The Earth's Critical Zone is the “heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air, and living organisms regulate the natural habitat and determine the availability of life-sustaining resources” (NRC, 2001).
The Critical Zone includes the land surface, vegetation, and water bodies, and extends through the pedosphere, unsaturated vadose zone, and saturated groundwater zone. The critical zone is the most heterogeneous portion of the Earth. An array of important physical, chemical, and biological interfacial processes and reactions occur in the critical zone over a range of spatial and temporal scales. These processes impact mass and energy exchange necessary for biomass productivity, chemical recycling, and water storage. They also control transport and cycling of contaminants including organics, metals, and radionuclides.
Read more about Earth's Critical Zone: History
Famous quotes containing the words earth, critical and/or zone:
“till seven years were gane and past,
True Thomas on earth was never seen.”
—Unknown. Thomas the Rhymer (l. 79–80)
“To take pride in a library kills it. Then, its motive power shifts over to the critical if admiring visitor, and apologies are necessary and acceptable and the fat is in the fire.”
—Carolyn Wells (1862–1942)
“In the zone of perdition where my youth went as if to complete its education, one would have said that the portents of an imminent collapse of the whole edifice of civilization had made an appointment.”
—Guy Debord (b. 1931)