Final Report: Contaminant Binding to the Humin Fraction of Soil Organic Matter

EPA Grant Number: R825549C058
Subproject: this is subproject number 058 , established and managed by the Center Director under grant R825549
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: HSRC (1989) - Great Plains/Rocky Mountain HSRC
Center Director: Erickson, Larry E.
Title: Contaminant Binding to the Humin Fraction of Soil Organic Matter
Investigators: Rice, James A.
Institution: South Dakota State University
EPA Project Officer: Hahn, Intaek
Project Period: May 18, 1995 through May 17, 1998
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989) RFA Text |  Recipients Lists
Research Category: Analysis/Treatment of Contaminated Soil , Land and Waste Management

Objective:

The goal of this research is to understand contaminant binding to soil organic matter, particularly the fraction known as humin. The overall objectives of the proposed study can be placed into two groups; to study contaminant-humin binding mechanisms and to develop a model to describe the binding phenomena. The specific objectives of this proposal are:

Contaminant-Humin Binding Mechanisms

1 . determine whether polynuclear aromatic hydrocarbons and polychlorinated biphenyls bound to humin are more likely to be associated with the insoluble residue, the lipid (bitumen and/or bound lipid) or the bound-humic acid components of humin.

2 . test the hypothesis that PAHs and PCBs bind to the Sephadex fraction of the bound-humic component of humin with the highest aromatic carbon content.

3 . begin to identify the nature of the bound contaminants. Determine whether it is the parent contaminant itself, or its degradation or alteration product, which is bound to humin.

Modeling the Binding Phenomena

4. determine the role of bitumen and bound lipids in the binding of contaminants to humin. Specifically, it is proposed that contaminants are first partitioned into the bitumen and/or bound-lipid components of humin before being irreversibly bound and that the removal of bitumen from a humin sample will decrease its affinity for these compounds.

5 . develop a conceptual model to describe contaminant binding to humin. It is proposed that bitumen and bound-lipids are responsible for the initial steps of contaminant binding. The contaminants subsequently react with the humic components of humin to form more recalcitrant residues.

Summary/Accomplishments (Outputs/Outcomes):

Most previous work on the nature of contaminant binding to soil organic matter has utilized 14C-labeled compounds to reconstruct the fate of contaminants introduced into a soil system. Essentially all of these studies have stopped at the point of assigning a fraction of the bound-radioactivity to one of the humic fractions of soil organic matter; no studies have been able to characterize the actual nature of bound- residues or the nature of their interaction with a humic material.
The humin fraction of humic substances is usually the predominant organic material in most soils; humin organic-carbon typically represents more than 50% of the total organic-carbon in a soil, and a significant fraction of most anthropogenic organic compounds (e.g., pesticides, herbicides, polynuclear aromatic hydrocarbons (PAHS) and polychlorinated biphenyls (PCBs)) bind rapidly, and in many cases, irreversibly, to it. Yet, despite these compelling reasons for a detailed understanding of the nature of contaminant binding to humin, very little is known about its environmental chemistry.

The proposed study utilizes a new technique that not only isolates humin, but for the first time, permits the separation of humin's organic components from its inorganic component and fractionates the organic components into recognized compound classes (lipids, humic acid-like, and a mineral dominated insoluble residue). This method uses the water-immiscible organic solvent methyl-isobutylketone (MIBK) and an aqueous phase whose pH is varied to isolate and subsequently fractionate humin. It represents the fundamental advance necessary to study contaminant binding to humin. Carbon- 14 and carbon- 13 labeled contaminants (atrazine, 2,4-D (2,4-dichlorophenoxyacetic acid), the polynuclear aromatic hydrocarbons naphthalene, phenanthrene and benzo[a]pyrene and the polychlorinated biphenyls 4,4'-dichlorobiphenyl and 2,2',4,5,5'-pentachlorobiphenyl will be incubated with two soils of different composition in separate experiments. The organic components of the soil will be isolated by a combination of traditional and the MIBK methods. Humin will be fractionated into its components using the MIBK method. Using Sephadex gel filtration and scintillation counting and 13C CPMAS NMR the organic matter will be fractionated and the qualitative and quantitative nature of contaminant binding to humin assessed. The role of lipids in contaminant binding to humin will be investigated utilizing column adsorption studies with humin from which first the lipids and then the humic component have been selectively removed. These results will be evaluated in light of the partitioning model of contaminant sorption to soil organic matter.

