Chapter 22Chapter 22Water PollutionWater Pollution

Types of Water PollutionTypes of Water Pollution

o Water pollutionWater pollution• Any physical or chemical change in water Any physical or chemical change in water

that adversely affects the health of humans that adversely affects the health of humans and other organisms and other organisms

• Varies in magnitude and type of pollutant Varies in magnitude and type of pollutant by locationby location

o Major water pollution issue globallyMajor water pollution issue globally• Lack of disease-free waterLack of disease-free water

Types of Water PollutionTypes of Water Pollution

o Eight categoriesEight categories• SewageSewage• Disease-causing agentsDisease-causing agents• Sediment pollutionSediment pollution• Inorganic plant and algal nutrientsInorganic plant and algal nutrients• Organic compoundsOrganic compounds• Inorganic chemicalsInorganic chemicals• Radioactive substancesRadioactive substances• Thermal pollution Thermal pollution

o Some categories are interrelatedSome categories are interrelated

SewageSewage

o The release of wastewater from drains The release of wastewater from drains or sewers or sewers • Includes human wastes, soaps, and Includes human wastes, soaps, and

detergents detergents

o Causes 2 serious environmental Causes 2 serious environmental problems:problems:• EnrichmentEnrichment• Increase in Biological Oxygen Demand Increase in Biological Oxygen Demand

(BOD)(BOD)

EnrichmentEnrichment

o Fertilization of a body of water by high Fertilization of a body of water by high levels of plant and algal nutrients levels of plant and algal nutrients (nitrogen and phosphorus)(nitrogen and phosphorus)

o Microorganisms decompose materials Microorganisms decompose materials into COinto CO22, water, other inoffensive , water, other inoffensive materialsmaterials• Cellular respiration – requires oxygenCellular respiration – requires oxygen

Biological Oxygen DemandBiological Oxygen Demand

o Amount of oxygen needed by Amount of oxygen needed by microorganisms to decompose microorganisms to decompose biological wastesbiological wastes• Expressed as mg of DO/L for a specific Expressed as mg of DO/L for a specific

number of days at a given temperaturenumber of days at a given temperature

o As BOD increases Dissolved Oxygen As BOD increases Dissolved Oxygen (DO) decreases(DO) decreases

Dissolved OxygenDissolved Oxygen

o Oxygen has a limited ability to dissolve in Oxygen has a limited ability to dissolve in waterwater

o When aquatic ecosystem contains a large When aquatic ecosystem contains a large amount of sewage, decomposing amount of sewage, decomposing organisms use up most of DOorganisms use up most of DO• Little left for fishes and other aquatic animalsLittle left for fishes and other aquatic animals• Extremely low DO, anaerobic microorganisms Extremely low DO, anaerobic microorganisms

produce compounds with unpleasant odorsproduce compounds with unpleasant odors• Further deteriorates water qualityFurther deteriorates water quality

Dissolved OxygenDissolved Oxygen

Oligotrophic LakeOligotrophic Lake

o Unenriched, clear water that supports Unenriched, clear water that supports small populations of aquatic organisms small populations of aquatic organisms

Eutrophic LakeEutrophic Lakeo Slow-flowing stream, lake or estuary Slow-flowing stream, lake or estuary

enriched by inorganic plant and algal enriched by inorganic plant and algal nutrients such as phosphorus nutrients such as phosphorus

o Often due to fertilizer or sewage runoffOften due to fertilizer or sewage runoff

EutrophicationEutrophication

o Enrichment of lake, estuary, or slow-Enrichment of lake, estuary, or slow-flowing stream by inorganic plant and flowing stream by inorganic plant and algal nutrientsalgal nutrients

o Increased photosynthetic productivityIncreased photosynthetic productivityo Water becomes cloudy (pea soup-like) Water becomes cloudy (pea soup-like)

because of presence of algae and because of presence of algae and cyanobacteriacyanobacteria

EutrophicationEutrophication

o Over time, bodies of water become Over time, bodies of water become eutrophic naturallyeutrophic naturally• Slowly grow enriched, shallowerSlowly grow enriched, shallower• Plants start to take rootPlants start to take root• Becomes a marshBecomes a marsh

o Artificial eutrophication – human-Artificial eutrophication – human-induced processinduced process• Fertilizer runoff and sewageFertilizer runoff and sewage

