an underground layer of sand or rock that contains usable water. Can be unconfined (down to the first impervious rock layer) or confined (between the first and the second layers).
reducible by bacteria as opposed to something that remains in the environment (plastic, certain industrial wastes).
a natural or artificial basement for
trapping water. One natural version catches rainfall and feeds it into a stream that drains the catchment area.
the degradation of moist land into a
desert. Some desertification is natural, but most is from erosion, climate change (global warming), or overgrazing.
a biotic community and its
surroundings, part inorganic (abiotic) and part organic (biotic), the latter including producers, consumers, and decomposers.
the path of food energy transfer from
green plants (primary producers) to grazers (primary consumers), omnivors and carnivores (secondary consumers), and to their predators (top carnivores).
heat energy from the Earth's
interior. Geysers and volcanos are naturally occuring examples.
the ongoing transformation of
water in the biosphere from ocean water evaporation to clouds, rain, groundwater and runoff, storage in organisms, etc. until its return to the oceans. The Earth holds roughly 326 cubic million miles of water, 97% of it in the oceans.
wedge of ice whose expansions and
contractions from melting and freezing open large cracks in the ground.
the flushing or percolation of chemicals,
minerals, or other substances through soil. Pesticides, fertilizers, poisons from mines or feedlots, and wastes from industrial plants sometimes leach into groundwater. Leaching also refers to washing the salt from soil to increase its fertility.