The humin fraction of the humic substances is usually the predominant organic material in most soils and sediments; humin organic-carbon typically represents more than 50% of the total organic-carbon in a soil. A significant fraction of most anthropogenic organic compounds (e.g., polynuclear aromatic hydrocarbons (PAHS) and polychlorinated biphenyls (PCBs) bind rapidly, and in many cases, irreversibly, to it forming what are known as "bound residues". The role of humin and its organic components in the formation of bound residues is systematically explored in this study. The goals of this study were to begin to develop an understanding of mechanism(s) of PAH and PCB binding to humin and develop a model to describe the binding phenomena. The specific objectives of the study were to determine the quantitative importance of humin and the individual components of humin in bound residue formation, examine the binding phenomena using a variety of analytical techniques including nuclear magnetic resonance and isotopic labeling of PAH and PCB molecules using 14C and 19F, and determine whether a partitioning, "dual-mode" sorption, or "distributed reactivity" model best describes the binding process. This study utilized a technique that not only isolated humin, but for the first time, permitted the separation of humin's organic components from its inorganic component and fractionated the organic components into recognized compoundclasses (lipids, humic acid-like, and a mineral-dominated insoluble residue). This method used the water-immiscible organic solvent methyl-isobutylketone (MIBK) and an aqueous phase whose pH is varied to isolate and subsequently fractionate humin. This method represented the fundamental advance necessary to study contaminant binding to humin.

The following is a list of accomplishments that represent the major findings of this study. Other accomplishments that have been the result of collaborations with other HSRC investigators, or outgrowths of this project, are also noted.

Project Accomplishments:

  • PAHs and PCBs irreversibly bind predominantly (>50% of the total HOC introduced) to the humin fraction of soil organic matter.
  • Of the constituents of humin, the bound PAHs and PCBs preferentially associate with the bound-lipid component. Because the bound humic acid component represents a much larger fraction of the organic carbon in humin, more bound contaminant is associated with this component on an absolute basis.
  • PAH binding to soil organic matter and humin is nonlinear which indicates site specific interactions. This is in contrast to the generally cited partitioning model, which describes hydrophobic organic contaminant (HOC) interaction with soil organic matter as a solute partitioning phenomena.
  • Using 19F PAHs and PCBs and solid-state 19F NMR, it was observed that bound-residue formation occurred in a manner that is consistent with either the dual-mode sorption or distributed reactivity models.
  • Using solid-state 19F NMR observation of bound residue formation, this study corroborated sorption experiments using 14C-labeled PAHs and PCBs which demonstrated that lipids compete for PAH sorption sites.
  • Removal of lipids decreased the tendency of PAHs and PCBs to form bound residues. For example incubation of benzo[a]pyrene with soil extracted to remove lipids decreased the percentage of HOC bound from 52% to 31%. Thus, lipids not only occupy similar binding sites as anthropogenic HOCs in the soil matrix, but enhance the binding sites or initial interactions that are necessary to form bound PAH and PCB residues.

    Other Accomplishments:

  • The MIBK method has been applied to fractionate bound FAH residues in soil from an actual contaminated soil in collaboration R.C. Sims and J.K.C. Nieman, Utah State University.
  • A comparison of the MIBK method and the traditional alkaline extraction method for fractionating soil organic matter has been prepared based on the work done in this study.
  • A comparison of the effect of solvent and supercritical fluid HOC extraction methods on the surface morphology of soil particles using small-angle x-ray scattering and surface area measurements is currently in the final stages of data evaluation.

