Grantee Research Project Results
2001 Progress Report: Modeling Microbial PCB Degradation and Binding
EPA Grant Number: R826652Title: Modeling Microbial PCB Degradation and Binding
Investigators: Balaz, Stefan
Institution: North Dakota State University Main Campus
EPA Project Officer: Aja, Hayley
Project Period: September 1, 1998 through August 31, 2001 (Extended to August 31, 2002)
Project Period Covered by this Report: September 1, 2001 through August 31, 2002
Project Amount: $375,000
RFA: Exploratory Research - Environmental Chemistry (1998) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , Land and Waste Management , Air , Safer Chemicals
Objective:
The objective of this research project is to develop a complete kinetic description of the fate of individual PCB congeners in aqueous media and soil systems as determined by structure and physicochemical properties of congeners.Progress Summary:
Partitioning between aqueous and nonpolar phases of biological systems is one of the factors governing the PCB fates. The process is most comfortably studied in defined model systems, in absence of any complicating interactions. We used a modified slow-stirring method (de Bruijn, et al., 1990) with increased throughput for kinetic experiments.The partitioning was monitored for selected pure PCB congeners, present either in Delor 103, Delor 106, or both. In some cases, the partitioning for various initial PCB concentrations and binary PCB mixtures was studied. The 1?octanol/water partition coefficients Kow of individual PCB congeners in technical mixtures are lower than the respective values observed for pure congeners by up to 230 percent. The higher the overall hydrophobicity (chlorination) of the technical mixture, the lower the value of Kow.
To gain more insight, the 1?octanol concentrations in the aqueous phase also were analyzed, and the variations ranged from +25 percent to -28 percent of solubility. Complexity of the phenomenon is illustrated using partitioning of pure biphenyl and biphenyl/2-chlorobiphenyl mixture with varying initial biphenyl concentration in the experimental system (Figures 1 and 2).
For pure biphenyl, the values of log Kow increase with concentration by about 0.5 unit. In the, biphenyl/2?chlorobiphenyl mixture, the changes are significantly smaller. The results indicate that different molecular species may be present in the phases of the experimental system. To characterize and quantitatively describe the fractions of the actual molecular species present during biphenyl and PCB partitioning in individual phases of the 1?octanol/water system, experiments on evaporation kinetics of biphenyl and PCBs from individual phases were initiated.
Future Activities:
Kinetics of evaporation from individual phases of the 1-octanol/water system for biphenyl and individual PCB congeners, both as pure and in mixtures, will be studied. The aim is to reveal the composition of the PCB solutions in terms of number of molecular species and their fractions. Partitioning in phospholipid monolayers that imitate biological membranes will be monitored and modeled. Interactions of PCB congeners with individual soil components and complete soils after a yearlong incubation will be studied by extraction. Degradation of PCB in soils will be monitored and described in a similar way as for the liquid media.Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 39 publications | 18 publications in selected types | All 12 journal articles |
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Type | Citation | ||
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Balaz S, Lukacova V. Subcellular pharmacokinetics and its potential for library focusing. Journal of Molecular Graphics & Modelling 2002;20(6):479-490. |
R826652 (2001) R826652 (Final) |
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Supplemental Keywords:
quantitative structure-activity relationships, QSAR, quantitative structure-time-activity relationships, QSTAR, biosorption, hydrophobicity, lipophilicity., RFA, Scientific Discipline, Air, Toxics, Waste, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, National Recommended Water Quality, Physics, Remediation, Environmental Chemistry, Ecosystem/Assessment/Indicators, Ecosystem Protection, Ecological Effects - Environmental Exposure & Risk, Bioremediation, Ecological Risk Assessment, Engineering, Chemistry, & Physics, Ecological Indicators, aquatic ecosystem, ecological exposure, ecological effects, fate and transport, risk assessment, aquatic, dioxin, bioremediation model, biostabilization of PCBs, decontamination of soil and water, microbial degradation, fate of PCB congeners, enzymes, PCBs, biokinetic model, chemical transport, modeling, bioremediation of soils, contaminants in soil, binding, PCB, polychlorinated biphenyls, chemical kinetics, human exposure, hydrophobic chemicals, soil, furans, quantitative structure activity relationship, bioacummulationRelevant Websites:
http://www.ndsu.nodak.edu/instruct/balaz/pcbdegrb.htm
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.