Definition: Gas Sampling
Gas sampling is done to characterize the chemical, thermal, and hydrological properties of a surface or subsurface hydrothermal system. Various methods are applied to obtain samples used for determination of the composition of gases present in soils or hydrothermal discharges. The flux of volatile gases emitted from a hydrothermal system can also be determined by measuring the flow of gases at specific locations and comparing it to average background emissions. Anomalously high gas flux can provide an indication of hydrothermal activity at depth that is otherwise not apparent.