Name
Class
CHAPTER 13
Date
Exploring the Oceans
SECTION
5 Ocean Pollution
BEFORE YOU READ
After you read this section, you should be able to answer
these questions:
• What are the different types of pollution in the ocean?
• How can we preserve ocean resources?
What Pollutes the Ocean?
Many human activities produce pollution that can harm
the oceans. Some of this pollution comes from a specific
source. Pollution that can be traced to one source is called
point-source pollution. However, some pollution comes
from many sources. Pollution that cannot be traced to a
single source is called nonpoint-source pollution.
TRASH DUMPING
STUDY TIP
Summarize As you read,
underline the main ideas in
each paragraph. When you
finish reading, write a short
summary of the section using
the ideas you underlined.
READING CHECK
People dump trash in many places, including the
ocean. In the 1980s, scientists became alarmed by
the kinds of trash that were washing up on beaches.
Bandages, vials of blood, and other medical wastes were
found among the trash.
The Environmental Protection Agency (EPA) found
that hospitals in the United States were dumping medical
wastes into the oceans. Much of this waste is now buried
in sanitary landfills. However, other kinds of trash are
still dumped into the oceans.
1. Define Write your own
definition for nonpoint-source
pollution.
TAKE A LOOK
2. Identify How does trash
get into the oceans?
Barges like this one carry garbage out to sea. The garbage is dumped
into the open ocean.
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Name
SECTION 5
Class
Date
Ocean Pollution continued
EFFECTS OF TRASH DUMPING
Trash thrown into the ocean can affect the organisms that live there. It also affects the organisms, such as
people, that depend on the ocean for food. For example,
most plastic material that is thrown into the ocean does
not break down for thousands of years. Animals can mistake plastic material for food and choke on it.
TAKE A LOOK
3. Describe How can trash
harm the organisms that live
in the oceans?
Marine animals, such as this
bird, can choke on plastic
trash that is thrown into the
oceans.
SLUDGE DUMPING
Critical Thinking
4. Compare How is raw
sewage different from
sludge?
Raw sewage is all of the liquid and solid wastes that
are flushed down toilets and poured down drains. In most
places, raw sewage is collected and sent to a treatment
plant. The treatment removes solid waste and cleans the
raw sewage. The solid waste that remains is called sludge.
In many places, people dump sludge into the ocean.
Currents can stir up the sludge and move it closer to
shore. The sludge can pollute beaches and kill ocean life.
Many countries have banned sludge dumping. However, it
still happens in many parts of the world.
Sludge that is dumped into
the oceans can carry bacteria.
It can make beaches dirty and
harm marine organisms.
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SECTION 5
Class
Date
Ocean Pollution continued
OIL SPILLS
Most of the world uses oil as an energy source.
However, oil is only found in certain places around the
world. Therefore, large tankers must transport billions of
barrels of oil across the oceans. Sometimes, the tankers
break open and the oil spills out of them.
Oil spills can cause many problems for the environment.
Oil is poisonous to plants and animals. It is also very hard to
clean up oil spills, so their effects can last for a long time.
In 1990, the United States Congress passed the Oil
Pollution Act. This law states that all oil tankers that
travel in United States waters must have two hulls. If the
outer hull of a ship is damaged, the inner hull can keep
oil from spilling into the ocean.
READING CHECK
5. Explain Why can the
effects of an oil spill last a
long time?
Inner
hull
Outer
hull
Oil
Ocean
The Oil Pollution Act may help to prevent large oil spills.
However, as the figure below shows, big spills only cause
about 5% of the oil pollution in the ocean. Most of the oil in
the ocean comes from nonpoint-source pollution on land.
2UNOFFFROMLAND
2OUTINESHIP
MAINTENANCE
Math Focus
6. Read a Graph What are
the three largest sources of
oil pollution in the oceans?
"IGSPILLS
!IRPOLLUTION
.ATURALSEEPS
/FFSHOREDRILLING
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SECTION 5
Class
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Ocean Pollution continued
NONPOINT-SOURCE POLLUTION
READING CHECK
7. Explain How can
human activities on land
cause ocean pollution?
Nonpoint-source pollution is pollution that comes
from many sources instead of a single place. Most ocean
pollution is nonpoint-source pollution. Things that people
do on land can pollute rivers. The rivers can carry the
pollution into the oceans.
Nonpoint-source pollution is hard to control because it
enters the water in many different ways. However, there
are things that people can do to help reduce nonpointsource pollution. For example, we can throw away chemicals, such as used motor oil, properly instead of pouring
them into sewers.
Oil and gasoline can leak out
of cars and trucks and onto the
streets. Rain can wash the oil
and gasoline into rivers, which
carry them to the oceans.
Boats and other watercraft can
leak oil, gasoline, and other
chemicals into the water.
TAKE A LOOK
8. Identify Give three
examples of nonpoint-source
pollution.
People use chemicals to help
their lawns grow. Rain can wash
the chemicals into rivers, which
carry them to the oceans.
How Can We Protect Our Ocean Resources?
People have begun to take steps to save and protect
our ocean resources. From international treaties to volunteer cleanups, efforts to conserve and protect ocean
resources are making a difference around the world.
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SECTION 5
Date
Ocean Pollution continued
NATIONS TAKE NOTICE
In the 1970s and 1980s, ocean pollution was very bad.
