Transcript Chapter 21 PowerPoint

Water Pollution
Chapter 21 (pgs 338-355)
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 Problem
 For many years, people dumped garbage
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into waterways
As 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 carries
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organic 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 Plants
 Sewage 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 chemicals
 Bacteria – break down organic pollutants
 Chemicals (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
Pathogens
 Pathogens – parasites, bacteria,
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and viruses that cause diseases in
living things
Many pathogens spend part of their
lifecycle in water – they enter the
water 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
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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 chemicals
 Describe the process of eutrophication and its
effects on lake ecosystems
 Think 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 Chemicals
 Include acids, salts, heavy metals, and
plant nutrients
 Heavy 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, Japan
 Animals began to behave strangely – birds fell
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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 Chemicals
 Chemicals from living things or
synthetically made
 Gasoline, oils, plastics, some
pesticides, fertilizers, solvents,
and wood preservatives
 Enter water as:
 Wastes from petroleum
refineries, chemical factories,
and from canning, meatpacking, and food processing
plants
 Runoff from farmland
 Crude oil spills
Exxon Valdez
 1989- 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
Eutrophication
 Fertilizers and detergents contain nutrients, phosphates, and
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nitrates
They enter the water system and promote the growth of algae and
aquatic plants
When plants die, get huge amounts of decomposing bacteria
Bacteria use up all the oxygen and the fish die
More 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
pollution
 Think 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
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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 water
2,100 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
oxygen
 Increased 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 oxygen
 Higher 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 Pollution
 Objectives:
 Identify government attempts to control water pollution.
 Describe the problems involved in enforcing laws
regarding water pollution.
 Think Critically
 Water pollution is found almost everywhere.
 Laws have been made to control this pollution.
 Why might these be hard to enforce?
Laws
 Beginning in 1898, laws were designed
to control water pollution.
 But, the laws were not strong enough and not enforced.
 Individual states responsible for enforcing laws
 Scientific reports on pollution were not accurate
 Several sources could be responsible for pollution – who pats?
 Little was known about the effects of pollution on ecosystems
 The 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 water
pollution? 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?