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Page 1: Water pollution

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Water Pollution

Page 2: 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

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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

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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

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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

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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

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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

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Kinds of Water Pollution

• Inorganic Pollutants• Organic Pollutants• Biologic Pollutants

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Inorganic Pollutants

• Examples:• Pb in gasoline• Radionuclides• Phosphorus, nitrogen (Great Lakes)• Other heavy metals

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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

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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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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

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Reducing Water Pollution through Sewage Treatment

• Primary and Secondary sewage treatment. Figure 20-19