water pollution

sewage and other waste

An example of point-source pollution is the release of pollution into a body of water through a pipe from a factory or sewage treatment plant. Waste water from a factory might contain dangerous chemicals such as strong acids, mercury, or lead. Water from a sewage treatment plant might contain untreated or partially treated sewage. Such pollution can make water dangerous for drinking or other uses. You can learn more about the problem of sewage contaminating the water in U.S. coastal communities by watching this video: MEDIA Click image to the left or use the URL below. URL: In poor nations, many people have no choice but to drink water from polluted sources. Drinking sewage-contaminated water causes waterborne diseases, due to pathogens such as protozoa, viruses, or bacteria. Most waterborne diseases cause diarrhea.

thermal pollution

If heated water is released into a body of water, it may cause thermal pollution. Thermal pollution is a reduction in the quality of water because of an increase in water temperature. A common cause of thermal pollution is the use of water as a coolant by power plants and factories. This water is heated and then returned to the natural environment at a higher temperature. Warm water cant hold as much dissolved oxygen as cool water, so an increase in the temperature of water decreases the amount of oxygen it contains. Fish and other organisms adapted to a particular temperature range and oxygen concentration may be killed by the change in water temperature.

dead zones

Eventually, the algae in an algal bloom die and decompose. Their decomposition uses up oxygen in the water so that the water becomes hypoxic (without oxygen). This has occurred in many bodies of fresh water and large areas of the ocean, creating dead zones. Dead zones are areas where the hypoxic water cant support life. A very large dead zone exists in the Gulf of Mexico (see Figure 25.6). Nutrients carried into the Gulf by the Mississippi River caused this dead zone. Cutting down on the use of chemical fertilizers is one way to prevent dead zones in bodies of water. Preserving wetlands is also important. Wetlands are habitats such as swamps, marshes, and bogs where the ground is soggy or covered with water much of the year. Wetlands slow down and filter runoff before it reaches bodies of water. Wetlands also provide breeding grounds for many different species of organisms.

textbook_image

pointsource pollution

Unlike runoff, which enters bodies of water everywhere, some sources of pollution enter the water at a single point. This type of water pollution is called point-source pollution.

ocean acidification

Ocean water normally dissolves some of the carbon dioxide in the atmosphere. The burning of fossil fuels has increased the amount of carbon dioxide in the atmosphere. As a result, ocean water is also dissolving more carbon dioxide. When carbon dioxide dissolves in water, it forms a weak acid. With higher levels of dissolved carbon dioxide in ocean water, the water becomes more acidic. This process is called ocean acidification. Ocean acidification can kill some aquatic organisms, including corals and shellfish. It may make it more difficult for other aquatic organisms to reproduce. Both effects of acidification interfere with marine food webs, threatening the survival of many aquatic organisms.

ocean pollution

The ocean is huge but even this body of water is becoming seriously polluted. Climate change also affects the quality of ocean water for living things.

plastic waste

One way that the ocean is becoming polluted is with trash, mainly plastics. The waste comes from shipping accidents, landfill erosion, and the dumping of trash. Plastics may take hundreds or even thousands of years to break down. In the meantime, the waste can be very dangerous to aquatic organisms. Some organisms may swallow plastic bags, for example, and others may be strangled by plastic six-pack rings. You can see some of the trash that routinely washes up on coastlines in Figure 25.7. There are five massive garbage patches floating on the Pacific Ocean. Watch this video to learn more about them: . MEDIA Click image to the left or use the URL below. URL:

textbook_image

algal blooms

When fertilizer ends up in bodies of water, the added nutrients cause excessive growth of algae. This is called an algal bloom. You can see one in Figure 25.5. The algae out-compete other water organisms. They may make the water unfit for human consumption or recreation.

textbook_image

algal blooms and dead zones

Water pollution has many causes. One of the biggest causes is fertilizer in runoff. Runoff dissolves fertilizer as it flows over farm fields, lawns, and golf courses. It carries the dissolved fertilizer into bodies of water. More dissolved fertilizer may enter a body of water at the mouth of a river, but there is generally no single point where this type of pollution enters the water. Thats why this type of water pollution is called nonpoint-source pollution.

instructional diagrams

No diagram descriptions associated with this lesson

questions

Most of Earths liquid water is in

a. lakes.

b. rivers.

c. wetlands.

