PYRENE AVAILABILITY AS DETERMINED BY THE INTERACTIONS OF NATURAL ORGANIC MATTER WITH THE SOIL MINERAL MATRIX Denise Marie Brown A dissertation submitted to the faculty of the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Environmental Sciences and Engineering, School of Public Health. Chapel Hill 2006 Approved by: Advisor: Professor Frederic K. Pfaender Reader: Professor Michael D. Aitken Reader: Professor Marc J.
Alperin Reader: Professor Russell F. Christman Reader: Professor Steven C. Whalen UMI Number: 3239256 UMI Microform 3239256 Copyright 2007 by ProQuest Information and Learning Company. All rights reserved.
This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P. Box 1346 Ann Arbor, MI 48106-1346 © 2006 Denise Marie Brown ALL RIGHTS RESERVED ii ABSTRACT DENISE MARIE BROWN: Pyrene Availability as Determined by the Interactions of Natural Organic Matter with the Soil Mineral Matrix. (Under the direction of Professor Frederic K.
Pfaender) Soil organic matter (SOM), especially humic substances and biological material, profoundly affect polyaromatic hydrocarbon (PAH) movement, toxicity, and degradation when assessing acceptable end points for in situ remediation practices. The complex, inter- dependent relationship between soil chemical and physical attributes makes determining absolute PAH fate, transport, and availability a formidable task. This research attempted to correlate the impact known SOM components have on pyrene sorption as related to sorbent loading and type and mineral phase aggregation. The objective was achieved by generating a synthetic soil, composed of mineral matter, humic acid (HA), and peptidoglycan (PG), and comparing this matrix to freshly contaminated and aged natural soils, using pyrene as the representative hydrophobic organic contaminant.
In contrast to HA, a larger concentration of PG sorbed to both mineral phases (hematite and montmorillonite clay); thus, promoting further particle aggregation, and effectually resulting in greater pyrene sorption as evidenced by HPLC and fluorescence microscopy. The greater the concentration and number of constituents introduced into the synthetic matrix, culminating in a HA+PG mixture loaded onto clay, the greater the resulting pyrene sorption and similarity to spiked natural soils, both in chemical and physical attributes. The final result was a compiled fluorescence map visually detailing pyrene iii location and percentage sorbed in relation to PG, HA, and the mineral phases for natural and synthetic soils, where the biological constituent held a significant influence over pyrene compared to that by the humic substances. In summary, the type and concentration of SOM constituents, specifically humic substances and biological material, sorbed to a mineral phase significantly impact soil physical and chemical characteristics, and therefore, should be accounted for when determining pyrene fate, transport, and availability within contaminated soil systems.
Potentially, when these observations are combined with fluorescence microscopy, consultants could determine the most effective remediation technology to target specific locations, such as pore spaces, or strong sorptive entities, such as PG, and achieve acceptable end-points. iv This dissertation is dedicated to those that supported me the most…. To my parents, Robert and Sandy Brown, who taught me to persevere and strive for the best. To my brother and sister-in-law, Darren and Angela Brown, who always knew when to ask “Aren’t you done yet?” Finally, to my nephew, Austin, who always inspires me.
Finally, to my husband, Jeff Zborowski, who was kind enough to go to Iraq for seven months and leave me alone to finish this monstrosity, but also the one to make me smile through the frustration and love me through the tears. v ACKNOWLEDGEMENTS This research was supported by the Superfund Hazardous Substances Basic Research Program grant (5P42ES05948). For use of their scientific instruments, I thank Professor Marc Alperin (TOC), Professor Mike Aitken (HPLC), Dr. Wallace Ambrose (SEM), and Dr.
For their valuable assistance, I acknowledge Dr. Robert Schoonhoven (image analysis and compilation), Dr. Chad Roper (flow cell and HPLC method), Tom Long and Joanna Park (HPLC method), and Dr. For brainstorming, support, and therapeutic complaint sessions, I deeply thank Julie Swanson, Sabrina Powell, Kate Lindsay, Dr.
David Singleton, Michelle Sullivan, and Maiysha Jones. Finally, for their research guidance, I also thank my committee, Professors Fred Pfaender (my advisor), Mike Aitken, Marc Alperin, Russ Christman, and Steve Whalen. vi TABLE OF CONTENTS LIST OF TABLES .xii LIST OF FIGURES .xiv LIST OF ABBREVIATIONS. INTRODUCTION AND OBJECTIVES ……………………………………….1 Soil Chemical Structure .1 Soil Organic Matter (SOM) .1 Soil Organic Matter Components ……….2 Dual Mode Model: Glassy versus Amorphous Carbon …………………14 2.2 Soil Organic Matter Sorption to Mineral Phases .1 Humic Substance Sorption to Mineral Phases .2 Peptidoglycan Sorption to Mineral Phases .2 Soil Physical Structure ………….1 Dual Mode Sorption Model ………………………….1 PAH Dissolution into SOM ………………………………………….2 Filling SOM and Mineral Phase Holes with PAHs ….
