Formatted Title:

Evaluation of Potential Ongoing PCB Sources Using a Combination of Data at the Apra Harbor Sediment Site

Background/Objectives:

Sediment contamination requiring remediation for polychlorinated biphenyls (PCBs) has been identified at the Apra Harbor Sediment site. However, remediation should not take place prior to identification and mitigation of potential ongoing sources of PCB to the harbor. Collocated bulk sediment, fish tissue, porewater, water column, and sediment trap data were collected to provide additional data for an evaluation of potential ongoing sources prior to site sediment remediation. PCB concentrations and congener profiles for each environmental media were evaluated to assess relationships between the various media and the potential to use porewater, water column, sediment, fish tissue and sediment trap data relationships to evaluate ongoing sources.

As part of the 2014 remedial investigation at the site, collocated sediment and fish tissue samples were collected at various locations throughout the harbor to evaluate risks from exposure to PCBs in sediment. Collocated sediment and fish tissue data were used to establish biota-sediment accumulation factors and establish the preliminary remediation goals for sediment remediation. Additional collocated sediment and fish tissue data were collected as part of the 2017 feasibility study. Most recently in 2024, during the basis of design phase, collocated bulk sediment, fish tissue, porewater, water column, and sediment trap data were collected. Passive samplers were used to collect porewater data, as well as water column data. Sediment traps were used to collect data over a four-month period on sediment entering the harbor as part of the Navy’s ongoing source investigation. The objectives of this evaluation were to determine if there are ongoing sources of PCB to the harbor, to identify temporal trends in PCB concentrations in sediment, porewater, water column, and fish tissue prior to remedy implementation, add to the baseline fish tissue and porewater dataset, and assess how PCBs are distributed between sediment, fish tissue, porewater, and the water column in Apra Harbor.

Approach/Activities:

Total PCB concentrations (calculated as two times the sum of the NOAA-18 congeners) in sediment (bulk and from sediment traps), porewater, water column, and fish tissue were compared between the various data sets (2014, 2017, and 2024) to evaluate potential ongoing sources and temporal trends. PCB concentrations in sediment, fish tissue, and porewater were plotted against each other to evaluate correlation between the different media. Analysis of congener profile distributions in sediment (bulk and from sediment traps), fish tissue, porewater, and water column were conducted to evaluate how PCBs are distributed and correlated between these environmental media, and if any significant ongoing sources are present.

Results/Lessons Learned:

The collocated bulk sediment and sediment trap data, fish tissue, porewater, and water column dataset provide insight to the PCB congener distribution for all environmental media sampled. The results of this evaluation indicate that PCBs are present in all three media and concentration distributions generally show strong correlation between sediment, fish tissue, and porewater. Based on the overall evaluation, ongoing sources of PCBs to the harbor are insignificant and should not prevent implementation of future sediment remediation.

Adam Miyamoto

Affiliation

Refine Results

(Group 2, Poster Board #24) Evaluation of Potential Ongoing PCB Sources Using a Combination of Data at the Apra Harbor Sediment Site