| Calorie
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| Fundamental unit of energy. The amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius. All forms of energy can be converted to heat and measured in calories. Calories used in connection with food are kilocalories, (1000 calories) the amount of heat required to raise the temperature of 1 liter of water 1 degree Celsius.
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| Cancer
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| Invasive, out-of-control cell growth that results in malignant tumors.
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| Capillary water
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| Water that clings in small pores, cracks, and spaces against the pull of gravity, like water held in a sponge.
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| Capital
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| Any form of wealth, resources, or knowledge available for use in the production of more wealth.
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| Captive breeding
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| Raising plants or animals in zoos or other controlled conditions to produce stock for subsequent release into the wild.
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| Carbohydrate
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| An organic compound consisting of a ring or chain of carbon atoms with hydrogen and oxygen attached; examples are sugars, starches, cellulose, and glycogen.
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| Carbon cycle
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| The cycling of carbon between organisms and the environment.
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| Carbon monoxide
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| A highly poisonous gas, the molecules of which consist of a carbon atom with one oxygen attached. Not to be confused with nonpoisonous carbon dioxide, a natural gas in the atmosphere.
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| Carbon monoxide (CO)
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| Colorless, odorless, nonirritating but highly toxic gas produced by incomplete combustion of fuel, incineration of biomass or solid waste, or partially anaerobic decomposition of organic material.
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| Carbon sink
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| Places of carbon accumulation, such as in large forests (organic compounds) or ocean sediments (calcium carbonate); carbon is thus removed from the carbon cycle for moderately long to very long periods of time.
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| Carbon source
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| Originating point of carbon that reenters the carbon cycle; cellular respiration and combustion.
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| Carbon tax
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| A tax levied on all fossil fuels in proportion to the amount of carbon dioxide that is released as they burn.
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| Carcinogen
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| A chemical or physical agent that causes cancer to develop, often decades after the original exposure.
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| Carcinogenic
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| Having the property of causing cancer, at least in animals and by implication in humans.
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| Carnivore
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| An animal that feeds more or less exclusively on other animals.
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| Carrying capacity
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| Maximum population size that a given ecosystem can support for an indefinite period or on a sustainable basis.
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| Cash crops
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| Crops that are sold rather than consumed or bartered.
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| Castings
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| The humus-rich pellets resulting from earthworm activity.
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| Catalyst
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| A substance that promotes a given chemical reaction without itself being consumed or changed by the reaction. Enzymes are catalysts for biological reactions. Also, catalysts are used in some pollution control devices, e.g., the catalytic converter.
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| Catalytic converter
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| The device used by U.S. automobile manufacturers to reduce the amount of carbon monoxide and hydrocarbons in the exhaust. The converter contains a catalyst that oxidizes these compounds to carbon dioxide and water as the exhaust passes through.
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| Catastrophic systems
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| Dynamic systems that jump abruptly from one seemingly steady state to another without any intermediate stages.
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| Cation
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| Any one of many kinds of positively charged ions.
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| Cell
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| The basic unit of life; the smallest unit that still maintains all the attributes of life. Many microscopic organisms consist of a single cell. Large organisms consist of trillions of specialized cells functioning together.
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| Cell respiration
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| The chemical process that occurs in all living cells wherein organic compounds are broken down to release energy required for life processes. Higher plants and animals recluire oxygen for the process as well and release carbon dioxide and water as waste products, but certain microorganisms do not require oxygen. (See anaerobic respiration.)
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| Cellular respiration
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| The process in which a cell breaks down sugar or other organic compounds to release energy used for cellular work; may be anaerobic or aerobic, depending on the availability of oxygen.
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| Cellulose
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| The organic macromolecule that is the prime constituent of plant cell walls and hence the major molecule in wood, wood products, and cotton. It is composed of glucose molecules, but because it cannot be digested by humans, its dietary value is only as fiber, bulk, or roughage.
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| Center pivot irrigation
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| An irrigation system consisting of a spray arm several hundred meters long supported by wheels pivoting around a central well from which water is pumped.
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| Centrally planned economy
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| An economic system in which a ruling class makes most of the basic decisions about how the economy will be structured; typical of communist countries.
