Barium (Ba) is a metallic alkaline earth metal with no stable isotopes. The most common naturally occurring minerals are the barium sulfate (BaSO4) and barium carbonate (BaCO3) both of which have low solubility. Barium is most abundant in igneous rocks compared to sandstones, shale or carbonate.
Source of barium in waters come from mineral weathering, such as K-feldspar, biotite and barite. Solubility is largely controlled by saturation with respect to barite and when SO4 concentrations are high, Ba remains low.
Ba is measured using inductively coupled plasma mass spectroscopy (ICP-MS)
Barium concentration in waters is strongly controlled by barite solubility. Barium quickly reaches saturation or oversaturation where SO42-and/or CO32- are present. Therefore, barium cannot be used as a residence time indicator. In young groundwaters and which contain low sulphate conentrations, Ba remains undersaturated with respect to barite and its concentration in these circumstances may be an indicator of residence time
References and Further Reading
- Edmunds, W M. and Shand, P. 2008. Natural groundwater quality. Blackwell.