Victor A. McFarland

Bioaccumulation Potential of Sediment-Associated Polychlorinated Biphenyls (PCBs) in Ashtabula Harbor, Ohio

Ashtabula Harbor, Ohio is designated as a Great Lakes Area of Concern contaminated by PCBs. Information on the bioaccumulation of PCBs from sediments is important for sediment management strategies such as dredging to restore navigable depths in the harbor. To ascertain the bioaccumulation of these PCBs, the aquatic earthworm Lumbriculus variegatus was exposed in the laboratory to contaminated sediments collected from 15 areas in the harbor. Data from these bioaccumulation experiments were used to determine the bioaccumulation potential of PCBs through the calculation of Biota- Sediment Accumulation Factors (BSAFs). The results showed that the mean values of the experimentally derived BSAFs for individual harbor areas ranged from 0.27 to 1.69. The median BSAF for sediments in the lower river sector of the harbor (0.38) was significantly lower than that for upper river sediments (1.34), indicating that the high adsorptive properties of coal soot particles constrained PCB bioavailability in the lower river sediments. These results indicate that the origin of total organic carbon (TOC) has a major influence on the bioavailability of total PCBs in harbor sediments. Moreover, the empirical BSAFs were well below the 4.0 default BSAF value recommended in joint USEPA/USACE protocols that are used to evaluate the Theoretical Bioaccumulation Potential, or bioavailability, of neutral organic chemicals in Great Lakes sediments. These empirical values should be used to more precisely predict the bioavailability of total PCBs in Ashtabula Harbor sediments.

PROFILING THE DEPTH AND EXTENT OF CONTAMINATION OF A SHIP CHANNEL USING THE P450RGS CELL-BASED ASSAY FOR DIOXINS AND RELATED COMPOUNDS

A rapid and sensitive cell-based screening assay for dioxin equivalences (TCDD EQs) in dredged sediments has been developed. The P450RGS assay employs a transgenic human hepatoma cell line in which the firefly luciferase gene, Zuc, has been stably inserted as a reporter. P450RGS conforms to APHA Standard Method 8070 and ASTM Standard E-1853. EPA has promulgated the assay as EPA Method 4425 in update IVA of the EPA SW846 Methods Manual. Modifications to the method made at USACE ERDC-WES include a combined extraction/cleanup procedure using accelerated solvent extraction (ASE) with a sulfuric acid/silica gel packing in the extraction cell, and a 96-well microtiter plate format for the assay. These modifications substantially increase the volume of sample throughput and reduce the cost of the assay. Assays in which TCDD EQs are reported are typically less than l/lOth the cost of dioxin analysis using GC/MS, and have comparable sensitivity. In this study 13 stations were designated at intervals extending from the mouth to the apex of a navigation channel requiring dredging. Cores from 3 to 12-l? sediment depth were sectioned and assayed for TCDD EQs using P450RGS. Seven of the cores were also analyzed by conventional chemical methods for chemical contaminants. Additional cores were taken for bioaccumulation and toxicity testing. The pattern and relative magnitudes of contamination found with the chemical analyses was highly correlated with that identified by the P450RGS assay (r2 = 0.816 to 0.892, P << 0.001). Additionally, the P450RGS results provided a surrogate for highly expensive GC/MS analysis for dioxins at a small fraction of the cost of chemical analysis. More extensive sampling than would have been affordable using only conventional chemistry resulted in a fuller characterization of the extent and depth of contamination, and demonstrated the utility of the cell-based assay as a screening and monitoring tool for navigation channel sediments.