WaterWaterChapter 5Chapter 5

Part IIPart II

II. Freshwater PollutionII. Freshwater Pollution

A. Water pollution is A. Water pollution is the introduction of chemical, the introduction of chemical, physical, or biological material into the water physical, or biological material into the water which degrades the water quality and affects the which degrades the water quality and affects the organisms that live in it or drink it.organisms that live in it or drink it.

1. In some countries, the main problem is 1. In some countries, the main problem is industrialindustrial and and agricultural agricultural pollution that pollution that are not are not controlled by the controlled by the governmentgovernment

2. In very poor countries, the 2. In very poor countries, the populationpopulation is is too big too big and water is often and water is often polluted by polluted by sewage and sewage and agriculture.agriculture.

3. As we see here, the two underlying 3. As we see here, the two underlying causes of causes of water pollution are:water pollution are:

a. a. industrializationindustrializationb. b. human population explosionhuman population explosion

B. B. Point pollutionPoint pollution is pollution that is discharged from is pollution that is discharged from a a single sourcesingle sourceexamples:factory; waste treatment plant; oil examples:factory; waste treatment plant; oil

tanker…)tanker…)1. Easy to 1. Easy to regulateregulate and and control control because it can be because it can be

identifiedidentified2. May still be difficult to 2. May still be difficult to enforceenforce and and clean upclean up

C. C. Nonpoint pollutionNonpoint pollution is pollution that comes from is pollution that comes from many many sources, not just one specific site.sources, not just one specific site.1. Runs into waterways from 1. Runs into waterways from streetsstreets and and storm storm

sewerssewers2. Can come from 2. Can come from homeshomes, , lawnslawns, , farmsfarms, ,

highwayshighways,,almost almost anywhereanywhere..

3. Extremely difficult to 3. Extremely difficult to controlcontrol and and regulateregulatea. a. 9696% of polluted bodies of water in the % of polluted bodies of water in the

U.S. U.S. are contaminated by are contaminated by nonpoint nonpoint sourcessources

b. b. educating the publiceducating the public will be the most will be the most effective solution.effective solution.

D. Wastewater Treatment D. Wastewater Treatment PlantsPlants1. Most of the water that goes down the 1. Most of the water that goes down the drain drain ((waste waterwaste water) goes to a ) goes to a treatment planttreatment plant

a. water is a. water is treated treated before before being being returned to a returned to a river or lakeriver or lake

b. fig 5-21 on page 135 is of b. fig 5-21 on page 135 is of a a treatment treatment plantplant..

2. Treatment plants cannot remove 2. Treatment plants cannot remove all all harmful harmful substancessubstances

a most wastewater from homes is a most wastewater from homes is biodegradablebiodegradable and and easy to purifyeasy to purifyb. b. industrial waste waterindustrial waste water and and storm storm

runoffrunoff from from streetsstreets and and fields fields contain contain toxic toxic substances substances that interfere with that interfere with

treatmenttreatment

3. One of the products of wastewater 3. One of the products of wastewater treatment is treatment is sludgesludge = = the solid material the solid material left after treatmentleft after treatment

a. Contains a. Contains dangerousdangerous, , toxic toxic chemicals, so it is usually chemicals, so it is usually

disposed disposed of as of as hazardous wastehazardous waste..b. it is often b. it is often incineratedincinerated then then

buriedburied in a in a secure landfillsecure landfillc. it is so c. it is so expensive to deal expensive to deal

withwith that communities are that communities are making it less making it less toxictoxic so it can be so it can be used:used:

i. can be used as i. can be used as fertilizerfertilizerii. can be combined with ii. can be combined with

clayclay to make to make bricksbricks

E. Pathogens are E. Pathogens are disease causing disease causing organismsorganisms

examples:examples: bacteriabacteria, , virusesviruses, , parasitic parasitic wormsworms

1. Can enter water supplies in 1. Can enter water supplies in untreated untreated waste waterwaste water or or anima fecesanima feces

2. Many diseases are caused by 2. Many diseases are caused by drinking drinking pathogen polluted waterpathogen polluted water

examples:examples: choleracholera, , hepatitishepatitis, , tyohoidtyohoid, , etc.etc.