Disease-causing AgentsDisease-causing Agents

o Infectious organisms Infectious organisms that cause diseasesthat cause diseases• Originate in the Originate in the

wastes of infected wastes of infected individuals individuals

o Common bacterial or Common bacterial or viral diseases:viral diseases:• Typhoid, cholera, Typhoid, cholera,

bacterial dysentery, bacterial dysentery, polio, and infectious polio, and infectious hepatitishepatitis

Disease-causing AgentsDisease-causing Agents

o Monitored by testing for presence of E. Monitored by testing for presence of E. coli in the water via a coli in the water via a fecal coliform testfecal coliform test• Indicates the presence of pathogenic Indicates the presence of pathogenic

organismsorganisms

E. ColiE. Coli

o Safe drinking water – no more than 1 Safe drinking water – no more than 1 bacterium/100 mLbacterium/100 mL

o Safe swimming water – no more than Safe swimming water – no more than 200/100 mL200/100 mL

o Safe general recreation water (boating) Safe general recreation water (boating) – no more than 2000/100 mL– no more than 2000/100 mL

o Raw sewage – several million/100 mLRaw sewage – several million/100 mL

Sediment PollutionSediment Pollution

o Excessive amounts of suspended soil Excessive amounts of suspended soil particlesparticles• Originates from erosion of agricultural Originates from erosion of agricultural

lands, forest soils exposed by logging, lands, forest soils exposed by logging, degraded stream banks, overgrazed degraded stream banks, overgrazed rangelands, strip mines, and construction rangelands, strip mines, and construction

o ProblemsProblems• Limits light penetrationLimits light penetration• Covers aquatic animals and plantsCovers aquatic animals and plants• Brings insoluble toxins into waterwaysBrings insoluble toxins into waterways

Sediment PollutionSediment Pollution

o Makes water turbid (cloudy)Makes water turbid (cloudy)o Extreme turbidityExtreme turbidity

• Reduces number of photosynthetic algae and Reduces number of photosynthetic algae and plants that require light for photosynthesisplants that require light for photosynthesis

• Decreases number of aquatic organisms that Decreases number of aquatic organisms that feed on producersfeed on producers

o Sediments can form layer over coral reefs Sediments can form layer over coral reefs or shellfish beds that can clog gills and or shellfish beds that can clog gills and feeding structures of aquatic animalsfeeding structures of aquatic animals

Sediment PollutionSediment Pollution

o Particles can also carry toxic chemicals Particles can also carry toxic chemicals (inorganic and organic) into water(inorganic and organic) into water

o Can also transport disease-causing Can also transport disease-causing agentsagents

Sediment PollutionSediment Pollution

o 1998 EPA study – sediments in 7% of 1998 EPA study – sediments in 7% of watersheds are so seriously watersheds are so seriously contaminated with toxic pollutants that contaminated with toxic pollutants that eating fishes from those waterways eating fishes from those waterways would threaten human healthwould threaten human health

o Sediments can fill in waterways – Sediments can fill in waterways – problem in lakes and channels through problem in lakes and channels through which ships have to passwhich ships have to pass

Inorganic Plant and Algal Inorganic Plant and Algal NutrientsNutrients

o Chemicals such as nitrogen and phosphorus Chemicals such as nitrogen and phosphorus that stimulate the growth of plants and algaethat stimulate the growth of plants and algae• Essential for normal functioning of healthy Essential for normal functioning of healthy

ecosystemecosystem• Harmful in large concentrationsHarmful in large concentrations

o Sources:Sources:• Human and animal wastes, plant residues, Human and animal wastes, plant residues,

atmospheric deposition, and fertilizer runoffatmospheric deposition, and fertilizer runoff

o Causes:Causes:• Enrichment, bad odors, and a high BOD Enrichment, bad odors, and a high BOD

Mississippi Dead ZoneMississippi Dead Zone

Mississippi Dead ZoneMississippi Dead Zone

o Fertilizer runoff from midwestern fields, Fertilizer runoff from midwestern fields, manure runoff from livestock operationsmanure runoff from livestock operations

o 1998 Senate Agriculture Hearings -- US 1998 Senate Agriculture Hearings -- US livestock produce 20 times the feces livestock produce 20 times the feces and urine that humans doand urine that humans do• Not covered by water quality lawsNot covered by water quality laws• Do not go to wastewater treatment plantsDo not go to wastewater treatment plants

