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Environmental Science Cheat Sheet by

Environmental science key terms.


The surrou­ndings or conditions in which a person, animal, or plant lives or operates.


A social movement dedicated to protecting the earth's life support systems for us and other species.
Key principles and goals of enviro­nme­ntalism include:
Pollution Prevention
Climate Action
Enviro­nmental Justice
Public Awareness and Education


The variety of life in the world or in a particular habitat or ecosystem.
It encomp­asses the diversity of species of plants, animals, fungi, and microo­rga­nisms, as well as the genetic diversity within each species and the variety of ecosystems and habitats in which they live.


Scientific study of intera­ctions among organisms and between organisms and their enviro­nment


A biological community of intera­cting organisms and their physical enviro­nment.


It refers to the living components or factors of an ecosystem.
These include all living organisms such as plants, animals, fungi, bacteria, and other microo­rga­nisms that interact with each other and with their enviro­nment.
Play essential roles in ecosystem functi­oning, including energy produc­tion, nutrient cycling, and mainta­ining ecological balance.


refers to the non-living components or factors of an ecosystem.
These are physical and chemical factors that influence the structure and function of ecosystems but do not involve living organisms.
Abiotic factors play crucial roles in shaping the enviro­nment, determ­ining the distri­bution and abundance of species, and regulating ecosystem processes.
Ex. climate, geology, soil, water, light and atmosp­here.

Biogeo­che­mical cycles

Process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another.
Pathways through which nutrients and other elements move through the biotic (living) and abiotic (non-l­iving) components of Earth's ecosys­tems.
Carbon Cycle
Nitrogen Cycle
Phosphorus Cycle
Water Cycle
Sulfur Cycle
They play critical roles in regulating nutrient availa­bility, supporting ecosystem functi­oning, and sustaining life on Earth.


Organisms that make their own food.


Part of Earth in which life exists including land, water, and air or atmosp­here.


An organism's particular role in an ecosystem, or how it makes its living.
It describes how an organism meets its needs for survival and reprod­uction, including its habitat requir­ements, resource use, behavior, and ecological relati­ons­hips.


The natural home or enviro­nment of an animal, plant, or other organism.


All the different popula­tions that live together in an area.


Organisms that rely on other organisms for energy and nutrients.
Consumers can be broadly catego­rized into different groups based on their feeding habits and position in the food chain:
Primary Consumers (Herbi­vores)
Secondary Consumers (Carni­vores)
Tertiary Consumers (apex predators)


It refers to a group of indivi­duals of the same species that live in the same geographic area and interb­reed, producing offspring.
It is one of the fundam­ental units of ecological study and is charac­terized by its size, density, distri­bution, age structure, and genetic compos­ition.


A single organism.

Decomp­osers (sapro­phytes)

Eat organisms that are already dead or the waste products of the living.
Play a vital role in breaking down dead organic matter into simpler substa­nces, such as nutrients and minerals, and returning them to the enviro­nment.
Example: bacteria, fungi, certain types of protists, and invert­ebrates such as earthw­orms, millip­edes, and beetles.


An ecosystem charac­terized by land dominated by trees.

Marine ecosystem

An ecosystem found in oceans, seas, and gulfs where the water has a salt content of at least 3.5%.

Fresh-­water ecosystem

An ecosystem that is classified as having lakes, ponds, rivers, or streams, but can include a variety of habitats.

Food chain

a linear sequence of organisms, each of which serves as a source of food or energy for the next organism in the sequence.
It represents the flow of energy and nutrients through an ecosystem.
Composed of primary producer, primary consumer, secondary consumer, tertiary consumers, quaternary consumers, and so on.
also include decomp­osers, such as bacteria and fungi, which break down dead organic matter and return nutrients to the soil, completing the nutrient cycle.

Food web

A community of organisms where there are several interr­elated food chains.
More complex and interc­onn­ected repres­ent­ation of the feeding relati­onships within an ecosystem compared to a simple linear food chain.
Multiple food chains are interc­onn­ected, showing the network of feeding relati­onships between different species.
It accounts for the fact that most organisms in an ecosystem feed on multiple species and are themselves consumed by multiple predators. This complexity reflects the diverse intera­ctions and interd­epe­nde­ncies that exist within ecosys­tems.


A process by which nutrients, partic­ularly phosphorus and nitrogen, become highly concen­trated in a body of water, leading to increased growth of organisms such as algae or cyanob­act­eria.


Release of harmful materials into the enviro­nment.


Harmful substances in the air, water, or soil.
are substances or agents that contam­inate the enviro­nment and cause adverse effects on living organisms, ecosys­tems, and the enviro­nment as a whole.

Air pollution

The contam­ination of the atmosphere by the introd­uction of pollutants from human and natural sources.

Ozone layer

Protective layer in atmosphere that shields earth from UV radiation.

Carbon monoxide

A colorless, odorless, and tasteless gas that is produced by the incomplete combustion of carbon­-co­nta­ining fuels such as gasoline, natural gas, coal, wood, and oil.
It is often referred to as the "­silent killer­" because it is difficult to detect without special equipment, and exposure to high levels of carbon monoxide can be deadly.

Carbon dioxide

A colorless, odorless gas produced by burning carbon and organic compounds and by respir­ation. It is naturally present in air (about 0.03 percent) and is absorbed by plants in photos­ynt­hesis.


Widely used, man-made chemical that destroys strato­spheric ozone and lasts a long time in the strato­sphere.


