Page 737 - Environment: The Science Behind the Stories

water moves along the surface and colder, salt- toxicity The degree of harm a chemical sub- in the new urbanism style are arrayed around
ier water (which is denser) moves deep beneath stance can inflict. stops on a major rail transit line.
the surface.
toxicology The scientific field that examines transpiration The release of water vapor by
thermosphere The atmosphere’s top layer, the effects of poisonous chemicals and other plants through their leaves.
extending upward to an altitude of 500 km agents on humans and other organisms. trawling Fishing method that entails dragging
(300 mi).
Toxic Substances Control Act A 1976 U.S. immense cone-shaped nets through the water,
thin-film solar cells Photovoltaic materials law that directs the Environmental Protec- with weights at the bottom and floats at the top
compressed into ultra-thin lightweight sheets tion Agency to monitor thousands of industrial to keep the nets open. Compare bottom-trawling.
that may be incorporated into various surfaces chemicals and gives the EPA authority to regu- treatment The portion of an experiment in
to produce photovoltaic solar power. late and ban substances found to pose exces- which a variable has been manipulated in order
Thoreau, Henry David (1817–1862) sive risk. to test its effect. Compare control.
American transcendentalist author, poet, and toxin A toxic chemical stored or manufactured treaty See convention.
philosopher. His book Walden, recording his in the tissues of living organisms. For example,
observations and thoughts while he lived at a chemical that plants use to ward off herbi- tributary A smaller river that flows into a
Walden Pond away from the bustle of urban vores or that insects use to deter predators. larger one.
Massachusetts, remains a classic of American triple bottom line An approach to sustainabil-
literature. trade winds Prevailing winds between the ity that attempts to meet environmental, eco-
equator and 30° latitude that blow from east
Three Mile Island Nuclear power plant in to west. nomic, and social goals simultaneously.
Pennsylvania that in 1979 experienced a par- traditional agriculture Biologically powered trophic cascade A series of changes in the pop-
tial meltdown. The term is often used to denote ulation sizes of organisms at different trophic
the accident itself, the most serious nuclear agriculture, in which human and animal mus- levels in a food chain, occurring when preda-
cle power, along with hand tools and simple
reactor malfunction that the United States has tors at high trophic levels indirectly promote
thus far experienced. Compare Chernobyl, machines, perform the work of cultivating, har- populations of organisms at low trophic levels
vesting, storing, and distributing crops. Com-
Fukushima Daiichi. by keeping species at intermediate trophic lev-
pare industrial agriculture.
threshold dose The amount of a toxicant at els in check. Trophic cascades may become ap-
which it begins to affect a population of test tragedy of the commons The process by parent when a top predator is eliminated from
animals. Compare ED ; LD . which publicly accessible resources open to a system.
50 50 unregulated use tend to become damaged and
tidal energy Energy harnessed by erecting a depleted through overuse. Coined by Gar- trophic level Rank in the feeding hierarchy of a
dam across the outlet of a tidal basin. Water rett Hardin and widely applicable to resource food chain. Organisms at higher trophic levels
flowing with the incoming or outgoing tide issues. consume those at lower trophic levels.
through sluices in the dam turns turbines to tropical deciduous forest See tropical dry
generate electricity. transboundary park A reserve of protected forest.
land that overlaps national borders.
tide The periodic rise and fall of the ocean’s tropical dry forest A biome that consists of
height at a given location, caused by the gravi- transcendentalism A philosophical move- deciduous trees and occurs at tropical and sub-
tational pull of the moon and sun. ment that flourished in the United States in tropical latitudes where wet and dry seasons
the 1840s. Transcendentalist writers such as
topography The study of the shape and ar- Henry David Thoreau, Ralph Waldo Emerson, each span about half the year. Widespread in
rangement of landforms. Compare bathymetry. and Walt Whitman viewed nature as a mani- India, Africa, South America, and northern
topsoil That portion of the soil that is most nu- festation of the divine, championed a spiritual Australia. Also known as tropical deciduous
forest.
tritive for plants and is thus of the most direct approach to life, and critiqued society’s focus
importance to ecosystems and to agriculture. on material goods. tropical rainforest A biome characterized
Also known as the A horizon. transform plate boundary The area where by year-round rain and uniformly warm tem-
tornado A type of cyclonic storm in which fun- two tectonic plates meet and slip and grind peratures. Found in Central America, South
America, Southeast Asia, west Africa, and
nel clouds pick up soil and objects, threatening alongside one another, creating earthquakes.
life and great damage to property. For example, the Pacific Plate and the North other tropical regions. Tropical rainforests
American Plate rub against each other along have dark, damp interiors; lush vegetation; and
tort law A system of law addressing harm highly diverse biotic communities.
caused by one entity to another, which oper- California’s San Andreas Fault. Compare con-
vergent plate boundary and divergent plate
ates primarily through lawsuits. tropopause The boundary between the tropo-
boundary. sphere and the stratosphere. Acts like a cap,
total fertility rate (TFR) The average number transgene A gene that has been extracted from limiting mixing between these atmospheric
of children born per female member of a popu- layers.
lation during her lifetime. the DNA of one organism and transferred into
the DNA of an organism of another species. troposphere The bottommost layer of the at-
toxic air pollutant Air pollutant that is mosphere; it extends to 11 km (7 mi) above
known to cause cancer, reproductive defects, transgenic Term describing an organism that sea level.
or neurological, developmental, immune sys- contains DNA from another species.
tem, or respiratory problems in humans, and/ transitional stage The second stage of the de- tropospheric ozone Ozone that occurs in the
or to cause substantial ecological harm by af- mographic transition model, which occurs dur- troposphere, where it is a secondary pollutant
fecting the health of nonhuman animals and ing the transition from the pre-industrial stage created by the interaction of sunlight, heat, ni-
plants. The Clean Air Act of 1990 identifies to the industrial stage. It is characterized by trogen oxides, and volatile carbon-containing
188 toxic air pollutants, ranging from the declining death rates but continued high birth chemicals. A major component of smog, it can
heavy metal mercury to volatile organic com- rates. See also post-industrial stage. Compare injure living tissues and cause respiratory prob-
pounds (VOCs) such as benzene and methyl- industrial stage, post-industrial stage, pre- lems. An EPA criteria pollutant.
ene chloride. industrial stage. true cost accounting See full cost accounting.
toxicant A substance that acts as a poison to transit-oriented development A develop- tsunami An immense swell, or wave, of ocean
G-22 humans or wildlife. ment approach in which compact communities water triggered by an earthquake, volcano, or

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