Glossary - Environmental Science - page 335

Superfund sites Polluted sites that are specified to be part of the federal government's program to clean up
hazardous waste.
surface mining A type of mining that removes the soil and rock surface over a large amount of land.
surface water Water that collects on the Earth's surface, usually in the form of streams, rivers, lakes, and
oceans.
survivorship curve A graph that represents the number of individuals surviving at each age for a given spe-
cies. The y -axis shows the number of individuals and the x -axis reflects time or age. There are Type I, Type II,
and Type III survivorship curves.
sustainability The nondepletion of resources, usually referring to human use that allows resources to regener-
ate at a pace commensurate with use.
sympatric speciation A type of speciation that occurs when a population of organisms evolves to use a loca-
tion's resources in different ways, eventually becoming so distinct that they lose the ability to interbreed.
synfuel Synthetic, liquefied fuel obtained from nonpetroleum sources such as coal, natural gas, oil shale, and
biomass; synthetic fuel derived from waste, such as plastic or rubber.
taiga A forest biome composed primarily of coniferous trees (pines), located south of the Arctic tundra in
North America, Europe, and Asia; also called the boreal.
tar sands A combination of sand, clay, water, and bituminous sands; also known as oil sands.
tectonic plates The seven major plates and many smaller plates, all in constant motion, that make up the crust
of the Earth; also called lithospheric plates.
teratogen A substance that affects embryo development or harms or kills the fetus.
terracing A farming technique used on steep slopes of a mountainous terrain. Often looking like steps, terra-
cing is used to minimize erosion and retain water in areas otherwise unable to be used for crops.
thermal energy Heat energy from the vibration and movement of atoms and molecules within substances.
thermopause The boundary between the thermosphere and the exosphere.
thermosphere The fourth and deepest layer of the Earth's atmosphere, above the mesosphere and below the
exosphere.
threshold dose The minimum amount or concentration of a substance that affects an organism or population.
timber plantations Typically, monocultures of fast growth species of trees planted by timber companies in or-
der to maximize an area's economic benefit.
toxin Poisonous or toxic substance.
traditional agriculture Agriculture that uses human power, animal power, and simple tools.
transform plate boundaries Areas where tectonic plates slide past one another.
transgenic A term used to describe an organism that has genetic material artificially transferred from another
organism.