A toxic metal that is harmful to human health and the enviro­nment. It is found naturally in the earth's crust and can be released into the enviro­nment through human activities such as mining, smelting, and refining.


A form of oxygen that has three oxygen atoms in each molecule instead of the usual two.
Found both in the Earth's upper atmosphere (strat­osp­here) and at ground level (tropo­sph­ere).
Forms a protective layer known as the ozone layer, which absorbs the majority of the sun's harmful ultrav­iolet (UV) radiation.
Formed through complex chemical reactions involving sunlight, nitrogen oxides (NOx), and volatile organic compounds (VOCs) emitted from sources such as vehicle exhaust, industrial emissions, and chemical solvents.

Nitrogen dioxide (NO2)

Produced from humans by vehicle emissions, contri­butes to photoc­hemical smog and acid rain. It is also referred as brown gas.
It can also be produced by natural sources such as wildfires and lightning can also contribute to NO2 emissions.

Partic­ulate matter

A small discrete mass of solid or liquid matter that remains indivi­dually dispersed in gas or liquid emissions (usually considered to be an atmosp­heric pollut­ant).
PM10 (particles with a diameter of 10 microm­eters or less) and PM2.5 (particles with a diameter of 2.5 microm­eters or less)
It can originate from both natural and human-made sources.
Natural sources include dust, pollen, sea salt, and particles from wildfires and volcanic eruptions.
Human-made sources include emissions from vehicles, industrial processes, constr­uction activi­ties, agricu­ltural practices, and burning of fossil fuels.

Sulfur dioxide

A colorless, corrosive gas directly damaging to both plants and animals.
Sulfur dioxide is produced primarily by the combustion of sulfur­-co­nta­ining fossil fuels, such as coal and oil, in power plants and industrial facili­ties. It is also emitted during volcanic eruptions and some natural processes.
When released into the atmosp­here, sulfur dioxide can react with other compounds to form sulfuric acid (H2SO4), contri­buting to acid rain.

Volatile Organic Compounds

Abbrev­iated VOCs; compounds that contain carbon (organic) and evaporate very easily (volat­ile).
ex. benzene, formal­dehyde, toluene, and xylene, among many others.
It can be found in paints, solvents, cleaning agents, fuels, and building materials, as well as in outdoor air pollutants such as vehicle exhaust and industrial emissions.
It causes formation of ground­-level ozone and smog

Water Pollution

The contam­ination of streams, rivers, lakes, oceans, or ground­water with substances produced through human activi­ties.

Land Pollution

The contam­ination of land by both solid and hazardous waste.

Nuclear Pollution

Sometimes also referred to as radioa­ctive contam­ina­tion. It is the deposition or presence of radioa­ctive materials within solids, liquids, gases, or on surfaces.


The sponta­neous emission of radiation from a nuclear reaction. It can be alpha, beta, or gamma decay, and it has different units and modes.

Noise Pollution

Type of pollution charac­terized by unwanted or potent­ially damaging sound.

Alpha Particles

Positively charged particles with about four times the mass of a hydrogen atom
Are a type of ionizing radiation, consisting of two protons and two neutrons, essent­ially a helium nucleus. They are relatively large and heavy compared to other types of radiation, such as beta particles and gamma rays.
Alpha particles are commonly emitted during the radioa­ctive decay of certain heavy elements, such as uranium and radium.
Have low penetr­ating power and can be stopped by a sheet of paper or the outer layers of skin.

Beta Particle

A high-speed electron or positron emitted in the decay of a radioa­ctive isotope.
It can penetrate materials such as paper and skin, but they can be stopped by denser materials like aluminum or plastic.
During beta decay, a neutron in the nucleus of an atom is transf­ormed into a proton and either an electron (β-) or a positron (β+). The electron or positron is ejected from the nucleus at high speed, carrying away energy.

Gamma Rays

High-e­nergy electr­oma­gnetic waves emitted from a nucleus as it changes from an excited state to a ground energy state
Highly penetr­ating and can travel through most materials, including human tissue.
Produced by certain nuclear reactions, such as the decay of radioa­ctive isotopes, nuclear fission, or fusion processes.


The time it takes for half of the radioa­ctive atoms in a substance to decay into a different element or isotope.
For example, if you have a sample of a radioa­ctive substance with a half-life of 10 years, after 10 years, half of the radioa­ctive atoms in the sample will have decayed into a different element or isotope, and after another 10 years, half of the remaining radioa­ctive atoms will have decayed, and so on.
Different radioa­ctive elements and isotopes have different half-l­ives, ranging from fractions of a second to billions of years.


Unit that measures the rate at which a sample of radioa­ctive material decays; 1 Bq = decay of 1 atom or nucleus per second.


Energy that is radiated or transm­itted in the form of rays or waves or particles.
It is a natural phenomenon that exists throughout the universe and comes in various forms, including electr­oma­gnetic radiation (such as light, radio waves, microw­aves, X-rays, and gamma rays) and partic­ulate radiation (such as alpha particles, beta particles, and neutrons).
It can be classified into two main types based on its effect on atoms: ionizing radiation and non-io­nizing radiation.
Radiation is produced by natural sources such as the sun, cosmic rays, and radioa­ctive elements in the Earth's crust, as well as human-made sources such as X-ray machines, nuclear power plants, and nuclear weapons.

Radioa­ctive Pollution

The release of radioa­ctive substances or high-e­nergy particles into the air, water, or earth as a result of human activity.


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