Presenter: Dalia Bercow (Haverford College)

Description:
In October 2020, oil and oiled debris from a mystery source was detected across Delaware Bay shorelines. In this study, we present the chemical analysis of oiled field samples collected in October and November 2020, and January, March, and May of 2021 from locations spanning Bowers Beach, DE to Assateague Island, MD. The oil was present on beaches as emulsified residues, as well as oil mixed with sand and other beach debris including plant material, bird feathers, and plastic trash. Based on gas chromatographic analysis, the spilled product was consistent with a mixture of at least two products best characterized by a dominant aromatic rich fraction from carbon range C12-C15 and a less abundant unresolved complex mixture spanning C10-C30. To provide greater insight into the source of the spilled product, one oil sample collected in October 2020 was analyzed by comprehensive two-dimensional gas chromatography (GC×GC). The GC×GC chromatogram for the Delaware Bay oil spill extract has many of the same characteristics as the Bouchard-120 oil spill that occurred in Buzzards Bay, MA in April 2003. Specifically, the two oils have a similar distribution of the naphthalene aromatic hydrocarbons compared to the Bouchard-120 cargo. To investigate how the spilled oil was chemically altered by environmental processes, oiled field samples collected between October 2020 and May 2021 were analyzed via gas chromatography with flame ionization detection (GC-FID) and mass spectrometry (GC-MS). The distribution of alkanes, alkyl benzenes, and polycyclic aromatic hydrocarbons present in the oil were examined to understand how weathering processes changed the composition of the oil during the months following the initial oiling. The findings of this study contribute to our overall understanding of oil spills and their potential impacts to shoreline ecosystems.