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Water Pollution
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Definition = physical, chemical, biological changes in water quality that adversely affect living organisms. (i.e., degradation)
Types:Infectious AgentsOxygen-Demanding WastesInorganic PollutantsOrganic ChemicalsSediment (Particulates) Thermal Pollution
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Infectious Agents
Infectious Agents = pathogenic organisms. Water-borne diseases from infectious agents include typhoid, cholera, bacterial and amoebic dysentery, polio, infectious hepatitis, guinea worm and schistosomiasis. Due to lack of sanitation.
Analyze coliform bacteria (E. coli). Presume if coliform bacteria are present, infectious pathogens are also present.
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Key ConceptsKey Concepts
Types, sources, and effects of water pollutants
Major pollution problems of surface water
Major pollution problems of groundwater
Reduction and prevention of water pollution
Drinking water quality
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Types, Effects, and Sources of Water Pollution
• Water is polluted by infectious bacteria, inorganic and organic chemicals, and excess heat.
• Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms.
• The WHO estimates that 3.4 million people die prematurely each year from waterborne diseases.
• In the U.S., an estimated 1.5 million people a year become ill from infectious agents.
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• Scientists monitor water quality by using bacterial counts, chemical analysis, and indicator organisms.
• One method of measuring water quality involves measuring the number of colonies of fecal coliform bacteria present in a water sample.
• Drinking water should not contain any colonies/100 milliliters,
• Chemical analysis includes checking inorganic and organic chemicals present, sediment content, and turbidity of water.
• Indicator species are living organisms that are monitored to determine levels of pollution.
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Sources of Water Pollution
Point sources
Nonpoint sources
Water quality
Supply of Water Resources
FreshwaterFreshwater Readily accessible freshwaterReadily accessible freshwater
Biota0.0001%
Biota0.0001%
Rivers0.0001%Rivers
0.0001%
Atmosphericwater vapor
0.0001%
Atmosphericwater vapor
0.0001%
Lakes0.0007%
Soilmoisture0.0005%
Groundwater0.592%
Groundwater0.592%
Ice capsand glaciers
0.592%
0.014%0.014%
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Inorganic PollutantsNonmetallic Salts:
Arsenic from mining or drainage of desert soils Causes: - anemia
- cancer- death.
Sodium Chloride: Salinization
Acids: Sulfur and nitrogen compounds from coal.
Causes: - pH changes which affect species- leaches aluminum
Evaporation and transpiration
Evaporation
Stream
Infiltration
Water tableInfiltration
Unconfined aquifer
Lake
Well requiring a pump
Flowingartesian well
Runoff
Precipitation
ConfinedRecharge Area
Aquifer
Ground Water
Fig. 15-3 p. 308
Use of Water Resources
Humans use about 54% of reliable runoff Humans use about 54% of reliable runoff
Agriculture Agriculture
Industry Industry
Domestic Domestic
Power plants Power plantsIndustry 11%
Public 10%
Powercooling
38%
Agriculture38%
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Point 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 pollution
The leading sources of water pollution are agriculture, industries, and mining.
1.Agricultural activities are the leading cause of water pollution from erosion, overgrazing, fertilizers and pesticides, and excess salt from irrigated soils.
2.Industrial facilities are another large source of water pollution, and mining is a third source.
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• One of every five people in the world lacks access to safe drinking water.
• Ninety-five percent of people in developed countries and 74% of people in developing countries have access to clean drinking water.
• In a warmer world, too much rain and too
little rain can increase water pollution.
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Pollution of Freshwater Streams
Streams can recover from moderate levels of degradable water pollutants if the flows are not reduced.
1.A combination of dilution and biodegradation can allow recovery of stream pollution
2.The breakdown of pollutants by bacteria creates an oxygen sag curve. Organisms that have a high oxygen demand can’t survive in the curve.
3.Volume of the stream, volume of wastes entering, flow rate, temperature, and pH levels all affect how great a sag curve is produced.
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Oxygen Sag Curve
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Water Pollution: Now
Most developed countries have reduced point source pollution, but toxic chemicals and pollution from non-point sources are still problems.
Stream pollution in most developing countries is a serious and growing problem. Half of the world’s 500 major rivers are heavily polluted, and most of them run through developing countries where waste treatment is minimal or nonexistent.
For example: Religious beliefs, cultural traditions, poverty, little economic development, and a large population interact to cause severe pollution of the Ganges River in India.
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Pollution of Lakes
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Groundwater Pollution: CausesGroundwater Pollution: Causes
Low flow rates Few bacteria Cold temperatures
Coal strip mine runoff
Pumping well
Waste lagoon
Accidental spills
Groundwater flow
Confined aquifer
Discharge
Leakage from faulty casing
Hazardous waste injection well
Pesticides
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 oxygen
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Pollution of Groundwater
Experts rate groundwater pollution as a low-risk ecological problem; it is rated as a high-risk health problem.
The extent of groundwater contamination is
generally unknown Prevention is the most effective and
affordable way to protect groundwater from pollutants.
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Ocean PollutionOcean Pollution
Fig. 22-11 p. 504
Problems with Using Groundwater
Water lable lowering Water lable lowering
Depletion Depletion
Subsidence Subsidence
Saltwater intrusion Saltwater intrusion
Chemical contaminationChemical contamination
Reduced stream flows Reduced stream flows
Groundwater Pollution
• >70,000 chemicals are used not; effects of many are not known
• Each year another 700-800 new chemicals are produced
• 55 million tons of hazardous chemical wastes are produced in the US each year
• The 20 most abundant compounds in groundwater at industrial waste disposal sites include TCE, benzene, vinyl chloride…all are carcinogens, and also affect liver, brain, and nervous system
Kinds of Water Pollution
• Inorganic Pollutants• Organic Pollutants• Biologic Pollutants
Inorganic Pollutants
• Examples:• Pb in gasoline• Radionuclides• Phosphorus, nitrogen (Great Lakes)• Other heavy metals
Inorganic Pollutants
• 3 groups• 1) Produce no health effects until a threshold
concentration is exceeded—e.g., NO3 at , 50mg/liter; at higher levels: methaemoglobinaemia
• 2) No threshold—e.g.—genotoxic substances: some natural and synthetic organic compounds, microorganic compunds, some pesticides, arsenic
• 3) Essential to diets: F, I, Se—absence causes problems, but too much also causes problems
Inorganic Trace Contaminants• Mercury—methyl Hg and dimethyl Hg
in fish—probably most significant path to humans—Minamata Bay, Japan, 1950’s
• Rhine River drains 185,000 sq km—heavily polluted by 1970’s
• Lead—toxicity has been known for a long time– 1859 book– Tetraethyl lead—anti-knowck additive for
gas, 1930-1966
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Oil SpillsSources: offshore wells,
tankers, pipelines and storage tanks
Effects: death of organisms, loss of animal insulation and buoyancy
Significant economic impacts
Mechanical cleanup methods: skimmers and blotters
Chemical cleanup methods: coagulants and dispersing agents
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Solutions: Preventing and Reducing Surface Water Pollution
Nonpoint Sources Point Sources
Reduce runoff
Buffer zone vegetation
Reduce soil erosion
Clean Water Act
Water Quality Act
Reducing Water Pollution through Sewage Treatment
• Primary and Secondary sewage treatment. Figure 20-19