Page 734 - Environment: The Science Behind the Stories

replacement fertility The total fertility rate environmental damage, or economic loss) will sand Sediment consisting of particles 0.005–2.0
(TFR) that maintains a stable population size. result from a given action, event, or substance. mm in diameter. Compare clay; silt.
reproductive window The portion of a wom- risk assessment The quantitative measurement sanitary landfill A site at which solid waste
an’s life between sexual maturity and meno- of risk, together with the comparison of risks is buried in the ground or piled up in large
pause during which she may become pregnant. involved in different activities or substances. mounds for disposal, designed to prevent the
reserves-to-production ratio (R/P ratio) The risk management The process of considering waste from contaminating the environment.
total remaining reserves of a fossil fuel divided information from scientific risk assessment in Compare incineration.
by the annual rate of production (extraction and light of economic, social, and political needs savanna A biome characterized by grassland
processing). and values, in order to make decisions and de- interspersed with clusters of acacias and other
reservoir (1) An artificial water body behind a sign strategies to minimize risk. trees. Savanna is found across parts of Africa
dam that stores water for human use. (2) See river system A river and all its tributaries. (where it was the ancestral home of our spe-
pool. River systems drain watersheds. cies), South America, Australia, India, and
other dry tropical regions.
residence time (1) In a biogeochemical cycle, RNA See ribonucleic acid.
the amount of time a nutrient remains in a roadless rule A 2001 Clinton Administration science (1) A systematic process for learning
given pool or reservoir before moving to an- executive order that put 31% of national forest about the world and testing our understanding
other. Compare flux. (2) In the atmosphere, the land off-limits to road construction or mainte- of it. (2) The accumulated body of knowledge
amount of time a gas molecule or a pollutant nance. that arises from this dynamic process.
remains aloft. scientific method A formalized method for
rock A solid aggregation of minerals.
resilience The ability of an ecological com- testing ideas with observations that involves
munity to change in response to disturbance rock cycle The very slow process in which a more-or-less consistent series of interrelated
but later return to its original state. Compare rocks and the minerals that make them up are steps.
resistance. heated, melted, cooled, broken, and reassem- scrubber Technology to chemically treat
bled, forming igneous, sedimentary, and meta-
resistance The ability of an ecological com- morphic rocks. gases produced in combustion in order to
munity to remain stable in the presence of a reduce smokestack emissions. These devices
disturbance. Compare resilience. rotation time The number of years that pass typically remove hazardous components and
between the time a forest stand is cut for timber neutralize acidic gases, such as sulfur dioxide
Resource Conservation and Recovery Act
(RCRA) Congressional legislation (enacted and the next time it is cut. and hydrochloric acid, turning them into water
in 1976 and amended in 1984) that specifies, r–selected Term denoting a species with high and salt.
among other things, how to manage sanitary biotic potential whose members produce a secondary consumer An organism that con-
landfills to protect against environmental con- large number of offspring in a relatively short sumes primary consumers and feeds at the
tamination. time but do not care for their young after birth. third trophic level.
Populations of r–selected species are gener-
resource management Strategic decision secondary extraction The extraction of crude
making about how to extract resources, so that ally regulated by density-independent factors. oil remaining after primary extraction by using
resources are used wisely and conserved for the Compare K–selected. solvents or by flushing underground rocks with
future. runoff The water from precipitation that flows water or steam. Compare primary extraction.
into streams, rivers, lakes, and ponds, and (in
resource partitioning The process by which secondary forest Forest that has grown back
species adapt to competition by evolving to many cases) eventually to the ocean. after primary forest has been cut. Consists of
use slightly different resources, or to use their run-of-river Any of several methods used to second-growth trees.
shared resources in different ways, thus mini- generate hydroelectric power without greatly secondary pollutant A hazardous substance
mizing interference with one another. disrupting the flow of river water. Run-of-river produced through the reaction of substances
response The type or magnitude of negative ef- approaches eliminate much of the environmen- added to the atmosphere with chemicals nor-
fects an animal exhibits in response to a dose of tal impact of large dams. Compare pumped mally found in the atmosphere. Compare pri-
toxicant in a dose-response analysis. Compare storage, storage. mary pollutant.
dose.
secondary production The total biomass that
restoration ecology The study of the historical safe harbor agreement A cooperative agree- heterotrophs generate by consuming auto-
conditions of ecological communities as they ment that allows landowners to harm threat- trophs. Compare primary production.
existed before humans altered them. Principles ened or endangered species in some ways if secondary succession A stereotypical series of
of restoration ecology are applied in the prac- they voluntarily improve habitat for the species
tice of ecological restoration. in others. changes as an ecological community develops
over time, beginning when some event disrupts
revolving door The movement of powerful of- salinization The buildup of salts in surface soil or dramatically alters an existing community.
ficials between the private sector and govern- layers. Compare primary succession.
ment agencies.
salt marsh Flat land that is intermittently secondary treatment A stage of wastewater
ribonucleic acid (RNA) A usually single- flooded by the ocean where the tide reaches in- treatment in which biological means are used
stranded nucleic acid composed of four nucleo- land. Salt marshes occur along temperate coast- to remove contaminants remaining after pri-
tides, each of which contains a sugar (ribose), a lines and are thickly vegetated with grasses, mary treatment. Wastewater is stirred up in the
phosphate group, and a nitrogenous base. RNA rushes, shrubs, and other herbaceous plants. presence of aerobic bacteria, which degrade
carries the hereditary information for living or- organic pollutants in the water. The wastewa-
ganisms and is responsible for passing traits salvage logging The removal of dead trees ter then passes to another settling tank, where GLOSS ARY
from parents to offspring. Compare DNA. following a natural disturbance. Although it remaining solids drift to the bottom. Compare
may be economically beneficial, salvage log-
riparian Relating to a river or the area along ging can be ecologically destructive, because primary treatment.
a river. snags provide food and shelter for wildlife and second-growth Term describing trees that have
risk The mathematical probability that some because removing timber from recently burned sprouted and grown to partial maturity after
harmful outcome (for instance, injury, death, land can cause erosion and damage to soil. virgin timber has been cut. G-19

Z06_WITH7428_05_SE_Gloss.indd 19 13/12/14 10:53 AM