Mississippi Dead ZoneMississippi Dead Zone

o Dead zone extends from sea floor up Dead zone extends from sea floor up into water column to within several into water column to within several meters from surfacemeters from surface

o Floods and droughts change its sizeFloods and droughts change its sizeo Persists from March/April to SeptemberPersists from March/April to September

• Most severe in June, July, AugustMost severe in June, July, August

o 2002 – more than 22,000 km2002 – more than 22,000 km22 – size of – size of MassachusettsMassachusetts

Mississippi Dead ZoneMississippi Dead Zone

o No life other than anaerobic bacteriaNo life other than anaerobic bacteria• Active swimmers avoid areaActive swimmers avoid area• Bottom dwellers suffocateBottom dwellers suffocate

o Hypoxia affects more than 146 coastal Hypoxia affects more than 146 coastal areas in worldareas in world

Organic CompoundsOrganic Compounds

o Chemicals that contain carbon atomsChemicals that contain carbon atoms• Natural examples: sugars, amino acids, and Natural examples: sugars, amino acids, and

oils oils • Human-made examples: pesticides, Human-made examples: pesticides,

solvents, industrial chemicals, and plastics solvents, industrial chemicals, and plastics

Organic CompoundsOrganic Compounds

o 2002 USGS Study of 139 streams in 30 2002 USGS Study of 139 streams in 30 states:states:• Tested for 95 organic compoundsTested for 95 organic compounds• Found low concentrations of 82 compoundsFound low concentrations of 82 compounds

• One found in 80% of streamsOne found in 80% of streams• More than 1/3 contained traces of 10 or moreMore than 1/3 contained traces of 10 or more

o Effects on human health largely Effects on human health largely unknownunknown

Inorganic ChemicalsInorganic Chemicals

o Contaminants that contain elements Contaminants that contain elements other than carbonother than carbon• Examples: acids, salts, and heavy metals Examples: acids, salts, and heavy metals

o Do not degrade easilyDo not degrade easily

LeadLead

o Found in old paint, industrial pollutants, Found in old paint, industrial pollutants, leaded gasolineleaded gasoline• 1978 – lead paint banned1978 – lead paint banned• 1986 – leaded gasoline outlawed1986 – leaded gasoline outlawed

• Dust released into atmosphere, contaminates soil, Dust released into atmosphere, contaminates soil, especially inner cities near highwaysespecially inner cities near highways

• Contaminates soil, surface water, and Contaminates soil, surface water, and groundwater when incinerator ash dumped in groundwater when incinerator ash dumped in landfillslandfills

• Pesticides, fertilizersPesticides, fertilizers• Food cans and certain types of dinnerwareFood cans and certain types of dinnerware

MercuryMercury

o Vaporizes at room temperatureVaporizes at room temperatureo Coal-fired power plants release 40% of Coal-fired power plants release 40% of

mercury in environmentmercury in environmento Fluorescent lights and thermostatsFluorescent lights and thermostatso Also released during metal smeltingAlso released during metal smeltingo Mercury bioaccumulates in the muscles Mercury bioaccumulates in the muscles

of top predators of the open ocean of top predators of the open ocean o Human exposure primarily due to eating Human exposure primarily due to eating

fishes and marine mammalsfishes and marine mammals

Radioactive SubstancesRadioactive Substances

o Contain atoms of unstable isotopes that Contain atoms of unstable isotopes that spontaneously emit radiation spontaneously emit radiation

o SourcesSources• MiningMining• Processing radioactive materialsProcessing radioactive materials• Nuclear power plantsNuclear power plants• Natural sourcesNatural sources

Thermal PollutionThermal Pollution

o Occurs when heated Occurs when heated water produced water produced during industrial during industrial processes is released processes is released into waterways into waterways

o Organisms affectedOrganisms affected• Temperature affects Temperature affects

reproductive cycles, reproductive cycles, digestion rates, and digestion rates, and respiration rates respiration rates

• Warm water holds less Warm water holds less DO than cold waterDO than cold water