Effects of unconventional gas development on groundwater: a call for total dissolved gas pressure field measurements.

One of the primary public concerns with new development of shale and other unconventional gas resources is potential contamination of shallow groundwater with natural gas (largely methane). Natural gas contamination of shallow groundwater can result from leaky gas production wellbores (e.g. Stein et al., 2003; Van Stempvoort et al., 2005). However, there is also concern that hydraulic fracturing may enhance natural gas migration from deep formations to shallow groundwater (see Jackson et al., this issue, for further details). Measurements of groundwater gases will be needed to appropriately address these concerns. Field measurement of total dissolved gas pressure (PTDG) can provide useful information during investigations of the effects of natural gas development on groundwater, but it is not being widely used. We make the case here that PTDG has a critical role as we endeavour to collect accurate and objective data for assessing the impacts of shale gas development. .