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Trace Elements in Otoliths as Indicators of Surface Water Contamination from Natural Gas Mining Operations 


Estuarine Research Chesapeake (ERC) Endowment

Principal Investigator(s):

David H. Keller, M.S., Project Coordinator/Scientist, Fisheries Section, Academy of Natural Sciences of Drexel University

Paula Zelanko, M.S., Staff Scientist II, Biogeochemistry Section, Academy of Natural Sciences of Drexel University

Dr. Richard J. Horwitz, Professor, Biodiversity, Earth and Environmental Science and Fisheries Section Leader, Academy of Natural Sciences of Drexel University

Dr. David J. Velinsky, Professor, Biodiversity, Earth and Environmental Science, Vice President, Center for Academy Science, Biogeochemistry Section Leader, Academy of Natural Sciences of Drexel University

IExE Cluster:

Energy, Environment & Society


Once an ancient sea bed, the Marcellus Shale formation is now an underground (mostly), rock formation that stretches throughout the mid-Atlantic portion of the Appalachian Mountains. Trapped within the shale is natural gas that is being mined by hydraulic fracturing or “fracking”. Fracking uses large volumes of water mixed with sand and chemicals to free natural gas trapped within the shale rock. Freed natural gas is collected at the surface along with generated waters (GW; flowback and produced waters) that contain chemicals used in the fracking process and salts and other elements from the ancient sea bed.  These chemicals, salts and other elements may contaminate surface waters if spilled or leaked. Detecting past surface water contamination is difficult in streams where contamination was sporadic or occurred in low concentrations. However, fish residing in these streams may provide evidence of past contamination. Fish incorporate trace elements of the ambient water into their otoliths. Their otolith microchemistry may be used to monitor elemental changes in water chemistry. GW contains high concentrations of Sr, Ba, and other elements know to occur in fish otoliths. Changes in the concentrations of these and other elements in the fish otolith may indicate past surface water contamination due to natural gas mining. The primary objectives of this work are to 1) in a laboratory setting, demonstrate that Brook Trout will incorporate elements of GW into the otolith, 2) identify the GW microchemical signature in the otolith, and 3) use the GW microchemical signature to identify wild fish that have been exposed to surface water contamination caused by GW.