    The technology transfer activities of this project have been in the form of disseminating the results of the work in the form of oral presentations at national and regional meetings, preparation of written publication of these results and sharing our expertise in the MIBK method with Dr. Sims, HSRC project (#93- 21). Dr. Rice had numerous consultations with Karl Nieman, a graduate student working with Dr. Sims, to assist him in applying the MIBK method for fractionating soil organic matter and humin to their work. This work has resulted in a presentation and two publications. Dr. Rice has also shared the MIBK method with Dr. Pat Shea (University of Nebraska-Lincoln) who has had a HSRC-sponsored project (#95-32), and discussed its application with him on the phone on several occasions.


  • Journal Articles on this Report : 4 Displayed | Download in RIS Format

    Other subproject views: All 17 publications 4 publications in selected types All 4 journal articles
    Other center views: All 904 publications 230 publications in selected types All 182 journal articles
    Type Citation Sub Project Document Sources
    Journal Article Kohl SD, Rice JA. The binding of contaminants to humin: a mass balance. Chemosphere 1998;36(2):251-261. R825549C058 (Final)
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  • Journal Article Kohl SD, Toscano PJ, Hou W, Rice JA. Solid-state 19F NMR investigation of hexafluorobenzene sorption to soil organic matter. Environmental Science & Technology 2000;34(1):204-210. R825549C058 (Final)
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  • Journal Article Kohl SD, Rice JA. Contribution of lipids to the nonlinear sorption of polycyclic aromatic hydrocarbons to soil organic matter. Organic Geochemistry 1999;30(8 Part 2):929-936. R825549C058 (Final)
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  • Journal Article Nieman JKC, Sims RC, Sims JL, Sorenson DL, McLean JE, Rice JA. [14C]Pyrene bound residue evaluation using MIBK fractionation method for creosote-contaminated soil. Environmental Science & Technology 1999;33(5):776-781. R825549C051 (Final)
    R825549C058 (Final)
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  • Abstract: ACS-Abstract
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  • Supplemental Keywords:

    contaminant binding, humin, soil organic matter, binding mechanisms., RFA, Scientific Discipline, Waste, Geographic Area, Water, Contaminated Sediments, Remediation, Environmental Chemistry, Geochemistry, Chemistry, Analytical Chemistry, Hazardous Waste, Ecology and Ecosystems, Hazardous, EPA Region, fate and transport, sediment treatment, contaminant transport, NAPL, fate and transport , soil and groundwater remediation, contaminated sediment, contaminated soil, hazardous organic contaminants, Region 7, Region 8, oil spills, contaminated groundwater, hydrocarbons, hazardous organic compounds, phytoremediation, groundwater, binding interactions, humin

    Relevant Websites:

    http://www.engg.ksu.edu/HSRC Exit

    Progress and Final Reports:

    Original Abstract
  • 1995
  • 1996

  • Main Center Abstract and Reports:

