Environmental Health - Toxic Substances
U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting Charleston South Carolina March 8-12,1999--Volume 2 of 3--Contamination of Hydrologic Systems and Related Ecosystems, Water-Resources Investigation Report 99-4018B
Evaluation of Polychlorinated Biphenyl Contamination in the Saginaw River Using Sediments, Caged Fish and SPMDs
By Kathy R. Echols, Robert W. Gale, Ted R. Schwartz, Jim N. Huckins, Lisa L. Williams, John C. Meadows, Carl E. Orazio, Jimmie D. Petty, and Donald E.Tillitt
This paper is available in pdf format: Echols.pdf
The Saginaw River is contaminated with a number of industrial pollutants including polychlorinated biphenyls (PCBs). Understanding of the risk posed by PCBs in the aquatic system requires measurement of the dissolved, bioavailable levels of PCBs. In this study, three means of assessing bioavailability were compared: sediments, caged fish, and semipermeable membrane devices (SPMDs). Caged channel catfish and SPMDs were placed in the river for one month at five sites where sediments were also sampled. PCBs were analyzed by congener specific methods to determine PCB concentrations and patterns. Total PCB concentrations ranged 33 - 277 ng/g in sediments, 46 - 290 ng/g in caged fish, and 77 - 792 ng/g in SPMDs. SPMD and sediments provide complementary PCB information: sediments reflecting long term accumulation while SPMDs indicate what was present in the water at the site during the sampling period. Differences in PCB patterns in caged fish and SPMDs are due to lower chlorinated PCBs having reached steady state with the fish but not with the SPMD. Sediments were assumed to have reached equilibrium with PCBs in the water. Concentrations and patterns of dissolved PCB congeners were estimated from sediment data using an equilibrium model. The SPMD-based dissolved concentrations were estimated by using SPMD accumulation rates for 86 PCBs that were determined in an earlier SPMD calibration study. Steady-state bioconcentration factors for PCB congeners were used to estimate times required to reach steady state; congener concentrations in the fish were then normalized to steady state, and an equilibrium model was applied. The three methods indicated that similar patterns and concentrations of dissolved PCBs were present in the Saginaw River.