Final Report: Investigation on the Fate and Biotransformation of Hexachlorobutadiene and Chlorobenzenes in a Sediment-Water Estuarine System

EPA Grant Number: R825513C007
Subproject: this is subproject number 007 , established and managed by the Center Director under grant R825513
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: HSRC (1989) - South and Southwest HSRC
Center Director: Reible, Danny D.
Title: Investigation on the Fate and Biotransformation of Hexachlorobutadiene and Chlorobenzenes in a Sediment-Water Estuarine System
Investigators: Pavlostathis, Spyros G.
Institution: Georgia Institute of Technology
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1992 through January 1, 1995
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Hazardous Substance Research Centers , Land and Waste Management


Although research on contaminated sediments has been intensified in the last decade, we still lack fundamental knowledge of the processes and process interactions that govern the partitioning and transformation of sediment-bound toxic organic compounds. Information is lacking on the factors which control both the rate and extent of transformation of polychlorinated organic compounds to natural contaminated sediments. In order to address this need, we undertook an investigation into the contaminant fate processes, in particular microbial reductive dechlorination taking place in the sediments of Bayou d' Inde, a tributary of the Calcasieu River near Lake Charles, Louisiana. The major chlorinated contaminants in these sediments are hexachlorobenzene (HCB), other less chlorinated benzene congeners and hexachloro-1,3-butadiene (HCBD).

The specific objectives of this study were:

1) Characterization of selected sites in the Bayou d'Inde sediment/water estuarine system.
2) Assessment of the rate and extent of biotransformation of the target halogenated organic contaminants.
3) Investigation of the abiotic release mechanisms responsible for the fate of the target halogenated organic compounds.

Summary/Accomplishments (Outputs/Outcomes):

This research project was divided into three experimental phases. During Phase I, in-situ measurements as well as sediment and water samples were collected from representative stations within the estuarine system. Detailed analyses of these samples were performed in the laboratory. Based on these analyses, chlorinated benzenes and HCBD became the primary components for this study. During Phase II, desorption studies were conducted with field contaminated sediments. The rate and extent of contaminant desorption was examined. The objective of Phase III was to elucidate and quantify the rate and extent of the anaerobic biotransformation of sediment-bound chlorinated compounds. Sediment samples were incubated under simulated in-situ conditions with or without any addition of electron donors and nutrients. Liquid cultures were developed and the biotransformation of the chlorinated compounds was studied under predominately methogenic conditions. The effect of both contaminant and organic matter bioavailability on the microbial dehalogenation of the sediment-bound chlorinated organic compounds was also studied. All cultures were either batch or were fed semi-continuously.

Quantification of chronic sediment contamination remains a challenge. Based on the methods used in this study, the conventional Soxhlet extraction method produced the best results (high extraction efficiency and reproducibility). Contaminant extraction efficiency and variability introduce uncertainties in the assessment of both the environmental fate and hazards associated with recalcitrant, hydrophobic contaminants.

Desorption of chlorobenzenes and HCBD from contaminated sediments in Bayou d'Inde exhibited a biphasic initially fast then slow desorption pattern. The extent of HCBD desorption was the least of all other contaminants. All but 1,2,4-TrCB achieved less than 0.5% desorption in batch kinetic tests performed for 62 days. Successive desorption cycles enhanced the overall rate and extent of contaminated desorption. 1,2,4-TrCB exhibited the highest extent of desorption (ca. 17%). The extent and rate of desorption strongly correlated to the organic carbon-based partition coefficient of the contaminants. A significant fraction of the solid-phase contaminant concentration was found to be non-labile. Therefore, use of interstitial water contaminant concentrations, assuming equilibrium partitioning, would result in underestimation of sediment contaminant levels.

The implications of slow incomplete contaminant desorption are far reaching. The rate of release of chlorinated hydrophobic compounds not only is very slow but also a large fraction of the contaminant is desorption-resistant or non-labile within relatively short equilibration times. This desorption behavior combined with the recalcitrant nature of the chlorinated organic compounds lead to long-term persistence of these compounds in natural contaminated sediments. It appears that desorption could be the rate-limiting step in sediment remediation technologies such as in situ or ex situ bioremediation which are presently under consideration. In order to achieve an acceptable rate of sediment remediation, a means must be found to enhance both the rate and extent of contaminant desorption (e.g., use of surfactants).

