Denise Marie Brown - Doctoral Dissertation Final Defense
| July 17, 2006 | |
| Denise Brown presents her doctoral dissertation final defense on July 7, 2006 at 2:00pm in 2005 Michael Hooker Research Center. Abstract follows.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 (such as humic acid (HA) and peptidoglycan (PG)) and black carbon (BC), and the complex, inter-dependent relationship between soil chemical and physical attributes profoundly affect polyaromatic hydrocarbon (PAH) fate, transport, toxicity, and availability when assessing acceptable end points for in situ remediation practices. Compared to HA, a larger concentration of PG sorbed to hematite and montmorillonite clay; thus, promoting greater particle aggregation and resulting in more pyrene sorption. The greater the concentration and number of constituents introduced into the synthetic matrix, culminating in a HA+PG mixture loaded onto a hematite:clay ratio, the greater the sorbed pyrene concentration and similarity to spiked natural soils, both in chemical and physical attributes. The final result was a compiled fluorescence map visually detailing pyrene location and percentage sorbed in relation to PG, HA, and the mineral phases for natural and synthetic soils, where the biological component had a significant influence over pyrene compared to that by HA. To examine the particle-scale kinetics of pyrene preference for BC, static and flow cell experiments were conducted with the synthetic and natural soils. Over 48 hours of static equilibration, pyrene fluorescence decreased independent of contamination age and type, likely due to desorption from the soils followed by sorption and quenching within BC. However, for the flow cells contamination age was a major factor, causing an actual increase in fluorescence intensity for the aged soils. In summary, the type and concentration of SOM constituents, specifically BC and biological material, sorbed to a mineral phase significantly impacts soil physical and chemical characteristics, and therefore, should be considered when determining pyrene fate, transport, and availability within contaminated soil systems. When these observations are combined with fluorescence microscopy, consultants could potentially determine the most effective remediation technology to target specific locations, such as pore spaces, or strong sorptive entities, such as BC, and achieve acceptable end-points. Committee Members: For further information please contact Rebecca Riggsbee Lloyd by email at Rebecca_Lloyd@unc.edu |
