Water PollutionChapter 11 Section 3

Water PollutionWater pollution is the introduction of chemical, physical, or biological agents into water that degrade water quality and adversely affect the organisms that depend on the water

The two biggest causes of water pollution are industrialization and human population growth

To prevent pollution, people must know from where water pollution comes

Point-Source PollutionPoint-source pollution is pollution discharged from a single source

Examples are a factory, waste water treatment plant, leaking oil tanker

Point-source pollution can often be identified and traced to a source, but enforcing cleanup can be difficult

Sources of Point Pollution• Leaking septic-tank systems

• Leaking storage lagoons for polluted waste

• Unlined landfills

• Leaking underground storage tanks that contain chemicals or fuels such as gasoline

• Polluted water from abandoned and active mines

• Water discharges by industries

• Public industrial waste water treatment plants

Nonpoint-Source PollutionNonpoint-source pollution comes

from many different sources that are often difficult to identify

Because nonpoint-source pollutants can enter bodies of water in many different ways, they are extremely difficult to regulate and control

96% of polluted bodies of water in the U.S. come from non point-sources

Controlling nonpoint-source pollution depends on public awareness of the effects of activities such as using lawn chemicals and using storm drains to dispose of used motor oil

Copy this chart!

Nonpoint-source Pollution• Chemicals added to road surfaces (salt and other

de-icing agents)

• Water runoff from city and suburban streets that may contain oil, gasoline, animal feces, and litter

• Pesticides, herbicides, and fertilizer from residential lawns, golf courses, and farmland

• Feces and agricultural chemicals from livestock feedlots

• Precipitation containing air pollutants

• Soil runoff from farms and construction sites

• Oil and gasoline from personal watercraft

WastewaterWater goes down the drain through a series of sewage pipes that carry it to a waste water treatment plant

Wastewater is water that contains waste from homes and industry

Wastewater treatment plants filter the water until it is clean enough to return to a river or lake

Wastewater Treatment ProcessFiltration: Wastewater is passed through a large screen

to remove solid objects.

First settling tank: Wastewater is sent into a large tank, where smaller particles sink to the bottom and form sewer sludge. The sludge is removed from the water.

Aeration tank: Wastewater is mixed with oxygen and bacteria. The bacteria use the oxygen and feed on the wastes.

Second settling tank: Bacteria grown in the aeration tank, as well as other solid wastes, are removed in the form of sludge.

Chlorination: chlorine is added to disinfect the water before it is released into a stream, lake, or ocean.

Treating WastewaterMost of the water used in homes contains biodegradable material that can be broken down by living organisms

Wastewater from toilets and kitchen sinks contain animal and plant waste, paper, and soap all of which re biodegradable

Wastewater treatment plants may not remove all of the harmful substances in water

Sewage SludgeOne of the products of wastewater treatment is sewage sludge, the solid material that remains after treatment

If sludge contains toxic chemicals, it must be disposed of as hazardous waste

Sludge is often incinerated and the ash buried in a landfill

The problem of sludge disposal has led many communities to look for new uses for this waste such as fertilizer or mixing with clay to make bricks

Artificial Eutrophication

Most nutrients in water come from organic matter, such as leaves, that is broken down into mineral nutrients

Nutrients are essential, but an over abundance can disrupt an ecosystem

When slow moving water contains an abundance of nutrients it is eutrophic

The natural process of eutrophication is accelerated when inorganic plant nutrients enter the water from sewage and fertilizer runoff

Eutrophication caused by humans is called artificial eutrophication

Thermal PollutionWhen the temperature of a body of water increases, thermal pollution can happen

It can occur when power plants and other industries use water in their cooling systems and then discharge the warm water into a lake or river

The warm water reduces the amount of available oxygen causing aquatic organisms to suffer

Groundwater PollutionPollutants usually enter

groundwater when polluted surface water percolates down from Earth's surface

Pesticides, herbicides, chemical fertilizers, and petroleum products are common groundwater pollutants

The U.S. has millions of underground storage tanks and leakage from those is another source of groundwater pollution

More modern underground storage tanks are encased in concrete and have features to prevent leaks

Cleaning up Groundwater Pollution

One of the most challenging environmental problems faced because even if it stopped today, it would still be polluted for generations

Reasons for this are it takes a long time for groundwater to recharge and pollution can cling to the materials that make up an aquifer

Ocean PollutionPollutants are often dumped directly into the oceans

85% of ocean pollution comes from activities on land

Sensitive coastal ecosystems, such as coral reefs, estuaries, and coastal marshes, are the most affected by pollution

Oil SpillsEach year approximately 37 million gallons of oil from tanker accidents are spilled into the oceans

Oil spills have dramatic effects, but they only account for 5% of oil pollution in the ocean. Most comes from cities and towns. 200 - 300 million gallons enter the ocean from nonpoint-sources on land

Water Pollution and EcosystemsWater pollution can cause immediate

damage to an ecosystem, and the effects can be far reaching.

Many pollutants accumulate because they do not decompose quickly.

Polluted soil settles at the bottom of a river where it is eaten by insect larvae which are eaten by fish which are eaten by birds...

This buildup of pollutants at higher levels of the food chain is called biomagnification. Biomagnification has alarming consequences for organisms at the top of the food chain. Many states limit the amount of fish that can be eaten from certain bodies of water because of biomagnification.

Cleaning Up Water PollutionIn 1969, the Cuyahoga River in

Cleveland, OH, was so polluted it caught on fire and burned for days.

This led to the passing of the Clean Water Act of 1972. It's purpose was to restore and maintain the chemical, physical, and biological integrity of the nation's waters. The goal was to make surface water clean enough for fishing and swimming by 1983.

Although the goal was not achieved, much progress was made.

Federal Laws to Improve Water Quality• 1972--Clean Water Act--surface water fit for swimming and fishing by

1983 and banned pollutant discharge into surface water after 1985. Metals are to be removes from wastewater.

• 1972--Marine Protection Research and Sanctuaries Act--empowered EPA to control the dumping of sewage wastes and toxic chemicals in U.S. waters.

• 1975--Safe Drinking Water Act--introduced programs to protect groundwater and surface water from pollution. Emphasized sound science and risk-based standards for water quality.

• 1980--Comprehensive Environmental Response Compensation and Liability Act--Superfund Act--makes owners, operators, and customers of hazardous waste sites responsible for the cleanup of the sites. This act has reduced the pollution of groundwater by toxic substances leaching from hazardous waste dumps.

• 1987--Water Quality Act--supports state and local efforts to clean polluted runoff.

• 1990--Oil Pollution Act--attempts to protect U.S. waterways from oil pollution by requiring that oil tankers in U.S. waters be double-hulled by 2015.

Copy now, answer laterExplain why point-source pollution is easier to control than nonpoint-source pollution.

List the major types of water pollutants. Suggest ways to reduce the leVels of each type of pollutant in a water supply.

Describe the unique problems of cleaning up groundwater pollution.

Describe the source of most ocean pollution. Is it point-source or nonpoint-source pollution?

Draw a diagram that shows the biomagnification of a pollutant in an ecosystem.