Pollution is the introduction of harmful materials into the environment. These harmful materials are called pollutants. Pollutants can be natural, such as volcanic ash. They can also be created by human activity, such as trash or runoff produced by factories. Pollutants damage the quality of air, water, and land.

Many things that are useful to people produce pollution. Cars spew pollutants from their exhaust pipes. Burning coal to create electricity pollutes the air. Industries and homes generate garbage and sewage that can pollute the land and water. Pesticides—chemical poisons used to kill weeds and insects—seep into waterways and harm wildlife.

All living things—from one-celled microbes to blue whales—depend on Earth’s supply of air and water. When these resources are polluted, all forms of life are threatened.

Pollution is a global problem. Although urban areas are usually more polluted than the countryside, pollution can spread to remote places where no people live. For example, pesticides and other chemicals have been found in the Antarctic ice sheet. In the middle of the northern Pacific Ocean, a huge collection of microscopic plastic particles forms what is known as the Great Pacific Garbage Patch.

Air and water currents carry pollution. Ocean currents and migrating fish carry marine pollutants far and wide. Winds can pick up radioactive material accidentally released from a nuclear reactor and scatter it around the world. Smoke from a factory in one country drifts into another country.

In the past, visitors to Big Bend National Park in the U.S. state of Texas could see 290 kilometers (180 miles) across the vast landscape. Now, coal-burning power plants in Texas and the neighboring state of Chihuahua, Mexico have spewed so much pollution into the air that visitors to Big Bend can sometimes see only 50 kilometers (30 miles).

The three major types of pollution are air pollution, water pollution, and land pollution.

Air Pollution


Sometimes, air pollution is visible. A person can see dark smoke pour from the exhaust pipes of large trucks or factories, for example. More often, however, air pollution is invisible.

Polluted air can be dangerous, even if the pollutants are invisible. It can make people’s eyes burn and make them have difficulty breathing. It can also increase the risk of lung cancer.

Sometimes, air pollution kills quickly. In 1984, an accident at a pesticide plant in Bhopal, India, released a deadly gas into the air. At least 8,000 people died within days. Hundreds of thousands more were permanently injured.

Natural disasters can also cause air pollution to increase quickly. When volcanoes erupt, they eject volcanic ash and gases into the atmosphere. Volcanic ash can discolor the sky for months. After the eruption of the Indonesian volcano of Krakatoa in 1883, ash darkened the sky around the world. The dimmer sky caused fewer crops to be harvested as far away as Europe and North America. For years, meteorologists tracked what was known as the “equatorial smoke stream.” In fact, this smoke stream was a jet stream, a wind high in Earth’s atmosphere that Krakatoa’s air pollution made visible.

Volcanic gases, such as sulfur dioxide, can kill nearby residents and make the soil infertile for years. Mount Vesuvius, a volcano in Italy, famously erupted in 79, killing hundreds of residents of the nearby towns of Pompeii and Herculaneum. Most victims of Vesuvius were not killed by lava or landslides caused by the eruption. They were choked, or asphyxiated, by deadly volcanic gases.

In 1986, a toxic cloud developed over Lake Nyos, Cameroon. Lake Nyos sits in the crater of a volcano. Though the volcano did not erupt, it did eject volcanic gases into the lake. The heated gases passed through the water of the lake and collected as a cloud that descended the slopes of the volcano and into nearby valleys. As the toxic cloud moved across the landscape, it killed birds and other organisms in their natural habitat. This air pollution also killed thousands of cattle and as many as 1,700 people.

Most air pollution is not natural, however. It comes from burning fossil fuels—coal, oil, and natural gas. When gasoline is burned to power cars and trucks, it produces carbon monoxide, a colorless, odorless gas. The gas is harmful in high concentrations, or amounts. City traffic produces highly concentrated carbon monoxide.

Cars and factories produce other common pollutants, including nitrogen oxide, sulfur dioxide, and hydrocarbons. These chemicals react with sunlight to produce smog, a thick fog or haze of air pollution. The smog is so thick in Linfen, China, that people can seldom see the sun. Smog can be brown or grayish blue, depending on which pollutants are in it.

Smog makes breathing difficult, especially for children and older adults. Some cities that suffer from extreme smog issue air pollution warnings. The government of Hong Kong, for example, will warn people not to go outside or engage in strenuous physical activity (such as running or swimming) when smog is very thick.


