Environmental Problems, Their Causes, and Sustainability 1

and with atoms of one or more other elementssuch as hydrogen, oxygen, nitrogen,sulfur, phosphorus, chlorine, and fluorine.All other compounds are called inorganiccompounds.organic farming Producing crops andlivestock naturally by using organic fertilizer(manure, legumes, compost) and naturalpest control (bugs that eat harmfulbugs, plants that repel bugs, and environmentalcontrols such as crop rotation)instead of using commercial inorganic fertilizersand synthetic pesticides and herbicides.See sustainable agriculture.organic fertilizer Organic material suchas animal manure, green manure, and compost,applied to cropland as a source ofplant nutrients. Compare commercial inorganicfertilizer.organism Any form of life.other resources Identified and undiscoveredresources not classified as reserves.Compare identified resources, reserves, undiscoveredresources.output Matter, energy, or informationleaving a system. Compare input,throughput.output pollution control See pollutioncleanup.overburden Layer of soil and rock overlyinga mineral deposit. Surface miningremoves this layer.overfishing Harvesting so many fish of aspecies, especially immature fish, that notenough breeding stock is left to replenishthe species and it becomes unprofitable toharvest them.overgrazing Destruction of vegetationwhen too many grazing animals feed toolong and exceed the carrying capacity of arangeland or pasture area.overnutrition Diet so high in calories,saturated (animal) fats, salt, sugar, andprocessed foods and so low in vegetablesand fruits that the consumer runs high risksof diabetes, hypertension, heart disease, andother health hazards. Compare malnutrition,undernutrition.oxygen-demanding wastes Organic materialsthat are usually biodegraded by aerobic(oxygen-consuming) bacteria if there isenough dissolved oxygen in the water. Seealso biological oxygen demand.ozone depletion Decrease in concentrationof ozone (O 3 ) in the stratosphere. Seeozone layer.ozone layer Layer of gaseous ozone (O 3 )in the stratosphere that protects life on earthby filtering out most harmful ultravioletradiation from the sun.PANs Peroxyacyl nitrates. Group of chemicalsfound in photochemical smog.parasite Consumer organism that lives onor in and feeds on a living plant or animal,known as the host, over an extended periodof time. The parasite draws nourishmentfrom and gradually weakens its host; it mayor may not kill the host. See parasitism.parasitism Interaction between species inwhich one organism, called the parasite,preys on another organism, called the host,by living on or in the host. See host, parasite.parts per billion (ppb) Number of partsof a chemical found in 1 billion parts of aparticular gas, liquid, or solid.parts per million (ppm) Number of partsof a chemical found in 1 million parts of aparticular gas, liquid, or solid.parts per trillion (ppt) Number of parts ofa chemical found in 1 trillion parts of a particulargas, liquid, or solid.passive solar heating system System thatcaptures sunlight directly within a structureand converts it into low-temperature heatfor space heating or for heating water fordomestic use without the use of mechanicaldevices. Compare active solar heating system.pasture Managed grassland or enclosedmeadow that usually is planted withdomesticated grasses or other forage to begrazed by livestock. Compare feedlot, rangeland.pathogen Organism that produces disease.PCBs See polychlorinated biphenyls.per capita GDP Annual gross domesticproduct (GDP) of a country divided by itstotal population at midyear. It gives theaverage slice of the economic pie per person.Used to be called per capita GNP. Seegross domestic product.percolation Passage of a liquid throughthe spaces of a porous material such as soil.perennial Plant that can live for morethan 2 years. Compare annual.permafrost Perennially frozen layer of thesoil that forms when the water there freezes.It is found in arctic tundra.permeability The degree to which undergroundrock and soil pores are interconnectedand thus a measure of the degree towhich water can flow freely from one poreto another. Compare porosity.perpetual resource An essentially inexhaustibleresource on a human time scale.Solar energy is an example. Compare nonrenewableresource, renewable resource.persistence How long a pollutant stays inthe air, water, soil, or body. See also inertia.persistent pollutant See slowly degradablepollutant.pest Unwanted organism that directly orindirectly interferes with human activities.pesticide Any chemical designed to kill orinhibit the growth of an organism that peopleconsider undesirable. See fungicide, herbicide,insecticide.petrochemicals Chemicals obtained byrefining (distilling) crude oil. They are usedas raw materials in manufacturing mostindustrial chemicals, fertilizers, pesticides,plastics, synthetic fibers, paints, medicines,and many other products.petroleum See crude oil.pH Numeric value that indicates the relativeacidity or alkalinity of a substance on ascale of 0 to 14, with the neutral point at 7.Acid solutions have pH values lower than7, and basic or alkaline solutions have pHvalues greater than 7.phosphorus cycle Cyclic movement ofphosphorus in different chemical formsfrom the environment to organisms andthen back to the environment.photochemical smog Complex mixture ofair pollutants produced in the lower atmosphereby the reaction of hydrocarbons andnitrogen oxides under the influence of sunlight.Especially harmful componentsinclude ozone, peroxyacyl nitrates (PANs),and various aldehydes. Compare industrialsmog.photosynthesis Complex process thattakes place in cells of green plants. Radiantenergy from the sun is used to combine carbondioxide (CO 2 ) and water (H 2 O) to produceoxygen (O 2 ) and carbohydrates (suchas glucose, C 6 H 12 O 6 ) and other nutrientmolecules. Compare aerobic respiration,chemosynthesis.photovoltaic cell (solar cell) Device thatconverts radiant (solar) energy directly intoelectrical energy.physical change Process that alters one ormore physical properties of an element or acompound without altering its chemicalcomposition. Examples are changing the sizeand shape of a sample of matter (crushingice and cutting aluminum foil) and changinga sample of matter from one physical state toanother (boiling and freezing water). Comparechemical change, nuclear change.physical resources See manufacturedresources.phytoplankton Small, drifting plants,mostly algae and bacteria, found in aquaticecosystems. Compare plankton, zooplankton.pioneer community First integrated set ofplants, animals, and decomposers found inan area undergoing primary ecological succession.See immature community, maturecommunity.pioneer species First hardy species, oftenmicrobes, mosses, and lichens, that begincolonizing a site as the first stage of ecologicalsuccession. See ecological succession, pioneercommunity.plaintiff The individual, group of individuals,corporation, or government agencybringing the charges in a lawsuit. Comparedefendant.planetary management worldviewBeliefs that (1) we are the planet’s mostimportant species; (2) we will not run out ofresources because of our ingenuity in developingand finding new ones; (3) the potentialfor economic growth is essentially limitless;and (4) our success depends on howwell we can understand, control, and managethe earth’s life-support systems mostlyfor our own benefit. See spaceship-earthworldview. Compare environmental wisdomworldview, frontier worldview, stewardshipworldview.GLOSSARYG13