AN ISOTOPIC PERSPECTIVE ON WATER AND CARBON SOURCES IN COMPLEX GEOCHEMICAL SETTINGS OF THE APPALACHIANS

Understanding sources of water and carbon are important for tracking recharge sources as well as assessing any changes in water quality associated with shale gas drilling and/or coal mining in the Appalachians. Natural stable isotopes have become an increasing tool for determining sources and cycling of water, carbon, nutrients and other trace elements. The variations in water-rock interactions, recharge sources, recharge pathways, and age can impart unique isotopic signatures to different water sources. The main objectives of this study was to use stable isotopes of water (δ¹⁸O_H2O and δ²H _H2O), DIC (δ¹³C_DIC) and SO₄ (δ³⁴S_SO4 and δ¹⁸O_SO4) to delineate sources of water and carbon in natural springs, coal mine discharges and brines produced during Marcellus Shale gas drilling in the Appalachian region. The natural spring sites are located in southwestern Pennsylvania, southeastern West Virginia and southwestern Virginia; the mine discharge and produced brine sampling sites are located southern Pennsylvania. Preliminary data indicates that stable isotopes can be used in conjunction with routine geochemistry to understand sources of carbon and water at each site as well as understanding any biogeochemical transformations that lead to isotopic fractionation.