Glossary
Glossary of Terms
- Acid Rock Drainage (ARD)
- The formation of sulfuric acid due to the natural oxidation of sulfide minerals assisted by naturally occurring bacteria that is in excess of the natural capacity of the rock material to neutralize the acid. The produced acid may liberate metallic contaminants and, if assisted by infiltrating precipitation or other sources of water, transport the acid and contaminants to the surrounding environment.
- Acid-Base Account (ABA)
- A screening test for potential ARD that relies on a comparison between the theoretical amount of sulfuric acid that could be produced from the sulfur contained in the rock and the amount of acid neutralization available in the rock.
- Acre-Foot or Acre-Feet (acre-ft)
- The volume of water that covers an area of one acre to a depth of one foot (43,560 cubic feet or 325,851 gallons).
- Affected Environment
- The resource values potentially affected by the Proposed Action and alternatives analyzed in a NEPA document.
- AGFD
- Arizona Game and Fish Department
- Allotment
- See “Grazing Allotment.”
- Ambient Air
- The portion of the atmosphere, external to buildings, to which the public has general access (40 CFR 50).
- Ambient Concentration
- The mass of a pollutant in a given volume of air, typically measured as micrograms of pollutant per cubic meter of air.
- Ambient Standards
- The absolute maximum level of a pollutant allowed to protect either public health (primary) or welfare (secondary).
- Ammonium Nitrate–Fuel Oil (ANFO)
- Primary blasting agent used in open pit mining; a mixture of solid ammonium nitrate and liquid fuel oil.
- Animal Unit Month (AUM)
- Amount of forage required to sustain a cow/calf unit (one cow and one calf) or equivalent for one month.
- Aquifer
- A water-bearing layer of permeable rock, sand, or gravel. A formation, group of formations, or part of a formation that contains sufficient saturated permeable material to conduct groundwater and yield quantities of water to wells and springs.
- AR
- Administrative record
- Attainment Area
- Geographic area identified in regulations as in compliance with National Ambient Air Quality Standards (A.R.S. 49-401.01.6).
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