POSTER Session 2

OPTICALLY-BASED EVALUATION OF STORMWATER AS A POTENTIAL SOURCE OF POLYCHLORINATED BIPHENYLS (PCBS) TO PEARL HARBOR, HAWAII

Optically-based assessment of chemical contaminants was implemented to determine whether stormwater from Oscar 1 Pier outfall is a contributing source of polychlorinated biphenyl (PCBs) to Decision Unit (DU) N-2, Pearl Harbor Sediment Site, Honolulu, Hawaii USA. OPTICS (OPTically-based In-situ Characterization System) is a tool that combines robust, in-situ aquatic instrumentation, discrete analytical samples, and a multi-parameter statistical modeling technique to provide concentrations of chemical contaminants at high temporal or spatial resolution relative to traditional sampling methods. The OPTICS study was conducted at DU N-2 in Pearl Harbor during the rainy season, between November 2022 and March 2023. The study involved mobile (vessel-mounted) OPTICS monitoring to characterize stormwater plume spatial variability and near-continuous stationary (moored) OPTICS monitoring to evaluate baseline conditions and stormwater discharge over time-varying conditions (tidal, dry periods, stormwater flow). Results suggested that PCBs were discharged from the outfall, remained in suspension, and dispersed elsewhere before settling. Stormwater PCBs were characterized by heavier congeners, likely associated with particles. Surface water PCB samples collected throughout DU N-2 exhibited heavier congeners and lighter congeners that are typically associated with the dissolved phase. These lighter congeners could have originated from a different source(s) and/or partitioned from the suspended phase. This PCB study employed optically-based techniques to assess and characterize stormwater delivery of PCBs to an industrial harbor. Understanding the mechanisms and pathways of PCB transport via stormwater is crucial for assessing the extent of contamination, identifying sources, and implementing effective management strategies to mitigate environmental impacts.

Grace Chang, Integral Consulting Inc., USA, https://orcid.org/0000-0002-5771-9636

Frank Spada, Integral Consulting Inc., USA

Keith Brodock, Integral Consulting Inc., USA

Craig Hutchings, Integral Consulting Inc., USA

Kim Markillie, Naval Facilities Engineering System Command Pacific, USA

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