SYNTHETIC CLAY AS A SURROGATE FOR MODELING PYRENE SORPTION TO NATURAL SOIL .3 Aqueous Phase PG and HA Analysis …………………………………………42 3.4 Particle Surface Area (PSA) Analysis …………………………………….5 Pyrene Application to Synthetic and Natural Soils ………………….6 Aqueous Phase Pyrene Analysis ………………………………………….8 Fluorescence Intensity Analysis …………………………………….1 Comparison of Physical and Chemical Attributes ……………….2 Particle Surface Area (PSA) Analysis …………………………………….3 Pyrene Sorption to Natural and Synthetic Soils ………………………………49 viii 3. IMPACT OF HUMIC ACID AND PEPTIDOGLYCAN ON THE TOTAL ORGANIC CARBON CONCENTRATION AND PARTICLE AGGREGATION OF SYNTHETIC SOIL ……………………….2 Aqueous Phase PG and HA Analysis …………………………………………57 4.3 Particle Surface Area (PSA) Analysis …………………………………….4 Fluorescent Labeling of Peptidoglycan ……………………………….7 Fluorescence Intensity Analysis ………………………………………….1 Humic Acid (HA) Sorption ……………………………………………….3 Humic Acid (HA) and Peptidoglycan (PG) Combined Sorption …………. INFLUENCE OF SOM COMPONENTS ON PYRENE FRESHLY SPIKED IN SYNTHETIC AND NATURAL SOILS …………………………….1 Natural and Synthetic Soils ………………………………………….2 Pyrene Application to Synthetic and Natural Soils ………………….3 Aqueous Phase Pyrene Analysis …………………………………….4 Fluorescent Labeling of Peptidoglycan ……………………………….7 Fluorescence Intensity Analysis ………………………………………………92 5.8 Fluorescence Histograms to Determine Pyrene-SOM Associations ….1 Background Interference and Pyrene Sorption Tests …………………………95 5.2 Pyrene Sorption to HA Synthetic Soils ……………………………….3 Pyrene Sorption to PG Synthetic Soils ……………………………….4 Pyrene Sorption to HA + PG Synthetic Soils ……………………………….5 Pyrene Sorption to Natural Soils …………………………………….6 Pyrene Preference and “Mapping” Contaminated Soils ……………………. FLUORESCENCE INTENSITY AS A TECHNIQUE TO STUDY PAH CONCENTRATIONS, FATE, AND TRANSPORT WITHING SOILS …………………………………………………………………….1 Natural and Synthetic Soils ……………………………………………….4 Fluorescence Intensity Analysis …………………………………….5 Estimating PAH Content by Fluorescence Intensity ……………….1 Fluorescence Intensity Calibration Curves to Determine Unknown PAH Contents ………………………………………………….2 Dual-Mode Progression of Pyrene Sorption with Aging ………………….
SUMMARY AND CONCLUSIONS …………………………………………….1 Summary of Results ……………………………………………………………. FUTURE RESEARCH AND IMPROVEMENTS …………………………………….161 xi LIST OF TABLES Table 3.1: Characteristics of Natural and Synthetic Soil Samples ……………………….2: Distribution Coefficients for Pyrene Sorbed to Synthetic Clay, Blank Clay, and Natural Soils ………………………………………….1: Distribution Coefficients for HA Sorption Experiments ………………….2: …68 Distribution Coefficients for PG Sorption Experiments …………………….3: Distribution Coefficients for HA + PG Sorption Experiments ……………….4: Distribution Coefficients for HA and PG Sorption Experiments ………….1: Pyrene Sorption on Glass Beads …………………………………………….2: Pyrene Sorption on Molecular Sieves ………………………………….3: Comparison of Pyrene Sorption in Soil Slurries and Columns ……………….4: Pyrene Sorption on Synthetic Clay via a Diesel Fuel Carrier ………….5: Distribution Coefficients for Pyrene Sorption on Blank and HA-Loaded Clays …………………………………………….6: Distribution Coefficients for Pyrene Sorption on Blank and PG-Loaded Clays ………………………………………………………….7: Distribution Coefficients for Pyrene Sorbed to HA+PG Synthetic Soils ………………………………………………………….8: Distribution Coefficients for Pyrene Sorbed to Natural Soils ………….9: Distribution Coefficients for Pyrene Sorbed to Multiple- and Single-Component Synthetic Soils ………………………………………….10: Distribution Coefficients for Pyrene Sorbed to Synthetic and Natural Soils ………………………………………………………………….1: Characteristics of Natural and Synthetic Soil Samples …………………….2: Relative Fluorescence Intensities (RFIs) for 16 Priority PAHs ……………….3: Comparison of Measured and Estimated Sorbed Pyrene Amounts …….4: Estimated and Extracted PAH Concentrations for Aged Contaminated Soils ………………………………………………………….141 xiii LIST OF FIGURES Figure 2.1: Fractionation of SOM and humic substances……….2: SEM images of crystallized HA …………………………………….3: Representative three-dimensional humic acid complex …………….4: FTIR spectra of S. subtilis PG samples ……………….5: Chemical structure of the glycan tetrapeptide in PG ………….6: Chemical structure of S.7: Schematic of glassy versus amorphous carbon .8: Theoretical model of an organic-mineral macromolecule ………………….9: Hypothetical structure of a nonviable organic coating on clay …….10: Hypothetical construct of PG sorption to clay …………….11: Three-dimensional models for montmorillonite clay and hematite ……….12: Diagrammatic representation of montmorillonite