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3381243 
Journal Article 
Supplemental Data 
Elevated levels of diesel range organic compounds in groundwater near Marcellus gas operations are derived from surface activities: Supplementary material 
Drollette, BD; Hoelzer, K; Warner, NR; Darrah, TH; Karatum, O; O'Connor, MP; Nelson, RK; Fernandez, LA; Reddy, CM; Vengosh, A; Jackson, RB; Elsner, M; Plata, DL 
2015 
1 
Proceedings of the National Academy of Sciences of the United States of America
ISSN: 0027-8424
EISSN: 1091-6490 
112 
43 
13184-13189 
English 
is a supplement to 3071003 Elevated levels of diesel range organic compounds in groundwater near Marcellus gas operations are derived from surface activities
Hundreds of organic chemicals are used during natural gas extraction via high-volume hydraulic fracturing (HVHF). However, it is unclear whether these chemicals, injected into deep shale horizons, reach shallow groundwater aquifers and affect local water quality, either from those deep HVHF injection sites or from the surface or shallow subsurface. Here, we report detectable levels of organic compounds in shallow groundwater samples from private residential wells overlying the Marcellus Shale in northeastern Pennsylvania. Analyses of purgeable and extractable organic compounds from 64 groundwater samples revealed trace levels of volatile organic compounds, well below the Environmental Protection Agency's maximum contaminant levels, and low levels of both gasoline range (0-8 ppb) and diesel range organic compounds (DRO; 0-157 ppb). A compound-specific analysis revealed the presence of bis(2-ethylhexyl) phthalate, which is a disclosed HVHF additive, that was notably absent in a representative geogenic water sample and field blanks. Pairing these analyses with (i) inorganic chemical fingerprinting of deep saline groundwater, (ii) characteristic noble gas isotopes, and (iii) spatial relationships between active shale gas extraction wells and wells with disclosed environmental health and safety violations, we differentiate between a chemical signature associated with naturally occurring saline groundwater and one associated with alternative anthropogenic routes from the surface (e.g., accidental spills or leaks). The data support a transport mechanism of DRO to groundwater via accidental release of fracturing fluid chemicals derived from the surface rather than subsurface flow of these fluids from the underlying shale formation.