The 2010 explosion of the <i>Deepwater Horizon</i> (DWH) drilling rig introduced an unprecedented level of oil contamination to the Louisiana salt mash sediment that was subsequently subjected to various environmental weathering processes. Preliminary analysis of saltmarsh sediments impacted by the DWH spill between 2010-2014 identifies highly polar oxygenated hydrocarbons with carboxylic acid functionalities. These highly polar, high molecular weight compounds are not detectable by routine gas chromatography based techniques and require advanced analytical techniques that can address the complexity and polarity. Here, we document, and catalog oil transformation compounds detected in oiled saltmarsh sediments up to 8 years after the spill and determine their toxicity. Samples are continuously collected from well-established 21 sampling stations from northern Barataria Bay. Oil contamination remains in saltmarsh sediments eight years after the spill in concentrations that exceed non-oiled reference sites. Combining chromatographic fractionation, conventional GC/MS, and ultrahigh-resolution FT-ICR Mass Spectrometry analyses, we identified tens-of-thousands of biotic and abiotic crude oil transformation products that remain persistent and reveal how they evolve in the environment. Heavily oxygenated transformation products which are mostly only accessible by FT-ICR MS, span a wide range of chemical functionalities. Toxicity of the non-GC amenable fraction of oil contaminants were measured to determine the health risk of weathered oil residues left in the salt marsh environment, and were linked to known molecular compositional changes identified by FT-ICR MS. Since chemical functionalities of these petrogenic contaminants dictate their toxicity, water solubility, stable emulsion formation, and bioavailability, molecular level characterization is necessary for understanding the fate and long-term impact of these emerging environmental contaminants.

8 Years after the <i>Deepwater Horizon</i> spill: The evolution of oil transformation compounds in Louisiana Salt Marsh Sediments revealed by FT-ICR mass spectrometry

2019 Spring National Meeting

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8 Years after the Deepwater Horizon spill: The evolution of oil transformation compounds in Louisiana Salt Marsh Sediments revealed by FT-ICR mass spectrometry