Page 732 - Environment: The Science Behind the Stories

ancient riverbed deposits, generally using run- repeated molecules. Important biological mol- predator An organism that hunts, captures,
ning water to separate lightweight mud and ecules, such as DNA and proteins, are examples kills, and consumes individuals of another spe-
gravel from heavier minerals of value. of polymers. cies, the prey.
plastics Synthetic (human-made) polymers pool A location in which nutrients in a biogeo- prediction A specific statement, generally
used in numerous manufactured products. chemical cycle remain for a period of time be- arising from a hypothesis, that can be tested
fore moving to another pool. Can be living or directly and unequivocally.
plate tectonics The process by which Earth’s
surface is shaped by the extremely slow move- nonliving entities. Synonymous with reservoir. prescribed (controlled) burns The practice
ment of tectonic plates, or sections of crust. Compare flux; residence time. of burning areas of forest or grassland under
Earth’s surface includes about 15 major tec- population A group of organisms of the same carefully controlled conditions to improve the
tonic plates. Their interaction gives rise to species that live in the same area. Species are health of ecosystems, return them to a more
processes that build mountains, cause earth- often composed of multiple populations. natural state, reduce fuel loads, and help pre-
quakes, and otherwise influence the landscape. vent uncontrolled catastrophic fires.
population density The number of individu-
poaching The illegal killing of wildlife, usually als within a population per unit area. Compare preservation ethic An ethic holding that we
for meat or body parts. population size. should protect the natural environment in a
point source A specific spot—such as a population distribution The spatial arrange- pristine, unaltered state. Compare conserva-
factory—where large quantities of air pollut- ment of organisms within a particular area. tion ethic.
ants or water pollutants are discharged. Com- population ecology The study of the quanti- prey An organism that is killed and consumed
pare non-point source. by a predator.
tative dynamics of population change and the
polar cell One of a pair of cells of convective factors that affect the distribution and abun- primary consumer An organism that con-
circulation between the poles and 60° north dance of members of a population. sumes producers and feeds at the second
and south latitude that influence global climate population growth rate The rate of change trophic level.
patterns. Compare Ferrel cell; Hadley cell.
in a population’s size per unit time (generally primary extraction The initial drilling and
polar stratospheric clouds High-altitude icy expressed in percent per year), taking into ac- pumping of the most easily accessible crude
clouds containing condensed nitric acid, which counts births, deaths, immigration, and emigra- oil. Compare secondary extraction.
enhance the destruction of stratospheric ozone tion. Compare rate of natural increase.
in the spring. primary forest Forest uncut by people. Com-
population size The number of individual or- pare secondary forest.
polar vortex Circular wind currents that trap air ganisms present at a given time in a population.
over Antarctica during winter, worsening ozone positive feedback loop A feedback loop in primary pollutant A hazardous substance,
depletion over the continent. such as soot or carbon monoxide, that is
which output of one type acts as input that emitted into the troposphere in a form that
policy A rule or guideline that directs individ- moves the system in the same direction. The is directly harmful. Compare secondary pol-
ual, organizational, or societal behavior. input and output drive the system further to- lutant.
pollination A plant-animal interaction in ward one extreme or another. Compare nega- primary producer See autotroph.
which one organism (for example, a bee or a tive feedback loop.
hummingbird) transfers pollen (containing post-industrial stage The fourth and final primary production The conversion of solar
male sex cells) from flower to flower, fertiliz- stage of the demographic transition model, in energy to the energy of chemical bonds in sug-
ing ovaries (containing female sex cells) that which both birth and death rates have fallen to ars during photosynthesis, performed by auto-
grow into fruits with seeds. a low level and remain stable there, and popu- trophs. Compare secondary production.
polluter-pays principle Principle specifying lations may even decline slightly. Compare in- primary succession A stereotypical series of
that the party responsible for producing pol- dustrial stage, pre-industrial stage, transition changes as an ecological community develops
lution should pay the costs of cleaning up the stage. over time, beginning with a lifeless substrate.
pollution or mitigating its impacts. potential energy Energy of position. Compare In terrestrial systems, primary succession be-
pollution The release of matter or energy into kinetic energy. gins when a bare expanse of rock, sand, or
sediment becomes newly exposed to the at-
the environment that causes undesirable im- prairie See temperate grassland. mosphere and pioneer species arrive. Compare
pacts on the health and well-being of humans precautionary principle The idea that one secondary succession.
or other organisms. Pollution can be physical,
chemical, or biological, and it can affect water, should not undertake a new action until the primary treatment A stage of wastewater
ramifications of that action are well under-
air, or soil. treatment in which contaminants are physi-
stood. cally removed. Wastewater flows into tanks in
polybrominated diphenyl ethers (PBDEs)
Synthetic compounds that provide fire-retard- precedent A legal ruling that serves as a guide which sewage solids, grit, and particulate mat-
ter settle to the bottom. Greases and oils float to
ant properties and are used in a diverse array for later cases, steering judicial decisions
of consumer products, including computers, through time. the surface and can be skimmed off. Compare
secondary treatment.
televisions, plastics, and furniture. Released precipitation Water that condenses out of the
during production, disposal, and use of prod- atmosphere and falls to Earth in droplets or principle of utility An ethical standard, elabo-
ucts, these chemicals persist and accumulate crystals. rated by British philosophers Jeremy Bentham
in living tissue and appear to be endocrine pre-industrial stage The first stage of the de- and John Stuart Mill, holding that something
disruptors. mographic transition model, characterized by is right when it produces the greatest practical
polyculture The planting of multiple crops in conditions that defined most of human history. benefits for the most people.
a mixed arrangement or in close proximity. An In pre-industrial societies, both death rates and probability A quantitative description of the GLOSS ARY
example is some traditional Native American birth rates are high. Compare industrial stage, likelihood of a certain outcome.
farming that mixed maize, beans, squash, and post-industrial stage, transitional stage. producer (autotroph) An organism that uses
peppers. Compare monoculture. predation The process in which one species energy from sunlight to produce its own food.
polymer A chemical compound or mixture (the predator) hunts, tracks, captures, and ul- Includes green plants, algae, and cyanobacte-
of compounds consisting of long chains of timately kills its prey. ria. See autotroph. G-17

Z06_WITH7428_05_SE_Gloss.indd 17 13/12/14 10:53 AM