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Water PollutionWater Pollution

Reference:Reference: G. Tyler Miller’sG. Tyler Miller’s

Living in the EnvironmentLiving in the Environment1414thth Edition Edition

Prepared by Prepared by

Shohail Motahir ChoudhuryShohail Motahir Choudhury

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Key ConceptsKey Concepts

Types, sources, and effects of water pollutantsTypes, sources, and effects of water pollutants

Major pollution problems of surface waterMajor pollution problems of surface water

Major pollution problems of groundwaterMajor pollution problems of groundwater

Reduction and prevention of water pollutionReduction and prevention of water pollution

Drinking water qualityDrinking water quality

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Types, Effects, and Sources of Types, Effects, and Sources of Water PollutionWater Pollution

• Water is polluted by Water is polluted by infectious bacteriainfectious bacteria, inorganic , inorganic and organic and organic chemicalschemicals, and , and excess heatexcess heat..

• Water pollution is any chemical, biological, or Water pollution is any chemical, biological, or physical change in water quality that has a physical change in water quality that has a harmful effect on living organisms.harmful effect on living organisms.

• The WHO estimates that The WHO estimates that 3.4 million people die3.4 million people die prematurely each year from waterborne diseases.prematurely each year from waterborne diseases.

• In the U.S., an estimated In the U.S., an estimated 1.5 million people1.5 million people a year a year become ill from infectious agents.become ill from infectious agents.

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• Scientists monitor water quality by using Scientists monitor water quality by using bacterial counts, bacterial counts, chemical analysis, and indicator organismschemical analysis, and indicator organisms..

• One method of measuring water quality involves measuring One method of measuring water quality involves measuring the number of colonies of fecal the number of colonies of fecal coliform bacteriacoliform bacteria present in a present in a water sample.water sample.

• Drinking water should not contain Drinking water should not contain any colonies/100any colonies/100 milliliters, milliliters,

• Chemical analysisChemical analysis includes checking inorganic and organic includes checking inorganic and organic chemicals present, sediment content, and turbidity of water.chemicals present, sediment content, and turbidity of water.

• Indicator speciesIndicator species are living organisms that are monitored to are living organisms that are monitored to determine levels of pollution.determine levels of pollution.

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Sources of Water PollutionSources of Water Pollution

Point sources

Nonpoint sources

Water quality

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Point and Nonpoint SourcesPoint and Nonpoint Sources

NONPOINT SOURCES

Urban streets

Suburban development

Wastewater treatment plant

Rural homes

Cropland

Factory

Animal feedlot

POINT SOURCES

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Sources of water pollutionSources of water pollution

The leading sources of water pollution are agriculture, The leading sources of water pollution are agriculture, industries, and mining.industries, and mining.

1.1.Agricultural activitiesAgricultural activities are the leading cause of water are the leading cause of water pollution from erosion, overgrazing, fertilizers and pollution from erosion, overgrazing, fertilizers and pesticides, and excess salt from irrigated soils. pesticides, and excess salt from irrigated soils.

2.2.Industrial facilitiesIndustrial facilities are another large source of are another large source of water pollution, and mining is a third source.water pollution, and mining is a third source.

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• One of every fiveOne of every five people in the world lacks people in the world lacks access to safe drinking water.access to safe drinking water.

• Ninety-five percentNinety-five percent of people in developed of people in developed countries and countries and 74%74% of people in developing of people in developing countries have access to clean drinking countries have access to clean drinking water.water.

• In a warmer world, too much rain and too In a warmer world, too much rain and too little rain can increase water pollution.little rain can increase water pollution.

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Pollution of Freshwater StreamsPollution of Freshwater StreamsStreams Streams can recover from moderate levelscan recover from moderate levels of degradable of degradable

water pollutants if the flows are not reduced.water pollutants if the flows are not reduced.

1.1.A combination of A combination of dilution and biodegradationdilution and biodegradation can allow can allow recovery of stream pollution recovery of stream pollution

2.2.The breakdown of pollutants by bacteria creates an The breakdown of pollutants by bacteria creates an oxygen sag curveoxygen sag curve. Organisms that have a high oxygen . Organisms that have a high oxygen demand can’t survive in the curve.demand can’t survive in the curve.

3.3.Volume of the stream, volume of wastes entering, flow Volume of the stream, volume of wastes entering, flow rate, temperature, and pH levels all affect how great a rate, temperature, and pH levels all affect how great a sag curve is produced.sag curve is produced.