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| CFCs
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| See chlorofluorocarbons.
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| Chain reaction
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| A self-sustaining reaction in which the fission of nuclei produces subatomic particles that cause the fission of other nuclei.
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| Channelization/Channelized
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| The straightening and deepening of stream or river channels to speed water flow and reduce flooding. A waterway so treated is said to be channelized.
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| Chaotic systems
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| Systems that exhibit variability, which may not be necessarily random, yet whose complex patterns are not discernible over a normal human timescale.
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| Chemical barrier
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| In reference to genetic pest control, a chemical aspect of the plant that makes it resist pest attack.
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| Chemical bond
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| The force that holds molecules together.
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| Chemical energy
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| The potential energy that is contained in certain chemicals; most importantly, the energy contained in organic compounds such as food and fuels, which may be released through respiration or burning.
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| Chemical technology
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| Applied to the control of agricultural pests, it refers to the use of pesticides and herbicides to control or eradicate the pests.
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| Chemosynthesis
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| Autotrophic synthesis of organic compounds by certain bacteria; uses energy from inorganic compounds.
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| Chlorinated hydrocarbons
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| Synthetic organic molecules in which one or more hydrogen atoms have been replaced by chlorine atoms. They are extremely hazardous compounds because they tend to be nonbiodegradable and therefore to bioaccumulate; many have been shown to be carcinogenic. Also called organochlorides.
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| Chlorination
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| The disinfection process of adding chlorine to drinking water or sewage water in order to kill microorganisms that may cause disease.
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| Chlorine cycle
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| In the stratosphere, a cyclical chemical process involving chlorine monoxide that breaks down ozone.
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| Chloro-fluorocarbons
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| Chemical compounds with a carbon skeleton and one or more attached chlorine and fluorine atoms. Commonly used as refrigerants, solvents, fire retardants, and blowing agents.
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| Chloro-fluorocarbons (CFCs)
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| Synthetic organic molecules that contain one or more of both chlorine and fluorine atoms, and are kno~vn to cause ozone destruction.
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| Chlorophyll
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| The green pigment in plants responsible for absorbing the light energy required for photosynthesis.
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| Chloroplasts
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| Chlorophyll-containing organelles in eukaryotic organisms; sites of photosynthesis.
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| Chromosome
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| In a living organism, one of a number of structures on which genes are arranged in a linear fashion.
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| Chronic bronchitis
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| Persistent inflammation of the bronchi due to pollutants in ambient air and tobacco smoke. Characterized by persistent cough.
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| Chronic effects
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| In general, the delayed health results of toxic agents, for example, emphysema, bronchitis, and cancer. Contrast with acute effects.
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| Chronic food shortages
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| Long-term undernutrition and malnutrition; usually caused by people’s lack of money to buy food or lack of opportunity to grow it themselves.
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| Chronic toxicity
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| Poisoning generally caused by long-term exposures to low levels of one or more toxic agents. Symptoms appear long after exposure. Examples: emphysema and cancer.
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| Circle of poisons
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| Importation of food contaminated with pesticides banned for use in this country but made here and sold abroad.
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| CITES (Convention on Trade in Endangered Species)
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| An international treaty conveying some protection to endangered and threatened species by restricting trade in those species or their products.
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| City
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| A differentiated community with a sufficient population and resource base to allow residents to specialize in arts, crafts, services, and professional occupations.
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| Classical economics
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| Modern, western economic theories of the effects of resource scarcity, monetary policy, and competition on supply and demand of goods and services in the marketplace. This is the basis for the capitalist market system.
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| Clean Air Act of 1970
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| Amended in 1977 and 1990, this is the foundation of U.S. air pollution control efforts.
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| Clean Water Act of 1972
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| The cornerstone of federal legislation addressing water pollution.
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| Clear-cut
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| Cutting every tree in a given area, regardless of species or size; an appropriate harvest method for some species; can be destructive if not carefully controlled.
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| Clearcutting
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| In forestry, cutting every tree, leaving the area completely clear.
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| Climate
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| A description of the long-term pattern of weather in a particular area.
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| Climax community
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| A relatively stable, longlasting community reached in a successional series; usually determined by climate and soil type.