When air pollutants such as nitrogen oxide and sulfur dioxide mix with moisture, they change into acids. They then fall back to earth as acid rain. Wind often carries acid rain far from the pollution source. Pollutants produced by factories and power plants in Spain can fall as acid rain in Norway.

Acid rain can kill all the trees in a forest. It can also devastate lakes, streams, and other waterways. When lakes become acidic, fish can’t survive. In Sweden, acid rain created thousands of “dead lakes,” where fish no longer live.

Acid rain also wears away marble and other kinds of stone. It has erased the words on gravestones and damaged many historic buildings and monuments. The Taj Mahal, in Agra, India, was once gleaming white. Years of exposure to acid rain has left it pale.

Governments have tried to prevent acid rain by limiting the amount of pollutants released into the air. In Europe and North America, they have had some success, but acid rain remains a major problem in the developing world, especially Asia.  

Greenhouse gases are another source of air pollution. Greenhouse gases such as carbon dioxide and methane occur naturally in the atmosphere. In fact, they are necessary for life on Earth. They absorb sunlight reflected from Earth, preventing it from escaping into space. By trapping heat in the atmosphere, they keep Earth warm enough for people to live. This is called the greenhouse effect.

But human activities such as burning fossil fuels and destroying forests have increased the amount of greenhouse gases in the atmosphere. This has increased the greenhouse effect, and average temperatures across the globe are rising. The decade that began in the year 2000 was the warmest on record. This increase in worldwide average temperatures, caused in part by human activity, is called global warming.

Global warming is causing ice sheets and glaciers to melt. The melting ice is causing sea levels to rise at a rate of 2 millimeters (0.09 inches) per year. The rising seas will eventually flood low-lying coastal regions. Entire nations, such as the islands of Maldives, are threatened by this climate change.

Global warming also contributes to the phenomenon of ocean acidification. Ocean acidification is the process of ocean waters absorbing more carbon dioxide from the atmosphere. Fewer organisms can survive in warmer, less salty waters. The ocean food web is threatened as plants and animals such as coral fail to adapt to more acidic oceans.

Scientists have predicted that global warming will cause an increase in severe storms. It will also cause more droughts in some regions and more flooding in others.

The change in average temperatures is already shrinking some habitats, the regions where plants and animals naturally live. Polar bears hunt seals from sea ice in the Arctic. The melting ice is forcing polar bears to travel farther to find food, and their numbers are shrinking.

People and governments can respond quickly and effectively to reduce air pollution. Chemicals called chlorofluorocarbons (CFCs) are a dangerous form of air pollution that governments worked to reduce in the 1980s and 1990s. CFCs are found in gases that cool refrigerators, in foam products, and in aerosol cans.

CFCs damage the ozone layer, a region in Earth’s upper atmosphere. The ozone layer protects Earth by absorbing much of the sun’s harmful ultraviolet radiation. When people are exposed to more ultraviolet radiation, they are more likely to develop skin cancer, eye diseases, and other illnesses.

In the 1980s, scientists noticed that the ozone layer over Antarctica was thinning. This is often called the “ozone hole.” No one lives permanently in Antarctica. But Australia, the home of more than 22 million people, lies at the edge of the hole. In the 1990s, the Australian government began an effort to warn people of the dangers of too much sun. Many countries, including the United States, now severely limit the production of CFCs.

Water Pollution

Some polluted water looks muddy, smells bad, and has garbage floating in it. Some polluted water looks clean, but is filled with harmful chemicals you can’t see or smell.

Polluted water is unsafe for drinking and swimming. Some people who drink polluted water are exposed to hazardous chemicals that may make them sick years later. Others consume bacteria and other tiny aquatic organisms that cause disease. The United Nations estimates that 4,000 children die every day from drinking dirty water.

Sometimes, polluted water harms people indirectly. They get sick because the fish that live in polluted water are unsafe to eat. They have too many pollutants in their flesh.

There are some natural sources of water pollution. Oil and natural gas, for example, can leak into oceans and lakes from natural underground sources. These sites are called petroleum seeps. The world’s largest petroleum seep is the Coal Oil Point Seep, off the coast of the U.S. state of California. The Coal Oil Point Seep releases so much oil that tar balls wash up on nearby beaches. Tar balls are small, sticky pieces of pollution that eventually decompose in the ocean.


Human activity also contributes to water pollution. Chemicals and oils from factories are sometimes dumped or seep into waterways. These chemicals are called runoff. Chemicals in runoff can create a toxic environment for aquatic life. Runoff can also help create a fertile environment for cyanobacteria, also called blue-green algae. Cyanobacteria reproduce rapidly, creating a harmful algal bloom (HAB). Harmful algal blooms prevent organisms such as plants and fish from living in the ocean. They are associated with “dead zones” in the world’s lakes and rivers, places where little life exists below surface water.