3. 3. Public water suppiesPublic water suppies are routinely are routinely checked for pathogens.checked for pathogens.

example:example: fecal coliform fecal coliform test to test to look for look for E. Coli bacteriaE. Coli bacteria

F. How Water Pollution Affects F. How Water Pollution Affects EcosystemsEcosystems

1. Water pollution can affect all levels of the 1. Water pollution can affect all levels of the food food chainchain

a. Toxins may a. Toxins may get into the tissues of get into the tissues of organismsorganisms

b. At each step in the food chain, the b. At each step in the food chain, the amount amount of toxin passed to the next of toxin passed to the next “eater” “eater” increasesincreases

= = biological magnificationbiological magnificationexample:example: Toxins get into the tissues of a tiny, river- Toxins get into the tissues of a tiny, river-

bottom organism; one small fish eats bottom organism; one small fish eats hundreds hundreds of of these organisms; one big fish eats these organisms; one big fish eats hundredshundreds of the of the contaminated small fish; an contaminated small fish; an eagle eats eagle eats tenten of the of the contaminated contaminated big fishbig fish. . The toxin is building up at The toxin is building up at each each levellevel..

2. Water pollution can cause 2. Water pollution can cause immediate damage immediate damage to to an ecosysteman ecosystem

example:example: spills of spills of tixic chemicalstixic chemicals directly directly into a into a river can kill nearly all living things river can kill nearly all living things for for miles miles downstreamdownstream

3. Water pollution can be harmful to 3. Water pollution can be harmful to human human healthhealth

a. toxins in a. toxins in fish tissuesfish tissues can can make it make it too too dangerousdangerous for for humans to eat.humans to eat.

b. some b. some heavy metalsheavy metals and and toxic toxic chemicalschemicals in in waterways cause waterways cause cancercancer or or birth defects;birth defects; affect affect reproductionreproduction;damage the ;damage the nervous nervous

systemsystem, , liverliver or or kidneyskidneys

G. Artificial Eutrophication = G. Artificial Eutrophication = eutrophication caused eutrophication caused by by humans humans

1. When a lake or stream becomes eutrophic, 1. When a lake or stream becomes eutrophic, they they contain lots of contain lots of nutrientsnutrients

a. occurs naturally over a. occurs naturally over a long period of a long period of timetime

b. organisms b. organisms diedie, , decomposersdecomposers use use oxygen to oxygen to break them down into break them down into nutrientsnutrients, , plantsplants grow grow in the nutrient rich shallows, in the nutrient rich shallows, fishfish and and other other organismsorganisms die because of die because of lack of oxygen lack of oxygen eventually, a eventually, a marshmarsh or or swampswamp forms. forms.

2. The process speeds up when 2. The process speeds up when plant nutrientsplant nutrients ( ( NN and and PP) get into the water from ) get into the water from sewage sewage and and fertilizerfertilizer runoff. runoff.

a. a. phosphorus (P)phosphorus (P) in in detergentsdetergents, , animal animal wastewaste, and , and fertilizerfertilizer cause cause algal bloomsalgal blooms

which which lead to eutrophicationlead to eutrophicationb. some states have b. some states have bannedbanned or or limited limited phosphate detergentsphosphate detergents

H. Thermal Pollution occurs when H. Thermal Pollution occurs when excessive excessive amounts of heatamounts of heat are added to a body of water. are added to a body of water.

1. Occurs when 1. Occurs when power plantspower plants and and industries industries along along lakes or rivers use water in their lakes or rivers use water in their cooling cooling systemssystems..

a. cool water is pulled from the lake or a. cool water is pulled from the lake or river river to to absorb heatabsorb heat from engines. from engines.

b. b. warm waterwarm water is returned to the lake or is returned to the lake or river.river.

2. Can cause 2. Can cause fish killsfish kills if it is if it is too warm for the too warm for the fishfish

3. Warm water cannot hold as much 3. Warm water cannot hold as much oxygenoxygen, , so so some organisms some organisms suffocate.suffocate.

4. If it is continuous, the whole ecosystem 4. If it is continuous, the whole ecosystem may be may be changeschanges because some organisms because some organisms could not could not adjust adjust to the to the higher temperatureshigher temperatures

5. Citizens often oppose 5. Citizens often oppose power plantspower plants on on lakes and lakes and rivers and insist the water be rivers and insist the water be cooled cooled before it before it is put back into a waterway.is put back into a waterway.