The BBC has just reported an analysis of two recent studies from the University of Texas and Duke University into possible contamination of groundwater by chemicals from hydraulic fracturing in the USA. Both studies are a great improvement on previous studies in terms of methodology, and both show concentrations of chemicals in ground water.
- There is a tendency for groundwater to contain excess methane, ethane and propane close to shale gas wells. Currently, it is not known what proportion of this (if any) is due to leakage from shale gas wells and what is natural
- The chemical signature of the gas in ground water is commonly biogenic, but sometimes is thermogenic, and a few samples share the same signature as the deep shale gas. However, the gas may have found its way naturally to the surface having taken millennia to do so.
- There is an excess of four heavy metals (arsenic, strontium, barium and selenium) in the water wells. The cause is unknown, but is likely to be natural.
- There is an excess of methanol and ethanol in the water wells of the University of Texas study. The cause is unknown, but is unlikely to be natural and may come from the fracking fluid.