Mining and drilling can also contribute to water pollution. Acid mine drainage (AMD) is a major contributor to pollution of rivers and streams near coal mines. Acid helps miners remove coal from the surrounding rocks. The acid is washed into streams and rivers, where it reacts with rocks and sand. It releases chemical sulfur from the rocks and sand, creating a river rich in sulfuric acid. Sulfuric acid is toxic to plants, fish, and other aquatic organisms. Sulfuric acid is also toxic to people, making rivers polluted by AMD dangerous sources of water for drinking and hygiene.

Oil spills are another source of water pollution. In April 2010, the Deepwater Horizon oil rig exploded in the Gulf of Mexico, causing oil to gush from the ocean floor. In the following months, hundreds of millions of gallons of oil spewed into the gulf waters. The spill produced large plumes of oil under the sea and an oil slick on the surface as large as 24,000 square kilometers (9,100 square miles). The oil slick coated wetlands in the U.S. states of Louisiana and Mississippi, killing marsh plants and aquatic organisms such as crabs and fish. Birds, such as pelicans, became coated in oil and were unable to fly or access food. More than 2 million animals died as a result of the Deepwater Horizon oil spill.

Buried chemical waste can also pollute water supplies. For many years, people disposed of chemical wastes carelessly, not realizing its dangers. In the 1970s, people living in the Love Canal area in Niagara Falls, New York, suffered from extremely high rates of cancer and birth defects. It was discovered that a chemical waste dump had poisoned the area’s water. In 1978, 800 families living in Love Canal had to abandon their homes.

If not disposed of properly, radioactive waste from nuclear power plants can escape into the environment. Radioactive waste can harm living things and pollute the water.

Sewage that has not been properly treated is a common source of water pollution. Many cities around the world have poor sewage systems and sewage treatment plants. Delhi, the capital of India, is home to more than 21 million people. More than half the sewage and other waste produced in the city are dumped into the Yamuna River. This pollution makes the river dangerous to use as a source of water for drinking or hygiene. It also reduces the river’s fishery, resulting in less food for the local community.

A major source of water pollution is fertilizer used in agriculture. Fertilizer is material added to soil to make plants grow larger and faster. Fertilizers usually contain large amounts of the elements nitrogen and phosphorus, which help plants grow. Rainwater washes fertilizer into streams and lakes. There, the nitrogen and phosphorus cause cyanobacteria to form harmful algal blooms.

Rain washes other pollutants into streams and lakes. It picks up animal waste from cattle ranches. Cars drip oil onto the street, and rain carries it into storm drains, which lead to waterways such as rivers and seas. Rain sometimes washes chemical pesticides off of plants and into streams. Pesticides can also seep into groundwater, the water beneath the surface of the Earth.

Heat can pollute water. Power plants, for example, produce a huge amount of heat. Power plants are often located on rivers so they can use the water as a coolant. Cool water circulates through the plant, absorbing heat. The heated water is then returned to the river. Aquatic creatures are sensitive to changes in temperature. Some fish, for example, can only live in cold water. Warmer river temperatures prevent fish eggs from hatching. Warmer river water also contributes to harmful algal blooms.

Another type of water pollution is simple garbage. The Citarum River in Indonesia, for example, has so much garbage floating in it that you cannot see the water. Floating trash makes the river difficult to fish in. Aquatic animals such as fish and turtles mistake trash, such as plastic bags, for food. Plastic bags and twine can kill many ocean creatures. Chemical pollutants in trash can also pollute the water, making it toxic for fish and people who use the river as a source of drinking water. The fish that are caught in a polluted river often have high levels of chemical toxins in their flesh. People absorb these toxins as they eat the fish.

Garbage also fouls the ocean. Many plastic bottles and other pieces of trash are thrown overboard from boats. The wind blows trash out to sea. Ocean currents carry plastics and other floating trash to certain places on the globe, where it cannot escape. The largest of these areas, called the Great Pacific Garbage Patch, is in a remote part of the Pacific Ocean. According to some estimates, this garbage patch is the size of Texas. The trash is a threat to fish and seabirds, which mistake the plastic for food. Many of the plastics are covered with chemical pollutants.

Land Pollution


Many of the same pollutants that foul the water also harm the land. Mining sometimes leaves the soil contaminated with dangerous chemicals.

