ABIOTIC
Nonliving or the never living elements in our environment. For example: rocks, soils and waters.

ACCREDITATION
The process of evaluating the academic qualifications or standards of an institution or program of study in accordance with pre established criteria.

ACID DEPOSITION
A phenomenon which occurs when emissions of sulphur and nitrogen compound, and other substances are transformed by chemical processes in the atmosphere, often far from the original sources, and then deposited on earth in either wet or dry form. The wet form, popularly called acid rain, can fall to earth as rain, snow or fog. The dry form is acidic gases or particulates.

AEROBIC
Living, active, or occurring only in the presence of oxygen.

AGENDA 21
A plan of action adopted at the "Earth Summit" in Rio de Janeiro in 1992 to promote sustainable development. A framework of political recommendations designed to protect the environment and encourage nations to move towards achieving sustainable development in the 21st Century. A blueprint for an economically, socially and environmentally sustainable planet in the 21st century. The main document to be produced at the Rio Earth Summit in 1992

ANAEROBIC
A process which occurs in, or is not destroyed by, the absence of oxygen.

ANTHROPISATION
The transformation of spaces, countryside or natural surroundings by human action.

AQUACULTURE
The controlled cultivation and harvest of aquatic plants or animals.

AQUIFER
Layer of water-bearing permeable rock, sand, or gravel capable of providing significant amounts of water.

ASBESTOS
A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled.

ATMOSPHERE
The mixture of gases surrounding the Earth. The Earth's atmosphere consists of about 79.1 percent nitrogen (by volume), 20.9 percent oxygen, 0.036 percent carbon dioxide and trace amounts of other gases.

AUTODEPURATION
Removal of chemical toxins from water.