Freshwater Pollution

EQ: What are some solutions to water pollution?

Pages 114-123

Key Terms

• water pollution - the addition of any substance that has a negative effect on water or the living things that depend on the water • pollutant - the substances that cause water pollution • point source - a specific source of pollution that can be identified

Key Terms

• nonpoint source - a widely spread source of pollution that can’t be tied to a specific point of origin • pesticide - chemicals intended to kill insects and other organisms that damage crops • acid rain - rain or another form of precipitation that is more acidic than normal

What is Pollution?

Page 115 Figure 10

Point Source Pollution

• A specific source of pollution that can be identified. You can see the pollution enter into the water supply.

• Example: drainage pipe with polluted water

Nonpoint Source Pollution

• The source of pollution is not obvious. • Pollutants may be carried along in runoff from a farm field, a street, or construction site. The pollutants eventually flow into a lake or river or seep into the groundwater.

• It is hard to trace the exact source of pollution.

Effects of Pollutants

• Some pollutants, such as pesticides, can build up in the bodies of living things.

• Pesticides are chemicals intended to kill insects and other organisms that damage crops.

• Example: DDT, dissolves in water and is absorbed by microscopic algae. The algae are eaten by small water animals, then larger water animals eat the smaller water animals. The further up the food pyramid they move the more concentrated the amount of DDT.

Effects of Pollutants

• When humans eat contaminated fish, the toxic chemicals also build up in our bodies. These toxins can build up to cause birth defects or cancer.

• Bathing or swimming in polluted water can irritate the skin or cause more serious problems.

Effects of Pollutants

Human Wastes

• Three major sources of water pollution – human wastes – industrial wastes – chemical runoff • Cholera is a disease caused by bacteria that live in human wastes. It can be fatal.

• Dr. Snow, in 1854, discovered the cause of a cholera outbreak. A sewage pipe was contaminating a drinking well.

Human Wastes

• Sewage in cities – Water treatment kills most bacteria, but some viruses and parasites are able to resist the chlorine and other water treatment processes.

– Most of these organisms come from human or animal wastes that get into the water supply.

Human Wastes

• Sewage in cities – During heavy rains and floods sanitary sewers often overflow and run into storm sewers.

– The storm sewers usually run directly into surface water, sewage from the sanitary sewers can pollute the water.

– People are often told to boil their water for drinking and cooking after a flood.

– Boiling kills many of the disease-causing organisms.

Human Wastes

• Sewage in Rural areas – you must be careful where you located a septic tank • it must not be too close to a stream, or on a hill or wastewater could leak into the stream or contaminate a well downhill from the septic tank – Wastes from farm animals can also be a problem. • Runoff from the pastures and barnyards can pass disease-causing bacteria and other kinds of pollution into bodies of water.

Industrial Wastes

• Three types of industrial waste – Chemicals – Smoke and Exhaust – Heat pollution (thermal pollution)

Industrial Wastes

• Chemicals – many factory processes involve toxic chemicals and strong acids.

– Some factories still release toxic chemicals directly into nearby rivers and lakes.

– Nonpoint sources • many of the wastes from factories were buried in barrels, these barrels have rusted or broken to release the chemicals polluting the soil and water in the surrounding areas.

Industrial Wastes

• Smoke and Exhaust – Many power plants and factories burn coal or oil to fuel their processes. – Cars, trucks, and buses burn gasoline.

– Smoke and exhaust release gases into the air.

• sulfur dioxide • nitrogen • oxygen

Industrial Wastes

• Smoke and Exhaust – the sulfur and nitrogen react with water to form sulfuric and nitric acids. The result is acid rain.

– Acid rain falls on lakes and ponds and can cause the water to become so acidic that fish and wildlife cannot survive.

– Acid rain causes harm to trees and buildings.

Industrial Wastes

• Heat Pollution – many water organisms can live only in a narrow range of temperatures.

– Warm water released by a factory into a nearby river or pond raises the temperature of the water, sometimes enough to harm the organisms living there.

Chemical Runoff

• Runoff from farms – the addition of fertilizers to ponds and lakes can speed up the process of eutrophication – Runoff from irrigation also carry other pollutants from the fields. Pesticides may be sprayed and carried off to steams and ponds • some are sprayed directly on ponds to kill mosquitoes.

Chemical Runoff

• Runoff from farms – These chemicals also harm insects that are not pests.

– These chemicals also kill insect-eating animals.

Chemical Runoff

• Runoff from Roads – When it rains it carries off oily substances from the roads. These substances are caused by gasoline and motor oil that leaked on the road.

– These oily substances make it to rivers, lakes, or underground into our groundwater. – During winter we use salt to melt the ice…this also pollute our water supplies.

– When these pollutants seep underground they can pollute our wells and aquifers.

Water Pollution Solutions

• Solving pollution problems involves cleaning up existing problems as well as preventing new ones. • Cleanup – many pollutants are removed from freshwater through natural cleanup processes.

• Wetlands can clean up water pollution – they act as natural filters

Water Pollution Solutions Cleanup

• Wetlands have been built near coal mines to treat acidic mining runoff before it returns to the environment.

Water Pollution Solutions Prevention

• Many industries have found recycling techniques that conserve water and prevent pollution.

– Example: cooling pools are used to cool the machinery, then reused instead of releasing back into the river.

• This reduces heat pollution • They try to use fewer toxic materials in their processes.

Water Pollution Solutions Prevention

• Farmers are collecting runoff from pastures to reuse this water for irrigation.

– This cuts down on the pollution of our waters • fecal matter from the pastures and barnyards • Farmers plant fields of grasses that filter out pollutants before the water reaches a river or a pond.

• Disposal of toxic substances properly cuts down on the amount of water pollution.