-->  d. the ocean.

__problem resulting from too much dissolved carbon dioxide in ocean water

a. algal bloom

b. wetland

c. fertilizer

d. runoff

-->  e. acidification

f. dead zone

g. thermal pollution

__main way that nonpoint-source pollution enters bodies of water

a. algal bloom

b. wetland

c. fertilizer

-->  d. runoff

e. acidification

f. dead zone

g. thermal pollution

Runoff dissolves fertilizer when it flows over

a. farm fields.

b. golf courses.

c. lawns and gardens.

-->  d. all of the above

The most effective way to prevent dead zones in bodies of water is to

a. add nutrients to the water.

-->  b. reduce the use of fertilizers.

c. promote the growth of algae.

d. allow algal blooms to decompose.

__main source of chemicals that cause algal blooms

a. algal bloom

b. wetland

-->  c. fertilizer

d. runoff

e. acidification

f. dead zone

g. thermal pollution

__area where water cannot support aquatic life because it is hypoxic

a. algal bloom

b. wetland

c. fertilizer

d. runoff

e. acidification

-->  f. dead zone

g. thermal pollution

Thermal pollution of water is generally caused by

a. nonpoint-source pollution.

b. home heating systems.

-->  c. power plants and factories.

d. global warming.

__reduction in water quality due to an increase in water temperature

a. algal bloom

b. wetland

c. fertilizer

d. runoff

e. acidification

f. dead zone

-->  g. thermal pollution

The dissolved oxygen content of water may be reduced by

a. thermal pollution.

b. decomposition of algae.

c. unusually cold weather.

-->  d. two of the above

__excessive growth of aquatic producers

-->  a. algal bloom

b. wetland

c. fertilizer

d. runoff

e. acidification

f. dead zone

g. thermal pollution

__habitat with moist soil, such as a swamp

a. algal bloom

-->  b. wetland

c. fertilizer

d. runoff

e. acidification

f. dead zone

g. thermal pollution

Trash that pollutes the ocean is made mainly of plastic.

-->  a. true

b. false

Ocean acidification can kill corals and some shellfish.

-->  a. true

b. false

An example of nonpoint-source pollution is the release of pollution into water through a pipe from a

a. true

-->  b. false

Symptoms of waterborne diseases usually include diarrhea.

-->  a. true

b. false

The total number of people on Earth who lack adequate clean, fresh water is about a million.

a. true

-->  b. false

What percent of Earths water is fresh, liquid water?

-->  a. 1 percent

b. 10 percent

c. 50 percent

d. 90 percent

Pollutants in Earths waters include

a. chemicals.

b. sewage.

c. heat.

-->  d. all of the above

How many people worldwide do not have enough clean, fresh water?

a. fewer than a hundred

b. about a thousand

c. about a million

-->  d. more than a billion

The main pollutant added to water by nonpoint-source pollution is

a. plastic trash.

b. pathogens.

-->  c. fertilizer.

d. none of the above

Water becomes hypoxic when algae in an algal bloom

a. undergo cellular respiration.

b. carry out photosynthesis.

c. grow and reproduce.

-->  d. die and decompose.

Why are wetlands important for the environment?

a. They filter runoff before it reaches bodies of water.

b. They provide breeding grounds for many different species.

c. They can be filled in with soil so more native plants will grow.

-->  d. two of the above

Which statement about point-source pollution is false?

a. It may enter the water from a factory.

b. It may include thermal pollution.

c. It may come from a sewage treatment plant.

-->  d. It enters a body of water in runoff.

Less than half of Earths water is in the ocean, glaciers, and ice caps.

a. true

-->  b. false

Algal blooms are due to excess nutrients polluting bodies of water.

-->  a. true

b. false

There is a very large dead zone in the Gulf of Mexico.

-->  a. true

b. false

Examples of wetlands include marshes and bogs.

-->  a. true

b. false

Waterborne diseases are caused by pathogens in drinking water.

-->  a. true

b. false

Virtually all thermal pollution of Earths water is caused by global warming.

a. true

-->  b. false

The ocean is so huge that it can never become seriously polluted.

a. true

-->  b. false

diagram questions

No diagram questions associated with this lesson