Key Features

Industrial Chemicals

Chlorofluorocarbons (CFCs), which are industrial chemicals that are present in groundwater less than 50 years old, can be used to calculate groundwater age in different parts of catchment. CFCs are useful tracers in hydrological studies as they are non-reactive and resistant to degradation and have low toxicity (Davis et al, 1980).

Likewise, sulfur hexafluoride (SF₆) can also be used as an environmental tracer, being a persistent and stable industrial chemical with emissions commencing in the 1950s. SF₆ is detectable at low concentrations (10^-16 mol/L) and non-toxic (Kass, 1998). It has been used in groundwater dating (Busenberg and Plummer, 2000) and for monitoring septic tank effluent (Dillon et al, 1999).

References

• Busenberg E and Plummer LN, 2000. Dating groundwater with sulphur hexafluoride: Natural and anthropogenic sources of sulphur hexafluoride. Water Resources Research 36:3011-3030.
• Davis SN, Thompson GM, Bentley HW, Stiles G, 1980. Ground-water tracers - a short review. Ground Water 18, 14-23.
• Dillon KS, Corbett DR, Chanton JP, Burnett WC, Furbish DJ, 1999. The use of sulfur hexafluoride SF6 as a tracer of septic tank effluent in the Florida Keys. Journal of Hydrology 220:129-140.
• Kass W, 1998. Tracing techniques in geohydrology. AA Balkema, Broofield Vt.