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| Climax ecosystem
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| The last stage in ecological succession. An ecosystem in which populations of all organisms are in balance with each other and with existing abiotic factors.
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| Clone
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| A group of genetically identical individuals derived from the asexual propagation of a single individual.
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| Closed canopy
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| A forest where tree crowns spread over 20 percent of the ground; has the potential for commercial timber harvests.
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| Closed system
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| A system that can exchange energy, but does not exchange matter, with the surrounding environment. Example: the earth. Contrast with open system.
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| Cloud forests
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| High mountain forests where temperatures are uniformly cool and fog or mist keeps vegetation wet all the time.
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| Coal gasification
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| Production of combustible organic gases (mostly methane) by applying heat and steam to coal in an oxygen-enriched environment. Carried out in surface vessels or in situ.
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| Coal liquefaction
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| Production of synthetic oil from coal.
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| Coal washing
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| Coal technology that involves crushing coal and washing out soluble sulfur compounds with water or other solvents.
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| Coastal wetlands
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| Wet or flooded regions along coastlines, including mangrove swamps, salt marshes, bays, and lagoons. Contrast with inland wetlands.
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| Coastal Zone Management Act
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| Legislation of 1972 that gave federal money to thirty seacoast and Great Lakes states for development and restoration projects.
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| Co-composting
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| Microbial decomposition of organic materials in solid waste into useful soil additives and fertilizer; often, extra organic material in the form of sewer sludge, animal manure, leaves, and grass clippings are added to solid waste to speed the process and make the product more useful.
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| Coevolution
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| The process in which species exert selective pressure on each other and gradually evolve new features or behaviors as a result of those pressures.
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| Cofactor
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| Nonprotein components needed by enzymes in order to function; often minerals or vitamins.
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| Cogeneration
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| The joint production of useful heat and electricity. For example, furnaces may be replaced with gas turbogenerators that produce electricity while the hot exhaust still serves as a heat source. An important avenue of conservation, it effectively avoids the waste of heat that normally occurs at centralized power plants.
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| Cold front
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| A moving boundary of cooler air displacing warmer air.
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| Coliform bacterium
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| Common bacterium found in the intestinal tracts of humans and other species. Used in water quality analysis to determine the extent of fecal contamination.
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| Combined-cycle natural gas unit
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| A recent technology for generating electricity, employing both a natural gas turbine and a steam turbine that uses excess heat coming from the gas turbine.
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| Combustion/Combustion facility
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| The practice of disposing of wastes by incineration in a special facility designed to handle large amounts of waste; modern combustion facilities also capture some of the energy by generating electricity on site.
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| Command-and-control strategy
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| The basic strategy behind most air and water pollution public policy. It involves setting limits on pollutant levels and specifying control technologies that must be used to accomplish those limits.
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| Commensalism
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| A symbiotic relationship in which one member is benefited and the second is neither harmed nor benefited.
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| Common law
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| Body of rules and principles based on judicial precedent rather than legislative enactments. Founded on an innate sense of justice, good conscience, and reason. Flexible and adaptive. Contrast with statutory law.
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| Commons, common pool resources
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| Resources (usually natural ones) owned by many people in common or, as in the case of the air or the open oceans, owned by no one but open to exploitation.
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| Communal resource management systems
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| Resources managed by a community for long-term sustainability.
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| Community ecology
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| The study of interactions of all populations living in the ecosystem of a given area.
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| Compaction
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| Packing down. Soil: Packing and pressing out air spaces present in the soil. Reduces soil aeration and infiltration and thus reduces the capacity of the soil to support plants. Trash: Packing down trash to reduce the space that it requires.
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| Competitive exclusion
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| A theory that no two -populations of different species will occupy the same niche and compete for exactly the same resources in the same habitat for very long; disputed by some ecologists who see biological communities as highly individualistic and variable.
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| Competitive exclusion principle
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| The concept that when two species compete very directly for resources, one eventually excludes the other from the area.
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| Complexity (ecological)
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| The number of species at each trophic level and the number of trophic levels in a community.
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| Composting
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| Aerobic decay of organic matter to generate a humus-like substance used to supplement soil.
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| Composting toilet
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| A toilet that does not flush wastes away with water but deposits them in a chamber where they will compost. (See composting.)
