Defining and Predicting PCB Fluxes and Their Ecological Effects in Stream and River Systems for Risk CharacterizationsEPA Grant Number: R832213
Title: Defining and Predicting PCB Fluxes and Their Ecological Effects in Stream and River Systems for Risk Characterizations
Investigators: Burton, Jr., G. Allen , Ren, Jianhong-Jennifer
Institution: Wright State University - Main Campus , Texas A & M University - Kingsville
EPA Project Officer: Carleton, James N
Project Period: March 1, 2005 through February 29, 2008 (Extended to February 28, 2009)
Project Amount: $325,000
RFA: Greater Research Opportunities: Persistent, Bioaccumulative Chemicals (2004) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Health Effects , Land and Waste Management , Safer Chemicals
The primary objective of this research project is to develop and verify a predictive model and approach for assessing polychlorinated biphenyls (PCB) flux and biological effects in lotic environments. The hypotheses are that the fate of PCBs is dominated and can be characterized by sediment type and flow conditions and directly relates to biological exposure and in situ effects.
This investigation necessarily involves laboratory experiments, theoretical modeling and field verification. Laboratory experiments will be conducted in stream recirculating flume systems (SRF) using a range of sediment types (low to high levels of gravel, sand, clay and organic matter) and flow conditions. The SRF will be loaded from above to simulate suspended solids loadings of PCB and from below to simulate groundwater upwellings and resuspension events. PCB contaminated sediments used in the SRF will be obtained from three well-studied sites (Dicks Creek, OH; Housatonic River, MA; Sheboygan River, WI), thus minimizing artifacts associated with pure compound spiking and equilibration concerns. The SRF will be used to calibrate the model and allow for simultaneous characterizations of bioaccumulation and adverse biological effects. Test organisms will be exposed to pore waters, surficial sediments, overlying waters and associated colloids and suspended sediments within the recirculating systems and in the field. PCB bioaccumulation and effects will be measured with Tenax, Lumbriculus variegates, Daphnia magna, Hyalella azteca, Chironomus tentans, and Pimephales promelas. These five test organisms and the biomimetic tool will link effects characterization with exposure over a range of typical riverine conditions, thus allowing for multi-species, ecological risk characterizations. The scope of this project will not allow for a complete field validation of the model; however, a field verification of flux process importance and the in situ assessment approach will be conducted in Dicks Creek.
In order to accurately determine ecological risk and effective remedial actions it is necessary to understand how ecosystem dynamics affect the linkage of exposure and ecological effects. In particular, a fundamental process that must be quantitatively understood is the flux of contaminants from the sediments into overlying water and biota. This research will demonstrate improved characterizations and predictions of solids-associated PCB exposure and effects to aquatic organisms. A comprehensive investigation of PCB fluxes between sediments and overlying water is needed that includes the dominant processes of resuspension, deposition, pore-water convection, and sorption/desorption. This will build on our previous investigations of sediment transport, contaminant flux and effects there and in other streams contaminated with persistent, bioaccumulative and toxic (PBT) compounds. Because the model is based on descriptions of dominant processes over a range of conditions, it will be readily transferable to other surface waters and to high flow events with minimal calibration. The accompanying in situ assessment approach will allow for accurate calibration of the model and generation of site-specific bioavailability and accumulation factors. This will provide improved determinations of PCB risk from contaminated sediments, thus improving risk management decision-making.