Many countries realized that they would need to work
together to reduce ocean pollution. In 1989, 64 countries
signed a treaty that bans the dumping of many harmful
materials into the ocean.
Many other treaties and laws have also been passed
to help protect the oceans. For example, Congress
passed the Clean Water Act in 1972. This law gave the
Environmental Protection Agency more control over the
trash that is dumped into the ocean.
Another law, the U.S. Marine Protection, Research,
and Sanctuaries Act, was also passed in 1972. This law
forbids people from dumping harmful materials into the
oceans. These laws have helped to reduce the pollution
entering the oceans. However, waste dumping and oil
spills still happen.
Critical Thinking
9. Infer Why do countries
need to work together to
reduce ocean pollution?
CITIZENS TAKE CHARGE
Citizens of many different countries have demanded that
their governments do more to prevent ocean pollution. They
have also begun to take the matter into their own hands.
For example, people began to organize beach cleanups.
Millions of tons of trash have been gathered from beaches.
Also, people are helping to spread the word about the problems with dumping wastes into the oceans.
READING CHECK
10. Explain How can
individual people help to
reduce ocean pollution?
During a beach cleanup, many people work together to
remove trash from a beach. This helps make the beach safer
for people, other animals, and plants.
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Section 5 Review
SECTION VOCABULARY
nonpoint-source pollution pollution that
comes from many sources rather than from a
single, specific site
point-source pollution pollution that comes
from a specific site
1. Compare How is point-source pollution different from nonpoint-source pollution?
2. Describe Fill in the table below to describe different sources of ocean pollution.
Type of Pollution
Description
Trash dumping
Oil spills
Chemical leaks
3. Infer Most of the trash in the United States is buried instead of being dumped
into the oceans. However, there is still trash in the oceans. Why is this?
4. Identify What type of pollution is most ocean pollution?
5. Describe Why is nonpoint-source pollution hard to control?
6. List Give two United States laws that protect ocean resources.
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Earth Science Answer Key continued
SECTION 5 OCEAN POLLUTION
2. northeast
3. Winds push water across the ocean’s surface
1. Possible answer: Nonpoint-source pollution
2.
3.
4.
5.
6.
7.
8.
9.
10.
is pollution that comes from many different
sources.
People dump it there.
Organisms can eat the trash and choke or
get sick. The trash can make it hard for
them to find food.
Raw sewage includes all liquid and solid
wastes that are flushed down drains. Sludge
is the solid waste left over after raw sewage
has been treated.
Oil is hard to clean up thoroughly.
runoff, ship maintenance, air pollution
Human activities can pollute rivers, which
carry pollution to the oceans.
oil leaks, watercraft, lawn chemicals
The oceans move material all across Earth’s
surface. Therefore, unless all countries
agree to protect the oceans, pollution will
still be found throughout Earth’s oceans.
cleaning up trash, asking for governmental
regulations
4.
5.
6.
7.
8.
9.
10.
Review
1. the wind
2. density differences
3. winds, continents, and the Coriolis effect
4. Temperature can decrease. Salinity can
increase through freezing. Salinity can
increase through evaporation.
5. Possible answers: Earth’s rotation; as the
Earth rotates, water near the equator moves
faster than water near the poles, and the difference in speed causes the Coriolis effect.
6. Cold, salty water is more dense. Cold water
is more dense than warm water. Salty water
is more dense than less salty water.
7. Answers may vary but should show that
students understand that winds and the
Coriolis effect also influence surface current
patterns. Possible answer: Surface currents
would flow along curved paths because the
Coriolis effect and global winds would cause
them to move in different directions.
Review
1. Point-source pollution can be traced to a
single source, but nonpoint-source pollution
cannot be.
2.
Type of pollution
Description
Trash dumping
People dump garbage into the
oceans.
Oil spills
Tankers carrying oil break open
and spill the oil into the ocean.
Chemical leaks
Boats and other watercraft leak
chemicals into the ocean.
as they blow.
It would probably keep flowing west instead
of turning.
Earth’s rotation causes surface currents to
follow curved paths.
northeast
Equatorial Countercurrent
Deep currents are found far below the surface and are not controlled by winds.
Salt does not become part of the ice. The
salinity of the remaining water increases,
causing the water to become denser.
The water at the poles is colder and is more
saline due to the formation of ice.
3. There are many countries that still dump
trash into the oceans. Also, not all of the
trash in the United States is buried, and
some of it still ends up in the oceans.
4. nonpoint-source pollution
5. It comes into the ocean from many different
places, so it is hard to control.
6. Clean Water Act; U.S. Marine Protection,
Research, and Sanctuaries Act
SECTION 2 CURRENTS AND CLIMATE
1. The Gulf Stream brings warm water to Great
Britain. The heat from the water warms the air.
2. southeast
3. Cold water rises toward the surface.
4. Winds push surface water away from shore.
Chapter 14 The Movement
of Ocean Water
Cold water rises to replace the surface water.
5.
SECTION 1 CURRENTS
Name
When does it happen?
El Niño
when surface-water temperatures
along the west coast of South America
rise
La Niña
when surface-water temperatures in
the eastern Pacific drop
1. A surface current is a mass of water that
flows along or near the surface of the ocean.
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Earth Science