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hë"#?#Ď#r$Ţ$•%Ú´ŽhBÚ% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h•%¸%!&Ż&č&1'Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h1'k'­'Ô'ő'(Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h()(N((Ž(˘(´(š()Ú´ŽhÚ´ŽB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h)’)Ž)*j*+h+Ú´ŽhBÚ% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hh+ž+,M,s,ľ,Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hľ,Ŕ,ů,&-‚-Ť-Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hŤ-ź-Ä-Ř-.9.K.Ú´Žh^8% h˜ţ3 4€h.h †zţ3†% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hK.i.Ž.ú./9/Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h9/X/I0¤0Ď0ö0Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hö01C1i1­1Ń1Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hŃ1ě1B2r2ť2â2Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hâ2<33ů3Œ4´4*5T5ž5Ú´ŽhB´Ž?3% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hž5,66d7 7H8c8Ś8Î89G9r9š9ÚÚÚÚÚ´ÚÚڎ„^% h˜ţ3 4€h.h †zţ3†% h˜ţ3 4€h.h% h˜ţ3 4€h.h% ¤˜ţ3 4˙€¤-¤ š9ą9:>:´:;Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h;Ć;í;<^<Ď<Ú´ŽhB% h˜ţ3 4€ h.h% h˜ţ3 4€ h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hĎ<đ<&=[=’=ß=Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hß=A>^>v>Ş>_??ÚĐŞ„^8% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h †zţ3†% h˜ţ3 4€h.h?Ô?@:@Y@Ţ@Ú´ŽhB% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hŢ@A‡AőAkB–BÚ´ŽhB% †zţ3 4€†.†% †zţ3 4€†.†% †zţ3 4€†.†% †zţ3 4€†.†% h˜ţ3 4€h.h–BŔBđB7CCŽCáC DLDÚ´ŽhBÚ´Ž% †zţ3 4€†.†% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hLDiDDE&E‚E›E§EŇE,F-F=FJFFÚ´ŽheaaaaNaaa¸lť ž ”˙TN č,"33% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h FřFůFGGHG‡GˆG‘G–GŚGÇGČGŘGßGüG+H,H-H™HšHĽHţHüéüüüüéüüüüéüüüüéćŔćšŔ% h˜ţ3 4€h.h% h˜ţ3 4€h.h3¸lť ž ”˙TN č,"3ţHCITI}I’I“I”I•I–IÚ´Žhee`]3<33% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.h% h˜ţ3 4€h.hK@ń˙Normal3a .@. Heading 1 đ< U]ck,@, Heading 2 đ< UV]c(@( Heading 3 đ<]c*@* Heading 4 đ<U]c$@$ Heading 5đ<c"A@ň˙Ą"Default Paragraph Font–F–I˙˙˙˙°I%ĆŰÓ c ř š ż <&Ln—/Ac/!ë"•%1'()h+ľ,Ť-K.9/ö0Ń1â2ž5š9;Ď<ß=?Ţ@–BLDFţH–I&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOP˙@1Times New Roman Symbol "Arial"€Đh”k…†”k…†5 3:ƒ|<Chapter 19 Water PollutionSkilesBHS SBAC  !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRţ˙˙˙ý˙˙˙Wţ˙˙˙_ţ˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙ţ˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙Root Entry˙˙˙˙˙˙˙˙ ŔFƒ¨9ÄV@WordDocument˙˙˙˙'ĽCompObj˙˙˙˙˙˙˙˙˙˙˙˙jSummaryInformation(˙˙˙˙˙˙˙˙źţ˙˙˙ţ˙˙˙ ţ˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙ţ˙ ˙˙˙˙ ŔFMicrosoft Word Document MSWordDocWord.Document.6ô9˛qţ˙ ŕ…ŸňůOhŤ‘+'łŮ0Œ˜źČŘäđ   H T `lt|„äChapter 19 Water PollutionbCSkiles]CYCNormal BHS SBAC2CMicrosoft Word for Windows 95@DocumentSummaryInformation8˙˙˙˙˙˙˙˙˙˙˙˙ Ř˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙˙ţ˙ ˙˙˙˙ ŔFMicrosoft Word Document MSWordDocWord.Document.8ô9˛qtä | Chapter 19 Water Pollution@ˆóć9Ä@ˆóć9Ä5 3:ţ˙ ŐÍ՜.“—+,ůŽ0¨@HT\ dl tä | Chapter 19 Water Pollution