Acid Drainage
Any drainage water from mine workings, waste and tailings, with a low (acidic) pH or excess acidity made acidic in most cases by a chemical reaction

Acidity
A measure of the capacity of a solution to neutralize a strong base

Aeration
Process of blowing air (or other gas such as carbon dioxide) through a liquid or solid

Aerobic
Any biological process the occurs in the presence of oxygen; also applies to organisms that require oxygen to survive

Alkalinity
A measure of the capacity of a solution to neutralize a strong acid

Anaerobic
Any process that can occur without oxygen; also applies to organisms that can survive without oxygen

Analysis
A close look at something to find out more about it; can involve looking closely at the individual parts of something and describing them

Anthropogenic
Caused or produced as a result of human activity

Aquatic
Relates to fresh and salt water; some plants and animals live in water and are called aquatic species

Aquifer
An underground layer of rock or soil that contains water and can supply a large quantity of water to wells and springs