| A | B |
|---|
| Abiotic | Pertaining to the non-living factors in an ecosystem |
| Acid deposition | Refers to any kind of release of acid precipitation, over a particular area |
| Acid precipitaion | Condensed of frozen water vapor that includes acid rain, acid fog and acid snow |
| Activated sludge | Refers to a material, typically found in waste water treatment process, made up of a mass of living bacterial organisms feeding on waste material that has settled |
| Adaption | An ecological or evolutionary adjustment to environmental changes, that may produce physical or structural changes in an organism, allowing it to cope better with the new conditions |
| Adiabatic cooling | Cooling that occurs when warm air rises and bumps into lower atmospheric pressure |
| Aeration | Occurs in both soil and in the water. In soil it refers to the exchange of oxygen and carbon |
| Aerobic respiration | Pertains to organisms that require oxygen during the break down of organic molecules, the end result is carbon dioxide and water |
| Aersols | Any small liquid or solid particle coming from land or water surfaces that are carried into the atmosphere |
| Aesthetics | Refers to the natural beauty of something |
| Agenda 21 | A program designed to promote sustainable developement |
| Age structure diagrams | Represents the proportions of people of different age groups |
| Algae | Photosynthetic microphytic plants that live and reproduce entirely in aquatic environments Planktonic forms, may be single or colonial |
| Algal bloom | A rapid development of plantonic algae, causing water clarity to decrease |
| Alkaline | Refers to a chemical that has a pH above 7.0. Alkalines absorb hydrogen ions and or release hydroxyl ions. |
| alternative energy | energy sources that do not require fossil fuels |
| ambient standards | air quality standards ststing that the outside average air should always maintain a certain level of purity |
| ammonification | a process in the nitrogen cycle cycle where soil bacteria convert organic wastes to ammonia |
| anaerobe | without oxygen |
| aquaculture | aquatic farming and usually refers to an artifical system |
| aquifer | an underground layer of porous rock, sand, or other material where water moves between layers of nonporous rock and clay |
| aquifer | major water supply tapped into by sinking wells hundreds of feet below the ground |
| asbestos fibers | crystals of asbestos, that form minute strands-known to cause cancer |
| assimilation | a process in living systems where nutrients are converted into organic molecules |