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| Compound
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| Any substance (gas, liquid, or solid) that is made up of two or more different kinds of atoms bonded together. (Contrast element.)
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Comprehensive Environmental Response,
Compensation, and Liability Act of 1980
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| See Superfund.
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| Condensation
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| The collecting of molecules from the vapor state to form the liquid state, as, for example, water vapor condenses on a cold sufface and forms droplets. Opposite: evaporation.
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| Condensation nuclei
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| Tiny particles that float in the air and facilitate the condensation process.
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| Conditions
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| Abiotic factors that vary in time and space but are not used up by organisms; for example, temperature.
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| Confusion technique
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| (of pest control) Release of insect sex attractant pheromones identical to pheromones released by normal breeding females to attract males for mating. Release in large quantities confuses males as to the location of the females, thus minimizing the chances of males finding females and helping to control pest populations.
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| Conhol rods
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| Part of the core of a nuclear reactor; the rods of neutron-absorbing material that are inserted or removed as necessary to control the rate of nuclear fissioning.
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| Conifers
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| Needle-bearing trees that produce seeds in cones.
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| Conservation
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| The management of a resource in such a way as to assure that it will continue to provide maximum benefit to humans over the long run. Conservation may include various degrees of use or protection, depending on what is necessary to maintain the resource over the long run. Energy: Saving energy. It entails not only cutting back on use of heating, air conditioning, lighting, transportation, and so on but also increasing the efficiency of energy use. That is, developing and instigating means of doing the same jobs, e.g., transporting people, with less energy.
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| Conservation development
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| Consideration of landscape history, human culture, topography, and ecological values in subdivision design. Using cluster housing, zoning, covenants, and other design features, at least half of a subdivision can be preserved as open space, farmland, or natural areas.
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| Conservation of matter
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| In any chemical reaction, matter changes form; it is neither created nor destroyed.
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| Consolidated Metropolitan Statistical Area (CMSA)
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| An area with more than one million people formed by the merger of two or more population centers meeting other specified requirements of the Census Bureau.
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| Consumers
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| In an ecosystem, those organisms that derive their energy from feeding on other organisms or their products.
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| Consumption
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| The fraction of withdrawn water that is lost in transmission or that is evaporated, absorbed, chemically transformed, or otherwise made unavailable for other purposes as a result of human use.
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| Consumptive use
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| In reference to the harvest of natural resources, the harvesting of those resources in order to provide for people’s immediate needs for food, shelter, fuel, and clothing.
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| Consumptive water use
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| Use of water for such things as irrigation, where the water does not remain available for potential purification and reuse.
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| Containment building
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| Reinforced concrete building housing the nuclear reactor. Designed to contain an explosion should one occur.
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| Continental drift
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| Movement of the earth's tectonic plates on a semiliquid layer of mantle, forcing continents to shift position over hundreds of thousands of years.
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| Contour farming
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| Soil erosion control technique in which row crops (corn) are planted along the contour lines in sloping or hilly fields rather than up and down the hills.
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| Contour plowing
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| Plowing along hill contours; reduces erosion.
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| Contraceptive
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| A device or method employed by couples during sexual intercourse to prevent the conception of a child.
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| Control rods
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| Neutron-absorbing material inserted into spaces between fuel assemblies in nuclear reactors to regulate fission reaction.
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| Conurbation
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| An area with more than one million people that is formed by the merger of two or more population centers and that meets other specified requirements.
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| Convection
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| The vertical movement of air due to heating and cooling atmospheric events.
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| Convection currents
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| Rising or sinking air currents that stir the atmosphere and transport heat from one area to another. Convection currents also occur in water; see spring overturn.
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| Convention on Biological Diversity
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| The Biodiversity Treaty signed by 158 nations at the Earth Summit in Rio de Janeiro in 1992 calling for various actions and cooperative steps between nations to protect the world's’s biodiversity.
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| Conventional pollutants
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| The seven substances (sulfur dioxide, carbon monoxide, particulates, hydrocarbons, nitrogen oxides, photochemical oxidants, and lead) that make up the largest volume of air quality degradation; identified by the Clean Air Act as the most serious threat of all pollutants to human health and welfare; also called criteria pollutants.