Pesticides and fertilizers from agricultural fields are blown by the wind. They can harm plants, animals, and sometimes people. Some fruits and vegetables absorb the pesticides that help them grow. When people consume the fruits and vegetables, the pesticides enter their bodies. Some pesticides can cause cancer and other diseases.


A pesticide called DDT (dichlorodiphenyltrichloroethane) was once commonly used to kill insects, especially mosquitoes. In many parts of the world, mosquitoes carry a disease called malaria, which kills a million people every year. Swiss chemist Paul Hermann Muller was awarded the Nobel Prize for his understanding of how DDT can control insects and other pests. DDT is responsible for reducing malaria in places such as Taiwan and Sri Lanka.

In 1962, American biologist Rachel Carson wrote a book called Silent Spring, which discussed the dangers of DDT. She argued that it could contribute to cancer in humans. She also explained how it was destroying bird eggs, which caused the number of bald eagles, brown pelicans, and ospreys to drop. In 1972, the United States banned the use of DDT. Many other countries also banned it. But DDT didn’t disappear entirely. Today, many governments support the use of DDT because it remains the most effective way to combat malaria.

Trash is another form of land pollution. Around the world, paper, cans, glass jars, plastic products, and junked cars and appliances mar the landscape. Litter makes it difficult for plants and other producers in the food web to create nutrients. Animals can die if they mistakenly eat plastic.

Garbage often contains dangerous pollutants such as oils, chemicals, and ink. These pollutants can leech into the soil and harm plants, animals, and people.

Inefficient garbage collection systems contribute to land pollution. Often, the garbage is picked up and brought to a dump, or landfill. Garbage is buried in landfills. Sometimes, communities produce so much garbage that their landfills are filling up. They are running out of places to dump their trash.

A massive landfill near Quezon City, Philippines, was the site of a land pollution tragedy in 2000. Hundreds of people lived on the slopes of the Quezon City landfill. These people made their living from recycling and selling items found in the landfill. However, the landfill was not secure. Heavy rains caused a trash landslide, killing 218 people.

Sometimes, landfills are not completely sealed off from the land around them. Pollutants from the landfill leak into the earth in which they are buried. Plants that grow in the earth may be contaminated, and the herbivores that eat the plants also become contaminated. So do the predators that consume the herbivores. This process, where a chemical builds up in each level of the food web, is called bioaccumulation.

Pollutants leaked from landfills also leak into local groundwater supplies. There, the aquatic food web (from microscopic algae to fish to predators such as sharks or eagles) can suffer from bioaccumulation of toxic chemicals.

Some communities do not have adequate garbage collection systems, and trash lines the side of roads. In other places, garbage washes up on beaches. Kamilo Beach, in the U.S. state of Hawaii, is littered with plastic bags and bottles carried in by the tide. The trash is dangerous to ocean life and reduces economic activity in the area. Tourism is Hawaii’s largest industry. Polluted beaches discourage tourists from investing in the area’s hotels, restaurants, and recreational activities.

Some cities incinerate, or burn, their garbage. Incinerating trash gets rid of it, but it can release dangerous heavy metals and chemicals into the air. So while trash incinerators can help with the problem of land pollution, they sometimes add to the problem of air pollution.

Reducing Pollution


Around the world, people and governments are making efforts to combat pollution. Recycling, for instance, is becoming more common. In recycling, trash is processed so its useful materials can be used again. Glass, aluminum cans, and many types of plastic can be melted and reused. Paper can be broken down and turned into new paper.

Recycling reduces the amount of garbage that ends up in landfills, incinerators, and waterways. Austria and Switzerland have the highest recycling rates. These nations recycle between 50 and 60 percent of their garbage. The United States recycles about 30 percent of its garbage.

Governments can combat pollution by passing laws that limit the amount and types of chemicals factories and agribusinesses are allowed to use. The smoke from coal-burning power plants can be filtered. People and businesses that illegally dump pollutants into the land, water, and air can be fined for millions of dollars. Some government programs, such as the Superfund program in the United States, can force polluters to clean up the sites they polluted.

International agreements can also reduce pollution. The Kyoto Protocol, a United Nations agreement to limit the emission of greenhouse gases, has been signed by 191 countries. The United States, the world’s second-largest producer of greenhouse gases, did not sign the agreement. Other countries, such as China, the world’s largest producer of greenhouse gases, have not met their goals.  

