Combining horizontal drilling with high volume slick water hydraulic fracturing (HVHF) has dramatically increased the extraction of hydrocarbons from low-permeability oil and gas (O&G) formations across the US over the past 10 years. Increased production of unconventional O&G has occurred with an increase in wastewater production. Surface water disposal of O&G wastewater from centralized waste treatment (CWT) plants, permissible in Pennsylvania, can lead to sediment contamination. We have focused on one river lake where the operation of a downstream dam has led to a coherent temporal record of sediment accumulation. Sediment cores were collected and a distinct geochemical signal was identified in the sediment layers corresponding to the time of maxium discharge of unconventional O&G wastewater (2009-2011). Major element chemistry (Cl, Br, Na, Sr, Ba) and isotope ratios (87Sr/86Sr and 228Ra/226Ra) from both sediments and porewater identified the relative impact of unconventional versus conventional O&G wastewater. A suite of bioanalytical assays coupled with targeted and non-trageted analyses of organic pollutants were applied to the sediment samples to evaluate toxicity. Cell- and mechanism-based bioassays systems have an advantage that they can take into account mixture effects among chemicals rather than focusing on individual chemicals. We tested bioassays indicative of molecular initiating events in various toxic responses, specifically: Aryl hydrocarbon receptor (AhR); Pregnane X receptor (PXR); Estrogen receptor alpha (ESR1); Oxidative stress (Nrf2) and; inflammation (NFκB). We also tested in vitro hepatocyte toxicity (TOX) to determine cytotoxic and DNA damage response. These six bioassays have been selected to probe a wide range of potential effects to human and aquatic health, and shown to be particularly relevant for water quality monitoring programs [1]. Both porewater and solvent extracts of the sediments were tested. Results from these studies will be presented and implications for the long-term persistence of toxicological effects from O&G wastewater management will be discussed.

Biological toxicity associated with lake sediments impacted by oil & gas wastewater disposal

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.