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| Conveyor system
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| The giant pattern of oceanic currents that moves water masses from the surface to the depths and back again, producing major effects on the climate.
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| Cool deserts
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| Deserts such as the American Great Basin characterized by cold winters and sagebrush.
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| Cooling tower
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| A massive tower designed to dissipate waste heat from a power plant (or other industrial process) into the atmosphere.
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| Coral reefs
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| Prominent oceanic features composed of hard, limy skeletons produced by coral animals; usually formed along edges of shallow, submerged ocean banks or along shelves in warm, shallow, tropical seas.
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| Core
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| The dense, intensely hot mass of molten metal, mostly iron and nickel, thousands of kilometers in diameter at the earth’s center.
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| Core region
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| The primary industrial region of a country; usually located around the capital or largest port; has both the greatest population density and the greatest economic activity of the country.
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| Coriolis effect
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| The influence of friction and drag on air layers near the earth; deflects air currents to the direction of the earth’s rotation.
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| Cornucopian fallacy
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| The belief that nature is limitless in its abundance and that perpetual growth is not only possible but essential.
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| Corridor
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| A strip of natural habitat that connects two adjacent nature preserves to allow migration of organisms from one place to another.
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| Corrosion
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| In a nuclear power plant, the deterioration of pipes receiving hot pressurized water in the circulation system that conveys heat from one part of the unit to another.
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| Cosmetic spraying
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| Spraying of pesticides to control pests that damage only the surface appearance of fruits and vegetables.
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| Cosmic radiation
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| High-energy electromagnetic radiation similar to cosmic rays but originating from periodic solar flare-ups. Possesses extraordinary ability to penetrate materials, including cement walls.
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| Cost-benefit analysis
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| An analysis and/or comparison of the value benefits in contrast to the costs of any particular action or project. (also see benefit-cost analysis.)
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| Cost-effective
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| Pertaining to a project or procedure that produces economic returns or benefits that are significantly greater than the costs.
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| Covalent bond
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| A chemical bond between two atoms, formed by sharing a pair of electrons between the two atoms. Atoms of all organic compounds are joined by covalent bonds.
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| Cover crops
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| Plants, such as rye, alfalfa, or clover, that can be planted immediately after harvest to hold and protect the soil.
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| Credit associations
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| Associated with microlending. Groups of poor people with no collateral to assure loans forming an association to assure each other’s loans.
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| Criteria pollutants
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| See conventional pollutants.
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| Critical factor
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| The single environmental factor closest to a tolerance limit for a given species at a given time. See limiting factors.
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| Critical level
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| The level of one or more pollutants above which severe damage begins to occur and below which few if any ill effects are noted.
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| Critical number
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| The minimum number of individuals of a given species that is required to maintain a healthy, viable population of the species. If a population falls below its critical number, its extinction will almost certainly occur.
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| Critical thinking
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| An ability to evaluate information and opinions in a systematic, purposeful, efficient manner. Although based on logic and reason, critical thinking also brings context, empathy, history, and values to bear in understanding and interpreting arguments and positions.
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| Crop rotation
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| The practice of alternating the crops grown on a piece of land. For example, corn one year, hay for two vears, then back to corn. (Contrast monocropping)
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| Croplands
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| Lands used to grow crops.
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| Crude birth rate
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| Number of births per 1000 people in a population at the midpoint of the year.
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| Crude birthrate
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| The number of births in a year divided by the midyear population.
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| Crude death rate
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| The number of deaths per thousand persons in a given year; also called crude mortality rate.
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| Crust
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| The cool, lightweight, outermost layer of the earth’s surface that floats on the soft, pliable underlying layers; similar to the "skin" on a bowl of warm pudding.
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| Cultivar
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| A cultivated variety of a plant species. All individuals of the cultivar are genetically highly uniform.
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| Cultural control
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| A change in the practice of growing. harvesting, storing, handling, or disposing of wastes that reduces the susceptibility or exposure to pests. For example, spraying the house with insecticides to kill flies is a chemical control; putting screens on the windows to keep flies out is a cultural control.
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| Cultural eutrophication
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| An increase in biological productivity and ecosystem succession caused by human activities.
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