Still, many gains have been made. In 1969, the Cuyahoga River, in the U.S. state of Ohio, was so clogged with oil and trash that it caught on fire. The fire helped spur the Clean Water Act of 1972. This law limited what pollutants could be released into water and set standards for how clean water should be. Today, the Cuyahoga River is much cleaner. Fish have returned to regions of the river where they once could not survive.

But even as some rivers are becoming cleaner, others are becoming more polluted. As countries around the world become wealthier, some forms of pollution increase. Countries with growing economies usually need more power plants, which produce more pollutants.

Reducing pollution requires environmental, political, and economic leadership. Developed nations must work to reduce and recycle their materials, while developing nations must work to strengthen their economies without destroying the environment. Developed and developing countries must work together toward the common goal of protecting the environment for future use.

pollution
Garbage in, garbage out.

Light Pollution
Light pollution is the excess amount of light in the night sky. Light pollution, also called photopollution, is almost always found in urban areas. Light pollution can disrupt ecosystems by confusing the distinction between night and day. Nocturnal animals, those that are active at night, may venture out during the day, while diurnal animals, which are active during daylight hours, may remain active well into the night. Feeding and sleep patterns may be confused. Light pollution also indicates an excess use of energy.

The dark-sky movement is a campaign by people to reduce light pollution. This would reduce energy use, allow ecosystems to function more normally, and allow scientists and stargazers to observe the atmosphere.

Noise Pollution
Noise pollution is the constant presence of loud, disruptive noises in an area. Usually, noise pollution is caused by construction or nearby transportation facilities, such as airports.

Noise pollution is unpleasant, and can be dangerous. Some songbirds, such as robins, are unable to communicate or find food in the presence of heavy noise pollution. The sound waves produced by some noise pollutants can disrupt the sonar used by marine animals to communicate or locate food.

How Long Does It Last?
Different materials decompose at different rates. How long does it take for these common types of trash to break down?

  • Paper: 2-4 weeks
  • Orange peel: 6 months
  • Milk carton: 5 years
  • Plastic bag: 15 years
  • Tin can: 100 years
  • Plastic bottle: 450 years
  • Glass bottle: 500 years
  • Styrofoam: Never

Indoor Air Pollution
The air inside your house can be polluted. Air and carpet cleaners, insect sprays, and cigarettes are all sources of indoor air pollution.

absorb
Verb

to soak up.

acid
Noun

chemical compound that reacts with a base to form a salt. Acids can corrode some natural materials. Acids have pH levels lower than 7.

acid mine drainage
Noun

flow of acid or acidic liquid from metal mines or coal mines.

acid rain
Noun

precipitation with high levels of nitric and sulfuric acids. Acid rain can be manmade or occur naturally.

adapt
Verb

to adjust to new surroundings or a new situation.

adequate
Adjective

suitable or good enough.

aerosol can
Noun

container of liquid material under high pressure. When released through a small opening, the liquid becomes a spray or foam.

agribusiness
Noun

the strategy of applying profit-making practices to the operation of farms and ranches.

Noun

the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).

Noun

harmful chemicals in the atmosphere.

algae
Plural Noun

(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.

aluminum
Noun

silvery, reflective metallic element with the symbol Al.

Antarctic
Noun

region at Earth's extreme south, encompassed by the Antarctic Circle.

aquatic
Adjective

having to do with water.

asphyxiate
Verb

to choke or suffocate.

Noun

layers of gases surrounding a planet or other celestial body.

Plural Noun

(singular: bacterium) single-celled organisms found in every ecosystem on Earth.

ban
Verb

to prohibit, or not allow.

Noun

narrow strip of land that lies along a body of water.

bioaccumulation
Noun

process by which chemicals are absorbed by an organism, either from exposure to a substance with the chemical or by consumption of food containing the chemical.

biologist
Noun

scientist who studies living organisms.

birth defect
Noun

physical disorder present at birth and not developed later.

blue-green algae
Noun

type of aquatic bacteria (not algae) that can photosynthesize light to create energy. Also called cyanobacteria and (in freshwater habitats) pond scum.

cancer
Noun

growth of abnormal cells in the body.

Noun

city where a region's government is located.

carbon dioxide
Noun

greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.

carbon monoxide
Noun

colorless, odorless, and tasteless gas that is slightly less dense than air. It can be toxic to humans.

cattle
Noun

cows and oxen.

chlorofluorocarbon (CFC)
Noun

chemical compound mostly used in refrigerants and flame-retardants. Some CFCs have destructive effects on the ozone layer.

circulate
Verb

to move around, often in a pattern.

