Identification of local groundwater pollution in northeastern Pennsylvania: Marcellus flowback or not?

Abstract

Using graphical and statistical methods, geochemical data from 21 allegedly contaminated ground water wells in northeastern Pennsylvania were compared with data from historical ground water, Marcellus flow-back fluid, and other contaminated waters. The graphical methods included box and whisker plots, Piper diagrams, Stiff diagrams, and Cl/Br vs. Cl cross-plots. The statistical methods included summary statistics, analysis of variance, and discriminant analysis. The geochemical data collected for this study included the following major ions, trace metals, nutrients, and physical properties: sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), barium (Ba), strontium (Sr), manganese (Mn), iron (Fe), aluminum (Al), chloride (Cl), bromide (Br), sulfate (SO 4), arsenic (As), nitrate-nitrite as N, total Kjeldahl nitrogen, total nitrogen, alkalinity, and total dissolved solids (TDS). The graphical and statistical results show that none of the 2012-2013 ground water wells were detectably impacted by flow-back fluids. Instead, the results show that at least one well is contaminated with animal waste or septic effluent. Discriminant analysis of the 2012-2013 ground water samples supports this observation. The remaining wells are geochemically similar to historical ground water wells both graphically and statistically. These findings suggest that the major and trace element geochemistry of northeastern Pennsylvania ground water has not been detectably influenced by flow-back fluid spills at these 21 sites.

Evaluation of β-cyclodextrin–polyethylene glycol as green scale inhibitors for produced-water in shale gas well

“…Besides, 10-70% of the wastewater produced from hydraulic fracturing is subsequently recovered as flow back water [4,5]. The impaired water stream contains different potentially hazardous inorganic ingredients with extremely high concentrations, of which the constituents (e.g., calcium, barium, sulfate, and carbonate) can potentially form stable carbonate and sulfate precipitates in the wellbore (e.g., CaCO 3 , BaSO 4 ), making the effective inner diameters of pipelines smaller and eventually causing the reduction of gas production [6][7][8].…”

Potential Impacts of Shale Gas Development on Inorganic Groundwater Chemistry: Implications for Environmental Baseline Assessment in Shallow Aquifers

“…Structural and geochemical evidence suggests that formation brines naturally migrate through faults and fractures along deformational features. , These areas have been suggested to be at greater risk of contamination by upward fluid migration due to the occurrence of conductive pathways between deep formations and shallow aquifers, although the time scale for potential brine migration is poorly constrained , (Figure ). A number of geochemical and isotopic tools have been applied to detect brine contribution to shallow groundwater in shale gas basins including concentrations and ratios of dissolved ions such as Cl, Br, Ba, Na, Li, Sr, and I, stable and radiogenic isotopes of dissolved elements (δ 11 B, δ 7 Li, 87 Sr/ 86 Sr, 228 Ra/ 226 Ra), and elemental and isotopic compositions of noble gases ( 3 He, 4 He, 20 Ne, 21 Ne, 22 Ne, 36 Ar, 38 Ar, 40 Ar). ,,,− Stable isotope ratios of water have been found to be less sensitive to small contributions of brines, in comparison with isotopes of dissolved constituents …”

“…In rural areas, groundwater obtained from domestic/farm wells may be impacted by surface contamination sources such as deicing road salts, septic tank effluents, and agricultural residues , (Figure ). As a result, shallow groundwater may contain a number of dissolved contaminants prior to shale gas development including chloride, sodium, nitrate, and pesticides.…”

“…Landfill leachates and agricultural residues can also cause elevated CH 4 concentrations in groundwater. , Baseline studies of shallow aquifers have often used major and minor ion concentrations to distinguish between surface contamination and natural sources of salinity. For instance, domestic and agricultural contaminations have been commonly identified using NO 3 concentrations. ,, Road salt contamination has often been detected using ion ratios such as Br/Cl and (Ba + Sr)/Mg, as deicing salts are usually composed of halite and thus contain low levels of Br, Ba, and Sr. ,, However, the application of ion ratios can be limited by minor element concentrations being below the quantification limit. , The delineation of surface contamination of shallow groundwater is greatly complicated by the use of oil and gas wastewaters on roads for deicing or dust suppression in some regions. , Importantly, surface contamination effects have been spatially correlated with land use (e.g., road network, agriculture) and hydrogeological conditions (e.g., confinement conditions, flow path). , …”

Assessing unconventional natural gas development: Understanding risks in the context of the EU

“…32 That being said, in one study nearly all analyzed samples in the Marcellus region failed on at least one water quality metric, and the cause of these failures were uncertain. 33 Aquifer water quality is site specific: a function of, for example, geology, aquifer depletion, agricultural activity. 34 In order to assess change (and quantify risks) due to UNGD, Member…”