    R825549    HSRC (1989) - Great Plains/Rocky Mountain HSRC

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R825549C006 Fate of Trichloroethylene (TCE) in Plant/Soil Systems
    R825549C007 Experimental Study of Stabilization/Solidification of Hazardous Wastes
    R825549C008 Modeling Dissolved Oxygen, Nitrate and Pesticide Contamination in the Subsurface Environment
    R825549C009 Vadose Zone Decontamination by Air Venting
    R825549C010 Thermochemical Treatment of Hazardous Wastes
    R825549C011 Development, Characterization and Evaluation of Adsorbent Regeneration Processes for Treament of Hazardous Waste
    R825549C012 Computer Method to Estimate Safe Level Water Quality Concentrations for Organic Chemicals
    R825549C013 Removal of Nitrogenous Pesticides from Rural Well-Water Supplies by Enzymatic Ozonation Process
    R825549C014 The Characterization and Treatment of Hazardous Materials from Metal/Mineral Processing Wastes
    R825549C015 Adsorption of Hazardous Substances onto Soil Constituents
    R825549C016 Reclamation of Metal and Mining Contaminated Superfund Sites using Sewage Sludge/Fly Ash Amendment
    R825549C017 Metal Recovery and Reuse Using an Integrated Vermiculite Ion Exchange - Acid Recovery System
    R825549C018 Removal of Heavy Metals from Hazardous Wastes by Protein Complexation for their Ultimate Recovery and Reuse
    R825549C019 Development of In-situ Biodegradation Technology
    R825549C020 Migration and Biodegradation of Pentachlorophenol in Soil Environment
    R825549C021 Deep-Rooted Poplar Trees as an Innovative Treatment Technology for Pesticide and Toxic Organics Removal from Soil and Groundwater
    R825549C022 In-situ Soil and Aquifer Decontaminaiton using Hydrogen Peroxide and Fenton's Reagent
    R825549C023 Simulation of Three-Dimensional Transport of Hazardous Chemicals in Heterogeneous Soil Cores Using X-ray Computed Tomography
    R825549C024 The Response of Natural Groundwater Bacteria to Groundwater Contamination by Gasoline in a Karst Region
    R825549C025 An Electrochemical Method for Acid Mine Drainage Remediation and Metals Recovery
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    R825549C027 Heavy Metals Removal from Dilute Aqueous Solutions using Biopolymers
    R825549C028 Neutron Activation Analysis for Heavy Metal Contaminants in the Environment
    R825549C029 Reducing Heavy Metal Availability to Perennial Grasses and Row-Crops Grown on Contaminated Soils and Mine Spoils
    R825549C030 Alachlor and Atrazine Losses from Runoff and Erosion in the Blue River Basin
    R825549C031 Biodetoxification of Mixed Solid and Hazardous Wastes by Staged Anaerobic Fermentation Conducted at Separate Redox and pH Environments
    R825549C032 Time Dependent Movement of Dioxin and Related Compounds in Soil
    R825549C033 Impact of Soil Microflora on Revegetation Efforts in Southeast Kansas
    R825549C034 Modeling the use of Plants in Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances
    R825549C035 Development of Electrochemical Processes for Improved Treatment of Lead Wastes
    R825549C036 Innovative Treatment and Bank Stabilization of Metals-Contaminated Soils and Tailings along Whitewood Creek, South Dakota
    R825549C037 Formation and Transformation of Pesticide Degradation Products Under Various Electron Acceptor Conditions
    R825549C038 The Effect of Redox Conditions on Transformations of Carbon Tetrachloride
    R825549C039 Remediation of Soil Contaminated with an Organic Phase
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    R825549C041 Heavy Metals Removal from Contaminated Water Solutions
    R825549C042 Metals Soil Pollution and Vegetative Remediation
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    R825549C046 Fate and Transport of Heavy Metals and Radionuclides in Soil: The Impacts of Vegetation
    R825549C047 Vegetative Interceptor Zones for Containment of Heavy Metal Pollutants
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    R825549C050 Evaluation of Biosparging Performance and Process Fundamentals for Site Remediation
    R825549C051 Field Scale Bioremediation: Relationship of Parent Compound Disappearance to Humification, Mineralization, Leaching, Volatilization of Transformaiton Intermediates
    R825549C052 Chelating Extraction of Heavy Metals from Contaminated Soils
    R825549C053 Application of Anaerobic and Multiple-Electron-Acceptor Bioremediation to Chlorinated Aliphatic Subsurface Contamination
    R825549C054 Application of PGNAA Remote Sensing Methods to Real-Time, Non-Intrusive Determination of Contaminant Profiles in Soils
    R825549C055 Design and Development of an Innovative Industrial Scale Process to Economically Treat Waste Zinc Residues
    R825549C056 Remediation of Soils Contaminated with Wood-Treatment Chemicals (PCP and Creosote)
    R825549C057 Effects of Surfactants on the Bioavailability and Biodegradation of Contaminants in Soils
    R825549C058 Contaminant Binding to the Humin Fraction of Soil Organic Matter
    R825549C059 Identifying Ground-Water Threats from Improperly Abandoned Boreholes
    R825549C060 Uptake of BTEX Compounds by Hybrid Poplar Trees in Hazardous Waste Remediation
    R825549C061 Biofilm Barriers for Waste Containment
    R825549C062 Plant Assisted Remediation of Soil and Groundwater Contaminated by Hazardous Organic Substances: Experimental and Modeling Studies
    R825549C063 Extension of Laboratory Validated Treatment and Remediation Technologies to Field Problems in Aquifer Soil and Water Contamination by Organic Waste Chemicals