Clean Water Act
Noun

(1972) federal law protecting water from pollution.

Noun

gradual changes in all the interconnected weather elements on our planet.

Noun

visible mass of tiny water droplets or ice crystals in Earth's atmosphere.

coal
Noun

dark, solid fossil fuel mined from the earth.

Coal Oil Point
Noun

place in the Pacific Ocean off the coast of the U.S. state of California that naturally emits gases such as methane; a seep field.

Noun

edge of land along the sea or other large body of water.

combat
Verb

to fight.

concentration
Noun

measure of the amount of a substance or grouping in a specific place.

consume
Verb

to use up.

contaminate
Verb

to poison or make hazardous.

coolant
Noun

substance, usually a liquid or gas, that reduces the temperature of a system or piece of machinery.

Noun

tiny ocean animal, some of which secrete calcium carbonate to form reefs.

Noun

bowl-shaped depression formed by a volcanic eruption or impact of a meteorite.

Noun

agricultural produce.

Noun

steady, predictable flow of fluid within a larger body of that fluid.

cyanobacteria
Noun

type of aquatic bacteria that can photosynthesize light to create energy. Also called blue-green algae (even though it is not algae) and (in freshwater habitats) pond scum.

DDT
Noun

(dichloro-diphenyl-trichloroethane) toxic chemical used as an insecticide but illegal for most uses in the U.S. since 1972.

dead lake
Noun

body of water where fish or other aquatic organisms no longer live beneath the surface due to natural or manmade pollution.

Noun

area of low oxygen in a body of water.

decade
Noun

10 years.

decompose
Verb

to decay or break down.

Deepwater Horizon
Noun

oil rig in the Gulf of Mexico that exploded in 2010.

descend
Verb

to go from a higher to a lower place.

devastate
Verb

to destroy.

developing world
Noun

nations with low per-capita income, little infrastructure, and a small middle class.

discourage
Verb

to disapprove or encourage someone not to do something.

dispose
Verb

to throw away or get rid of.

drab
Adjective

dull or boring.

drill
Verb

to make a hole using a rotating digging tool.

Noun

period of greatly reduced precipitation.

Noun

our planet, the third from the Sun. The Earth is the only place in the known universe that supports life.

economic
Adjective

having to do with money.

eject
Verb

to get rid of or throw out.

electricity
Noun

set of physical phenomena associated with the presence and flow of electric charge.

environment
Noun

conditions that surround and influence an organism or community.

erupt
Verb

to explode or suddenly eject material.

exhaust
Noun

gases and particles expelled from an engine.

expel
Verb

to eject or force out.

factory
Noun

one or more buildings used for the manufacture of a product.

fertilizer
Noun

nutrient-rich chemical substance (natural or manmade) applied to soil to encourage plant growth.

fine
Verb

to punish, usually by charging an economic penalty or fee. Or, the penalty or fee itself.

fishery
Noun

industry or occupation of harvesting fish, either in the wild or through aquaculture.

Noun

overflow of a body of water onto land.

Noun

clouds at ground level.

Noun

material, usually of plant or animal origin, that living organisms use to obtain nutrients.

Noun

all related food chains in an ecosystem. Also called a food cycle.

forest
Noun

ecosystem filled with trees and underbrush.

fossil fuel
Noun

coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.

gasoline
Noun

liquid mixture made from oil and used to run many motor vehicles.

generate
Verb

to create or begin.

Noun

mass of ice that moves slowly over land.

gleam
Verb

to shine brightly.

Noun

increase in the average temperature of the Earth's air and oceans.

government
Noun

system or order of a nation, state, or other political unit.

gravestone
Noun

stone marking a person's burial place, often engraved with the person's name and dates of birth and death.

Noun

area of the North Pacific Ocean where currents have trapped huge amounts of debris, mostly plastics.

Noun

phenomenon where gases allow sunlight to enter Earth's atmosphere but make it difficult for heat to escape.

greenhouse gas
Noun

gas in the atmosphere, such as carbon dioxide, methane, water vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere.

Noun

water found in an aquifer.

Noun

environment where an organism lives throughout the year or for shorter periods of time.

harmful
Adjective

damaging.

harmful algal bloom (HAB)
Noun

rapid growth of algae, bacteria, or other plankton that can threaten an aquatic environment by reducing the amount of oxygen in the water, blocking sunlight, or releasing toxic chemicals.

harvest
Noun

the gathering and collection of crops, including both plants and animals.

hazard
Noun

danger or risk.

haze
Noun

group of solid and liquid particles in the air that makes it difficult to see.

heavy metal
Noun

chemical substance with a specific gravity of at least 5.0.

