Anne: These Piper diagrams show the geochemistry of flowback water from fracking operations in the Marcellus shale of Pennsylvania, relative to literature values of groundwater contaminated with road salt, septic waste, and animal manure. The information on these Piper diagrams, along with other geochemical analyses, were used to assess whether alleged contamination of rural, residential well water in northeastern Pennslyvania was likely to be due to the extensive shale gas development occurring in the area. Based on major and trace ion water chemistry, Anne and her coauthors found no evidence of flowback fluid in the tested residential wells. While this work was not definitive proof that flowback contamination is entirely absent, it was a good reminder that contamination of rural, residential wellwater is much more likely to come from leaky septic systems and other less exotic sources.
Figure 3 from Reilly, D., Singer, D., Jefferson, A., and Eckstein, Y., 2015. Identification of Local Groundwater Pollution in Northeastern Pennsylvania: Marcellus Flow-back or Not?, Environmental Earth Sciences, 73(12): 8097-8109. doi:10.1007/s12665-014-3968-0.