Published by Australian Academy of Science
Glossary | Cleaner production – a solution to pollution?

corporate social responsibility. A concept whereby organisations take responsibility for their impact on society and the environment.

effluent. Liquid waste. Usually refers to discharge from industrial processes or from sewage treatment plants.

ion, anion, cation, and divalent ion. An ion is an electrically charged atom or group of atoms. The charge is the result of the loss (positive ion) or gain (negative ion) of one or more electrons.

The gain of one or more electrons produces an ion with a negative charge (anion). The loss of one or more electrons produces an ion with a positive charge (cation). Ions that have gained or lost two electrons are called divalent ions.

parts per million. This is a way of expressing very dilute concentrations of substances. Just as per cent means out of a hundred, so parts per million or ppm means out of a million. Therefore 500,000 ppm is the same as 50 per cent, because 500,000 is half of a million. The concentration of oxygen in unpolluted fresh water is about 8 ppm – only 8 parts of oxygen for every 1 million parts of other substances.

More information on parts per million can be found at the following site:

• How much is a part per million? (Extension Toxicology Network, USA)

smelting. A high-temperature process that separates out a pure metal, usually in a molten form, from an ore.