This study proposes to examine and characterize humate-induced remediation processes occurring in surface soil contaminated with crude oil, hereafter referred to as petroleum. Humates are high-molecular weight, natural salts of humic and fulvic acids (HA and FA), originating from the diagenesis of terrestrial, marine, and lacustrine organic matter. Humates have a propensity for sorbing hydrophobic compounds, as well as improving soil structure, increasing water retention, and providing nutrients, such that bio- and phytoremediation may become viable secondary remediation strategies. Despite this, very little is known regarding the mechanisms of humate-induced remediation of petroleum-contaminated surface soils.
The proposed research will determine: 1) if humate-induced remediation is a viable and feasible remediation technique, and 2) if it is, determine the primary remediation mechanism, i.e., stimulation of biodegradation, sorption, or a combination of both. These objectives will be accomplished by: 1) identifying the humate, or humates, with the greatest sorption capacity, and 2) identifying and characterizing the predominant mechanisms(s) of the humate-induced remediation process(es) using microcosms containing either pristine or contaminated surface soil collected from a petroleum drilling field near Oklahoma City, OK.
Microcosm experiments will be used to monitor the process and efficacy of humate-induced remediation of soil-petroleum mixtures prepared in the laboratory, as well as with contaminated and pristine soil samples collected from the field. Interactions and mechanisms responsible for humate-induced petroleum remediation will be examined with a variety of analytical instrumentation: Rock Eval pyrolysis, gas chromatography/mass spectrometry (GCMS), pyrolysis-GCMS, thermochemolysis-GCMS, and 2 H and 13C nuclear magnetic resonance (NMR).
These research results will build a foundation for developing an environment-friendly, technically-simple, and cost-effective remediation strategy. Since humates are commercially available, relatively inexpensive, and require minimal application technology, humate-induced remediation may prove to be a highly economical remediation strategy that is easy to implement at remote sites, or at sites where it is unfeasible to use advanced remediation technology.