2 Question of the DayThe Leading cause of water pollution is?
3 Answer of the DayAgricultural activities which cause sediment erosion from agricultural lands and overgrazed rangeland, followed by fertilizers and pesticides, and bacteria form livestock and food processing wastes, also excess salt form soils of irrigated cropland.
4 Water Pollution: Types, Effects, and Sources What is water pollution?Major types of pollutants, sources and effects (Table 11-1, p. 254)Point and nonpoint sourcesIs the water safe to drink?
6 Polluted Streams Factors influencing stream recovery from pollution Oxygen sag curveImportance of wastewater treatment plantsImprovements in quality of US streamsCuyahoga River of OhioEffect of regulations in USPressures from US citizen groupsProblems with nonpoint, accidental and illegal releasesProblems in developing countries
7 Pollution in Streams Fig. 11-24, p. 256 Normal clean water organisms (trout, perch, bass,mayfly, stonefly)Trash fish(carp, gar,leeches)Fish absent, fungi,sludge worms,bacteria(anaerobic)Trash fish(carp, gar,leeches)Normal clean water organisms(trout, perch, bass,mayfly, stonefly)8 ppmTypes oforganisms8 ppmDissolved oxygen (ppm)Biological oxygendemandClean ZoneRecovery ZoneSeptic ZoneDecompositionZoneClean ZoneFig , p. 256
8 Lake Pollution Dilution less effective than with streams Stratification in lakes and relatively little flow hinder rapid dilution of pollutantsLakes more vulnerable to pollutants than streamsHow pollutants enter lakesEutrophication: causes and effectsOligotrophic and eutrophic lakesCultural eutrophicationPreventing or removing eutrophication
10 Groundwater Pollution: Causes and Persistence Sources of groundwater pollutionSlow flowing: slow dilution and dispersionConsequences of lower dissolved oxygenFewer bacteria to decompose wastesCooler temperatures: slow down chemical reactions“Degradable” and nondegradable wastes in groundwater
12 Extent of Groundwater Pollution Not much is known about groundwater pollutionOrganic contaminants, including fuel leaksArsenicProtecting groundwater: Prevention is best
13 Preventing and Cleaning Up Pollution in Groundwater SolutionsGroundwater PollutionPreventionCleanupFind substitutes for toxic chemicalsPump to surface, clean, and return to aquifer (very expensive)Keep toxic chemicals out of the environmentInstall monitoring wells nearlandfills and underground tanksInject microorganisms to clean up contamination (less expensive but still costly)Require leak detectors on underground tanksBan hazardous waste disposalin landfills and injection wellsPump nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed)Store harmful liquids in aboveground tanks with leak detection and collection systemsFig , p. 259
14 Ocean Pollution How much pollution can oceans tolerate? Some pollutants degrade and dilute in oceansOcean dumping controversies
15 Coastal Water Pollution IndustryNitrogen oxides from autos and smokestacks; toxicchemicals, and heavymetals in effluents flow into bays and estuaries.CitiesToxic metals andoil from streets andparking lots pollutewaters; sewageadds nitrogen andphosphorus.Urban sprawlBacteria and viruses from sewers and septic tanks contaminate shellfish beds and close beaches; runoff of fertilization from lawns adds nitrogen and phosphorus.Construction sitesSediments are washed into waterways,choking fish and plants, cloudingwaters, and blocking sunlight.FarmsRun off of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.Red tidesExcess nitrogen causes explosive growth of toxic microscopic algae, poisoning fish and marine mammals.Closedshellfish bedsClosedbeachOxygen-depletedzoneToxic sedimentsChemicals and toxic metalscontaminate shellfish beds,kill spawning fish, andaccumulate in the tissuesof bottom feeders.Healthy zoneClear, oxygen-rich waterspromote growth of planktonand sea grasses, and support fish.Oxygen-depleted zoneSedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat.Fig , p. 260
16 Oxygen-depleted Water in the Gulf of Mexico MississippiRiver BasinOhioRiverMississippiRiverMissouriRiverLOUISIANAMississippiRiverDepleted OxygenGulf of MexicoFig , p. 261
17 Chesapeake Bay Largest US estuary Pollution “sink” Oxygen depletion Chesapeake Bay ProgramFig , p. 261
