Groundwaters in Northeastern Pennsylvania near intense hydraulic fracturing activities exhibit few organic chemical impacts.

Horizontal drilling with hydraulic fracturing (HDHF) relies on the use of anthropogenic organic chemicals in proximity to residential areas, raising concern for groundwater contamination. Here, we extensively characterized organic contaminants in 94 domestic groundwater sites in Northeastern Pennsylvania after ten years of activity in the region. All analyzed volatile and semi-volatile compounds were below recommended United States Environmental Protection Agency maximum contaminant levels, and integrated concentrations across two volatility ranges, gasoline range organic compounds (GRO) and diesel range organic compounds (DRO), were low (0.

A geospatially resolved database of hydraulic fracturing wells for chemical transformation assessment.

Hydraulically fractured wells with horizontal drilling (HDHF) accounted for 69% of all oil and gas wells drilled and 670 000 of the 977 000 producing wells in 2016. However, only 238 flowback and produced water samples have been analyzed to date for specific organic chemicals. To aid the development of predictive tools, we constructed a database combining additive disclosure reports and physicochemical conditions at respective well sites with the goal of making synthesized analyses accessible.

Oxidative Breakers Can Stimulate Halogenation and Competitive Oxidation in Guar-Gelled Hydraulic Fracturing Fluids.

A number of flowback samples derived from horizontally drilled hydraulic fracturing (HDHF) operations reveal consistent detections of halogenated organic species , yet the source of these compounds remains uncertain. Studies simulating subsurface conditions have found that oxidative "breakers" can halogenate certain additives, but these pathways are unverified in the presence of cross-linked-gels, common features of HDHF operations. Using a high-throughput custom reactor system, we implemented a reaction matrix to test the capacity for halogenation of two frequently disclosed compounds with demonstrated halogenation pathways (cinnamaldehyde and citric acid) across guar gels with varied types and concentrations of cross-linkers and oxidative breakers.

A community-based evaluation of proximity to unconventional oil and gas wells, drinking water contaminants, and health symptoms in Ohio.

Over 4 million Americans live within 1.6 km of an unconventional oil and gas (UO&G) well, potentially placing them in the path of toxic releases. We evaluated relationships between residential proximity to UO&G wells and (1) water contamination and (2) health symptoms in an exploratory study.

Halogenation Chemistry of Hydraulic Fracturing Additives under Highly Saline Simulated Subsurface Conditions.

Unconventional natural gas extraction via hydraulic fracturing coupled with horizontal drilling (HDHF) has generated disruptive growth in the domestic energy sector. Field analyses of residual HDHF fluids have detected halogenated species, potentially the product of unexplored reactions between authigenic halides and HDHF additives. Utilizing a custom high-pressure reactor system, we simultaneously screened 12 frequently disclosed, functionally diverse HDHF additives to uncover transformation chemistry.

Exploring the hydraulic fracturing parameter space: a novel high-pressure, high-throughput reactor system for investigating subsurface chemical transformations.

Hydraulic fracturing coupled with horizontal drilling (HDHF) involves the deep-well injection of a fracturing fluid composed of diverse and numerous chemical additives designed to facilitate the release and collection of natural gas from shale plays. Analyses of flowback wastewaters have revealed organic contamination from both geogenic and anthropogenic sources. The additional detections of undisclosed halogenated chemicals suggest unintended in situ transformation of reactive additives, but the formation pathways for these are unclear in subsurface brines.

Indications of Transformation Products from Hydraulic Fracturing Additives in Shale-Gas Wastewater.

Unconventional natural gas development (UNGD) generates large volumes of wastewater, the detailed composition of which must be known for adequate risk assessment and treatment. In particular, transformation products of geogenic compounds and disclosed additives have not been described. This study investigated six Fayetteville Shale wastewater samples for organic composition using a suite of one- and two-dimensional gas chromatographic techniques to capture a broad distribution of chemical structures.

Model analysis of secondary organic aerosol formation by glyoxal in laboratory studies: the case for photoenhanced chemistry.

The reactive uptake of glyoxal by atmospheric aerosols is believed to be a significant source of secondary organic aerosol (SOA). Several recent laboratory studies have been performed with the goal of characterizing this process, but questions remain regarding the effects of photochemistry on SOA growth. We applied GAMMA (McNeill et al.

Aqueous-phase secondary organic aerosol and organosulfate formation in atmospheric aerosols: a modeling study.

We have examined aqueous-phase secondary organic aerosol (SOA) and organosulfate (OS) formation in atmospheric aerosols using a photochemical box model with coupled gas-phase chemistry and detailed aqueous aerosol chemistry. SOA formation in deliquesced ammonium sulfate aerosol is highest under low-NO(x) conditions, with acidic aerosol (pH = 1) and low ambient relative humidity (40%). Under these conditions, with an initial sulfate loading of 4.