Noun

organism that eats mainly plants and other producers.

hydrocarbon
Noun

chemical compound made entirely of the elements hydrogen and carbon.

hygiene
Noun

science and methods of keeping clean and healthy.

Noun

thick layer of glacial ice that covers a large area of land.

incinerate
Verb

to burn up entirely.

industry
Noun

activity that produces goods and services.

inefficient
Adjective

not able to perform a task well.

infertile
Adjective

unproductive or barren.

ink
Noun

dark liquid used for printing or artwork.

invest
Verb

to contribute time or money.

invisible
Adjective

unable to be seen.

Noun

body of land surrounded by water.

issue
Verb

to distribute, give away, or sell.

Noun

winds speeding through the upper atmosphere.

Krakatoa
Noun

island in Indonesia, site of major volcanic eruption in 1883. Also called Krakatau.

Kyoto Protocol
Noun

(1997) international agreement to reduce greenhouse gas emissions.

Noun

body of water surrounded by land.

landfill
Noun

site where garbage is layered with dirt and other absorbing material to prevent contamination of the surrounding land or water.

land pollution
Noun

introduction of harmful materials into the surface environment.

Noun

the geographic features of a region.

Noun

the fall of rocks, soil, and other materials from a mountain, hill, or slope.

lava
Noun

molten rock, or magma, that erupts from volcanoes or fissures in the Earth's surface.

law
Noun

public rule.

leech
Noun

carnivorous or bloodsucking worm.

Love Canal
Noun

New York town and the site of a former toxic waste dump.

lung
Noun

organ in an animal that is necessary for breathing.

malaria
Noun

infectious disease caused by a parasite carried by mosquitoes.

mar
Verb

to spoil or damage.

marble
Noun

type of metamorphic rock.

marine
Adjective

having to do with the ocean.

Noun

wetland area usually covered by a shallow layer of seawater or freshwater.

massive
Adjective

very large or heavy.

meteorologist
Noun

person who studies patterns and changes in Earth's atmosphere.

methane
Noun

chemical compound that is the basic ingredient of natural gas.

microbe
Noun

tiny organism, usually a bacterium.

microscopic
Adjective

very small.

mine
Verb

to extract minerals from the Earth.

mining
Noun

process of extracting ore from the Earth.

monument
Noun

large structure representing an event, idea, or person.

Noun

political unit made of people who share a common territory.

natural disaster
Noun

an event occurring naturally that has large-scale effects on the environment and people, such as a volcano, earthquake, or hurricane.

Noun

type of fossil fuel made up mostly of the gas methane.

nitrogen
Noun

chemical element with the symbol N, whose gas form is 78% of the Earth's atmosphere.

nitrogen oxide
Noun

one of many chemical compounds made of different combinations of nitrogen and oxygen.

Nobel Prize
Noun

one of five awards established by the Swedish businessman Alfred Nobel in 1901. Nobel Prizes are awarded in physics, chemistry, medicine, literature, and peace.

Noun

substance an organism needs for energy, growth, and life.

ocean acidification
Noun

decrease in the ocean's pH levels, caused primarily by increased carbon dioxide. Ocean acidification threatens corals and shellfish.

oil
Noun

fossil fuel formed from the remains of marine plants and animals. Also known as petroleum or crude oil.

oil rig
Noun

complex series of machinery and systems used to drill for oil on land.

oil slick
Noun

smooth, dark coating on the surface of a body of water caused by an oil spill or leak.

oil spill
Noun

accidental release of petroleum products into a body of water, either by an oil tanker or an offshore oil rig.

ozone hole
Noun

circular pattern, usually located near the Antarctic, of thin atmospheric ozone, which absorbs harmful ultraviolet sunlight.

Noun

layer in the atmosphere containing the gas ozone, which absorbs most of the sun's ultraviolet radiation.

particle
Noun

small piece of material.

Paul Hermann Muller
Noun

(1899-1965) Swiss chemist and businessman.

pelican
Noun

large marine bird with a big bill.

permanent
Adjective

constant or lasting forever.

pesticide
Noun

natural or manufactured substance used to kill organisms that threaten agriculture or are undesirable. Pesticides can be fungicides (which kill harmful fungi), insecticides (which kill harmful insects), herbicides (which kill harmful plants), or rodenticides (which kill harmful rodents.)