18 Effects of Oil on Ocean Life Crude and refined petroleumTanker accidents and blowoutsExxon ValdezVolatile hydrocarbons kill larvaeTar-like globs coat birds and marine mammalsOil destroys insulation and buoyancyHeavy oil sinks and kills bottom organismsCoral reefs dieSlow recoveryOil slicks ruin beachesLimited effectiveness of clean up methods
19 Preventing and Cleaning Up Pollution in Coastal Waters SolutionsCoastal Water PollutionPreventionCleanupReduce input of toxic pollutantsImprove oil-spill cleanupcapabilitiesSeparate sewage and storm linesBan dumping of wastes and sewage by maritime and cruise ships in coastal watersSprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without creating harmful byproducts(still under development)Ban ocean dumping of sludge and hazardous dredged materialProtect sensitive areas from development, oil drilling, and oil shippingRequire at least secondarytreatment of coastal sewageRegulate coastal developmentUse wetlands, solar-aquatic, orother methods to treat sewageRecycle used oilRequire double hulls for oil tankersFig , p. 263
20 Preventing Nonpoint Source Pollution Mostly agricultural wastesUse vegetation to reduce soil erosionReduce fertilizer useUse plant buffer zones around fieldsIntegrated pest management: Only use pesticides when necessaryUse plant buffers around animal feedlotsKeep feedlots away from slopes, surface water and flood zones
21 Laws for Reducing Point Source Pollution Clean Water ActWater Quality ActDischarge trading controversies
22 Question of the DayWastewater sewage treatment plants can be broken into two levels of treatment, Primary and Secondary. (Note: There is Tertiary also which we will discuss)Make a list of the processes which occur in each level and identify which is physical and which is a biological process.
23 Question of the Day Primary Secondary Steps In Process Which is Bio. Or Phys.
24 Answer of the Day Primary Secondary Steps Screens Aeration In Process Grit Tank Settling TankSettling Tank DisinfectionWhich isBio. Or Phys. Physical Biological
25 Sewage Treatment Systems Sewage treatment in rural and suburban areasSeptic tanksPrimary (physical) sewage treatmentSecondary (biological) sewage treatmentUrban sewage treatment (Clean Water Act)Sewage treatment facilities in many cities fail to meet federal standardsBleaching and disinfectionDisinfectants: chlorine, ozone, and ultraviolet radiation
26 Typical Septic Tank System Septic tank with manhole (for cleanout)HouseholdwastewaterNonperforated pipeDistribution box (optional)Gravel orcrushedstoneDrainfieldVent pipePerforated pipeFig , p. 264
27 Primary and Secondary Sewage Treatment Chlorinedisinfection tankBar screenGrit chamberSettling tankAeration tankSettling tankTo river, lake,or oceanSludgeActivated sludge(kills bacteria)Raw sewagefrom sewersAir pumpSludge digesterDisposed of in landfill or ocean or applied to cropland, pasture, or rangelandSludge drying bedFig , p. 265
28 Improving Sewage Treatment Systems that exclude hazardous wastesNon-hazardous substitutesComposting toilet systemsWorking with nature to treat sewageUsing wetlands to treat sewage
30 Reducing Water Pollution from Point Sources in the US ImprovementsBad news
31 Should the Clean Water Act be Strengthened? Yes: environmentalistsNo: farmers, libertarians, manufacturers, and developersState and local officials want more discretionHow Would You Vote exercise
32 Drinking Water Quality Purification of urban drinking waterPurification of drinking water in developing countriesBottled water
33 Reducing Water Pollution SolutionsWater PollutionPrevent groundwater contaminationGreatly reduce nonpoint runoffReuse treated wastewater for irrigationFind substitutes for toxic pollutantsWork with nature to treat sewagePractice four R's of resource use (refuse, reduce, recycle, reuse)Reduce resource wasteReduce air pollutionReduce povertyReduce birth ratesFig , p. 267
34 What Can We Do? What Can You Do? Water Pollution Fig. 11-36, p. 268 Fertilize your garden and yard plants with manure or compost instead of commercial inorganic fertilizer.Minimize your use of pesticides.Never apply fertilizer or pesticides near a body of water.Grow or buy organic foods.Compost your food wastes.Do not use water fresheners in toilets.Do not flush unwanted medicines down the toilet.Do not pour pesticides, paints, solvents, oil, antifreeze, or other products containing harmful chemicals down the drain or onto the ground.Fig , p. 268