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T
tailings - (4) (a) the ground rock waste product from a
mill or process plant, (b) the materials remaining after
the economically valuable elements are removed from the ore. To
remove the valuable elements, blasted rock typically goes through
several steps of crushing and extraction or washing. The tailings
usually leave the mill as a slurry of sand- or silt-sized particles
in water. Tailings are commonly stored in a surface impoundment
but can also be placed subaqueously in natural water bodies or backfilled
into underground workings.
tailings impoundment/tailings pond- (4) a tailings disposal
area or pond in which tailings are confined by the natural topography
or by one or more engineered dikes or dams.
take - (3) as defined by the Endangered Species Act, "
to harass, harm, pursue, hunt, shoot, wound, kill, capture, or collect,
or attempt to to engage in any such conduct".
taxa - (3) a group of organisms sharing common characteristics
in varying degrees of distinction and constituting one of the categories
of the taxonomic classification, such as phylum, order, family,
genus or species.
terrestrial species - (3) ground-dwelling plants and animals
thiobacillus ferrooxidans - (4) a naturally occuring bacteria
that can derive energy from the oxidation of sulfide to sulfate
and ferrous to ferric iron. Thought to accelerate the oxidation
of sulfides.
threatened (endangered) species - (3) any plant or animal
species likely to become endangered within the forseeable future
throughout all or part of its range and designated by the U.S. fish
and Wildlife Service under the Endangered Species Act.
titration - (4) determining the amount of one substance
by adding standardized increments of another. Often with an indicator
to identify the endpoint.
total dissolved solids (TDS) - (3) salt - an aggregate of
carbonates, bicarbonates, chlorides, sulfates, and nitrates of calcium,
magnesium, manganese, sodium, potassium, and other cations that
form salts. High TDS solutions can change the chemical nature of
water, exert varying degrees of osmotic pressure, and often become
lethal to aquatic life.
trace metals - (3) metals that are present in small concentrations
transpiration - (3) the photosynthetic and physiological
process by which water in plants is transported as water vapor into
the atmosphere. (4) process by which plants release water vapor
to the atmosphere. See also evapotranspiration.
trophic level - (3) the level in the nutritive series of
an ecosystem in which a group of organisms in a certain stage in
the food chain secures food in the same general manner. The first
or lower trophic level consists of producers (green plants), the
second level consists of herbivores, the third level consists of
secondary carnivores, and the fourth level consists of reducers
(decomposers).
troy ounce - (3) unit of measure based on troy weight (12
ounces to 1 pound) and equal to 1.09714 avoirdupois ounces. (An
avoirdupois ounce is the conventional U.S. weight measure in which
16 ounces equal 1 pound).
tundra - (3) treeless arctic and alpine areas where cover
may consist of bare ground, grasses, sedges, forbes, dwarf shrubs,
mosses, or lichens.
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