Noun

fossil fuel formed from the remains of ancient organisms. Also called crude oil.

petroleum seep
Noun

place where oil or natural gas from the Earth's interior leaks to the surface naturally.

phenomenon
Noun

an unusual act or occurrence.

phosphorus
Noun

chemical element with the symbol P.

plastic
Noun

chemical material that can be easily shaped when heated to a high temperature.

plume
Noun

single, upward flow of a fluid, such as water or smoke.

poison
Noun

substance that harms health.

pollutant
Noun

chemical or other substance that harms a natural resource.

Noun

introduction of harmful materials into the environment.

power plant
Noun

industrial facility for the generation of electric energy.

predator
Noun

animal that hunts other animals for food.

Rachel Carson
Noun

(1907-1964) American biologist and author.

radioactive
Adjective

having unstable atomic nuclei and emitting subatomic particles and radiation.

Noun

liquid precipitation.

recycle
Verb

to clean or process in order to make suitable for reuse.

reduce
Verb

to lower or lessen.

Noun

any area on Earth with one or more common characteristics. Regions are the basic units of geography.

remote
Adjective

distant or far away.

resource
Noun

available supply of materials, goods, or services. Resources can be natural or human.

reuse
Verb

to use again.

rock
Noun

natural substance composed of solid mineral matter.

Noun

overflow of fluid from a farm or industrial factory.

sand
Noun

small, loose grains of disintegrated rocks.

sea ice
Noun

frozen ocean water.

Noun

base level for measuring elevations. Sea level is determined by measurements taken over a 19-year cycle.

seep
Verb

to slowly flow through a border.

seldom
Adverb

not very often.

sewage
Noun

liquid and solid waste material from homes and businesses.

sewage treatment
Noun

process of removing harmful pollutants and contaminants from water discarded by homes and businesses, so the water is safe for most uses.

Silent Spring
Noun

(1962) nonfiction book by Rachel Carson that documented the consequences of a polluted environment, especially the use of the pesticide DDT.

Noun

type of air pollution common in manufacturing areas or areas with high traffic.

smoke
Noun

gases given off by a burning substance.

soil
Noun

top layer of the Earth's surface where plants can grow.

spew
Verb

to eject or discharge violently.

stone
Noun

piece of rock.

storm
Noun

severe weather indicating a disturbed state of the atmosphere resulting from uplifted air.

storm drain
Noun

system to empty streets of excess rainwater. Storm drains flow into local creeks, rivers, or seas.

Noun

body of flowing water.

strenuous
Adjective

energetic or requiring a lot of activity.

sulfur
Noun

chemical element with the symbol S.

sulfur dioxide
Noun

greenhouse gas that can cause acid rain.

sulfuric acid
Noun

toxic chemical made of hydrogen, sulfur, and oxygen.

Superfund
Noun

federal program to clean up hazardous waste sites in the U.S. Also called the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).

survive
Verb

to live.

Taj Mahal
Noun

(1632) large, white mausoleum complex in Agra, India, built by Shah Jahan for his wife Mumtaz.

tar ball
Noun

small, sticky piece of tar emitted by a natural or manmade oil spill that floats in the ocean and often washes up on beaches.

Noun

degree of hotness or coldness measured by a thermometer with a numerical scale.

Noun

rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun.

tourism
Noun

the industry (including food, hotels, and entertainment) of traveling for pleasure.

toxic
Adjective

poisonous.

traffic
Noun

movement of many things, often vehicles, in a specific area.

tree
Noun

type of large plant with a thick trunk and branches.

twine
Noun

strong thread made from at least two strings twisted together, often made of plastic.

ultraviolet radiation
Noun

powerful light waves that are too short for humans to see, but can penetrate Earth's atmosphere. Ultraviolet is often shortened to UV.

United Nations
Noun

international organization that works for peace, security and cooperation.

Noun

developed, densely populated area where most inhabitants have nonagricultural jobs.

valley
Noun

depression in the Earth between hills.

vast
Adjective

huge and spread out.

visible
Adjective

able to be seen.

Noun

fragments of lava less than 2 millimeters across.

volcanic gas
Noun

gas such as water vapor or carbon dioxide that is released into the atmosphere by a volcano.

Noun

an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.

water pollution
Noun

introduction of harmful materials into a body of water.

waterway
Noun

body of water that serves as a route for transportation.

Noun

area of land covered by shallow water or saturated by water.

wildlife
Noun

organisms living in a natural environment.

wind
Noun

movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.