Preservation of Historical Industrialization Trends in Bellingham Bay Sediments through PAH Contamination

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants consisting of two or more fused benzene rings. These molecules are either pyrogenic (originating from combustion processes) or petrogenic (originating from petroleum) in origin. PAHs are generally hydrophobic and tend to adsorb onto sediment particles, where they can be preserved and negatively affect aquatic organisms. Some PAHs are also probable human carcinogens, with 16 being classified as priority pollutants by the EPA. While measurable PAHs have been documented in Bellingham Bay via surface sediment grabs, to our knowledge, PAH analysis with depth in a sediment core has not been performed. This study aims to explore the potential of sediment cores from Bellingham Bay to examine historical trends in PAH concentrations and their potential connection to the industrialization history of the area. Sediment samples (n=19) were taken from two sister vibracores (VC09 R1 and R2) collected offshore of the Fairhaven neighborhood in Bellingham, Washington. These samples were analyzed for parent and alkylated PAHs via gas chromatography with mass spectral detection. PAHs were found in all 19 samples, with concentrations ranging from 939 to 4204 ng/g . Peak concentrations in the core occurred at 25 and 130 cm depth. Considering estimated sedimentation rates at the coring site, PAH spikes may correlate with historical pollution-causing events such as the 1999 Olympic Pipeline explosion and the industrialization of the Bellingham Bay shoreline in the late 1800s to early 1900s. PAH ratios to determine sourcing were also examined, with the majority of ratios pointing to a mostly pyrogenic origin. The results of this study indicate that historical trends of PAH release in Bellingham are preserved in Bellingham Bay sediment. Sediment cores from Bellingham Bay can therefore serve as a useful archive of anthropogenic activity in the local area.