Sediment nutrients (such as nitrogen and phosphorus) did not limit the biodegradation of the natural organic matter. Naturally occurring microrganisms mediate the reductive dechlorination of sediment-bound chlorinated organic compounds. However, because of the refractory nature of the sediment natural organic matter, as well as strong contaminant adsorption, a low extent of biotransformation was attained. Both an increase in contaminant hydrophobicity due to the effect of salinity, as well as the relatively high contaminant residence time may have contributed to the observed reduced contaminant bioavailability. On the other hand, microbial reductive dechlorination of the sediment-bound contaminants leads to the long-term release of less chlorinated and more mobile chlorinated compounds. The low electron transfer efficiency towards reductive dechlorination, as well as the limited extent of biotransformation of sediment contaminants need further investigation.

Our analysis of existing sediment contamination indicates that due to low contaminant desorption and biotransformation rates, these contaminants will persist for decades to come and that the predominant contaminant fate mechanism will be particle resuspension and transport. A better understanding of the factors involved in the bioavailability and transformation of sediment-bound contaminants will lead to a more accurate estimation of the impact of contaminant release on the aquatic environment, as well s to the development of means to either accelerate or control the dechlorination process for remediation processes.

Summary of Results:

  • Bioavailability of sediment organic matter limited by reductive dehalogenation in contaminated surficial sediments (LA)
  • Additions of bioavailable organic matter resulted in rapid dehalogenation of available contaminant
  • Desorption of contaminants was very slowly and to minimal levels (Supported work of Tomson)
  • Culture acclimated to hexachlorbutadiene rapidly dechlorinated hexachlorbenzene
  • Culture acclimated to hexchlorobenzene dechlorinated hexchlorobutadiene but at lower rates
  • Project led to EPA funded project "Influence of Non-ionic Surfactants on the Bioavailability of Chlorinated Benzenes for Microbial Reductive Dechlorination", $333,300, S.G. Pavlostathis and K.D. Pennell, GA Tech

  • Journal Articles on this Report : 6 Displayed | Download in RIS Format

    Other subproject views: All 26 publications 6 publications in selected types All 6 journal articles
    Other center views: All 392 publications 154 publications in selected types All 106 journal articles
    Type Citation Sub Project Document Sources
    Journal Article Booker RS, Pavlostathis SG. Microbial reductive dechlorination of hexachloro-1,3-butadiene in a methanogenic enrichment culture. Water Research 2000;34(18):4437-4445. R825513C007 (Final)
    not available
    Journal Article Gess P, Pavlostathis SG. Desorption of chlorinated organic compounds from a contaminated estuarine sediment. Environmental Toxicology & Chemistry 1997;16(8):1598-1605. R825513C007 (Final)
    not available
    Journal Article Pavlostathis SG. Model shows contaminants fate. Centerpoint 1993;2(2):10. R825513C007 (Final)
    not available
    Journal Article Pavlostathis SG, Prytula MT. Kinetics of the sequential microbial reductive dechlorination of hexachlorobenzene. Environmental Science & Technology 2000;34(18):4001-4009. R825513C007 (Final)
  • Full-text: ACS Full Text
  • Other: ACS PDF
  • Journal Article Prytula MT, Pavlostathis SG. Effect of contaminant and organic matter bioavailability on the microbial dehalogenation of sediment-bound chlorobenzenes. Water Research 1996;30(11):2669-2680. R825513C007 (Final)
  • Full-text: Science Direct Full Text
  • Abstract: Science Direct Abstract
  • Other: Science Direct PDF
  • Journal Article Prytula M, Pavlostathis SG. Extraction of sediment-bound chlorinated organic compounds: Implications on fate and hazard assessment. Water Science & Technology 1996;33(6):247-254. R825513C007 (Final)
    not available

    Supplemental Keywords:

    desorption, microbial transformation, and chlorinated organic compounds., RFA, Scientific Discipline, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Chemical Engineering, Contaminated Sediments, Environmental Chemistry, Fate & Transport, Analytical Chemistry, Hazardous Waste, Ecology and Ecosystems, Hazardous, Environmental Engineering, fate and transport, mathematical model, environmental technology, sediment treatment, hazardous waste management, hazardous waste treatment, risk assessment, contaminated marine sediment, soil and groundwater remediation, kinetics, confined disposal facilities, biodegradation, contaminated sediment, chemical contaminants, contaminated soil, hydrology, bioremediation of soils, marine sediments, remediation, chemical kinetics, currents, Chlorobenzenes, biotransformation, Hexachlorobutadiene, anaerobic biotransformation, extraction of metals, technology transfer, heavy metals, bioremediation, aquifer fate and treatment, technical outreach

