EXPLORING POTENTIAL IMPACTS OF HYDRAULIC FRACTURING ON PENNSYLVANIA’S SURFACEWATERS USING TRACE ELEMENTAL CONCENTRATIONS IN STREAMBED SEDIMENTS

Unconventional gas extraction, particularly in the Marcellus Shale, has transformed our energy supply; yet this transformative process is not without controversy. To date, a limited number of studies in the scientific literature have documented localized stream and well water contamination due to improper disposal and/or leakage of flowback and produced waters from drilled wells. However, discerning impacts of hydraulic fracturing activities at a regional level has been hindered by the lack of baseline data, the lack of regional sampling networks, and prohibitive costs of scaling up studies. Here we attempt to address these knowledge gaps by testing the use of streambed sediments as an integrator of contaminants within a watershed. Streambed sediments were collected from 24 small (<10mi²) watersheds in northeastern Pennsylvania in June 2015. Sediments were sieved to <63 µm (silt and clay) and processed through a partial acid digestion in order to recover the acid soluble fraction. The samples were subsequently analyzed using inductively coupled mass spectrometry (ICP-MS) for the presence of Ba, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, and Pb. Sample concentrations were statistically compared to a variety of factors for each watershed, including relative land use patterns, number of hydraulic fracturing well pads, spud dates, and number of drilling related violations. Statistically significant correlations were observed between particular trace elements and varying intensities of developed land and/or total well violations within the last three years. These findings suggest streambed sediments may have potential as an indicator of historical streamwater contamination in areas affected by hydraulic fracturing activities.