Doctor of Philosophy (PhD)
This work was done in order to deepen the understanding of interactions occurring during sorption of anthropogenic organic compounds and dissolved organic matter (DOM) onto soil. As well as the transformation DOM undergoes during the sorption process and the overall transformation OM undergoes in the environment. This was achieved through the use of a “bottom-up” synthetic investigation, “top-down” natural system study, and a combination of these approaches.
The “bottom-up” approach, discussed in Chapter 2, involved the synthesis of a modular multi-tiered engineered soil surrogate (ESS) designed to mimic OM and general trends identified in the literature that impacts sorption behavior. The sorption of Norflurazon (NOR) to the ESSs matched literature trends of; i) positive trend of sorption affinity to organic content; ii) negative trend of sorption affinity to oxygen content; and iii) positive relationship of sorption affinity to decrease in oxygen content through hydrolysis. Additionally, the carbon content-normalized sorption coefficient of ESS matched that found for NOR sorption to natural systems with high OM content.
The mixing approach, discussed in Chapter 3, combined the ESS systems with natural DOM and investigated the interactions that controlled the sorption behavior as well as the preferential sorption of DOM components with ESS. The sorption of DOM matched known interactions presented in literature with; i) strong irreversible sorption through electrostatic interaction and ii) negative relationship of organic content to sorption affinity of DOM. Additionally, the preferential sorption of humic-like terrestrial sourced DOM over lower conjugated DOM was identified using measured spectroscopic changes of the DOM before and after sorption.
In the “top-down” approach, discussed in Chapters 4 and 5, the biogeochemical transformation of OM in two natural ecosystems was studied through the use of spectroscopically determined indicators, nutrients measurements, temperature, salinity, satellite images, and geophysical measured properties. In Chapter 4, the carbon stored in a coastal marsh was determined to be lost to the environment upon tidal wave erosion. In Chapter 5, the sources and biogeochemical transformations of the DOM introduced into a shallow estuary during early season flooding was identified.
Haywood, Benjamin J., "Molecular Level Interactions and Transformations of Natural Organic Matter Within the Environment" (2018). LSU Doctoral Dissertations. 4724.
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