    Progress and Final Reports:

    Original Abstract
  • 1992
  • 1993

  • Main Center Abstract and Reports:

    R825513    HSRC (1989) - South and Southwest HSRC

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R825513C001 Sediment Resuspension and Contaminant Transport in an Estuary.
    R825513C002 Contaminant Transport Across Cohesive Sediment Interfaces.
    R825513C003 Mobilization and Fate of Inorganic Contaminant due to Resuspension of Cohesive Sediment.
    R825513C004 Source Identification, Transformation, and Transport Processes of N-, O- and S- Containing Organic Chemicals in Wetland and Upland Sediments.
    R825513C005 Mobility and Transport of Radium from Sediment and Waste Pits.
    R825513C006 Anaerobic Biodegradation of 2,4,6-Trinitrotoluene and Other Nitroaromatic Compounds by Clostridium Acetobutylicum.
    R825513C007 Investigation on the Fate and Biotransformation of Hexachlorobutadiene and Chlorobenzenes in a Sediment-Water Estuarine System
    R825513C008 An Investigation of Chemical Transport from Contaminated Sediments through Porous Containment Structures
    R825513C009 Evaluation of Placement and Effectiveness of Sediment Caps
    R825513C010 Coupled Biological and Physicochemical Bed-Sediment Processes
    R825513C011 Pollutant Fluxes to Aquatic Systems via Coupled Biological and Physicochemical Bed-Sediment Processes
    R825513C012 Controls on Metals Partitioning in Contaminated Sediments
    R825513C013 Phytoremediation of TNT Contaminated Soil and Groundwaters
    R825513C014 Sediment-Based Remediation of Hazardous Substances at a Contaminated Military Base
    R825513C015 Effect of Natural Dynamic Changes on Pollutant-Sediment Interaction
    R825513C016 Desorption of Nonpolar Organic Pollutants from Historically Contaminated Sediments and Dredged Materials
    R825513C017 Modeling Air Emissions of Organic Compounds from Contaminated Sediments and Dredged Materials title change in last year to "Long-term Release of Pollutants from Contaminated Sediment Dredged Material"
    R825513C018 Development of an Integrated Optic Interferometer for In-Situ Monitoring of Volatile Hydrocarbons
    R825513C019 Bioremediation of Contaminated Sediments and Dredged Material
    R825513C020 Bioremediation of Sediments Contaminated with Polyaromatic Hydrocarbons
    R825513C021 Role of Particles in Mobilizing Hazardous Chemicals in Urban Runoff
    R825513C022 Particle Transport and Deposit Morphology at the Sediment/Water Interface
    R825513C023 Uptake of Metal Ions from Aqueous Solutions by Sediments
    R825513C024 Bioavailability of Desorption Resistant Hydrocarbons in Sediment-Water Systems.
    R825513C025 Interactive Roles of Microbial and Spartina Populations in Mercury Methylation Processes in Bioremediation of Contaminated Sediments in Salt-Marsh Systems
    R825513C026 Evaluation of Physical-Chemical Methods for Rapid Assessment of the Bioavailability of Moderately Polar Compounds in Sediments
    R825513C027 Freshwater Bioturbators in Riverine Sediments as Enhancers of Contaminant Release
    R825513C028 Characterization of Laguna Madre Contaminated Sediments.
    R825513C029 The Role of Competitive Adsorption of Suspended Sediments in Determining Partitioning and Colloidal Stability.
    R825513C030 Remediation of TNT-Contaminated Soil by Cyanobacterial Mat.
    R825513C031 Experimental and Detailed Mathematical Modeling of Diffusion of Contaminants in Fluids
    R825513C033 Application of Biotechnology in Bioremediation of Contaminated Sediments
    R825513C034 Characterization of PAH's Degrading Bacteria in Coastal Sediments
    R825513C035 Dynamic Aspects of Metal Speciation in the Miami River Sediments in Relation to Particle Size Distribution of Chemical Heterogeneity