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Oxygen Sag CurveOxygen Sag Curve

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Water Pollution: NowWater Pollution: NowMost developed countries have Most developed countries have reduced point source reduced point source

pollutionpollution, but toxic chemicals and pollution from non-, but toxic chemicals and pollution from non-point sources are still problems. point sources are still problems.

Stream pollution in most developing countries is a serious Stream pollution in most developing countries is a serious and growing problem. and growing problem. Half of the world’s 500 major Half of the world’s 500 major riversrivers are heavily polluted, and most of them run are heavily polluted, and most of them run through developing countries where through developing countries where waste treatment is waste treatment is minimal or nonexistentminimal or nonexistent. .

For example: Religious beliefs, cultural traditions, poverty, For example: Religious beliefs, cultural traditions, poverty, little economic development, and a large population little economic development, and a large population interact to cause severe pollution of the interact to cause severe pollution of the Ganges River in Ganges River in IndiaIndia. .

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Pollution of LakesPollution of Lakes

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The Great LakesThe Great Lakes

Fig. 22-8p. 500

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Groundwater Pollution: CausesGroundwater Pollution: Causes

Low flow ratesLow flow rates Few bacteriaFew bacteria Cold temperaturesCold temperatures

Coal strip mine runoff

Pumping well

Waste lagoon

Accidental spills

Groundwater flow

Confined aquifer

Discharge

Leakage from faulty casing

Hazardous waste injection wellPesticides

Gasoline station

Buried gasoline and solvent tank

Sewer

Cesspool septic tank

De-icing road salt

Unconfined freshwater aquifer

Confined freshwater aquifer

Water pumping well Landfill

Low oxygenLow oxygen

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Pollution of GroundwaterPollution of Groundwater

Experts rate groundwater pollution as a low-Experts rate groundwater pollution as a low-risk ecological problem; it is rated as a risk ecological problem; it is rated as a high-risk health problem.high-risk health problem.

The extent of groundwater contamination is The extent of groundwater contamination is generally generally unknownunknown

PreventionPrevention is the most effective and is the most effective and affordable way to protect groundwater from affordable way to protect groundwater from pollutants.pollutants.

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Ocean PollutionOcean Pollution

Fig. 22-11 p. 504

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Case Study: Chesapeake BayCase Study: Chesapeake Bay

Largest US Largest US estuaryestuary

Relatively shallowRelatively shallow

Slow “flushing” Slow “flushing” action to Atlanticaction to Atlantic

Major problems with dissolved OMajor problems with dissolved O22

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Oil SpillsOil SpillsSources:Sources: offshore wells, offshore wells,

tankers, pipelines and tankers, pipelines and storage tanksstorage tanks

Effects:Effects: death of organisms, loss death of organisms, loss of animal insulation and of animal insulation and buoyancy, smotheringbuoyancy, smothering

Significant economic impactsSignificant economic impacts

Mechanical cleanup methods: skimmers and blottersMechanical cleanup methods: skimmers and blotters

Chemical cleanup methods: coagulants and dispersing Chemical cleanup methods: coagulants and dispersing agentsagents

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Solutions: Preventing and Reducing Solutions: Preventing and Reducing Surface Water PollutionSurface Water Pollution

Nonpoint SourcesNonpoint Sources Point SourcesPoint Sources

Reduce runoffReduce runoff

Buffer zone vegetationBuffer zone vegetation

Reduce soil erosionReduce soil erosion

Clean Water ActClean Water Act

Water Quality ActWater Quality Act

2020

Technological Approach: Septic Technological Approach: Septic SystemsSystems

Require suitable soils and maintenanceRequire suitable soils and maintenance

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Technological Approach: Technological Approach: Advanced (Tertiary) Sewage Advanced (Tertiary) Sewage TreatmentTreatment

Uses physical and chemical processesUses physical and chemical processes

Removes nitrate and phosphateRemoves nitrate and phosphate

ExpensiveExpensive

Not widely usedNot widely used

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Drinking Water QualityDrinking Water Quality

Safe Drinking Water ActSafe Drinking Water Act

Maximum contaminant levels (MCLs)Maximum contaminant levels (MCLs)

Purification of urban drinking waterPurification of urban drinking water

Bottled waterBottled water

Protection from terrorismProtection from terrorism

Purification of rural drinking waterPurification of rural drinking water