Gas Chromatograph/Mass Spectrometer (GC-MS)
Highly sophisticated instrument that identifies the molecular composition and concentrations of various chemicals in water and soil samples.

Gas Laws
Rules describing the behaviour of gases.

Gasification
Conversion of solid material such as coal into a gas for use as a fuel.

GC
Gas Chromatography.

GC-FPD
Gas Chromatography Flame Photometric Detection.

Geographic Information System (GIS)
A computer system designed for storing, manipulating, analysing, and displaying data in a geographic context.

Grab Sample
A single sample collected at a particular time and place that represents the composition of the item sampled only at that time and place.

Greenhouse Effect
The warming of the Earth’s atmosphere attributed to a build-up of carbon dioxide or other gases; some scientists think that this build-up allows the sun’s rays to heat the Earth, while infra-red radiation makes the atmosphere opaque to a counterbalancing loss of heat.

Ground Water
The supply of fresh water found beneath the Earth’s surface, usually in aquifers, which supply wells and springs. Because ground water is a major source of drinking water, there is growing concern over contamination from leaching agricultural or industrial pollutants or leaking underground storage tanks.