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Novel Assessment of the Toxicity of Groundwater Impacted by Petroleum Hydrocarbons: Lessons from an Aged Crude Oil Plume

Authors: Dalma Martinovic-Weigelt, Hannah Link, Sarah Shadle, Jennifer McGuire Illig, University of St. Thomas

Abstract: Emerging evidence indicates that chemicals found in petroleum may exhibit a variety of biological activities that can lead to adverse health effects. Given the recent intensification of state and federal efforts to consider contaminants of emerging concern in drinking and surface waters there is a need to characterize the potential of waters contaminated with petroleum hydrocarbons and their metabolites to interact with biological targets and exert toxicity. We utilized historical biogeochemical and chemical data from the well-studied petroleum-impacted waters at the Bemidji Crude Oil Spill Fate and Transport Research Site to identify groundwater sampling sites of interest. Toxicity was characterized using a Microtox system and a suite of high-throughput in vitro toxicology assays (48 human nuclear receptor assays). Acute toxicity was observed in samples with high nonvolatile dissolved organic carbon concentrations, but not in less contaminated or background samples. Higher levels of biological activity were observed in samples taken from methanogenic zones than those from iron-reducing zones within the plume, and no upregulation was observed in background samples. These data have implications for future decisions on the design and implementation of remediation strategies and regulatory action to manage drinking and surface water resources to protect human and ecosystem health.