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USGS Mendenhall Postdoctoral  Research Fellowship Program

14-8. Impacts of Hydraulic Fracturing produced water on microbial communities and water quality in near-surface environments

Exploitation of natural gas resources has been touted to provide the “bridge towards a low-carbon future” and therefore plays an integral role in our trajectory toward development of sustainable energy that protects both our environmental and national security interests (1).  Hydraulic fracturing (HF) of shale formations to access methane gas is a rapidly expanding practice that hopes to bolster domestic energy resources and is expected to comprise 20% of the total U.S. energy supply by 2020 (2).  HF for shale gas recovery produces an estimated 216,000 to 2.7 million gallons of produced water (PW) per well during drilling operations and as of 2011 it is estimated that there are over one million gas production wells. After the initial flowback water is collected, pumping continues to produce a complex mixture containing 1) water naturally present in the fractured geologic formation, 2) fracturing fluids and 3) reaction products released from the rock matrix.  Due to the mixing that occurs in the subsurface these PW may contain contaminants, with several individual components potentially exceeding regulatory standards and thereby posing a risk to human health and the environment.  PW can contain any number or combination of over 200 chemicals added to the HF fluids used to create fractures in addition to compounds characteristic of the geologic formation waters.

There are few studies of environmental fate and effects of PW.  Potential routes to the environment include surface pathways due to on-site handling accidents, leakage from storage impoundments, and intentional road spreading, and subsurface pathways from loss of PW during extraction or migration from waste injection wells. Contamination of groundwater through these routes is a chief concern and it is necessary to understand contaminant fate once they reach groundwater or surface-water.  This can be challenging with a single contaminant and is further complicated with complex mixtures, such as PW, where individual components likely affect transport, bioavailability, biodegradability, and toxicity of other components in the mixture.  The effects of these mixtures could conceivably be major drivers of PW toxicity, which is largely unstudied. Fundamental research is critically needed in order to guide informed decision-making regarding the future of this rapidly expanding and controversial energy technology.

This Research Opportunity will allow the Mendenhall Fellow to conduct novel field and laboratory experiments aimed at providing critical knowledge on the fate and impacts of complex mixtures present in PW.  The Fellow is expected to formulate a project focusing on characterizing contaminants in PW and their biogeochemical fate in groundwater or surface waters.  Such characterization might include trace organic analyses for compounds such as surfactants, biocides, and hydrocarbons.  Further the approach might include investigating changes in microbial communities impacted by PW and identifying microbial biodegradation pathways of such contaminants.  Although there are currently studies by the USGS and others looking at groundwater chemistry in shale gas production areas there are few studies investigating hydraulic fracturing impacts incorporating an interdisciplinary approach.  This Mendenhall Opportunity provides a place for a strong scientist with a background in geochemistry, microbiology, or a closely related environmental science to develop an interdisciplinary study focusing on the microbial and geochemical complexity of hydraulic fracturing PW to understand the potential environmental impact of PW. While the detailed technical plan is left to the postdoctoral fellow to formulate, it is expected that the proposed project employ an innovative interdisciplinary approach combining laboratory and field experiments with cutting-edge tools in geochemistry, molecular microbiology, and/or computational modeling.  Proposals that incorporate some aspects of toxicity measurements of these complex waters are also encouraged. The results will aid in assessing HF risk and inform corresponding policy, providing guidance for the feasibility of bioremediation and/or natural attenuation of potential environmental release.

Challenges and unique opportunities to conduct highly relevant science abound in this research. HF is underway in 34 states and there is widespread interest in expanding its use in other countries, including the UK, India, South Africa, and China (3-5).  HF has potential benefits including reductions in greenhouse gas emissions relative to conventional fuels (6).  However, there is concern about the sustainability of HF with respect human health, air and water quality.  The U.S. EPA is currently investigating the risks associated HF including the study of well construction, case studies of potentially contaminated sites, and toxicity of HF fluid components (2). The proposed work would compliment these efforts and provide valuable scientific data where there currently is a lack of information.

New energy resources must be harnessed with consideration of water quality in order to promote sustainable development and the proposed work will help characterize the risk posed by HF.  Better understanding of remediation potential for PWs will accelerate economical cleanup of contaminated waters, thereby protecting public health.  Further, better understanding of the risk posed by PW spills may influence industry to mitigate risk by developing onsite treatments or adjusting HF fluid formulations to produce more environmentally friendly PW.


  1. MIT Engergy Initiative, The future of natural gas: An interdiciplinary MIT study Interrum Report, 2010.
  2. Environmental Protection Agency. Hydraulic Fracturing. November 18, 2011;
  3. Mount Sinai Global Health Training Center’s 9th Annual Global Health Conference “Toxins: A Global Threat, Hydrofracking and Advocacy Panel Discussion, 2011.
  4. Shale gas in South Africa: Fracking the Karoo.  The Economist.. October 8, 2012  10/29/2012]; Available from:
  5. Yang, C.T. China Drills Into Shale Gas, Targeting Huge Reserves Amid Challenges.  National Geographic Daily News. August 8, 2012  10/29/2012]; Available from:
  6. Zomback, M., S. Kitasei, and B. Copithorne, Addressing the Environmental Risk from Shale Gas Development, 2010, World Watch Institue:  Natural Gas and Sustain. Energy Initiative.

Proposed Duty Station: Reston, VA

Areas of Ph.D.: Geochemistry, hydrology, microbial ecology, microbiology, geomicrobiology, environmental sciences, chemistry or related fields (candidates holding a Ph.D. in other disciplines but with knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet one of the following qualifications - Research Hydrologist, Research Chemist, Research Microbiologist, Research Ecologist, Research Geologist.

(This type of research is performed by those who have backgrounds for the occupations stated above.  However, other titles may be applicable depending on the applicant’s background, education, and research proposal. The final classification of theposition will be made by the Human Resources specialist).

Research Advisors: Isabelle Cozzarelli, (703) 648-5899,; Denise Akob, (703) 648-5819,

Human Resources Office Contact: Junell Norris, (303) 236-9557,

Go back to Summary of Opportunities

U.S. Department of the Interior, U.S. Geological Survey
URL: Cozzarelli.htm
Direct inquiries to Rama K. Kotra at
Maintained by: Mendenhall Research Fellowship Program Web Team
Last modified: 17:58:11 Tue 23 Jul 2013
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