Grantee Research Project Results
2005 Progress Report: Defining and Predicting PCB Fluxes and Their Ecological Effects in Stream and River Systems for Risk Characterizations
EPA Grant Number: R832213Title: 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: Hahn, Intaek
Project Period: March 1, 2005 through February 29, 2008 (Extended to February 28, 2009)
Project Period Covered by this Report: March 1, 2005 through February 29, 2006
Project Amount: $325,000
RFA: Greater Research Opportunities: Persistent, Bioaccumulative Chemicals (2004) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management , Safer Chemicals
Objective:
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.
Progress Summary:
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 sediments into overlying water and biota. This research will demonstrate improved characterizations and will predict how solids-associated PCB exposure affects aquatic organisms. This investigation of PCB fluxes between sediments and overlying water characterizes the dominant processes of resuspension, deposition, pore-water convection, and sorption/desorption and relates the resulting exposures to biological effects. This investigation 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 (Dick’s Creek, OH; Housatonic River, MA; Sheboygan River, WI), thus minimizing artifacts associated with pure compound spiking and equilibration concerns. Preliminary experiments are being conducted with dichlorodiphenyldichloroethylene (DDE), as a PCB surrogate. 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 solid phase microextraction (SPME) or Tenax, and with the following organisms: Lumbriculus variegates, Daphnia magna, Hyalella azteca, Chironomus tentans, and Pimephales promelas. These five U.S. Environmental Protection Agency (EPA) 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 Dick’s Creek. 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.
Four Ph.D. students have been placed on the project (despite the fact that there is funding for only two), and their work began in June 2005. During Year 1, the new students focused on literature review and establishing the SRFs, developing the analytical methods for DDE analyses and development of the process-based models. Difficulties were encountered at Washington State University (WSU) in getting a flume built via three contractors, but two SRFs are now nearing completion. The SRF at Texas A&M University-Kingsville (TAMUK) is functional and the focus there has been on the development of detailed DDE and PCB analytical protocols using a gas chromatography with an electron capture detector (GC-ECD). An SPME method was adopted and developed based on literature studies to extract DDE and PCB. Optimal SPME sorption periods of 30 minutes were determined. The optimal desorption period for GC analyses was found to be 2 minutes. Calibration studies found a sufficient amount of “unknown” DDE concentrations in water samples; thus the GC-ECD SPME method developed can be used in this research project.
Because the SRF to be used in the laboratory study is on a much smaller scale compared to any field experiments, the original in situ chamber for biological exposures had to be modified. The major modification of the current design of the in situ chamber is to replace part of the solid plastic tube with netting. This change is needed to minimize the flow disturbance caused by the installation of the chambers in the streambed. Another modification needed is to reduce the chamber dimensions so that higher resolution for subsurface sampling can be obtained and model predictions for subsurface contaminant distributions can be evaluated using the experimental results. These modification studies are ongoing at WSU and TAMUK. In addition, to better quantify the DDE and PCB concentration distributions in the streambed and across the surface water interface, new subsurface sampling techniques also are being tested. Annular grooves were cut every centimeter along the tube before sampling, which made the final cut of the tube after sampling a lot easier so that the sediment core remained in tact during the cutting processes.
Future Activities:
The short-term work plan for March 2006–March 2007 and expected results will include: (1) getting two new SRFs functional at WSU within 4 weeks; (2) adopting TAMUK SPME methods at WSU and conducting an inter-laboratory comparison using DDE; (3) completing the development of additional calibration curves to ensure the desired reliability of the DDE concentration analysis in water samples within the next 3 weeks; (4) conducting laboratory batch and column experiments to examine DDE adsorption and desorption kinetics and obtain input parameters to prepare subsequent model development; (5) completing modification of the in situ chambers for invertebrate exposures in the summer; (6) starting SRF experiments for the downwelling case in the fall; (7) applying the modified version of the multiphase transport model of Ren and Packman (2004) to the flume results obtained in the fall; (8) preparing the first journal publication focusing on the downwelling case in December 2006; and (9) initiating studies for the upwelling case in the fall.
Journal Articles:
No journal articles submitted with this report: View all 10 publications for this projectSupplemental Keywords:
sediment transport, bioassessment, sediment flux, PCB stream dynamics, sediment risk assessment,, RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Aquatic Ecosystem, Environmental Monitoring, Ecological Risk Assessment, bioassessment, risk assessment, aquatic sediments, aquatic ecosystems, PCB fluxes, riverine ecosystems, sediment dynamicsRelevant Websites:
http://www.wright.edu/~allen.burton
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.