clay ……………….13: Cross-section of a particle showing different sorption processes …….14: Pseudostructure describing SOM binding to silica sheets ………………….15: Two driving forces of hydrophobic sorption ….16: Pyrene association with a nonviable organic coating ….17: Trapping of a xenobiotic pesticide by SOM ……….18: SOM as a dual-mode amalgam of rubbery and glassy phases ……….19: Conceptual model of geosorbent domains ………………………………….1: Brief schematic of loading HA and PG procedure ………………………….2: Representative image of particle size analysis by BioQuant ……………….3: Comparison of PSA data for natural soils, HA+PG synthetic clays, and blank clay ……………………………………………………….4: Freundlich isotherms comparing the sorption of pyrene on natural soils, blank and synthetic clays ………………………………………….5: Comparison of fluorescence intensities for pyrene sorbed to natural soils and synthetic clays …………………………………………. aureus PG sample labeled with a FITC probe via an alternative Gram staining method …………………………………….2: Schematic of how individual images are combined ………………….3: Freundlich isotherms for HA sorption to clay and hematite ……………………62 4.4: Comparison of PSAs for HA-loaded clays ……………………………….5: Comparison of PSAs for HA-loaded clays and clay : hematite mixtures ………64 4.6: HA clay fluorescence images and intensity measurements ………………….7: Freundlich isotherms for PG sorption to clay and hematite ………….8: Comparison of PSAs for PG-loaded clays ………………………………………69 4.9: PG clay fluorescence images and intensity measurements ……………….10: Freundlich isotherms for HA+PG sorption on clay ………….11: Comparison of PSAs for blank, HA-, PG-, and HA+PG-clays …………….12: HA+PG clay fluorescence images and intensity measurements …………….13: Sorption isotherms for PG and HA on clay and hematite ………….14: Hypothetical construction of HA and PG sorption to clay ………………….15: Comparison of PSAs for blank, HA-, and PG-loaded clays ………….16: Theoretical representation of hematite inserted into clay particles ………….17: Sorption isotherms for SOM-coated clays and a clay : hematite mixture .18: Comparison of fluorescence intensities for SOM-coated clays …………….19: Theoretical desorption-resorption schematic and graph of HA+PG chronological sorption order …………………………………….1: Schematic of how histograms are used to determine pyrene association percentages ……………………………………………….2: Fluorescence images for pyrene attached to glass beads …………………….3: Fluorescence images for pyrene sorbed to molecular sieves …………….4: Fluorescence images for pyrene sorbed via soil columns and slurries .5: Fluorescence images for pyrene sorbed via a diesel fuel carrier ………….6: Polarized light images of CMN and synthetic clay ……………………….7: Freundlich isotherms for pyrene sorption to HA clays …………………….8: Fluorescence images and intensity measurements for pyrene sorbed to HA clays ………………………………………………….9: Freundlich isotherms for pyrene sorption to PG clays ……………….10: Fluorescence images and intensity measurements for pyrene sorbed to PG clays ………………………………………………….11: Freundlich isotherms for pyrene sorption to HA+PG synthetic soils …….12: Fluorescence images and intensity measurements for pyrene sorbed to HA+PG clays ………….13: Freundlich isotherms for pyrene sorption to natural soils ……………….14: Fluorescence images and intensity measurements for pyrene sorbed to natural soils …………………………………………….15: Pseudo-map for pyrene sorbed to HA+PG clay ……………………………….16: Pseudo-map for pyrene sorbed to PMN ………………………………….17: Example of overlapped histograms used to determine pyrene association percentages ……………………………………………….18: Graph of pyrene preference for specific SOM components ………….19: Use of one-dimensional strips to show pyrene preference .20: Freundlich isotherms depicting pyrene sorption on multiple- and single-component synthetic soils ……………………………………….21: Theoretical schematic of HA and PG integration on clay as it affects pyrene sorption ………………………………………………….22: Freundlich isotherms for pyrene sorption to natural and multiple-component synthetic soils ……………………………………….23: Pyrene fluorescence intensities for natural and synthetic soils …………….24: Schematic of a soil “pseudo-map” ……………………………………….1: Calibration curve of sorbed pyrene concentration versus fluorescence intensity ……………………………………………………….2: Fluorescence images of PMN freshly spiked with pyrene ……………….3: Fluorescence images of PMN incubated for six months with pyrene .4: Fluorescence images of aged CMN soil …………………………………….5: Comparison of fluorescence intensities for contaminated MN soil samples aged for various time periods ……………………………….6: Hypothetical schematic of the dual-mode model …………………….