Environmental Problems, Their Causes, and Sustainability 1

CFCsSee chlorofluorocarbons.chain reaction Multiple nuclear fissions,taking place within a certain mass of a fissionableisotope, that release an enormousamount of energy in a short time.chemical One of the millions of differentelements and compounds found naturallyand synthesized by humans. See compound,element.chemical change Interaction betweenchemicals in which there is a change in thechemical composition of the elements orcompounds involved. Compare nuclearchange, physical change.chemical evolution Formation of theearth and its early crust and atmosphere,evolution of the biological molecules necessaryfor life, and evolution of systems ofchemical reactions needed to produce thefirst living cells. These processes arebelieved to have occurred about 1 billionyears before biological evolution. Comparebiological evolution.chemical formula Shorthand way to showthe number of atoms (or ions) in the basicstructural unit of a compound. Examplesare H 2 O, NaCl, and C 6 H 12 O 6 .chemical reaction See chemical change.chemosynthesis Process in which certainorganisms (mostly specialized bacteria)extract inorganic compounds from theirenvironment and convert them into organicnutrient compounds without the presenceof sunlight. Compare photosynthesis.chlorinated hydrocarbon Organic compoundmade up of atoms of carbon, hydrogen,and chlorine. Examples are DDT andPCBs.chlorofluorocarbons (CFCs) Organiccompounds made up of atoms of carbon,chlorine, and fluorine. An example isFreon-12 (CCl 2 F 2 ), used as a refrigerant inrefrigerators and air conditioners and inmaking plastics such as Styrofoam. GaseousCFCs can deplete the ozone layer whenthey slowly rise into the stratosphere andtheir chlorine atoms react with ozonemolecules.chromosome Agrouping of various genesand associated proteins in plant and animalcells that carry certain types of geneticinformation. See genes.chronic undernutrition An ongoingcondition suffered by people who cannotgrow or buy enough food to meet theirbasic energy need. Compare malnutrition,overnutrition.civil suit Lawsuit in which a plaintiffseeks to collect damages for injuries or foreconomic loss or have the court issue a permanentinjunction against further wrongfulaction. Compare class action suit.class action suit Civil lawsuit in which agroup files a suit on behalf of a larger numberof citizens who allege similar damagesbut who need not be listed and representedindividually. Compare civil suit.clear-cutting Method of timber harvestingin which all trees in a forested area areremoved in a single cutting. Compare seedtreecutting, selective cutting, shelterwood cutting,strip cutting.climate Physical properties of the troposphereof an area based on analysis of itsweather records over a long period (at least30 years). The two main factors determiningan area’s climate are temperature, with itsseasonal variations, and the amount anddistribution of precipitation. Compareweather.climax community See maturecommunity.coal Solid, combustible mixture of organiccompounds with 30–98% carbon by weight,mixed with various amounts of water andsmall amounts of sulfur and nitrogen compounds.It forms in several stages as theremains of plants are subjected to heat andpressure over millions of years.coal gasification Conversion of solid coalto synthetic natural gas (SNG).coal liquefaction Conversion of solid coalto a liquid hydrocarbon fuel such as syntheticgasoline or methanol.coastal wetland Land along a coastline,extending inland from an estuary, that iscovered with salt water all or part of theyear. Examples are marshes, bays, lagoons,tidal flats, and mangrove swamps. Compareinland wetland.coastal zone Warm, nutrient-rich, shallowpart of the ocean that extends from thehigh-tide mark on land to the edge of ashelflike extension of continental landmasses known as the continental shelf.Compare open sea.coevolution Evolution in which two ormore species interact and exert selectivepressures on each other that can lead eachspecies to undergo various adaptations. Seeevolution, natural selection.cogeneration Production of two usefulforms of energy, such as high-temperatureheat or steam and electricity, from the samefuel source.cold front Leading edge of an advancingmass of cold air. Compare warm front.commensalism An interaction betweenorganisms of different species in which onetype of organism benefits and the other typeis neither helped nor harmed to any greatdegree. Compare mutualism.commercial extinction Depletion of thepopulation of a wild species used as aresource to a level at which it is no longerprofitable to harvest the species.commercial inorganic fertilizer Commerciallyprepared mixture of plant nutrientssuch as nitrates, phosphates, andpotassium applied to the soil to restore fertilityand increase crop yields. Compareorganic fertilizer.common law Body of unwritten rules andprinciples derived from thousands of pastlegal decisions. It is based on evaluation ofwhat is reasonable behavior in attemptingto balance competing social interests. Comparestatutory law.common-property resource Resourcethat people normally are free to use;each user can deplete or degrade theavailable supply. Most are renewable andowned by no one. Examples are cleanair, fish in parts of the ocean not underthe control of a coastal country, migratorybirds, gases of the lower atmosphere,and the ozone content of the upper atmosphere(stratosphere). See tragedy of thecommons.community Populations of all speciesliving and interacting in an area at aparticular time.competition Two or more individualorganisms of a single species (intraspecificcompetition) or two or more individuals ofdifferent species (interspecific competition)attempting to use the same scarce resourcesin the same ecosystem.competitive exclusion principle Notwo species can occupy exactly the samefundamental niche indefinitely in a habitatwhere there is not enough of a particularresource to meet the needs of both species.See ecological niche, fundamental niche, realizedniche.complexity In ecological terms, refers tothe number of species in a community ateach trophic level and the number oftrophic levels in a community.compost Partially decomposed organicplant and animal matter used as a soil conditioneror fertilizer.compound Combination of atoms, oroppositely charged ions, of two or moredifferent elements held together by attractiveforces called chemical bonds. Compareelement.concentration Amount of a chemical in aparticular volume or weight of air, water,soil, or other medium.condensation nuclei Tiny particleson which droplets of water vapor cancollect.coniferous evergreen plants Conebearingplants (such as spruces, pines,and firs) that keep some of their narrow,pointed leaves (needles) all year. Comparebroadleaf deciduous plants, broadleaf evergreenplants.coniferous trees Cone-bearing trees,mostly evergreens, that have needle-shapedor scalelike leaves. They produce woodknown commercially as softwood. Comparedeciduous plants.consensus science See sound science.conservation Sensible and carefuluse of natural resources by humans.People with this view are called conservationists.conservation biologist Biologist whoinvestigates human impacts on thediversity of life found on the earth(biodiversity) and develops practical plansfor preserving such biodiversity. Compareconservationist, ecologist, environmentalist,environmental scientist, preservationist,restorationist.GLOSSARYG3