Environmental Problems, Their Causes, and Sustainability 1

ionizing radiation Fast-moving alpha orbeta particles or high-energy radiation(gamma rays) emitted by radioisotopes.They have enough energy to dislodge oneor more electrons from atoms they hit,forming charged ions in tissue that can reactwith and damage living tissue. Comparenonionizing radiation.isotopes Two or more forms of a chemicalelement that have the same number of protonsbut different mass numbers becausethey have different numbers of neutrons intheir nuclei.J-shaped curve Curve with a shape similarto that of the letter J; can represent prolongedexponential growth. See exponentialgrowth.junk science Scientific results or hypothesespresented as sound science but nothaving undergone the rigors of the peerreview process. Compare frontier science,sound science.kerogen Solid, waxy mixture of hydrocarbonsfound in oil shale rock. Heatingthe rock to high temperatures causes thekerogen to vaporize. The vapor is condensed,purified, and then sent to a refineryto produce gasoline, heating oil, and otherproducts. See also oil shale, shale oil.keystone species Species that play rolesaffecting many other organisms in anecosystem. Compare indicator species, nativespecies, nonnative species.kilocalorie (kcal) Unit of energy equal to1,000 calories. See calorie.kilowatt (kW) Unit of electrical powerequal to 1,000 watts. See watt.kinetic energy Energy that matter hasbecause of its mass and speed or velocity.Compare potential energy.K-selected species Species that produce afew, often fairly large offspring but invest agreat deal of time and energy to ensure thatmost of those offspring reach reproductiveage. Compare r-selected species.K-strategists See K-selected species.kwashiorkor Type of malnutrition thatoccurs in infants and very young childrenwhen they are weaned from mother’smilk to a starchy diet low in protein. Seemarasmus.lake Large natural body of standing freshwaterformed when water from precipitation,land runoff, or groundwater flow fillsa depression in the earth created by glaciation,earth movement, volcanic activity, or agiant meteorite. See eutrophic lake,mesotrophic lake, oligotrophic lake.land degradation Occurs when natural orhuman-induced processes decrease thefuture ability of land to support crops, livestock,or wild species.landfill See sanitary landfill.land-use planning Process for decidingthe best present and future use of each parcelof land in an area.late successional plant species Mostlytrees that can tolerate shade and form afairly stable complex forest community.Compare early successional plant species, midsuccessionalplant species.latitude Distance from the equator. Comparealtitude.law of conservation of energy See firstlaw of thermodynamics.law of conservation of matter In anyphysical or chemical change, matter isneither created nor destroyed but merelychanged from one form to another; inphysical and chemical changes, existingatoms are rearranged into different spatialpatterns (physical changes) or differentcombinations (chemical changes).law of tolerance The existence, abundance,and distribution of a species in anecosystem are determined by whether thelevels of one or more physical or chemicalfactors fall within the range tolerated by thespecies. See threshold effect.LD50 See median lethal dose.LDC See developing country.leaching Process in which various chemicalsin upper layers of soil are dissolved andcarried to lower layers and, in some cases,to groundwater.less developed country (LDC) See developingcountry.life-cycle cost Initial cost plus lifetimeoperating costs of an economic good. Comparefull cost.life expectancy Average number of yearsa newborn infant can be expected to live.limiting factor Single factor that limits thegrowth, abundance, or distribution of thepopulation of a species in an ecosystem. Seelimiting factor principle.limiting factor principle Too much or toolittle of any abiotic factor can limit or preventgrowth of a population of a species inan ecosystem, even if all other factors are ator near the optimum range of tolerance forthe species.linear growth Growth in which a quantityincreases by some fixed amount duringeach unit of time. An example is growththat increases by units of two in thesequence 2, 4, 6, 8, 10, and so on. Compareexponential growth.liquefied natural gas (LNG) Natural gasconverted to liquid form by cooling to avery low temperature.liquefied petroleum gas (LPG) Mixtureof liquefied propane (C 3 H 8 ) and butane(C 4 H 10 ) gas removed from natural gas andused as a fuel.lithosphere Outer shell of the earth, composedof the crust and the rigid, outermostpart of the mantle outside the asthenosphere;material found in earth’s plates. Seecrust, mantle.loams Soils containing a mixture of clay,sand, silt, and humus. Good for growingmost crops.lobbying The process by which individualsor groups use public pressure, personalcontacts, and political action to persuadelegislators to vote or act in their favor.logistic growth Pattern in which exponentialpopulation growth occurs when thepopulation is small, and population growthdecreases steadily with time as the populationapproaches the carrying capacity. SeeS-shaped curve.low An air mass with a low pressure.Compare high.low-input agriculture See sustainableagriculture.low-quality energy Energy that is dispersedand has little ability to do usefulwork. An example is low-temperature heat.Compare high-quality energy.low-quality matter Matter that is diluteor dispersed or contains a low concentrationof a useful resource. Compare highqualitymatter.low-throughput economy Economybased on working with nature by recyclingand reusing discarded matter, preventingpollution, conserving matter and energyresources by reducing unnecessary wasteand use, not degrading renewableresources, building things that are easy torecycle, reuse, and repair, not allowing populationsize to exceed the carrying capacityof the environment, and preserving biodiversityand ecological integrity. See environmentalworldview. Compare high-throughputeconomy, matter-recycling economy.low-waste society See low-throughputeconomy.LPG See liquefied petroleum gas.macroevolution Long-term, large-scaleevolutionary changes among groups ofspecies. Compare microevolution.macronutrients Chemical elements thatorganisms need in large amounts to live,grow, or reproduce. Examples are carbon,oxygen, hydrogen, nitrogen, phosphorus,sulfur, potassium, calcium, magnesium, andiron. Compare micronutrients.magma Molten rock below the earth’ssurface.malnutrition Faulty nutrition, caused by adiet that does not supply an individual withenough protein, essential fats, vitamins,minerals, and other nutrients needed forgood health. Compare overnutrition, undernutrition.mangrove swamps Swamps found on thecoastlines in warm tropical climates. Theyare dominated by mangrove trees, any ofabout 55 species of trees and shrubs that canlive partly submerged in the salty environmentof coastal swamps.mantle Zone of the earth’s interiorbetween its core and its crust. Compare core,crust. See lithosphere.manufactured resources Manufactureditems made from natural resources andused to produce and distribute economicgoods and services bought by consumers.These include tools, machinery, equipment,factory buildings, and transportation andG10GLOSSARY