Chapter 21 (pgs 338-355)

Water Pollution

Section 21.1 Water Pollution Problem

Objectives:Explain the link between water pollution and

human disease.Identify the major types of water pollutants and

their sources.Think Critically

Medical waste on NY and NJ beaches, warnings not to eat shellfish in Delaware because of bacteria in the water, an oil slicks near Texas and Alaska discolor beaches and damage ecosystems.

What is the major cause of these problems?How can these problems be stopped?

Water Pollution ProblemFor many years, people dumped garbage

into waterwaysAs waters became contaminated,

infectious diseases (cholera, typhoid, dysentery) became more common

In 1885 in Chicago, 90,000 people died from a cholera outbreak

German doctor, Robert Koch, linked cholera outbreaks to contaminated water

People realized contaminated water was a problem and began dumping garbage further out at sea

But garbage in the ocean affects the ocean ecosystem and drifts back to shore

Sewage

Sewage – water that carriesorganic wastes from humans and industry

Comes from toilets, sinks, washing machines, and industrial equipment

The U.S. dumps approx. 8.9 trillion liters of sewage into the ocean each year

Most of this waste is treated, but some may not be treated and can contain toxic chemicals and metals

Also, in many developing countries, sewage is not treated at all

Sewage Treatment PlantsSewage Treatment Plant – a facility that

processes raw sewage before the sewage is returned to surface water systems

Sewage is 1st passed through screens that filter out plastics, fabrics, and metal objects

Further processing includes the treatment of solid materials called sludge, and the addition of bacteria and purifying chemicalsBacteria – break down organic pollutantsChemicals (chlorine) sanitize and deodorize

These treatments do nothing to remove organic matter

This organic matter can lead to an excess of nutrients in the water which causes eutrophication

PathogensPathogens – parasites, bacteria,

and viruses that cause diseases in living things

Many pathogens spend part of theirlifecycle in water – they enter thewater through infected raw sewage or animal wastes

Pathogens carried by water result in more human illness and death than any other environmental factor

With improved sanitation in developed countries diseases like cholera and typhoid are under control

In developing countries – still a problem!

Schistosomiasis

Disease caused by microscopic worms that enter through the skin of people who walk in water contaminated by infected human waste

The worms attack the liver, bladder, and intestines

Affects as many as 100 million people in the tropics and causes > 1 million deaths/year

Most common in Africa, the Middle East, and Egypt

Malaria

Disease caused by a protozoan

Transmitted to humans by bite of infected mosquito

Water serves as the breeding ground for the mosquitos

Worldwide > 800 million people are infected with malaria

One million people die each year

Common in Africa, East Asia, and Latin America

Types of Water Pollution

Check For Understanding

1. What is sewage?2. Create a flowchart that details

the relationship between sewage, contaminated water, pathogens, and humans

Section 21.2 Chemical Pollutants

Objectives:Examine the sources and effects of inorganic

and organic toxic chemicalsDescribe the process of eutrophication and its

effects on lake ecosystemsThink Critically

Did you ever read the book “Alice’s Adventures in Wonderland”?

There was a character called the Mad Hatter.Can you guess why he was called Mad?

Toxic Chemicals

Toxic chemicals – elements and molecules that are directly harmful to living things

Inorganic chemicals – elements or molecules not derived from organisms

Organic chemicals – molecules containing atoms of carbon that are derived from organisms

Inorganic ChemicalsInclude acids, salts, heavy metals,

and plant nutrientsHeavy metals – metallic elements

with high atomic masses (lead, mercury, arsenic, chromium, etc) that are often from industrial processes

Plant nutrients – molecules that do not contain carbon but are needed for plant growth (phosphates, nitrates)

Enter water through seepage, runoff and direct discharge into lakes, rivers, and streams, and oceans

Minamata, JapanAnimals began to behave strangely –

birds fell out of trees, cats acted crazy

Townspeople began to complain of headaches, dizziness, blurred vision, and numbness of hands and feet

The cause of symptoms turned out to be mercury poisoning

A plastics factory was discharging mercury directly into Minamata Bay

This contaminated the fish, which the people ate

Over 20 years, 8,000 people suffered paralysis or brain damage and several hundred people died.

Organic ChemicalsChemicals from living things

or synthetically madeGasoline, oils, plastics,

some pesticides, fertilizers, solvents, and wood preservatives

Enter water as:Wastes from petroleum

refineries, chemical factories, and from canning, meat-packing, and food processing plants

Runoff from farmlandCrude oil spills

Exxon Valdez1989- oil tanker ran

aground off coast of Alaska

42,000 metric tons of crude oil gushed into Prince William Sound

Ecosystem was devastated and thousands of birds, mammals, and other organisms dies

EutrophicationFertilizers and detergents contain nutrients,

phosphates, and nitratesThey enter the water system and promote the

growth of algae and aquatic plantsWhen plants die, get huge amounts of

decomposing bacteriaBacteria use up all the oxygen and the fish dieMore than 65% of the lakes in the U.S. are

affected

Issues – Lake Erie: A Success Story

Read page 346 in your textbook

Answer Decision questions on a sheet of paper and hand in before class is over.

Check For Understanding

1. What is eutrophication?2. Describe the difference between

an organic and inorganic chemical. Give one example of water pollution by each.

3. The Exxon Valdez oil spill occurred because of human error. Can the possibility of human error ever be eliminated?

Section 21.3 Radioactivity and Thermal Pollution

Objectives:Explain the problems of radioactive and

thermal water pollutionThink Critically

Nuclear power plants can produce energy that does not pollute the air.

But, they also produce a lot of radioactive wastes that are hard to get rid of.

Do you think we should rely on nuclear energy?

Radioactivity

Radioactive elements are used as fuels in nuclear power plants, as medicines, and in nuclear weapons

Radioactivity is very dangerous and radioactive wastes are difficult to handle

Whether a solid or a liquid, they may result in water pollution

In 1973, 1 million liters of radioactive waste leaked into the soil from the Hanford nuclear weapons site in Washington

The radiation contaminated the fish and drinking water2,100 people were exposed to dangerous levels of

radiation

Thermal Pollution

A large increase in water temperature due to human activity

Usually occurs in lakes, rivers, or shallow bays near power plants or industrial sites

Affects ecosystems in several ways:Increased water temperature decreases the amount of

dissolved oxygenIncreased water temperature increases the body

temperature of fish, which increases their metabolism so they need more oxygen

Fish suffocate because they can’t get enough oxygenHigher temperatures of water is also destructive to

developing fish eggs

Check For Understanding

1. What is thermal pollution?2. Nuclear power plants produce

large amounts of radioactive water? Why?

Section 21.4 Controlling Water PollutionObjectives:

Identify government attempts to control water pollution.

Describe the problems involved in enforcing laws regarding water pollution.

Think CriticallyWater pollution is found almost everywhere.Laws have been made to control this

pollution.Why might these be hard to enforce?

LawsBeginning in 1898, laws were designed

to control water pollution.But, the laws were not strong enough and not enforced.

Individual states responsible for enforcing lawsScientific reports on pollution were not accurateSeveral sources could be responsible for pollution – who

pats?Little was known about the effects of pollution on

ecosystemsThe politics of industry (money or environment?)

In response Congress passed the Clean Water Act

(1972) which was an attempt to set water quality standards for all states

Check For Understanding

1. What is being done to control waterpollution? Are these measures effective?

2. What can you do as an individual to reduce the effects of water pollution?

3. You are on the town planning community. A company that employs 75% of the people in your community has been cited for water pollution violations. The company says it will move if it is told to pay the fines. Will you vote to make the company pay?