Bacterial Biomarkers of Marcellus Shale Activity in Pennsylvania.

Jeremy R Chen See,Regina Lamendella,Christopher J Mclimans,Christopher J Grant,Maria F Campa,Terry C Hazen,Justin R Wright,Vasily Tokarev,Hephzibah Nwanosike,Nikea Ulrich,Daniel Ressler,Jonathan M Niles

doi:10.3389/fmicb.2018.01697

Abstract

Unconventional oil and gas (UOG) extraction, also known as hydraulic fracturing, is becoming more prevalent with the increasing use and demand for natural gas; however, the full extent of its environmental impacts is still unknown. Here we measured physicochemical properties and bacterial community composition of sediment samples taken from twenty-eight streams within the Marcellus shale formation in northeastern Pennsylvania differentially impacted by hydraulic fracturing activities. Fourteen of the streams were classified as UOG+, and thirteen were classified as UOG- based on the presence of UOG extraction in their respective watersheds. One stream was located in a watershed that previously had UOG extraction activities but was recently abandoned. We utilized high-throughput sequencing of the 16S rRNA gene to infer differences in sediment aquatic bacterial community structure between UOG+ and UOG- streams, as well as correlate bacterial community structure to physicochemical water parameters. Although overall alpha and beta diversity differences were not observed, there were a plethora of significantly enriched operational taxonomic units (OTUs) within UOG+ and UOG- samples. Our biomarker analysis revealed many of the bacterial taxa enriched in UOG+ streams can live in saline conditions, such as Rubrobacteraceae. In addition, several bacterial taxa capable of hydrocarbon degradation were also enriched in UOG+ samples, including Oceanospirillaceae. Methanotrophic taxa, such as Methylococcales, were significantly enriched as well. Several taxa that were identified as enriched in these samples were enriched in samples taken from different streams in 2014; moreover, partial least squares discriminant analysis (PLS-DA) revealed clustering between streams from the different studies based on the presence of hydraulic fracturing along the second axis. This study revealed significant differences between bacterial assemblages within stream sediments of UOG+ and UOG- streams and identified several potential biomarkers for evaluating and monitoring the response of autochthonous bacterial communities to potential hydraulic fracturing impacts.

Highlights

Over the past several years, the rapid increased use of natural gas in the United States (Lieskovsky et al, 2014; Laurenzi et al, 2016; U.S EIA, 2017a) has been driven by horizontal drilling and hydraulic fracturing (Brittingham et al, 2014; Jackson et al, 2014; Burden et al, 2016)
Final sampling sites were determined based upon presence of Unconventional oil and gas (UOG) gas wells and ability for access
We assessed the potential impacts of UOG development on stream sediment bacterial communities in 28 streams in northeastern PA

Summary

Introduction

Over the past several years, the rapid increased use of natural gas in the United States (Lieskovsky et al, 2014; Laurenzi et al, 2016; U.S EIA, 2017a) has been driven by horizontal drilling and hydraulic fracturing (Brittingham et al, 2014; Jackson et al, 2014; Burden et al, 2016). By 2050, the use of natural gas is predicted to increase more than any other fuel source in the United States (U.S EIA, 2017a). In the EIA’s reference case, natural gas consumption increases by 6.4 quadrillion BTUs to 32.27 quadrillion BTUs from 2015 to 2050 in the United States (U.S EIA, 2017a), and by 90.8 quadrillion BTUs from 2014 to 2050 to 218.2 quadrillion BTUs globally (U.S EIA, 2017b). In the United States, the Marcellus and Utica formations are predicted to be the primary drivers of this growth (U.S EIA, 2017a)

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Conclusion